[runtime_image] Share one scale_boundary() between draw() and the JPEG RGB565 tables; test uneven scales

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

esphome/components/ld2412/ld2412.cpp

@@ -186,19 +186,23 @@ static constexpr uint8_t CMD_DURATION_VALUE = 0x02;
 // Bitmasks for target states
 static constexpr uint8_t MOVE_BITMASK = 0x01;
 static constexpr uint8_t STILL_BITMASK = 0x02;
-using ld24xx::CMD_FRAME_FOOTER;
-using ld24xx::CMD_FRAME_HEADER;
-using ld24xx::HEADER_FOOTER_SIZE;
-using ld24xx::validate_header_footer;
-// Smallest frames whose values can all be read: the last value, data footer and check, then the frame footer
-static constexpr uint8_t PERIODIC_FRAME_MIN = STILL_ENERGY + 3 + HEADER_FOOTER_SIZE;
-static constexpr uint8_t ENGINEERING_FRAME_MIN = LIGHT_SENSOR + 3 + HEADER_FOOTER_SIZE;
+// Header & Footer size
+static constexpr uint8_t HEADER_FOOTER_SIZE = 4;
+// Command Header & Footer
+static constexpr uint8_t CMD_FRAME_HEADER[HEADER_FOOTER_SIZE] = {0xFD, 0xFC, 0xFB, 0xFA};
+static constexpr uint8_t CMD_FRAME_FOOTER[HEADER_FOOTER_SIZE] = {0x04, 0x03, 0x02, 0x01};
 // Data Header & Footer
 static constexpr uint8_t DATA_FRAME_HEADER[HEADER_FOOTER_SIZE] = {0xF4, 0xF3, 0xF2, 0xF1};
 static constexpr uint8_t DATA_FRAME_FOOTER[HEADER_FOOTER_SIZE] = {0xF8, 0xF7, 0xF6, 0xF5};
 // MAC address the module uses when Bluetooth is disabled
 static constexpr uint8_t NO_MAC[] = {0x08, 0x05, 0x04, 0x03, 0x02, 0x01};
 static constexpr uint8_t GATE_SENS_ACK_SIZE = ACK_PAYLOAD + TOTAL_GATES + HEADER_FOOTER_SIZE;
+// The length field counts the command word, the status word and the gates
+static constexpr uint16_t GATE_SENS_ACK_LENGTH = GATE_SENS_ACK_SIZE - COMMAND - HEADER_FOOTER_SIZE;
+
+static inline bool validate_header_footer(const uint8_t *header_footer, const uint8_t *buffer) {
+  return std::memcmp(header_footer, buffer, HEADER_FOOTER_SIZE) == 0;
+}
 
 void LD2412Component::dump_config() {
   char mac_s[MAC_ADDRESS_PRETTY_BUFFER_SIZE];
@@ -367,9 +371,6 @@ void LD2412Component::handle_periodic_data_() {
     0x02: Normal mode
   */
   bool engineering_mode = this->buffer_data_[DATA_TYPES] == 0x01;
-  if (this->buffer_pos_ < PERIODIC_FRAME_MIN) {
-    return;  // too short to hold the values
-  }
 #ifdef USE_SWITCH
   if (this->engineering_mode_switch_ != nullptr) {
     this->engineering_mode_switch_->publish_state(engineering_mode);
@@ -420,7 +421,8 @@ void LD2412Component::handle_periodic_data_() {
     this->detection_distance_sensor_.publish_state_if_not_dup(new_detect_distance);
   }
   if (engineering_mode) {
-    if (this->buffer_pos_ < ENGINEERING_FRAME_MIN) {
+    // Engineering mode needs at least LIGHT_SENSOR + 1 bytes
+    if (this->buffer_pos_ < LIGHT_SENSOR + 1) {
       ESP_LOGW(TAG, "Engineering mode packet too short: %u", this->buffer_pos_);
     } else {
       /*
@@ -475,15 +477,24 @@ static constexpr uint32_t GATE_QUERY_TIMEOUT_ID = 0;
 static constexpr uint32_t GATE_QUERY_TIMEOUT_MS = 2000;
 #endif
 
-void LD2412Component::handle_ack_data_() {
+bool LD2412Component::handle_ack_data_() {
   ESP_LOGV(TAG, "Handling ACK DATA for COMMAND %02X", this->buffer_data_[COMMAND]);
+  if (this->buffer_pos_ < 10) {
+    ESP_LOGW(TAG, "Invalid length");
+    return true;
+  }
+  if (!ld2412::validate_header_footer(CMD_FRAME_HEADER, this->buffer_data_)) {
+    char hex_buf[format_hex_pretty_size(HEADER_FOOTER_SIZE)];
+    ESP_LOGW(TAG, "Invalid header: %s", format_hex_pretty_to(hex_buf, this->buffer_data_, HEADER_FOOTER_SIZE));
+    return true;
+  }
   if (this->buffer_data_[COMMAND_STATUS] != 0x01) {
     ESP_LOGW(TAG, "Invalid status");
-    return;
+    return true;
   }
   if (this->buffer_data_[8] || this->buffer_data_[9]) {
     ESP_LOGW(TAG, "Invalid command: %02X, %02X", this->buffer_data_[8], this->buffer_data_[9]);
-    return;
+    return true;
   }
 
   switch (this->buffer_data_[COMMAND]) {
@@ -506,8 +517,8 @@ void LD2412Component::handle_ack_data_() {
       break;
 
     case CMD_QUERY_VERSION: {
-      if (this->buffer_pos_ < 12 + sizeof(this->version_) + HEADER_FOOTER_SIZE) {
-        break;  // too short to hold a version
+      if (this->buffer_pos_ < 12 + sizeof(this->version_)) {
+        return false;
       }
       std::memcpy(this->version_, &this->buffer_data_[12], sizeof(this->version_));
       char version_s[20];
@@ -521,9 +532,6 @@ void LD2412Component::handle_ack_data_() {
       break;
     }
     case CMD_QUERY_DISTANCE_RESOLUTION: {
-      if (this->buffer_pos_ < 11 + HEADER_FOOTER_SIZE) {
-        break;  // too short to hold the resolution
-      }
       const auto *distance_resolution = find_str(DISTANCE_RESOLUTIONS_BY_UINT, this->buffer_data_[10]);
       ESP_LOGV(TAG, "Distance resolution: %s", distance_resolution);
 #ifdef USE_SELECT
@@ -535,9 +543,6 @@ void LD2412Component::handle_ack_data_() {
     }
 
     case CMD_QUERY_LIGHT_CONTROL: {
-      if (this->buffer_pos_ < 12 + HEADER_FOOTER_SIZE) {
-        break;  // too short to hold the light settings
-      }
       this->light_function_ = this->buffer_data_[10];
       this->light_threshold_ = this->buffer_data_[11];
       const auto *light_function_str = find_str(LIGHT_FUNCTIONS_BY_UINT, this->light_function_);
@@ -557,7 +562,7 @@ void LD2412Component::handle_ack_data_() {
 
     case CMD_QUERY_MAC_ADDRESS: {
       if (this->buffer_pos_ < 20) {
-        break;  // too short to hold a MAC address
+        return false;
       }
 
       this->bluetooth_on_ = std::memcmp(&this->buffer_data_[10], NO_MAC, sizeof(NO_MAC)) != 0;
@@ -586,9 +591,6 @@ void LD2412Component::handle_ack_data_() {
       break;
 
     case CMD_QUERY_DYNAMIC_BACKGROUND_CORRECTION: {
-      if (this->buffer_pos_ < 11 + HEADER_FOOTER_SIZE) {
-        break;  // too short to hold the state
-      }
       ESP_LOGV(TAG, "Handled query dynamic background correction");
       bool dynamic_background_correction_active = (this->buffer_data_[10] != 0x00);
 #ifdef USE_BINARY_SENSOR
@@ -611,10 +613,14 @@ void LD2412Component::handle_ack_data_() {
     case CMD_QUERY_MOTION_GATE_SENS:
     case CMD_QUERY_STATIC_GATE_SENS: {
 #ifdef USE_NUMBER
-      if (this->buffer_pos_ != GATE_SENS_ACK_SIZE) {
-        // A length this driver does not know
+      const uint16_t declared = encode_uint16(this->buffer_data_[FRAME_LENGTH + 1], this->buffer_data_[FRAME_LENGTH]);
+      if (declared != GATE_SENS_ACK_LENGTH || this->buffer_pos_ > GATE_SENS_ACK_SIZE) {
+        // A truncated answer merged with the next frame, or a length this driver does not know
         ESP_LOGW(TAG, "Dropping gate threshold answer of %u bytes", this->buffer_pos_);
-        return;
+        return true;
+      }
+      if (this->buffer_pos_ < GATE_SENS_ACK_SIZE) {
+        return false;  // the footer pattern appeared inside the payload, keep reading
       }
       const bool motion = this->buffer_data_[COMMAND] == CMD_QUERY_MOTION_GATE_SENS;
       GateThresholds &group = this->gate_thresholds_(motion);
@@ -640,8 +646,8 @@ void LD2412Component::handle_ack_data_() {
     case CMD_QUERY_BASIC_CONF:  // Query parameters response
     {
 #ifdef USE_NUMBER
-      if (this->buffer_pos_ < 15 + HEADER_FOOTER_SIZE) {
-        break;  // too short to hold the configuration
+      if (this->buffer_pos_ < 15) {
+        return false;
       }
       /*
         Moving distance range: 9th byte
@@ -671,36 +677,42 @@ void LD2412Component::handle_ack_data_() {
     default:
       break;
   }
+
+  return true;
 }
 
 void LD2412Component::readline_(int readch) {
   if (readch < 0) {
     return;  // No data available
   }
-  // Periodic and command frames both carry their count after the header
-  ld24xx::feed_frame_byte(
-      this->buffer_data_, this->buffer_pos_, readch, DATA_FRAME_HEADER, ld24xx::cmd_frame_length,
-      [this](uint8_t frame_len) { return this->handle_frame_(frame_len); }, []() { ESP_LOGW(TAG, "Invalid length"); });
-}
-
-// Dispatches the frame of frame_len bytes at the start of the buffer when its footer is in place
-bool LD2412Component::handle_frame_(uint8_t frame_len) {
-  this->buffer_pos_ = frame_len;  // the handlers take the frame length from here
-  const uint8_t *tail = &this->buffer_data_[frame_len - HEADER_FOOTER_SIZE];
-  if (this->buffer_data_[0] == DATA_FRAME_HEADER[0]) {
-    if (!ld2412::validate_header_footer(DATA_FRAME_FOOTER, tail)) {
-      return false;
-    }
+  if (this->buffer_pos_ < HEADER_FOOTER_SIZE && readch != DATA_FRAME_HEADER[this->buffer_pos_] &&
+      readch != CMD_FRAME_HEADER[this->buffer_pos_]) {
+    this->buffer_pos_ = 0;
+    return;
+  }
+  if (this->buffer_pos_ < MAX_LINE_LENGTH - 1) {
+    this->buffer_data_[this->buffer_pos_++] = readch;
+    this->buffer_data_[this->buffer_pos_] = 0;
+  } else {
+    // We should never get here, but just in case...
+    ESP_LOGW(TAG, "Max command length exceeded; ignoring");
+    this->buffer_pos_ = 0;
+  }
+  if (this->buffer_pos_ < 4) {
+    return;  // Not enough data to process yet
+  }
+  if (ld2412::validate_header_footer(DATA_FRAME_FOOTER, &this->buffer_data_[this->buffer_pos_ - 4])) {
     ESP_LOGV_HEX(TAG, this->buffer_data_, this->buffer_pos_, MAX_LINE_LENGTH, "Handling Periodic Data: %s");
     this->handle_periodic_data_();
-    return true;
+    this->buffer_pos_ = 0;  // Reset position index for next message
+  } else if (ld2412::validate_header_footer(CMD_FRAME_FOOTER, &this->buffer_data_[this->buffer_pos_ - 4])) {
+    ESP_LOGV_HEX(TAG, this->buffer_data_, this->buffer_pos_, MAX_LINE_LENGTH, "Handling Ack Data: %s");
+    if (this->handle_ack_data_()) {
+      this->buffer_pos_ = 0;  // Reset position index for next message
+    } else {
+      ESP_LOGV(TAG, "Ack Data incomplete");
+    }
   }
-  if (!ld2412::validate_header_footer(CMD_FRAME_FOOTER, tail)) {
-    return false;
-  }
-  ESP_LOGV_HEX(TAG, this->buffer_data_, this->buffer_pos_, MAX_LINE_LENGTH, "Handling Ack Data: %s");
-  this->handle_ack_data_();
-  return true;
 }
 
 void LD2412Component::set_config_mode_(bool enable) {

esphome/components/ld2412/ld2412.h

@@ -111,8 +111,7 @@ class LD2412Component final : public Component, public uart::UARTDevice {
   void send_command_(uint8_t command_str, const uint8_t *command_value, uint8_t command_value_len);
   void set_config_mode_(bool enable);
   void handle_periodic_data_();
-  void handle_ack_data_();
-  bool handle_frame_(uint8_t frame_len);
+  bool handle_ack_data_();
   void readline_(int readch);
   void query_parameters_();
   void get_version_();

esphome/components/ld24xx/ld24xx.h

@@ -3,8 +3,6 @@
 #include "esphome/core/defines.h"
 #include "esphome/core/helpers.h"
 
-#include <algorithm>
-#include <cstring>
 #include <memory>
 #include <span>
 
@@ -55,74 +53,6 @@ inline void format_version_str(const uint8_t *version, std::span<char, 20> buffe
            version[2]);
 }
 
-// Commands and their answers share this header, a little-endian byte count and this footer
-static constexpr uint8_t HEADER_FOOTER_SIZE = 4;
-static constexpr uint8_t CMD_FRAME_HEADER[HEADER_FOOTER_SIZE] = {0xFD, 0xFC, 0xFB, 0xFA};
-static constexpr uint8_t CMD_FRAME_FOOTER[HEADER_FOOTER_SIZE] = {0x04, 0x03, 0x02, 0x01};
-
-inline bool validate_header_footer(const uint8_t *header_footer, const uint8_t *buffer) {
-  return std::memcmp(header_footer, buffer, HEADER_FOOTER_SIZE) == 0;
-}
-
-// Whole command frame length, or 0 until the count arrives; 32 bit so 0xFFFF cannot wrap to 0
-inline uint32_t cmd_frame_length(const uint8_t *buffer, uint8_t count) {
-  if (count < HEADER_FOOTER_SIZE + 2) {
-    return 0;
-  }
-  return HEADER_FOOTER_SIZE + 2 + encode_value_le<uint16_t>(&buffer[HEADER_FOOTER_SIZE]) + HEADER_FOOTER_SIZE;
-}
-
-// Drops the first `from` bytes and anything after them that does not begin a header; returns the bytes kept
-inline uint8_t drop_to_next_header(uint8_t *buffer, uint8_t count, uint8_t from, const uint8_t *data_header) {
-  for (; from < count; from++) {
-    const size_t n = std::min<size_t>(HEADER_FOOTER_SIZE, count - from);
-    if (std::memcmp(&buffer[from], CMD_FRAME_HEADER, n) == 0 || std::memcmp(&buffer[from], data_header, n) == 0) {
-      std::memmove(buffer, &buffer[from], count - from);
-      return count - from;
-    }
-  }
-  return 0;
-}
-
-// Feeds one byte into a frame buffer. A frame opens with the command header or `data_header` and ends at
-// `frame_length(buffer, count)` bytes (0 while unknown); `handle_frame(len)` returns false for a footer out
-// of place. A dropped or oversized frame calls `on_drop()`. The handler may overwrite `pos`; the splitter
-// works from the count it saved.
-template<size_t N, typename LengthFn, typename HandleFn, typename DropFn>
-void feed_frame_byte(uint8_t (&buffer)[N], uint8_t &pos, uint8_t byte, const uint8_t *data_header,
-                     LengthFn frame_length, HandleFn handle_frame, DropFn on_drop) {
-  // The first byte picks the header; bytes that do not continue it are dropped
-  if (pos > 0 && pos < HEADER_FOOTER_SIZE) {
-    const uint8_t *header = buffer[0] == data_header[0] ? data_header : CMD_FRAME_HEADER;
-    if (byte != header[pos]) {
-      pos = 0;
-    }
-  }
-  if (pos == 0 && byte != data_header[0] && byte != CMD_FRAME_HEADER[0]) {
-    return;
-  }
-  buffer[pos++] = byte;
-  // Drain every whole frame left in the buffer
-  while (true) {
-    const uint32_t frame_len = frame_length(buffer, pos);
-    if (frame_len == 0 || (frame_len <= N && pos < frame_len)) {
-      return;
-    }
-    const uint8_t total = pos;
-    // Keep only what begins a header: after the frame, or after its first byte when it is dropped
-    uint8_t from = 1;
-    if (frame_len <= N && handle_frame(static_cast<uint8_t>(frame_len))) {
-      from = frame_len;
-    } else {
-      on_drop();
-    }
-    pos = drop_to_next_header(buffer, total, from, data_header);
-    if (pos == 0) {
-      return;
-    }
-  }
-}
-
 #ifdef USE_SENSOR
 template<typename T> using SensorWithDedup = sensor::SensorWithDedup<T>;
 #endif

esphome/components/online_image/download_buffer.cpp

@@ -1,5 +1,6 @@
 #include "download_buffer.h"
 #include "esphome/core/log.h"
+#include <algorithm>
 #include <cstring>
 
 namespace esphome::online_image {
@@ -34,6 +35,46 @@ size_t DownloadBuffer::read(size_t len) {
   return this->unread_;
 }
 
+void DownloadSource::compact() {
+  if (this->keep_read_ || this->pos_ == this->start_)
+    return;
+  this->buffer_.read(this->pos_ - this->start_);
+  this->start_ = this->pos_;
+}
+
+int32_t DownloadSource::read(uint8_t *buf, uint32_t len) {
+  const size_t offset = this->pos_ - this->start_;
+  const size_t n = std::min<size_t>(len, this->buffer_.unread() - offset);
+  memcpy(buf, this->buffer_.data(offset), n);
+  this->pos_ += n;
+  return static_cast<int32_t>(n);
+}
+
+bool DownloadSource::seek(uint32_t position) {
+  // Only what is still in the buffer can be read again; a decoder never skips ahead of the download
+  if (position < this->start_ || position > this->start_ + this->buffer_.unread())
+    return false;
+  this->pos_ = position;
+  return true;
+}
+
+bool DownloadBuffer::grow(size_t size) {
+  if (this->size_ >= size)
+    return true;
+  RAMAllocator<uint8_t> allocator;
+  uint8_t *buffer = allocator.allocate(size);
+  if (buffer == nullptr) {
+    ESP_LOGE(TAG, "allocation of %zu bytes failed. Biggest block in heap: %zu Bytes", size,
+             allocator.get_max_free_block_size());
+    return false;
+  }
+  memcpy(buffer, this->buffer_, this->unread_);
+  allocator.deallocate(this->buffer_, this->size_);
+  this->buffer_ = buffer;
+  this->size_ = size;
+  return true;
+}
+
 size_t DownloadBuffer::resize(size_t size) {
   if (this->size_ >= size) {
     // Avoid useless reallocations; if the buffer is big enough, don't reallocate.

esphome/components/online_image/download_buffer.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "esphome/components/runtime_image/image_decoder.h"
 #include "esphome/core/helpers.h"
 #include <cstddef>
 #include <cstdint>
@@ -35,6 +36,8 @@ class DownloadBuffer {
 
   void reset() { this->unread_ = 0; }
   size_t resize(size_t size);
+  /// Make the buffer at least size bytes, keeping the unread data. Returns false if the allocation failed.
+  bool grow(size_t size);
 
  protected:
   uint8_t *buffer_;
@@ -43,4 +46,35 @@ class DownloadBuffer {
   size_t unread_;
 };
 
+/**
+ * @brief Lets a decoder read a download as it arrives, from the download buffer.
+ *
+ * The decoder reads at its own position in the buffer. Bytes it has read stay there until compact() drops
+ * them, and compact() keeps everything while set_keep_read(true) is in effect, so the decoder can seek back
+ * while it reads the headers.
+ */
+class DownloadSource : public runtime_image::DecodeSource {
+ public:
+  explicit DownloadSource(DownloadBuffer &buffer) : buffer_(buffer) {}
+
+  /// Start again at the beginning of a new download, keeping what is read
+  void reset() {
+    this->start_ = 0;
+    this->pos_ = 0;
+    this->keep_read_ = true;
+  }
+  void set_keep_read(bool keep) { this->keep_read_ = keep; }
+  /// Drop the bytes the decoder has read, to make room for more of the download
+  void compact();
+
+  int32_t read(uint8_t *buf, uint32_t len) override;
+  bool seek(uint32_t position) override;
+
+ protected:
+  DownloadBuffer &buffer_;
+  size_t start_{0};  // Position in the download of the first byte in the buffer
+  size_t pos_{0};    // Position in the download the decoder reads next
+  bool keep_read_{true};
+};
+
 }  // namespace esphome::online_image

esphome/components/online_image/image.py

@@ -22,6 +22,8 @@ DEPENDENCIES = ["http_request"]
 CODEOWNERS = ["@guillempages", "@clydebarrow"]
 
 CONF_ON_DOWNLOAD_FINISHED = "on_download_finished"
+CONF_ON_DOWNLOAD_STARTED = "on_download_started"
+CONF_ON_DOWNLOAD_PROGRESS = "on_download_progress"
 CONF_UPDATE = "update"
 
 online_image_ns = cg.esphome_ns.namespace("online_image")
@@ -43,7 +45,9 @@ ONLINE_IMAGE_SCHEMA = (
             cv.Optional(CONF_REQUEST_HEADERS): cv.All(
                 cv.Schema({cv.string: cv.templatable(cv.string)})
             ),
+            cv.Optional(CONF_ON_DOWNLOAD_STARTED): automation.validate_automation({}),
             cv.Optional(CONF_ON_DOWNLOAD_FINISHED): automation.validate_automation({}),
+            cv.Optional(CONF_ON_DOWNLOAD_PROGRESS): automation.validate_automation({}),
             cv.Optional(CONF_ON_ERROR): automation.validate_automation({}),
         }
     )
@@ -96,9 +100,17 @@ automation.register_apply_action(
 
 
 _CALLBACK_AUTOMATIONS = (
+    automation.CallbackAutomation(
+        CONF_ON_DOWNLOAD_STARTED, "add_on_download_started_callback"
+    ),
     automation.CallbackAutomation(
         CONF_ON_DOWNLOAD_FINISHED, "add_on_finished_callback", [(bool, "cached")]
     ),
+    automation.CallbackAutomation(
+        CONF_ON_DOWNLOAD_PROGRESS,
+        "add_on_progress_callback",
+        [(float, "progress"), (cg.size_t, "bytes_read")],
+    ),
     automation.CallbackAutomation(CONF_ON_ERROR, "add_on_error_callback"),
 )
 

esphome/components/online_image/online_image.cpp

@@ -4,6 +4,7 @@
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 #include <algorithm>
+#include <cmath>
 #include <cstdio>
 
 ESPHOME_LOG_TAG(TAG, "online_image");
@@ -15,6 +16,11 @@ static const char *const IF_MODIFIED_SINCE_HEADER_NAME = "if-modified-since";
 
 namespace esphome::online_image {
 
+// Time one loop pass may spend reading, and decoding a JPEG as it downloads
+static constexpr uint32_t PASS_BUDGET_MS = 20;
+// Shortest time between two on_download_progress calls
+static constexpr uint32_t PROGRESS_INTERVAL_MS = 100;
+
 OnlineImage::OnlineImage(const std::string &url, int width, int height, runtime_image::ImageFormat format,
                          image::ImageType type, image::Transparency transparency, image::Image *placeholder,
                          uint32_t buffer_size, bool is_big_endian)
@@ -140,8 +146,12 @@ void OnlineImage::update() {
     return;
   }
 
-  // JPEG requires the complete image in the download buffer before decoding
-  if (format == runtime_image::JPEG && total_size > this->download_buffer_.size() &&
+  // A JPEG of known size is decoded as it arrives, so the download buffer only has to hold its headers.
+  // Otherwise the decoder needs the complete image in the buffer.
+  this->streaming_ = total_size > 0 && total_size <= INT32_MAX && this->decoder_supports_source();
+  this->stream_started_ = false;
+  this->source_.reset();
+  if (!this->streaming_ && format == runtime_image::JPEG && total_size > this->download_buffer_.size() &&
       this->download_buffer_.resize(total_size) == 0) {
     // resize() logged the failed allocation; the next update() allocates the configured buffer again
     this->end_connection_();
@@ -152,6 +162,8 @@ void OnlineImage::update() {
   ESP_LOGI(TAG, "Downloading image (Size: %zu)", total_size);
   this->start_time_ = millis();
   this->last_data_time_ = this->start_time_;
+  this->download_started_callback_.call();
+  this->report_progress_(true);
   this->enable_loop();
 }
 
@@ -169,6 +181,11 @@ void OnlineImage::loop() {
     return;
   }
 
+  if (this->streaming_) {
+    this->loop_stream_();
+    return;
+  }
+
   // Check if download is complete — use decoder's format-specific completion check
   // to handle both known content-length and chunked transfer encoding
   if (this->is_decode_finished() || (this->downloader_->content_length > 0 &&
@@ -179,15 +196,22 @@ void OnlineImage::loop() {
   }
 
   // Download and decode more data
-  size_t available = this->download_buffer_.free_capacity();
-  if (available > 0) {
-    // Download in chunks to avoid blocking
-    available = std::min(available, this->download_buffer_initial_size_);
-    auto len = this->downloader_->read(this->download_buffer_.append(), available);
-
-    if (len > 0) {
-      this->last_data_time_ = App.get_loop_component_start_time();
+  if (this->download_buffer_.free_capacity() > 0) {
+    const uint32_t now = App.get_loop_component_start_time();
+    size_t received = 0;
+    int len;
+    do {
+      len = this->downloader_->read(this->download_buffer_.append(),
+                                    std::min(this->download_buffer_.free_capacity(), READ_CHUNK));
+      if (len <= 0)
+        break;
       this->download_buffer_.write(len);
+      received += len;
+    } while (this->download_buffer_.free_capacity() != 0 && millis() - now < PASS_BUDGET_MS);
+
+    if (received > 0) {
+      this->last_data_time_ = now;
+      this->report_progress_(false);
 
       // Feed data to decoder
       auto consumed = this->feed_data(this->download_buffer_.data(), this->download_buffer_.unread());
@@ -255,6 +279,114 @@ void OnlineImage::loop() {
   }
 }
 
+void OnlineImage::loop_stream_() {
+  const uint32_t now = App.get_loop_component_start_time();
+  const size_t total = this->downloader_->content_length;
+  if (this->stream_started_)
+    this->source_.compact();
+
+  if (this->downloader_->get_bytes_read() < total) {
+    if (this->download_buffer_.free_capacity() == 0) {
+      // compact() already ran, so a full buffer means the decoder read nothing in the last pass
+      if (now - this->last_data_time_ >= this->parent_->get_timeout()) {
+        ESP_LOGE(TAG, "Image does not fit in the %zu byte download buffer; increase buffer_size",
+                 this->download_buffer_.size());
+        this->fail_download_();
+        return;
+      }
+    } else {
+      int len;
+      do {
+        len = this->downloader_->read(this->download_buffer_.append(),
+                                      std::min(this->download_buffer_.free_capacity(), READ_CHUNK));
+        if (len <= 0)
+          break;
+        this->last_data_time_ = now;
+        this->download_buffer_.write(len);
+        this->report_progress_(false);
+      } while (this->downloader_->get_bytes_read() < total && this->download_buffer_.free_capacity() != 0 &&
+               millis() - now < PASS_BUDGET_MS);
+      if (len < 0) {
+        ESP_LOGE(TAG, "Error downloading image: %d", len);
+        this->fail_download_();
+        return;
+      } else if (now - this->last_data_time_ >= this->parent_->get_timeout()) {
+        ESP_LOGE(TAG, "No data received for %" PRIu32 " ms", this->parent_->get_timeout());
+        this->fail_download_();
+        return;
+      }
+    }
+  }
+  const bool arrived = this->downloader_->get_bytes_read() >= total;
+
+  if (!this->stream_started_) {
+    // The decoder reads the headers when it opens the image, so wait until they are in the buffer
+    if (!arrived && this->download_buffer_.free_capacity() != 0)
+      return;
+    const int err = this->begin_source(&this->source_);
+    if (err != 0) {
+      // Headers cut short by a full buffer fail to parse, or make the decoder seek past the buffer. Such an image
+      // still decodes once it is all in memory, as it did before JPEG images were decoded as they download.
+      if (!arrived && (err == runtime_image::DECODE_ERROR_INVALID_TYPE || err == runtime_image::DECODE_ERROR_READ)) {
+        ESP_LOGW(TAG,
+                 "The image headers do not fit the %zu byte download buffer, so the whole image is downloaded "
+                 "before it is decoded; increase buffer_size to decode it as it downloads",
+                 this->download_buffer_.size());
+        // grow() logs a failed allocation
+        if (this->download_buffer_.grow(total)) {
+          this->streaming_ = false;
+        } else {
+          this->fail_download_();
+        }
+        return;
+      }
+      ESP_LOGE(TAG, "Error decoding image: %s", runtime_image::decode_error_to_string(err));
+      this->fail_download_();
+      return;
+    }
+    this->source_.set_keep_read(false);
+    this->stream_started_ = true;
+    // Opening the image and allocating its buffer is enough for one pass
+    return;
+  }
+
+  do {
+    const int result = this->decode_step();
+    if (result == runtime_image::DECODE_STEP_MORE)
+      continue;
+    if (result == runtime_image::DECODE_STEP_DONE) {
+      this->finish_download_();
+    } else if (result == runtime_image::DECODE_STEP_NEED_DATA) {
+      if (!arrived)
+        return;
+      // JPEGDEC only waits for bytes short of the size it was given, so this guards against a hang
+      ESP_LOGE(TAG, "Download ended before the image was complete");
+      this->fail_download_();
+    } else {
+      ESP_LOGE(TAG, "Error decoding image: %s", runtime_image::decode_error_to_string(result));
+      this->fail_download_();
+    }
+    return;
+  } while (millis() - now < PASS_BUDGET_MS);
+}
+
+void OnlineImage::report_progress_(bool force) {
+  const uint32_t now = App.get_loop_component_start_time();
+  const size_t bytes = this->downloader_->get_bytes_read();
+  const size_t total = this->downloader_->content_length;
+  // The last bytes are always reported, so a progress bar reaches 100%
+  if (!force && now - this->last_progress_time_ < PROGRESS_INTERVAL_MS && (total == 0 || bytes < total))
+    return;
+  this->last_progress_time_ = now;
+  const float progress = total > 0 ? std::min(100.0f, bytes * 100.0f / total) : NAN;
+  this->download_progress_callback_.call(progress, bytes);
+}
+
+void OnlineImage::fail_download_() {
+  this->end_connection_();
+  this->download_error_callback_.call();
+}
+
 void OnlineImage::finish_download_() {
   // Must be read before end_decode() ends the decoding session
   bool decoder_finished = this->is_decode_finished();
@@ -288,6 +420,8 @@ void OnlineImage::end_connection_() {
     this->downloader_ = nullptr;
   }
   this->download_buffer_.reset();
+  this->streaming_ = false;
+  this->stream_started_ = false;
   this->disable_loop();
 }
 

esphome/components/online_image/online_image.h

@@ -16,6 +16,10 @@ using t_http_codes = enum {
   HTTP_CODE_NOT_FOUND = 404,
 };
 
+/// Largest download read(). A read() blocks until it has every byte it asked for, so this bounds how long one loop
+/// pass waits on a slow link.
+static constexpr size_t READ_CHUNK = 1460;
+
 /**
  * @brief Download an image from a given URL, and decode it using the specified decoder.
  * The image will then be stored in a buffer, so that it can be re-displayed without the
@@ -70,9 +74,17 @@ class OnlineImage final : public PollingComponent,
    */
   void release();
 
+  /// Called when the server has accepted the request and the image starts to download
+  template<typename F> void add_on_download_started_callback(F &&callback) {
+    this->download_started_callback_.add(std::forward<F>(callback));
+  }
   template<typename F> void add_on_finished_callback(F &&callback) {
     this->download_finished_callback_.add(std::forward<F>(callback));
   }
+  /// Called with the percentage downloaded (NAN when the server did not send the size) and the bytes read so far
+  template<typename F> void add_on_progress_callback(F &&callback) {
+    this->download_progress_callback_.add(std::forward<F>(callback));
+  }
   template<typename F> void add_on_error_callback(F &&callback) {
     this->download_error_callback_.add(std::forward<F>(callback));
   }
@@ -81,12 +93,20 @@ class OnlineImage final : public PollingComponent,
   bool validate_url_(const std::string &url);
   void end_connection_();
   void finish_download_();
+  /// loop() for a JPEG that is decoded as it downloads
+  void loop_stream_();
+  void fail_download_();
+  /// Reports download progress, at most every PROGRESS_INTERVAL_MS unless force is set
+  void report_progress_(bool force);
 
   CallbackManager<void(bool)> download_finished_callback_{};
   CallbackManager<void()> download_error_callback_{};
+  LazyCallbackManager<void()> download_started_callback_{};
+  LazyCallbackManager<void(float, size_t)> download_progress_callback_{};
 
   std::shared_ptr<http_request::HttpContainer> downloader_{nullptr};
   DownloadBuffer download_buffer_;
+  DownloadSource source_{download_buffer_};
   /**
    * This is the *initial* size of the download buffer, not the current size.
    * The download buffer can be resized at runtime; the download_buffer_initial_size_
@@ -109,6 +129,9 @@ class OnlineImage final : public PollingComponent,
 
   uint32_t start_time_{0};
   uint32_t last_data_time_{0};
+  uint32_t last_progress_time_{0};
+  bool streaming_{false};       // The decoder reads the download itself, as it arrives
+  bool stream_started_{false};  // The decoder has read the headers
 };
 
 }  // namespace esphome::online_image

esphome/components/runtime_image/image_decoder.cpp

@@ -2,7 +2,6 @@
 #include "runtime_image.h"
 #include "esphome/core/log.h"
 #include <algorithm>
-#include <cmath>
 
 namespace esphome::runtime_image {
 
@@ -11,8 +10,8 @@ ESPHOME_LOG_TAG(TAG, "image_decoder");
 bool ImageDecoder::set_size(int width, int height) {
   bool success = this->image_->resize(width, height) > 0;
   this->size_valid_ = success;
-  this->x_scale_ = static_cast<double>(this->image_->get_buffer_width()) / width;
-  this->y_scale_ = static_cast<double>(this->image_->get_buffer_height()) / height;
+  this->draw_width_ = width;
+  this->draw_height_ = height;
   return success;
 }
 
@@ -20,10 +19,24 @@ void ImageDecoder::draw(int x, int y, int w, int h, const Color &color) {
   if (!this->size_valid_) {
     return;
   }
-  auto width = std::min(this->image_->get_buffer_width(), static_cast<int>(std::ceil((x + w) * this->x_scale_)));
-  auto height = std::min(this->image_->get_buffer_height(), static_cast<int>(std::ceil((y + h) * this->y_scale_)));
-  for (int i = x * this->x_scale_; i < width; i++) {
-    for (int j = y * this->y_scale_; j < height; j++) {
+  // When shrinking, each target pixel is painted once, by the first source pixel that reaches it, rather than by every
+  // pixel that lands on it. Integer maths: the S3 has no double FPU.
+  const int buffer_width = this->image_->get_buffer_width();
+  const int buffer_height = this->image_->get_buffer_height();
+  int x1 = x;
+  int y1 = y;
+  int x2 = x + w;
+  int y2 = y + h;
+  if (buffer_width != this->draw_width_ || buffer_height != this->draw_height_) {
+    x1 = scale_boundary(x, this->draw_width_, buffer_width);
+    y1 = scale_boundary(y, this->draw_height_, buffer_height);
+    x2 = scale_boundary(x + w, this->draw_width_, buffer_width);
+    y2 = scale_boundary(y + h, this->draw_height_, buffer_height);
+  }
+  x2 = std::min(buffer_width, x2);
+  y2 = std::min(buffer_height, y2);
+  for (int i = x1; i < x2; i++) {
+    for (int j = y1; j < y2; j++) {
       this->image_->draw_pixel(i, j, color);
     }
   }

esphome/components/runtime_image/image_decoder.h

@@ -6,6 +6,15 @@
 
 namespace esphome::runtime_image {
 
+/// The first of `target` pixels that pixel n of `source` paints, rounded up: ceil(n * target / source). The spans of
+/// neighbouring pixels meet without overlapping, so a shrunk image paints each target pixel once.
+inline int scale_boundary(int n, int source, int target) {
+  if (source <= 0)
+    return 0;
+  return static_cast<int>((static_cast<uint32_t>(n) * static_cast<uint32_t>(target) + source - 1) /
+                          static_cast<uint32_t>(source));
+}
+
 enum DecodeError : int {
   DECODE_ERROR_INVALID_TYPE = -1,
   DECODE_ERROR_UNSUPPORTED_FORMAT = -2,
@@ -83,8 +92,8 @@ class ImageDecoder {
     this->expected_size_ = 0;
     this->decoded_bytes_ = 0;
     this->size_valid_ = true;
-    this->x_scale_ = 1.0;
-    this->y_scale_ = 1.0;
+    this->draw_width_ = 0;
+    this->draw_height_ = 0;
   }
 
   /**
@@ -184,8 +193,9 @@ class ImageDecoder {
   uint8_t *image_buffer_() const;
   bool image_is_big_endian_() const;
 
-  double x_scale_ = 1.0;
-  double y_scale_ = 1.0;
+  // Size of the image as the decoder draws it, which draw() spreads over the buffer
+  int draw_width_ = 0;
+  int draw_height_ = 0;
   RuntimeImage *image_;
   size_t expected_size_ = 0;  // Expected data size (0 if unknown)
   size_t decoded_bytes_ = 0;  // Bytes processed so far

esphome/components/runtime_image/jpeg_decoder.cpp

@@ -28,16 +28,14 @@ bool JpegDecoder::prepare_rgb565_scaling_(int width, int height) {
   this->source_height_ = height;
   this->x_boundaries_.clear();
   this->y_boundaries_.clear();
-  const uint32_t target_width = this->image_->get_buffer_width();
-  const uint32_t target_height = this->image_->get_buffer_height();
-  // Boundary n is the first target pixel source pixel n covers, rounded up. When shrinking, the source
-  // pixel whose span lands on a target pixel paints it, so an 8 to 4 scale keeps columns 0, 2, 4 and 6;
-  // the generic draw() path rounds down and keeps the odd ones instead
-  for (uint32_t x = 0; x <= static_cast<uint32_t>(width); x++) {
-    this->x_boundaries_.push_back(static_cast<uint16_t>((x * target_width + width - 1) / width));
+  const int target_width = this->image_->get_buffer_width();
+  const int target_height = this->image_->get_buffer_height();
+  // The same boundaries as the generic draw() path, so an 8 to 4 scale keeps columns 0, 2, 4 and 6 in both
+  for (int x = 0; x <= width; x++) {
+    this->x_boundaries_.push_back(static_cast<uint16_t>(scale_boundary(x, width, target_width)));
   }
-  for (uint32_t y = 0; y <= static_cast<uint32_t>(height); y++) {
-    this->y_boundaries_.push_back(static_cast<uint16_t>((y * target_height + height - 1) / height));
+  for (int y = 0; y <= height; y++) {
+    this->y_boundaries_.push_back(static_cast<uint16_t>(scale_boundary(y, height, target_height)));
   }
   return true;
 }
@@ -138,7 +136,7 @@ int HOT JpegDecoder::decode(uint8_t *buffer, size_t size) {
   const int err = this->start_();
   if (err != 0)
     return err;
-  if (!this->jpeg_.decode(0, 0, 0))
+  if (!this->jpeg_.decode(0, 0, this->scale_option_()))
     return this->fail_();
   this->decoded_bytes_ = size;
   this->jpeg_.close();
@@ -165,10 +163,28 @@ int JpegDecoder::start_() {
   } else {
     this->jpeg_.setPixelType(RGB8888);
   }
-  if (!this->set_size(this->jpeg_.getWidth(), this->jpeg_.getHeight())) {
+  const int width = this->jpeg_.getWidth();
+  const int height = this->jpeg_.getHeight();
+  if (!this->set_size(width, height)) {
     return DECODE_ERROR_OUT_OF_MEMORY;
   }
-  if (this->direct_rgb565_ && !this->prepare_rgb565_scaling_(this->jpeg_.getWidth(), this->jpeg_.getHeight())) {
+  // JPEGDEC can decode at 1/2, 1/4 or 1/8 size for much less work. Use the smallest size that still has at least as
+  // many pixels as the buffer, so a large image shown small is not decoded in full only to be thrown away.
+  const int buffer_width = this->image_->get_buffer_width();
+  const int buffer_height = this->image_->get_buffer_height();
+  this->scale_ = 1;
+  while (this->scale_ < JPEG_SCALE_EIGHTH && width / (this->scale_ * 2) >= buffer_width &&
+         height / (this->scale_ * 2) >= buffer_height) {
+    this->scale_ *= 2;
+  }
+  const int decoded_width = (width + this->scale_ - 1) / this->scale_;
+  const int decoded_height = (height + this->scale_ - 1) / this->scale_;
+  this->draw_width_ = decoded_width;
+  this->draw_height_ = decoded_height;
+  if (this->scale_ != 1) {
+    ESP_LOGD(TAG, "Decoding at 1/%d size, %d x %d", this->scale_, decoded_width, decoded_height);
+  }
+  if (this->direct_rgb565_ && !this->prepare_rgb565_scaling_(decoded_width, decoded_height)) {
     return DECODE_ERROR_OUT_OF_MEMORY;
   }
   return 0;
@@ -252,7 +268,7 @@ int JpegDecoder::begin_source(DecodeSource *source) {
     this->source_ = nullptr;
     return err;
   }
-  if (!this->jpeg_.decodeBegin(0, 0, 0))
+  if (!this->jpeg_.decodeBegin(0, 0, this->scale_option_()))
     return this->fail_();
   return 0;
 }

esphome/components/runtime_image/jpeg_decoder.h

@@ -31,12 +31,16 @@ class JpegDecoder : public ImageDecoder {
   int HOT decode_step() override;
 
   bool uses_direct_rgb565() const { return this->direct_rgb565_; }
+  /// JPEGDEC decodes the image at 1/get_scale() of its size: 1, 2, 4 or 8
+  int get_scale() const { return this->scale_; }
   void draw_rgb565(int x, int y, int w, int h, const uint8_t *pixels);
 
  protected:
   bool prepare_rgb565_scaling_(int width, int height);
   /// Set up an opened image for decoding. Returns 0, or a DecodeError.
   int start_();
+  /// The JPEGDEC option for scale_: JPEG_SCALE_HALF, _QUARTER and _EIGHTH are the divisors themselves
+  int scale_option_() const { return this->scale_ == 1 ? 0 : this->scale_; }
   /// The DecodeError for a failed read of the source or JPEGDEC's last error, closing the image
   int fail_();
 
@@ -49,6 +53,7 @@ class JpegDecoder : public ImageDecoder {
   FixedVector<uint16_t> y_boundaries_{};
   int source_width_{0};
   int source_height_{0};
+  int scale_{1};                   // JPEGDEC decodes at 1/scale_ of the image size
   DecodeSource *source_{nullptr};  // Set while a begin_source() decode is in progress
   bool direct_rgb565_{false};
   bool source_failed_{false};

tests/components/ld24xx/ld24xx_frame_splitter.cpp

@@ -1,152 +0,0 @@
-#include <cstdint>
-#include <cstring>
-#include <vector>
-#include <gtest/gtest.h>
-#include "esphome/components/ld24xx/ld24xx.h"
-
-namespace esphome::ld24xx::testing {
-
-namespace {
-constexpr uint8_t DATA_FRAME_HEADER[HEADER_FOOTER_SIZE] = {0xF4, 0xF3, 0xF2, 0xF1};
-constexpr uint8_t DATA_FRAME_FOOTER[HEADER_FOOTER_SIZE] = {0xF8, 0xF7, 0xF6, 0xF5};
-constexpr uint8_t DATA_FRAME_SIZE = 12;  // header, four payload bytes, footer
-constexpr size_t BUFFER_SIZE = 40;
-
-// Command frame around the payload
-std::vector<uint8_t> make_cmd_frame(const std::vector<uint8_t> &payload) {
-  std::vector<uint8_t> frame(std::begin(CMD_FRAME_HEADER), std::end(CMD_FRAME_HEADER));
-  frame.push_back(payload.size());
-  frame.push_back(0x00);
-  frame.insert(frame.end(), payload.begin(), payload.end());
-  frame.insert(frame.end(), std::begin(CMD_FRAME_FOOTER), std::end(CMD_FRAME_FOOTER));
-  return frame;
-}
-
-std::vector<uint8_t> make_data_frame(uint8_t fill) {
-  std::vector<uint8_t> frame(std::begin(DATA_FRAME_HEADER), std::end(DATA_FRAME_HEADER));
-  frame.insert(frame.end(), DATA_FRAME_SIZE - 2 * HEADER_FOOTER_SIZE, fill);
-  frame.insert(frame.end(), std::begin(DATA_FRAME_FOOTER), std::end(DATA_FRAME_FOOTER));
-  return frame;
-}
-}  // namespace
-
-// Data frames are fixed size, command frames carry their count, as in the radar components
-class LD24xxFrameSplitterTest : public ::testing::Test {
- protected:
-  void feed_(const std::vector<uint8_t> &bytes) {
-    for (uint8_t byte : bytes) {
-      feed_frame_byte(
-          this->buffer_, this->pos_, byte, DATA_FRAME_HEADER,
-          [](const uint8_t *buffer, uint8_t count) -> uint32_t {
-            if (count < HEADER_FOOTER_SIZE) {
-              return 0;
-            }
-            return buffer[0] == DATA_FRAME_HEADER[0] ? DATA_FRAME_SIZE : cmd_frame_length(buffer, count);
-          },
-          [this](uint8_t frame_len) { return this->handle_frame_(frame_len); }, [this]() { this->drops_++; });
-    }
-  }
-
-  bool handle_frame_(uint8_t frame_len) {
-    const uint8_t *footer = this->buffer_[0] == DATA_FRAME_HEADER[0] ? DATA_FRAME_FOOTER : CMD_FRAME_FOOTER;
-    if (!validate_header_footer(footer, &this->buffer_[frame_len - HEADER_FOOTER_SIZE])) {
-      return false;
-    }
-    this->frames_.emplace_back(this->buffer_, this->buffer_ + frame_len);
-    return true;
-  }
-
-  uint8_t buffer_[BUFFER_SIZE];
-  uint8_t pos_{0};
-  std::vector<std::vector<uint8_t>> frames_;
-  int drops_{0};
-};
-
-TEST_F(LD24xxFrameSplitterTest, FooterBytesInThePayloadDoNotEndTheFrame) {
-  auto frame = make_cmd_frame({0x61, 0x01, 0x00, 0x00, 0x04, 0x03, 0x02, 0x01, 0x55});
-  this->feed_(frame);
-  ASSERT_EQ(this->frames_.size(), 1u);
-  EXPECT_EQ(this->frames_[0], frame);
-  EXPECT_EQ(this->pos_, 0);
-  EXPECT_EQ(this->drops_, 0);
-}
-
-TEST_F(LD24xxFrameSplitterTest, BytesBeforeAHeaderAreNeverBuffered) {
-  this->feed_({0x00, 0x11, 0xFC, 0xFB, 0xFA, 0x04});
-  EXPECT_EQ(this->pos_, 0);
-  this->feed_(make_data_frame(0x22));
-  ASSERT_EQ(this->frames_.size(), 1u);
-  EXPECT_EQ(this->frames_[0], make_data_frame(0x22));
-}
-
-TEST_F(LD24xxFrameSplitterTest, AHeaderRestartsWhenItsBytesStopMatching) {
-  // F3 cannot continue the command header, and FD after FC starts it over
-  this->feed_({0xFD, 0xF3, 0xFD, 0xFC, 0xFD, 0xFC, 0xFB, 0xFA, 0x00, 0x00});
-  EXPECT_EQ(this->pos_, 6) << "only the header that matched through and its count are buffered";
-  this->feed_({0x04, 0x03, 0x02, 0x01});
-  ASSERT_EQ(this->frames_.size(), 1u);
-  EXPECT_EQ(this->frames_[0], make_cmd_frame({}));
-  EXPECT_EQ(this->drops_, 0);
-}
-
-TEST_F(LD24xxFrameSplitterTest, ImpossibleCountsAreDroppedAndTheNextFrameParsed) {
-  // 0xFFF6 totals 65536, which must not wrap to 0
-  this->feed_({0xFD, 0xFC, 0xFB, 0xFA, 0xF6, 0xFF});
-  this->feed_({0xFD, 0xFC, 0xFB, 0xFA, 0xFF, 0xFF});
-  EXPECT_EQ(this->drops_, 2);
-  EXPECT_EQ(this->pos_, 0);
-  this->feed_(make_data_frame(0x33));
-  ASSERT_EQ(this->frames_.size(), 1u);
-  EXPECT_EQ(this->frames_[0], make_data_frame(0x33));
-}
-
-TEST_F(LD24xxFrameSplitterTest, AFrameCaughtInsideADroppedFrameIsReplayed) {
-  // The count reaches 20 bytes in, past the whole frame that follows
-  std::vector<uint8_t> bytes = {0xFD, 0xFC, 0xFB, 0xFA, 0x0A, 0x00, 0x61, 0x01};
-  auto inner = make_data_frame(0x44);
-  bytes.insert(bytes.end(), inner.begin(), inner.end());
-  this->feed_(bytes);
-  EXPECT_EQ(this->drops_, 1);
-  ASSERT_EQ(this->frames_.size(), 1u);
-  EXPECT_EQ(this->frames_[0], inner);
-  EXPECT_EQ(this->pos_, 0);
-}
-
-TEST_F(LD24xxFrameSplitterTest, EveryWholeFrameLeftByADropIsDrained) {
-  // The window holds two whole data frames and the start of a third
-  std::vector<uint8_t> bytes = {0xFD, 0xFC, 0xFB, 0xFA, 0x18, 0x00, 0x61, 0x01};
-  for (uint8_t fill : {0x55, 0x66}) {
-    auto inner = make_data_frame(fill);
-    bytes.insert(bytes.end(), inner.begin(), inner.end());
-  }
-  bytes.insert(bytes.end(), {0xF4, 0xF3});
-  this->feed_(bytes);
-  EXPECT_EQ(this->drops_, 1);
-  ASSERT_EQ(this->frames_.size(), 2u);
-  EXPECT_EQ(this->frames_[0], make_data_frame(0x55));
-  EXPECT_EQ(this->frames_[1], make_data_frame(0x66));
-  EXPECT_EQ(this->pos_, 2) << "the partial header at the end stays buffered";
-}
-
-TEST_F(LD24xxFrameSplitterTest, AWrongFooterDropsOnlyThatFrame) {
-  auto bad = make_cmd_frame({0x01, 0x02});
-  bad[bad.size() - 1] = 0xEE;
-  this->feed_(bad);
-  EXPECT_EQ(this->drops_, 1);
-  EXPECT_TRUE(this->frames_.empty());
-  this->feed_(make_cmd_frame({0x03}));
-  ASSERT_EQ(this->frames_.size(), 1u);
-  EXPECT_EQ(this->frames_[0], make_cmd_frame({0x03}));
-}
-
-TEST_F(LD24xxFrameSplitterTest, BackToBackFramesOfBothKinds) {
-  this->feed_(make_data_frame(0x01));
-  this->feed_(make_cmd_frame({0xA0, 0x01, 0x00, 0x00}));
-  this->feed_(make_data_frame(0x02));
-  ASSERT_EQ(this->frames_.size(), 3u);
-  EXPECT_EQ(this->frames_[1], make_cmd_frame({0xA0, 0x01, 0x00, 0x00}));
-  EXPECT_EQ(this->frames_[2], make_data_frame(0x02));
-  EXPECT_EQ(this->drops_, 0);
-}
-
-}  // namespace esphome::ld24xx::testing

tests/components/online_image/common.yaml

@@ -19,6 +19,11 @@ image:
         } else {
           ESP_LOGD("online_image", "Cache miss: fresh download");
         }
+    on_download_started:
+      - logger.log: Download started
+    on_download_progress:
+      lambda: |-
+        ESP_LOGD("online_image", "Downloaded %.0f%% (%zu bytes)", progress, bytes_read);
   - platform: online_image
     id: online_binary_transparent_image
     url: http://www.libpng.org/pub/png/img_png/pnglogo-blk-tiny.png

tests/components/online_image/test_download_end.cpp

@@ -2,6 +2,7 @@
 
 #include <algorithm>
 #include <array>
+#include <cmath>
 #include <cstdint>
 #include <cstring>
 #include <memory>
@@ -27,6 +28,9 @@ class FakeContainer : public http_request::HttpContainer {
   }
 
   int read(uint8_t *buf, size_t max_len) override {
+    this->largest_read = std::max(this->largest_read, max_len);
+    if (this->read_error_)
+      return -1;
     size_t len = std::min(max_len, this->available_ - this->bytes_read_);
     std::memcpy(buf, this->body_.data() + this->bytes_read_, len);
     this->bytes_read_ += len;
@@ -42,13 +46,21 @@ class FakeContainer : public http_request::HttpContainer {
   }
 
   void set_content_length(size_t length) { this->content_length = length; }
+  /// Make every read from now on fail, like a dropped connection
+  void fail_reads() { this->read_error_ = true; }
+  /// Let len more bytes of the body arrive
+  void deliver(size_t len) { this->available_ = std::min(this->body_.size(), this->available_ + len); }
   void add_response_header(const std::string &name, const std::string &value) {
     this->response_headers_.push_back({name, value});
   }
 
+  /// The most bytes any one read() asked for
+  size_t largest_read{0};
+
  protected:
   std::vector<uint8_t> body_;
   size_t available_;
+  bool read_error_{false};
 };
 
 class FakeHttpRequest : public http_request::HttpRequestComponent {
@@ -123,13 +135,173 @@ static constexpr std::array<uint8_t, 69> PNG_1X1{
     0x0C, 0x49, 0x44, 0x41, 0x54, 0x78, 0x9C, 0x63, 0xF8, 0xCF, 0xC0, 0x00, 0x00, 0x03, 0x01, 0x01, 0x00, 0xC9,
     0xFE, 0x92, 0xEF, 0x00, 0x00, 0x00, 0x00, 0x49, 0x45, 0x4E, 0x44, 0xAE, 0x42, 0x60, 0x82};
 
+// 8x8 progressive JPEG, 521 bytes
+static const uint8_t JPEG_PROGRESSIVE[] = {
+    0xFF, 0xD8, 0xFF, 0xE0, 0x00, 0x10, 0x4A, 0x46, 0x49, 0x46, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x00, 0x01, 0x00,
+    0x00, 0xFF, 0xDB, 0x00, 0x43, 0x00, 0x10, 0x0B, 0x0C, 0x0E, 0x0C, 0x0A, 0x10, 0x0E, 0x0D, 0x0E, 0x12, 0x11, 0x10,
+    0x13, 0x18, 0x28, 0x1A, 0x18, 0x16, 0x16, 0x18, 0x31, 0x23, 0x25, 0x1D, 0x28, 0x3A, 0x33, 0x3D, 0x3C, 0x39, 0x33,
+    0x38, 0x37, 0x40, 0x48, 0x5C, 0x4E, 0x40, 0x44, 0x57, 0x45, 0x37, 0x38, 0x50, 0x6D, 0x51, 0x57, 0x5F, 0x62, 0x67,
+    0x68, 0x67, 0x3E, 0x4D, 0x71, 0x79, 0x70, 0x64, 0x78, 0x5C, 0x65, 0x67, 0x63, 0xFF, 0xDB, 0x00, 0x43, 0x01, 0x11,
+    0x12, 0x12, 0x18, 0x15, 0x18, 0x2F, 0x1A, 0x1A, 0x2F, 0x63, 0x42, 0x38, 0x42, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63,
+    0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63,
+    0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0x63,
+    0x63, 0x63, 0x63, 0x63, 0x63, 0x63, 0xFF, 0xC2, 0x00, 0x11, 0x08, 0x00, 0x08, 0x00, 0x08, 0x03, 0x01, 0x22, 0x00,
+    0x02, 0x11, 0x01, 0x03, 0x11, 0x01, 0xFF, 0xC4, 0x00, 0x15, 0x00, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0xFF, 0xC4, 0x00, 0x15, 0x01, 0x01, 0x01, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0x05, 0xFF, 0xDA, 0x00, 0x0C, 0x03,
+    0x01, 0x00, 0x02, 0x10, 0x03, 0x10, 0x00, 0x00, 0x01, 0x94, 0x05, 0x3F, 0xFF, 0xC4, 0x00, 0x14, 0x10, 0x01, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xDA, 0x00, 0x08,
+    0x01, 0x01, 0x00, 0x01, 0x05, 0x02, 0x7F, 0xFF, 0xC4, 0x00, 0x14, 0x11, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xDA, 0x00, 0x08, 0x01, 0x03, 0x01, 0x01, 0x3F,
+    0x01, 0x7F, 0xFF, 0xC4, 0x00, 0x14, 0x11, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xDA, 0x00, 0x08, 0x01, 0x02, 0x01, 0x01, 0x3F, 0x01, 0x7F, 0xFF, 0xC4, 0x00,
+    0x14, 0x10, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0xFF, 0xDA, 0x00, 0x08, 0x01, 0x01, 0x00, 0x06, 0x3F, 0x02, 0x7F, 0xFF, 0xC4, 0x00, 0x14, 0x10, 0x01, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xDA, 0x00, 0x08, 0x01,
+    0x01, 0x00, 0x01, 0x3F, 0x21, 0x7F, 0xFF, 0xDA, 0x00, 0x0C, 0x03, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x00, 0x00,
+    0x10, 0x0B, 0xFF, 0xC4, 0x00, 0x14, 0x11, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xDA, 0x00, 0x08, 0x01, 0x03, 0x01, 0x01, 0x3F, 0x10, 0x7F, 0xFF, 0xC4, 0x00,
+    0x14, 0x11, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0xFF, 0xDA, 0x00, 0x08, 0x01, 0x02, 0x01, 0x01, 0x3F, 0x10, 0x7F, 0xFF, 0xC4, 0x00, 0x14, 0x10, 0x01, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xDA, 0x00, 0x08, 0x01,
+    0x01, 0x00, 0x01, 0x3F, 0x10, 0x7F, 0xFF, 0xD9,
+};
+
+// 48x40 4:2:0 JPEG (quality 95), 2344 bytes: three rows of 16 pixel MCUs, with the scan starting at byte 609
+static const uint8_t JPEG_48X40[] = {
+    0xFF, 0xD8, 0xFF, 0xE0, 0x00, 0x10, 0x4A, 0x46, 0x49, 0x46, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x00, 0x01, 0x00,
+    0x00, 0xFF, 0xDB, 0x00, 0x43, 0x00, 0x02, 0x01, 0x01, 0x01, 0x01, 0x01, 0x02, 0x01, 0x01, 0x01, 0x02, 0x02, 0x02,
+    0x02, 0x02, 0x04, 0x03, 0x02, 0x02, 0x02, 0x02, 0x05, 0x04, 0x04, 0x03, 0x04, 0x06, 0x05, 0x06, 0x06, 0x06, 0x05,
+    0x06, 0x06, 0x06, 0x07, 0x09, 0x08, 0x06, 0x07, 0x09, 0x07, 0x06, 0x06, 0x08, 0x0B, 0x08, 0x09, 0x0A, 0x0A, 0x0A,
+    0x0A, 0x0A, 0x06, 0x08, 0x0B, 0x0C, 0x0B, 0x0A, 0x0C, 0x09, 0x0A, 0x0A, 0x0A, 0xFF, 0xDB, 0x00, 0x43, 0x01, 0x02,
+    0x02, 0x02, 0x02, 0x02, 0x02, 0x05, 0x03, 0x03, 0x05, 0x0A, 0x07, 0x06, 0x07, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A,
+    0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A,
+    0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A,
+    0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0xFF, 0xC0, 0x00, 0x11, 0x08, 0x00, 0x28, 0x00, 0x30, 0x03, 0x01, 0x22, 0x00,
+    0x02, 0x11, 0x01, 0x03, 0x11, 0x01, 0xFF, 0xC4, 0x00, 0x1F, 0x00, 0x00, 0x01, 0x05, 0x01, 0x01, 0x01, 0x01, 0x01,
+    0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A,
+    0x0B, 0xFF, 0xC4, 0x00, 0xB5, 0x10, 0x00, 0x02, 0x01, 0x03, 0x03, 0x02, 0x04, 0x03, 0x05, 0x05, 0x04, 0x04, 0x00,
+    0x00, 0x01, 0x7D, 0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12, 0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
+    0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xA1, 0x08, 0x23, 0x42, 0xB1, 0xC1, 0x15, 0x52, 0xD1, 0xF0, 0x24, 0x33, 0x62,
+    0x72, 0x82, 0x09, 0x0A, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x34, 0x35, 0x36, 0x37,
+    0x38, 0x39, 0x3A, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4A, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A,
+    0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x83, 0x84, 0x85,
+    0x86, 0x87, 0x88, 0x89, 0x8A, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6,
+    0xA7, 0xA8, 0xA9, 0xAA, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7,
+    0xC8, 0xC9, 0xCA, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7,
+    0xE8, 0xE9, 0xEA, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFF, 0xC4, 0x00, 0x1F, 0x01, 0x00,
+    0x03, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03,
+    0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0xFF, 0xC4, 0x00, 0xB5, 0x11, 0x00, 0x02, 0x01, 0x02, 0x04, 0x04,
+    0x03, 0x04, 0x07, 0x05, 0x04, 0x04, 0x00, 0x01, 0x02, 0x77, 0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21, 0x31,
+    0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71, 0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91, 0xA1, 0xB1, 0xC1, 0x09,
+    0x23, 0x33, 0x52, 0xF0, 0x15, 0x62, 0x72, 0xD1, 0x0A, 0x16, 0x24, 0x34, 0xE1, 0x25, 0xF1, 0x17, 0x18, 0x19, 0x1A,
+    0x26, 0x27, 0x28, 0x29, 0x2A, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4A,
+    0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, 0x73, 0x74, 0x75,
+    0x76, 0x77, 0x78, 0x79, 0x7A, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8A, 0x92, 0x93, 0x94, 0x95, 0x96,
+    0x97, 0x98, 0x99, 0x9A, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8, 0xA9, 0xAA, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7,
+    0xB8, 0xB9, 0xBA, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8,
+    0xD9, 0xDA, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9,
+    0xFA, 0xFF, 0xDA, 0x00, 0x0C, 0x03, 0x01, 0x00, 0x02, 0x11, 0x03, 0x11, 0x00, 0x3F, 0x00, 0xFC, 0xAA, 0xB8, 0xB7,
+    0xD3, 0xB5, 0xD8, 0x1E, 0xD6, 0xD1, 0xA5, 0x5B, 0x4B, 0x46, 0x10, 0xC1, 0x06, 0xA1, 0x29, 0x69, 0x25, 0xB7, 0xC2,
+    0xC6, 0x0C, 0x71, 0x26, 0x5E, 0x50, 0x15, 0x5D, 0xB6, 0x9C, 0x9E, 0x00, 0xC1, 0x67, 0x67, 0x4D, 0xCF, 0x84, 0xF7,
+    0x57, 0xA6, 0xDA, 0x08, 0x52, 0xF5, 0xE5, 0xBA, 0xB8, 0x7B, 0x5B, 0x68, 0xEE, 0x2F, 0x66, 0x89, 0xB7, 0xB7, 0x9B,
+    0xE5, 0x9C, 0x23, 0xAA, 0xFE, 0xF7, 0x68, 0x11, 0x9E, 0x5D, 0x18, 0x12, 0x48, 0x56, 0x5C, 0x9F, 0x57, 0xB6, 0xF8,
+    0x33, 0xF0, 0xE2, 0x5B, 0xFB, 0xCF, 0xF4, 0x51, 0x0C, 0xC6, 0x64, 0x30, 0x49, 0x71, 0x7C, 0xE2, 0x16, 0x90, 0x2E,
+    0xF4, 0x72, 0xEA, 0xE0, 0x34, 0x81, 0x77, 0x93, 0x9C, 0x07, 0xC2, 0x93, 0xB9, 0x61, 0xC0, 0xD3, 0xF0, 0x17, 0xC1,
+    0xBF, 0x03, 0xCD, 0xE1, 0xAD, 0x42, 0x3F, 0x0A, 0xD8, 0xC7, 0x2D, 0xAC, 0x36, 0xCB, 0xF6, 0x79, 0x22, 0x69, 0x84,
+    0xC4, 0x93, 0x29, 0x2A, 0x89, 0xB9, 0x00, 0x50, 0x62, 0x7C, 0xFF, 0x00, 0x16, 0xD9, 0x65, 0x00, 0x16, 0x65, 0x07,
+    0xFA, 0x5B, 0x36, 0xE2, 0xAC, 0xBF, 0x2D, 0x55, 0x79, 0x29, 0xB5, 0x26, 0x9B, 0xA9, 0x18, 0xB5, 0x15, 0x36, 0x9B,
+    0x53, 0xD1, 0xCA, 0x10, 0x93, 0x69, 0xB6, 0x94, 0x27, 0x16, 0xAF, 0x19, 0x29, 0xB8, 0xBB, 0x3F, 0x9A, 0xE1, 0x1E,
+    0x2A, 0xCB, 0x9E, 0x79, 0x4A, 0x92, 0x84, 0xDA, 0xD6, 0xED, 0xA4, 0xED, 0x7A, 0x72, 0xB5, 0xAC, 0xF6, 0xEB, 0xAD,
+    0xD5, 0x97, 0x91, 0xC9, 0x4D, 0xA4, 0xE9, 0xD7, 0x56, 0x45, 0x66, 0xD3, 0x9D, 0x85, 0xB1, 0x86, 0x59, 0x7E, 0xD9,
+    0x7E, 0xA0, 0xE0, 0xA8, 0x02, 0x17, 0x02, 0x3C, 0x36, 0x59, 0x18, 0xE2, 0x42, 0x1D, 0x40, 0x56, 0x0A, 0x77, 0x30,
+    0xAE, 0xFA, 0x56, 0xD4, 0xA4, 0x8A, 0xD9, 0xAD, 0xD6, 0x38, 0x1D, 0x7F, 0x77, 0x77, 0x1C, 0xB2, 0x4C, 0x22, 0x8C,
+    0x2B, 0xF3, 0x14, 0x64, 0x45, 0x85, 0x52, 0x47, 0x92, 0x7E, 0xF2, 0x0F, 0x34, 0x1D, 0xBC, 0x56, 0xDE, 0x85, 0xF0,
+    0x4B, 0xE1, 0x0A, 0xE9, 0xB0, 0xDB, 0x2D, 0x8C, 0x4C, 0xCD, 0x74, 0xF1, 0x42, 0x96, 0x93, 0xCF, 0xF6, 0x54, 0x0C,
+    0xB3, 0x44, 0x03, 0xAA, 0x6C, 0x49, 0x10, 0x87, 0x00, 0x88, 0xC2, 0xEE, 0x66, 0x6F, 0x9B, 0xAB, 0x57, 0xA4, 0x68,
+    0xDF, 0x0A, 0x3E, 0x1B, 0xDA, 0xE9, 0xDF, 0xD9, 0x96, 0xFE, 0x03, 0xB2, 0x8E, 0xD9, 0x8A, 0xDD, 0xC1, 0x77, 0x14,
+    0x97, 0x50, 0x2E, 0xE3, 0x20, 0x62, 0xA0, 0x33, 0x0C, 0xC6, 0x58, 0x48, 0x36, 0x6D, 0xC1, 0x20, 0xA2, 0x2B, 0x00,
+    0xB5, 0xF1, 0x99, 0xCF, 0x19, 0x65, 0x79, 0xAD, 0x0C, 0x3C, 0x2B, 0x61, 0xF9, 0x28, 0xD6, 0x52, 0x97, 0x35, 0x95,
+    0xD4, 0x61, 0x28, 0x5B, 0x99, 0xB8, 0xA9, 0xA9, 0x47, 0xD9, 0x3A, 0x69, 0xA9, 0xC6, 0x51, 0x52, 0x6A, 0x0D, 0x4A,
+    0x74, 0xA9, 0xC3, 0xFA, 0x7F, 0xC3, 0xFE, 0x25, 0xC1, 0x4E, 0xAE, 0x26, 0x2E, 0x13, 0x71, 0x5C, 0x8D, 0xFB, 0xB1,
+    0xD6, 0xEA, 0x6F, 0xF9, 0xAF, 0xBE, 0xB7, 0x4B, 0x55, 0x1D, 0x75, 0x4C, 0xF3, 0xDF, 0x05, 0xD9, 0xF8, 0x7B, 0xC3,
+    0xBA, 0xB5, 0xF1, 0xBC, 0x8D, 0x63, 0xDF, 0x1C, 0x32, 0x88, 0x1A, 0xF3, 0x74, 0x73, 0x89, 0x15, 0xC4, 0x8A, 0x25,
+    0x66, 0xDC, 0xAA, 0x98, 0x60, 0x06, 0x7F, 0xBD, 0xF2, 0x81, 0xF3, 0x36, 0xFE, 0x9D, 0xAF, 0x78, 0x8F, 0x54, 0xD3,
+    0xAD, 0xA6, 0x9E, 0xC5, 0xE5, 0x9C, 0x96, 0xDC, 0xB7, 0xE8, 0x84, 0x47, 0xFB, 0xB4, 0x54, 0x42, 0x0F, 0x03, 0xF8,
+    0xD7, 0xE5, 0x39, 0x60, 0xF8, 0x04, 0x79, 0x7B, 0xE3, 0xF4, 0x9F, 0x85, 0x5F, 0x08, 0xBE, 0x0D, 0x2C, 0x57, 0xCE,
+    0x6C, 0xA5, 0x2B, 0xA8, 0x08, 0x20, 0x82, 0x04, 0xB9, 0xB8, 0x82, 0x43, 0x28, 0x72, 0x55, 0xD5, 0x83, 0xB9, 0x05,
+    0xC2, 0x44, 0x55, 0x77, 0x8C, 0xFC, 0xEC, 0xD8, 0xCB, 0xE7, 0xBE, 0x9B, 0xE0, 0x5F, 0xC3, 0x9D, 0x32, 0xD4, 0x45,
+    0x26, 0x8B, 0x2C, 0x93, 0xC0, 0xF3, 0x95, 0x49, 0xEE, 0x2E, 0x0C, 0x26, 0x26, 0x31, 0xC9, 0xF3, 0xED, 0x95, 0x96,
+    0x32, 0xEC, 0x10, 0xE1, 0xB8, 0x60, 0x3A, 0x90, 0x1B, 0x3F, 0x9E, 0x66, 0x58, 0xFC, 0x14, 0x31, 0x15, 0xFD, 0x9C,
+    0x79, 0x57, 0x3A, 0x92, 0x84, 0x1C, 0x3D, 0xC9, 0xCD, 0x27, 0x6D, 0x12, 0xE5, 0xE7, 0xA6, 0xD5, 0x4D, 0x64, 0x93,
+    0xD1, 0x45, 0xC6, 0xAD, 0xE7, 0x2F, 0xE9, 0xEE, 0x17, 0xE3, 0x0C, 0x0A, 0xE1, 0x9C, 0x37, 0x34, 0x67, 0x2B, 0x73,
+    0x2B, 0xB4, 0xBA, 0x49, 0xF4, 0x72, 0x57, 0x51, 0xDD, 0x24, 0x9B, 0x5A, 0x36, 0x9A, 0x49, 0x1E, 0x15, 0xA7, 0x7E,
+    0xCE, 0xF6, 0x89, 0x6A, 0x96, 0x43, 0x55, 0xB5, 0xB3, 0xB6, 0xB8, 0x96, 0x2B, 0x9B, 0x78, 0xA0, 0xB4, 0x9E, 0xE5,
+    0x61, 0x90, 0xE0, 0xC2, 0xEC, 0x61, 0x91, 0x47, 0xCC, 0xDB, 0xF1, 0x80, 0xC0, 0x98, 0xD4, 0xE5, 0xDC, 0x64, 0xEC,
+    0x7C, 0x29, 0xFD, 0x98, 0x6C, 0xAF, 0xEC, 0xF5, 0x76, 0xB7, 0xF1, 0x36, 0x9A, 0x5D, 0x6F, 0x96, 0xE1, 0x74, 0xB5,
+    0xD3, 0x44, 0x91, 0xA8, 0x45, 0x0C, 0xE2, 0x3D, 0xAC, 0x85, 0xF9, 0x3B, 0x5B, 0x19, 0x8A, 0x43, 0x1F, 0xCA, 0x50,
+    0x9D, 0x87, 0xD2, 0x0F, 0xC2, 0x1F, 0x89, 0x4F, 0x6D, 0x04, 0x0F, 0xE1, 0x61, 0xAA, 0xEE, 0xB4, 0x8E, 0x56, 0xFB,
+    0x06, 0xAF, 0x04, 0xF3, 0x40, 0x9B, 0x55, 0x4E, 0xCB, 0x66, 0x91, 0xCB, 0x18, 0xC2, 0x88, 0xB6, 0xB1, 0x65, 0x60,
+    0xA4, 0x6E, 0xDC, 0xA4, 0x9E, 0xAF, 0xE1, 0xBF, 0xC2, 0x2F, 0x89, 0xA9, 0xE1, 0xFB, 0x8D, 0x6E, 0xC2, 0x3B, 0x4B,
+    0x30, 0xD7, 0x60, 0xDA, 0x41, 0x2D, 0xCC, 0x6C, 0x2E, 0x49, 0xF3, 0x1E, 0x42, 0x19, 0x5D, 0x58, 0x3C, 0x8A, 0x81,
+    0x82, 0xB8, 0x0C, 0xC9, 0xF2, 0xE5, 0x8F, 0x03, 0x8F, 0x36, 0xE3, 0x8A, 0x98, 0xCC, 0x14, 0xAB, 0x62, 0x2B, 0xC2,
+    0x34, 0xA2, 0xA5, 0x78, 0x37, 0x42, 0x12, 0x70, 0x8C, 0x62, 0xD2, 0x6D, 0x72, 0x7B, 0xAF, 0x9B, 0xDD, 0xFD, 0xE5,
+    0x4E, 0x79, 0x49, 0x45, 0x73, 0xA9, 0x72, 0x2F, 0xF0, 0x73, 0x83, 0xF8, 0xCE, 0xB4, 0x33, 0xE8, 0x3F, 0xAE, 0x42,
+    0xF7, 0x76, 0xB3, 0x83, 0x57, 0xE5, 0x95, 0xBE, 0xCE, 0x8F, 0x7B, 0xDE, 0xD7, 0x4B, 0x6B, 0x9C, 0x1E, 0x8D, 0xF0,
+    0x56, 0x7B, 0xDD, 0x26, 0x34, 0x5F, 0x1F, 0xDB, 0x9D, 0x37, 0x53, 0xB8, 0x96, 0xED, 0xA0, 0x16, 0xB1, 0xC9, 0x2C,
+    0x8B, 0xF2, 0x26, 0x58, 0x89, 0x37, 0xEE, 0x04, 0xB2, 0x97, 0x54, 0x2D, 0x88, 0xC0, 0x60, 0x0B, 0x03, 0x5E, 0x9B,
+    0x67, 0xFB, 0x36, 0xE9, 0x31, 0x2D, 0x9C, 0x37, 0x9E, 0x32, 0x84, 0x5D, 0x2C, 0x4A, 0xD6, 0xAD, 0x73, 0x63, 0x28,
+    0x36, 0xAA, 0x53, 0xF7, 0x90, 0x29, 0x8E, 0x5C, 0x92, 0xBE, 0x41, 0xDC, 0xC0, 0xB3, 0x2B, 0x46, 0x32, 0x4B, 0x96,
+    0x35, 0xAD, 0x1F, 0xC2, 0xDF, 0x89, 0x17, 0xF6, 0xB6, 0xFA, 0xB5, 0xED, 0xB8, 0xB7, 0x8E, 0x78, 0x66, 0x96, 0x09,
+    0x6C, 0x6E, 0x23, 0x32, 0x28, 0x08, 0xE8, 0xF2, 0xBA, 0xF9, 0x86, 0x48, 0xC0, 0x68, 0xFE, 0x63, 0xC8, 0x23, 0x82,
+    0xCC, 0xA5, 0x4A, 0xFA, 0x66, 0x8F, 0xF0, 0x37, 0xE2, 0x6D, 0xE5, 0xC9, 0x3A, 0x87, 0x86, 0xB4, 0xFB, 0x28, 0xAE,
+    0x61, 0x0F, 0x0B, 0x59, 0xDF, 0xC0, 0xD1, 0xAC, 0xE0, 0x24, 0x41, 0x42, 0xC4, 0x49, 0x1B, 0x10, 0x21, 0x50, 0xC0,
+    0x09, 0x11, 0x8B, 0xEE, 0x6E, 0x71, 0xE2, 0xE2, 0x78, 0xBB, 0x33, 0xFA, 0xC5, 0x1A, 0xB4, 0xEA, 0xC6, 0x74, 0xD2,
+    0x8C, 0x24, 0xA5, 0x2A, 0x3C, 0xB5, 0x2E, 0xB9, 0x9B, 0x71, 0x97, 0x34, 0xE0, 0xAA, 0x54, 0x93, 0x71, 0x56, 0x49,
+    0xB9, 0xC6, 0x4E, 0x9A, 0x9B, 0xD3, 0xFA, 0x7F, 0x81, 0xB8, 0xD6, 0xAC, 0xDD, 0x6F, 0x65, 0x8D, 0x82, 0x77, 0x85,
+    0x95, 0xE1, 0x7D, 0x1C, 0xD2, 0x8B, 0x7A, 0x27, 0xA2, 0xF4, 0xED, 0xEE, 0x9E, 0x67, 0xE0, 0x8F, 0x81, 0x37, 0xBA,
+    0xEF, 0x87, 0x67, 0xBF, 0x8F, 0xC4, 0xD2, 0xDD, 0x4F, 0x05, 0xA8, 0x61, 0x7B, 0x1E, 0x9E, 0xE1, 0x8C, 0xEA, 0xF3,
+    0x18, 0x99, 0xA3, 0xDE, 0x76, 0x66, 0x36, 0x2A, 0x30, 0xFB, 0x9B, 0x0F, 0xC3, 0x1C, 0xA3, 0x76, 0x4B, 0xFB, 0x3B,
+    0xE8, 0xBA, 0x66, 0xBF, 0x0E, 0x93, 0xFD, 0xAB, 0x23, 0xD9, 0xA5, 0xCE, 0x62, 0xF3, 0x34, 0xEB, 0x7F, 0x29, 0x0A,
+    0xA7, 0x04, 0x48, 0xF2, 0x79, 0x82, 0x42, 0x1D, 0x46, 0x4B, 0xA9, 0x1B, 0xD1, 0xBE, 0x52, 0x54, 0xD7, 0xA8, 0xF8,
+    0x33, 0xE1, 0xAF, 0xC4, 0xA8, 0x24, 0xD6, 0x6D, 0xED, 0xBC, 0x0A, 0xD3, 0x5A, 0x5C, 0xC4, 0xDF, 0x64, 0x17, 0x97,
+    0x36, 0xF0, 0x65, 0x52, 0x39, 0xD4, 0x23, 0x22, 0x9D, 0xD8, 0x64, 0x83, 0x04, 0x85, 0x38, 0xEF, 0xB8, 0x49, 0x91,
+    0xBB, 0xFF, 0x00, 0x0A, 0xDF, 0xE3, 0x77, 0x84, 0xAC, 0xD3, 0x4A, 0xBC, 0xF0, 0x3A, 0x5A, 0x5B, 0x4F, 0x72, 0x5E,
+    0xD7, 0x53, 0x8E, 0xE2, 0x12, 0x6D, 0xC6, 0x40, 0x20, 0x47, 0xE6, 0x3E, 0x71, 0x26, 0x70, 0x24, 0xE4, 0xB4, 0x63,
+    0x2A, 0xC0, 0xE0, 0x7E, 0x71, 0x98, 0x71, 0x35, 0x5C, 0x4E, 0x69, 0x5A, 0xBD, 0x7C, 0x7A, 0x9C, 0xE3, 0xC9, 0xCF,
+    0x38, 0x46, 0x8D, 0xA4, 0xDC, 0x63, 0x38, 0x4A, 0xE9, 0xED, 0x5A, 0x4E, 0x4A, 0x6D, 0xF3, 0xCA, 0x2D, 0xB9, 0x4D,
+    0xD3, 0x77, 0x8C, 0x7F, 0xA8, 0xF8, 0x53, 0x8D, 0x31, 0x32, 0xC8, 0xA9, 0xDB, 0x15, 0x04, 0x9F, 0xB4, 0xD2, 0xF4,
+    0xD3, 0xF8, 0xA5, 0x77, 0xCD, 0xB3, 0x49, 0x6C, 0xB4, 0xEA, 0x97, 0x46, 0x78, 0x45, 0xC4, 0x16, 0x5A, 0xDD, 0xA5,
+    0xA6, 0x8D, 0xA7, 0xEA, 0x77, 0x4A, 0x54, 0x47, 0x3C, 0x31, 0x41, 0x20, 0x06, 0x68, 0x00, 0x9A, 0x4F, 0x2A, 0x40,
+    0x5D, 0x5F, 0x69, 0xF3, 0x15, 0xCB, 0x32, 0x96, 0xDC, 0xC0, 0x90, 0xA5, 0xF0, 0xBD, 0xAF, 0xC3, 0x96, 0x83, 0x51,
+    0xB8, 0xD6, 0xA7, 0x48, 0xD2, 0xE8, 0x2B, 0x2C, 0x2D, 0x6B, 0xF6, 0xA4, 0x55, 0x8E, 0x45, 0x5F, 0xBA, 0x54, 0x2A,
+    0x36, 0x77, 0x12, 0x72, 0xE5, 0x9C, 0x14, 0x3B, 0x63, 0x6C, 0x62, 0x8A, 0x2B, 0xDE, 0xCD, 0x70, 0x74, 0xA7, 0x92,
+    0xE2, 0x31, 0x35, 0x2D, 0x29, 0x54, 0xBB, 0x97, 0xBB, 0x18, 0xF3, 0x38, 0x52, 0xA5, 0x38, 0xDF, 0x92, 0x31, 0x7E,
+    0xEB, 0x9B, 0x6A, 0xCD, 0x6B, 0xEF, 0x7C, 0x6E, 0x52, 0x7F, 0xE1, 0xF7, 0x0E, 0x54, 0x96, 0x1B, 0x3D, 0x52, 0x86,
+    0xF0, 0x73, 0x4B, 0xEE, 0x92, 0xD6, 0xD6, 0xBF, 0xC2, 0x8D, 0x9F, 0x0B, 0xDE, 0xEB, 0xF3, 0x69, 0x6B, 0x06, 0x9B,
+    0xA9, 0x5B, 0xE9, 0xF6, 0x6F, 0x76, 0x1E, 0x45, 0x8E, 0xE1, 0x54, 0xC8, 0xCD, 0xF3, 0x28, 0x8B, 0x1C, 0x9E, 0x25,
+    0x55, 0xDA, 0xA5, 0x58, 0x80, 0xCA, 0x46, 0x42, 0xA8, 0xF4, 0x1B, 0xEB, 0xBB, 0xBB, 0x8B, 0x69, 0xAF, 0xA5, 0x8E,
+    0xD0, 0x49, 0x25, 0x9C, 0x37, 0x73, 0xE9, 0xD7, 0xF2, 0x14, 0x8E, 0x55, 0x91, 0x64, 0x90, 0x46, 0xA8, 0xF9, 0x50,
+    0x57, 0x73, 0x2E, 0xE0, 0x55, 0xF6, 0x87, 0x45, 0x20, 0x2E, 0xC7, 0x28, 0xAF, 0xCD, 0x78, 0xA6, 0xA5, 0x5C, 0x26,
+    0x33, 0x01, 0x35, 0x2E, 0x67, 0x52, 0x35, 0xA0, 0xEE, 0x93, 0x56, 0x70, 0x4F, 0x48, 0xDB, 0x95, 0x6B, 0x76, 0xF4,
+    0xB4, 0xA5, 0x27, 0x29, 0x29, 0x35, 0x16, 0xBF, 0xA8, 0x7C, 0x3E, 0x92, 0xF6, 0x98, 0xA8, 0x5B, 0x4B, 0xC5, 0xDB,
+    0x5E, 0x8E, 0x4F, 0x7D, 0xFA, 0xDB, 0x57, 0xB2, 0x56, 0xD6, 0xED, 0xF7, 0x3E, 0x10, 0xB2, 0x82, 0xF6, 0xC2, 0xF2,
+    0xF3, 0x4E, 0xD4, 0xAF, 0xEE, 0x5A, 0xCA, 0xCE, 0xD2, 0xF1, 0xA7, 0xB8, 0x9D, 0xD4, 0x42, 0x8C, 0xF2, 0x3C, 0x8E,
+    0x42, 0x02, 0x24, 0xFD, 0xDA, 0x96, 0x60, 0xAD, 0xB0, 0xC9, 0x0E, 0x00, 0xC8, 0xC8, 0xEA, 0xEE, 0x12, 0x7B, 0x09,
+    0x6C, 0x6E, 0xCE, 0xA2, 0x0B, 0xAA, 0x32, 0xD9, 0xB9, 0x49, 0x66, 0xDF, 0x74, 0xCC, 0x31, 0x1B, 0xE4, 0xE6, 0x63,
+    0xF2, 0x91, 0x95, 0x42, 0x15, 0x8B, 0x7D, 0xE0, 0xAC, 0xB4, 0x51, 0x5F, 0x33, 0x3A, 0xD8, 0x8C, 0x46, 0x7A, 0x9C,
+    0xA6, 0xD7, 0x2C, 0x13, 0x49, 0x25, 0x6E, 0x6A, 0x73, 0xE4, 0x84, 0x9E, 0x9A, 0xC9, 0x29, 0x24, 0x9E, 0xE9, 0x42,
+    0x11, 0x8D, 0xA2, 0x9C, 0x5F, 0xF5, 0x37, 0x0D, 0x36, 0xF8, 0x7E, 0x9A, 0xEC, 0xE5, 0xE5, 0x7E, 0x67, 0x77, 0x7B,
+    0x7A, 0xBF, 0x5E, 0xB7, 0x3F, 0xFF, 0xD9,
+};
+
 static void set_loop_time(uint32_t now) { LoopBlockingGuard clock(nullptr, LOG_STR("test"), now); }
 
 class OnlineImageDownloadEnd : public ::testing::Test {
  protected:
-  std::unique_ptr<OnlineImage> make_image_(runtime_image::ImageFormat format) {
+  std::unique_ptr<OnlineImage> make_image_(runtime_image::ImageFormat format, uint32_t buffer_size = 256) {
     auto img = std::make_unique<OnlineImage>("http://example.com/image", 0, 0, format, image::IMAGE_TYPE_RGB,
-                                             image::TRANSPARENCY_OPAQUE, nullptr, 256);
+                                             image::TRANSPARENCY_OPAQUE, nullptr, buffer_size);
     img->set_parent(&this->http_);
     return img;
   }
@@ -286,4 +458,294 @@ TEST_F(OnlineImageDownloadEnd, JpegBufferAllocationFailureReportsError) {
   EXPECT_EQ(this->finished_, 0);
 }
 
+// The JPEG decoded with all of it in memory at once, to compare the downloaded images with
+static std::vector<uint8_t> reference_jpeg_pixels() {
+  runtime_image::RuntimeImage ref(runtime_image::JPEG, image::IMAGE_TYPE_RGB, image::TRANSPARENCY_OPAQUE);
+  std::vector<uint8_t> data(JPEG_48X40, JPEG_48X40 + sizeof(JPEG_48X40));
+  EXPECT_TRUE(ref.begin_decode(data.size()));
+  EXPECT_EQ(ref.feed_data(data.data(), data.size()), static_cast<int>(data.size()));
+  EXPECT_TRUE(ref.end_decode());
+  return std::vector<uint8_t>(ref.get_data_start(), ref.get_data_start() + ref.get_width_stride() * ref.get_height());
+}
+
+static std::vector<uint8_t> image_pixels(OnlineImage &image) {
+  return std::vector<uint8_t>(image.get_data_start(),
+                              image.get_data_start() + image.get_width_stride() * image.get_height());
+}
+
+// A JPEG of known size is decoded as it arrives, so a buffer smaller than the file only has to hold the headers
+TEST_F(OnlineImageDownloadEnd, JpegDecodesThroughASmallBuffer) {
+  auto image = this->make_image_(runtime_image::JPEG, 1024);
+  // Bytes after the image are never needed. Waiting for the whole file before decoding would read them all.
+  std::vector<uint8_t> body(JPEG_48X40, JPEG_48X40 + sizeof(JPEG_48X40));
+  body.resize(body.size() + 8192, 0);
+  auto container = std::make_shared<FakeContainer>(body, body.size(), false);
+  container->add_response_header("etag", "\"abc\"");
+  this->start_(*image, container);
+
+  for (int i = 0; i < 100 && this->finished_ + this->errors_ == 0; i++)
+    image->loop();
+
+  ASSERT_EQ(this->finished_, 1);
+  EXPECT_LT(container->get_bytes_read(), body.size()) << "the image was not decoded as it arrived";
+  EXPECT_EQ(this->errors_, 0);
+  ASSERT_EQ(image->get_width(), 48);
+  ASSERT_EQ(image->get_height(), 40);
+  EXPECT_EQ(image_pixels(*image), reference_jpeg_pixels());
+
+  // A complete image is cached
+  this->http_.next = std::make_shared<FakeContainer>(std::vector<uint8_t>{}, 0, false);
+  image->update();
+  EXPECT_TRUE(this->http_.sent_header("if-none-match"));
+}
+
+// A read() waits for every byte it asks for, so a large buffer is filled a little at a time rather than in one
+// read that blocks the loop until the whole buffer has arrived
+TEST_F(OnlineImageDownloadEnd, JpegReadsInSmallPiecesWithALargeBuffer) {
+  auto image = this->make_image_(runtime_image::JPEG, 65536);
+  auto container =
+      std::make_shared<FakeContainer>(std::vector<uint8_t>(JPEG_48X40, JPEG_48X40 + sizeof(JPEG_48X40)), 0, false);
+  this->start_(*image, container);
+
+  for (int i = 0; i < 100 && this->finished_ + this->errors_ == 0; i++) {
+    container->deliver(sizeof(JPEG_48X40));
+    image->loop();
+  }
+
+  ASSERT_EQ(this->finished_, 1);
+  EXPECT_EQ(this->errors_, 0);
+  EXPECT_LE(container->largest_read, READ_CHUNK);
+  EXPECT_EQ(image_pixels(*image), reference_jpeg_pixels());
+}
+
+// A downloaded PNG is read a little at a time too
+TEST_F(OnlineImageDownloadEnd, PngReadsInSmallPiecesWithALargeBuffer) {
+  auto image = this->make_image_(runtime_image::PNG, 65536);
+  std::vector<uint8_t> png(PNG_1X1.begin(), PNG_1X1.end());
+  auto container = std::make_shared<FakeContainer>(png, png.size(), false);
+  this->start_(*image, container);
+
+  for (int i = 0; i < 100 && this->finished_ + this->errors_ == 0; i++)
+    image->loop();
+
+  ASSERT_EQ(this->finished_, 1);
+  EXPECT_EQ(this->errors_, 0);
+  EXPECT_LE(container->largest_read, READ_CHUNK);
+}
+
+// A slow link: the decoder waits part way through the image for the rest to arrive
+TEST_F(OnlineImageDownloadEnd, JpegWaitsForASlowDownload) {
+  auto image = this->make_image_(runtime_image::JPEG, 1024);
+  auto container =
+      std::make_shared<FakeContainer>(std::vector<uint8_t>(JPEG_48X40, JPEG_48X40 + sizeof(JPEG_48X40)), 1024, false);
+  this->start_(*image, container);
+
+  int passes = 0;
+  for (; passes < 1000 && this->finished_ + this->errors_ == 0; passes++) {
+    image->loop();
+    if (passes == 5) {
+      EXPECT_EQ(this->finished_, 0) << "the image cannot be finished before the rest of it arrives";
+    }
+    container->deliver(40);
+  }
+
+  ASSERT_EQ(this->finished_, 1);
+  EXPECT_EQ(this->errors_, 0);
+  EXPECT_GT(passes, 10);
+  EXPECT_EQ(image_pixels(*image), reference_jpeg_pixels());
+}
+
+// A download that stops part way through times out rather than waiting for ever
+TEST_F(OnlineImageDownloadEnd, JpegDownloadThatStopsTimesOut) {
+  auto image = this->make_image_(runtime_image::JPEG, 1024);
+  auto container =
+      std::make_shared<FakeContainer>(std::vector<uint8_t>(JPEG_48X40, JPEG_48X40 + sizeof(JPEG_48X40)), 1500, false);
+  set_loop_time(1000);
+  this->start_(*image, container);
+
+  for (int i = 0; i < 10; i++)
+    image->loop();
+  EXPECT_EQ(this->errors_, 0) << "still within the timeout";
+
+  set_loop_time(1000 + this->http_.get_timeout());
+  image->loop();
+  EXPECT_EQ(this->errors_, 1);
+  EXPECT_EQ(this->finished_, 0);
+}
+
+// Headers that do not fit the download buffer cannot be read as the image arrives, so the whole image is
+// downloaded first, keeping the bytes already read
+TEST_F(OnlineImageDownloadEnd, JpegHeadersLargerThanTheBufferDownloadTheWholeImage) {
+  auto image = this->make_image_(runtime_image::JPEG, 256);
+  auto container = std::make_shared<FakeContainer>(std::vector<uint8_t>(JPEG_48X40, JPEG_48X40 + sizeof(JPEG_48X40)),
+                                                   sizeof(JPEG_48X40), false);
+  this->start_(*image, container);
+
+  for (int i = 0; i < 100 && this->finished_ + this->errors_ == 0; i++) {
+    image->loop();
+    container->deliver(256);
+  }
+
+  ASSERT_EQ(this->finished_, 1);
+  EXPECT_EQ(this->errors_, 0);
+  EXPECT_EQ(container->get_bytes_read(), sizeof(JPEG_48X40));
+  EXPECT_EQ(image_pixels(*image), reference_jpeg_pixels());
+}
+
+// The pass that opens the image does not decode any of it
+TEST_F(OnlineImageDownloadEnd, JpegOpensInAPassOfItsOwn) {
+  auto image = this->make_image_(runtime_image::JPEG, 1024);
+  auto container = std::make_shared<FakeContainer>(std::vector<uint8_t>(JPEG_48X40, JPEG_48X40 + sizeof(JPEG_48X40)),
+                                                   sizeof(JPEG_48X40), false);
+  this->start_(*image, container);
+
+  image->loop();
+  EXPECT_EQ(this->finished_ + this->errors_, 0);
+  for (int i = 0; i < 100 && this->finished_ + this->errors_ == 0; i++)
+    image->loop();
+  EXPECT_EQ(this->finished_, 1);
+}
+
+// A progressive JPEG is refused while it downloads, without blaming the buffer size
+TEST_F(OnlineImageDownloadEnd, JpegProgressiveReportsError) {
+  auto image = this->make_image_(runtime_image::JPEG, 256);
+  std::vector<uint8_t> body(JPEG_PROGRESSIVE, JPEG_PROGRESSIVE + sizeof(JPEG_PROGRESSIVE));
+  auto container = std::make_shared<FakeContainer>(body, 256, false);
+  this->start_(*image, container);
+
+  for (int i = 0; i < 10 && this->finished_ + this->errors_ == 0; i++)
+    image->loop();
+
+  EXPECT_EQ(this->errors_, 1);
+  EXPECT_EQ(this->finished_, 0);
+}
+
+// on_download_started fires once the server has accepted the request, before the first progress report, and not
+// for a response that has no image to download
+TEST_F(OnlineImageDownloadEnd, StartedFiresOnlyWhenTheDownloadBegins) {
+  auto image = this->make_image_(runtime_image::JPEG, 1024);
+  std::vector<std::string> events;
+  image->add_on_download_started_callback([&events]() { events.emplace_back("started"); });
+  image->add_on_progress_callback([&events](float, size_t) { events.emplace_back("progress"); });
+  this->start_(*image,
+               std::make_shared<FakeContainer>(std::vector<uint8_t>(JPEG_48X40, JPEG_48X40 + sizeof(JPEG_48X40)),
+                                               sizeof(JPEG_48X40), false));
+  ASSERT_GE(events.size(), 2u);
+  EXPECT_EQ(events[0], "started");
+  EXPECT_EQ(events[1], "progress");
+  for (int i = 0; i < 100 && this->finished_ + this->errors_ == 0; i++)
+    image->loop();
+  EXPECT_EQ(std::count(events.begin(), events.end(), std::string("started")), 1);
+
+  for (int status : {304, 404}) {
+    events.clear();
+    auto container = std::make_shared<FakeContainer>(std::vector<uint8_t>{}, 0, false);
+    container->status_code = status;
+    this->http_.next = container;
+    image->update();
+    EXPECT_TRUE(events.empty()) << "HTTP " << status;
+  }
+}
+
+// Progress starts at 0, is reported at most every 100 ms, and always reaches 100%
+TEST_F(OnlineImageDownloadEnd, ProgressIsReportedAsTheImageDownloads) {
+  auto image = this->make_image_(runtime_image::JPEG, 1024);
+  std::vector<float> reports;
+  image->add_on_progress_callback([&reports](float progress, size_t) { reports.push_back(progress); });
+  auto container =
+      std::make_shared<FakeContainer>(std::vector<uint8_t>(JPEG_48X40, JPEG_48X40 + sizeof(JPEG_48X40)), 100, false);
+  uint32_t now = 1000;
+  set_loop_time(now);
+  this->start_(*image, container);
+  ASSERT_EQ(reports.size(), 1u);
+  EXPECT_EQ(reports[0], 0.0f);
+
+  int passes = 0;
+  for (; passes < 1000 && this->finished_ + this->errors_ == 0; passes++) {
+    now += 50;
+    set_loop_time(now);
+    container->deliver(100);
+    image->loop();
+  }
+
+  ASSERT_EQ(this->finished_, 1);
+  EXPECT_EQ(reports.back(), 100.0f);
+  EXPECT_TRUE(std::is_sorted(reports.begin(), reports.end()));
+  // A report every 100 ms of a 50 ms loop, plus the start and the end
+  EXPECT_LE(reports.size(), static_cast<size_t>(passes / 2 + 2));
+  EXPECT_GT(reports.size(), 3u);
+}
+
+// Without a Content-Length the percentage is unknown, but the bytes read are still reported
+TEST_F(OnlineImageDownloadEnd, ProgressOfAChunkedDownloadHasNoPercentage) {
+  auto image = this->make_image_(runtime_image::PNG);
+  std::vector<std::pair<float, size_t>> reports;
+  image->add_on_progress_callback(
+      [&reports](float progress, size_t bytes_read) { reports.emplace_back(progress, bytes_read); });
+  auto container =
+      std::make_shared<FakeContainer>(std::vector<uint8_t>(PNG_1X1.begin(), PNG_1X1.end()), PNG_1X1.size(), true);
+  set_loop_time(1000);
+  this->start_(*image, container);
+  set_loop_time(2000);
+  for (int i = 0; i < 10 && this->finished_ + this->errors_ == 0; i++)
+    image->loop();
+
+  ASSERT_GE(reports.size(), 2u);
+  EXPECT_TRUE(std::isnan(reports.back().first));
+  EXPECT_EQ(reports.back().second, PNG_1X1.size());
+}
+
+// Scan data that cannot be decoded fails the download part way through
+TEST_F(OnlineImageDownloadEnd, JpegDecodeErrorFailsTheDownload) {
+  auto image = this->make_image_(runtime_image::JPEG, 1024);
+  std::vector<uint8_t> body(JPEG_48X40, JPEG_48X40 + sizeof(JPEG_48X40));
+  std::fill(body.begin() + 700, body.end() - 2, 0xFE);
+  auto container = std::make_shared<FakeContainer>(body, 1024, false);
+  this->start_(*image, container);
+
+  for (int i = 0; i < 100 && this->finished_ + this->errors_ == 0; i++) {
+    image->loop();
+    container->deliver(256);
+  }
+
+  EXPECT_EQ(this->errors_, 1);
+  EXPECT_EQ(this->finished_, 0);
+}
+
+// A read that fails part way through the download ends it with an error
+TEST_F(OnlineImageDownloadEnd, JpegReadErrorFailsTheDownload) {
+  auto image = this->make_image_(runtime_image::JPEG, 1024);
+  auto container =
+      std::make_shared<FakeContainer>(std::vector<uint8_t>(JPEG_48X40, JPEG_48X40 + sizeof(JPEG_48X40)), 1024, false);
+  this->start_(*image, container);
+  for (int i = 0; i < 5; i++)
+    image->loop();
+  ASSERT_EQ(this->errors_, 0);
+
+  container->fail_reads();
+  image->loop();
+  EXPECT_EQ(this->errors_, 1);
+  EXPECT_EQ(this->finished_, 0);
+}
+
+TEST(DownloadBufferGrow, KeepsTheUnreadData) {
+  DownloadBuffer buffer(16);
+  std::memcpy(buffer.append(), "abcdef", 6);
+  buffer.write(6);
+  buffer.read(2);
+
+  ASSERT_TRUE(buffer.grow(64));
+  EXPECT_EQ(buffer.size(), 64u);
+  ASSERT_EQ(buffer.unread(), 4u);
+  EXPECT_EQ(std::memcmp(buffer.data(), "cdef", 4), 0);
+
+  // A failed allocation leaves the buffer as it was
+  EXPECT_FALSE(buffer.grow(SIZE_MAX / 2));
+  EXPECT_EQ(buffer.size(), 64u);
+  EXPECT_EQ(std::memcmp(buffer.data(), "cdef", 4), 0);
+  // Growing to a smaller size changes nothing
+  EXPECT_TRUE(buffer.grow(8));
+  EXPECT_EQ(buffer.size(), 64u);
+}
+
 }  // namespace esphome::online_image::testing

tests/components/runtime_image/test_decoder_reuse.cpp

@@ -3,10 +3,13 @@
 
 #include <algorithm>
 #include <array>
+#include <cstdlib>
 #include <cstring>
+#include <utility>
 #include <vector>
 
 #include "esphome/components/runtime_image/image_decoder.h"
+#include "esphome/components/runtime_image/jpeg_decoder.h"
 #include "esphome/components/runtime_image/runtime_image.h"
 
 namespace esphome::runtime_image::testing {
@@ -362,6 +365,23 @@ static std::vector<uint8_t> pixel_bytes(TestableRuntimeImage &img) {
   return std::vector<uint8_t>(start, start + img.get_width_stride() * img.get_height());
 }
 
+// Shrinking a PNG keeps the first source pixel of each span, as the JPEG path does: the even rows and columns
+TEST(RuntimeImageDecoder, ShrunkPngKeepsTheFirstPixelOfEachSpan) {
+  TestableRuntimeImage img(PNG, image::IMAGE_TYPE_RGB, false, 2, 2);
+  ASSERT_TRUE(decode_all(img, PNG_RGB, sizeof(PNG_RGB), PNG));
+  ASSERT_EQ(img.get_width(), 2);
+  ASSERT_EQ(img.get_height(), 2);
+  for (int row = 0; row < 2; row++) {
+    for (int col = 0; col < 2; col++) {
+      const Color pixel = img.get_pixel(col, row);
+      const uint8_t *expected = PNG_RGB_EXPECTED[row * 2][col * 2];
+      EXPECT_EQ(pixel.r, expected[0]) << col << "," << row;
+      EXPECT_EQ(pixel.g, expected[1]) << col << "," << row;
+      EXPECT_EQ(pixel.b, expected[2]) << col << "," << row;
+    }
+  }
+}
+
 TEST(RuntimeImageDecoder, JpegDecoderStaysWarmAcrossDecodes) {
   TestableRuntimeImage img(JPEG);
 
@@ -377,6 +397,12 @@ TEST(RuntimeImageDecoder, JpegDecoderStaysWarmAcrossDecodes) {
   EXPECT_EQ(pixel_bytes(img), first_pixels) << "reused decoder must reproduce identical pixels";
 }
 
+// The RGB565 word at (x, y) of a decoded image, in its own byte order
+static uint16_t rgb565_word(const TestableRuntimeImage &img, int x, int y) {
+  const uint8_t *p = img.get_data_start() + (y * img.get_width() + x) * 2;
+  return p[0] | (p[1] << 8);
+}
+
 // JPEGDEC's colour conversion differs by one step between its SIMD and scalar builds, so each
 // channel is checked within one step; the byte order is still exact
 static void expect_rgb565_near(uint16_t actual, uint16_t expected, const char *order, size_t pixel) {
@@ -386,16 +412,12 @@ static void expect_rgb565_near(uint16_t actual, uint16_t expected, const char *o
 }
 
 TEST(RuntimeImageDecoder, JpegDecodesDirectlyToScaledRgb565WithBothByteOrders) {
-  // Halving the 8x8 gradient keeps its even rows and columns. The words are JPEGDEC's output for those
-  // pixels, red in the top five bits: a decode of the fixture with PIL gives (51, 7, 30) for source
-  // pixel (2, 0), which is word 0x3803 here.
-  static const uint16_t EXPECTED[4 * 4] = {
-      0x0000, 0x3803, 0x8008, 0xB80B, 0x0203, 0x3A07, 0x81EC, 0xBA0F,
-      0x03E7, 0x3C0B, 0x83F0, 0xBC13, 0x05EC, 0x3E0F, 0x85F4, 0xBE17,
-  };
+  // Halving the 8x8 gradient makes JPEGDEC decode it at half size, which averages each 2x2 block of pixels
+  TestableRuntimeImage full(JPEG, image::IMAGE_TYPE_RGB565, false, 8, 8);
   TestableRuntimeImage rgb565_little_endian(JPEG, image::IMAGE_TYPE_RGB565, false, 4, 4);
   TestableRuntimeImage rgb565_big_endian(JPEG, image::IMAGE_TYPE_RGB565, true, 4, 4);
 
+  ASSERT_TRUE(decode_all(full, JPEG_GRADIENT, sizeof(JPEG_GRADIENT)));
   ASSERT_TRUE(decode_all(rgb565_little_endian, JPEG_GRADIENT, sizeof(JPEG_GRADIENT)));
   ASSERT_TRUE(decode_all(rgb565_big_endian, JPEG_GRADIENT, sizeof(JPEG_GRADIENT)));
   ASSERT_EQ(rgb565_little_endian.get_width(), 4);
@@ -405,9 +427,45 @@ TEST(RuntimeImageDecoder, JpegDecodesDirectlyToScaledRgb565WithBothByteOrders) {
 
   const uint8_t *little = rgb565_little_endian.get_data_start();
   const uint8_t *big = rgb565_big_endian.get_data_start();
-  for (size_t i = 0; i < 4 * 4; i++) {
-    expect_rgb565_near(little[i * 2] | (little[i * 2 + 1] << 8), EXPECTED[i], "little-endian", i);
-    expect_rgb565_near((big[i * 2] << 8) | big[i * 2 + 1], EXPECTED[i], "big-endian", i);
+  for (int row = 0; row < 4; row++) {
+    for (int col = 0; col < 4; col++) {
+      int red = 0;
+      int green = 0;
+      int blue = 0;
+      for (int dy = 0; dy < 2; dy++) {
+        for (int dx = 0; dx < 2; dx++) {
+          const uint16_t word = rgb565_word(full, col * 2 + dx, row * 2 + dy);
+          red += word >> 11;
+          green += (word >> 5) & 0x3F;
+          blue += word & 0x1F;
+        }
+      }
+      const uint16_t expected = ((red + 2) / 4) << 11 | ((green + 2) / 4) << 5 | (blue + 2) / 4;
+      const size_t i = row * 4 + col;
+      expect_rgb565_near(little[i * 2] | (little[i * 2 + 1] << 8), expected, "little-endian", i);
+      expect_rgb565_near((big[i * 2] << 8) | big[i * 2 + 1], expected, "big-endian", i);
+    }
+  }
+}
+
+// The generic draw() path gets JPEGDEC's half size RGB8888 output. It must match the half size RGB565 decode checked
+// above. A full size RGB8888 decode is no reference: JPEGDEC's x86 SSE code writes it with red and blue swapped.
+TEST(RuntimeImageDecoder, JpegDecodesToScaledRgb) {
+  TestableRuntimeImage rgb565(JPEG, image::IMAGE_TYPE_RGB565, false, 4, 4);
+  TestableRuntimeImage rgb(JPEG, image::IMAGE_TYPE_RGB, false, 4, 4);
+  ASSERT_TRUE(decode_all(rgb565, JPEG_GRADIENT, sizeof(JPEG_GRADIENT)));
+  ASSERT_TRUE(decode_all(rgb, JPEG_GRADIENT, sizeof(JPEG_GRADIENT)));
+  ASSERT_EQ(static_cast<JpegDecoder *>(rgb.decoder())->get_scale(), 2);
+
+  for (int row = 0; row < 4; row++) {
+    for (int col = 0; col < 4; col++) {
+      const uint16_t word = rgb565_word(rgb565, col, row);
+      const Color pixel = rgb.get_pixel(col, row);
+      // RGB565 keeps the top 5 or 6 bits of each channel
+      EXPECT_LE(std::abs(pixel.r - ((word >> 11) << 3)), 8) << "pixel " << col << "," << row << " red";
+      EXPECT_LE(std::abs(pixel.g - (((word >> 5) & 0x3F) << 2)), 4) << "pixel " << col << "," << row << " green";
+      EXPECT_LE(std::abs(pixel.b - ((word & 0x1F) << 3)), 8) << "pixel " << col << "," << row << " blue";
+    }
   }
 }
 
@@ -415,10 +473,43 @@ TEST(RuntimeImageDecoder, JpegDecodesDirectlyToScaledRgb565WithBothByteOrders) {
 // prepare_rgb565_scaling_ rounds: source n covers targets ceil(n * target / source) up to the next start
 static uint16_t scaled_boundary(int n, int source, int target) { return (n * target + source - 1) / source; }
 
-// The RGB565 word at (x, y) of a decoded image, in its own byte order
-static uint16_t rgb565_word(const TestableRuntimeImage &img, int x, int y) {
-  const uint8_t *p = img.get_data_start() + (y * img.get_width() + x) * 2;
-  return p[0] | (p[1] << 8);
+// Every target pixel of a PNG drawn at a size that is not a whole multiple: enlarged with spans 1 or 2 pixels wide, and
+// shrunk with spans of 0, 1 or 2 pixels
+TEST(RuntimeImageDecoder, ScaledPngPaintsEachSourcePixelOverItsSpan) {
+  // A fixed size keeps the aspect ratio, so both are square
+  for (auto [width, height] : {std::pair{6, 6}, std::pair{3, 3}}) {
+    TestableRuntimeImage img(PNG, image::IMAGE_TYPE_RGB, false, width, height);
+    ASSERT_TRUE(decode_all(img, PNG_RGB, sizeof(PNG_RGB), PNG));
+    ASSERT_EQ(img.get_width(), width);
+    ASSERT_EQ(img.get_height(), height);
+    int painted = 0;
+    for (int m = 0; m < 4; m++) {
+      for (int n = 0; n < 4; n++) {
+        const uint8_t *expected = PNG_RGB_EXPECTED[m][n];
+        for (int y = scaled_boundary(m, 4, height); y < scaled_boundary(m + 1, 4, height); y++) {
+          for (int x = scaled_boundary(n, 4, width); x < scaled_boundary(n + 1, 4, width); x++) {
+            const Color pixel = img.get_pixel(x, y);
+            EXPECT_EQ(pixel.r, expected[0]) << width << "x" << height << " at " << x << "," << y;
+            EXPECT_EQ(pixel.g, expected[1]) << width << "x" << height << " at " << x << "," << y;
+            EXPECT_EQ(pixel.b, expected[2]) << width << "x" << height << " at " << x << "," << y;
+            painted++;
+          }
+        }
+      }
+    }
+    EXPECT_EQ(painted, width * height);
+  }
+}
+
+// JPEGDEC decodes at the smallest of full, 1/2, 1/4 and 1/8 size that still covers the buffer
+TEST(RuntimeImageDecoder, JpegDecodesAtTheSmallestSizeThatCoversTheBuffer) {
+  for (auto [size, scale] :
+       {std::pair{8, 1}, std::pair{5, 1}, std::pair{4, 2}, std::pair{3, 2}, std::pair{2, 4}, std::pair{1, 8}}) {
+    TestableRuntimeImage img(JPEG, image::IMAGE_TYPE_RGB565, false, size, size);
+    ASSERT_TRUE(decode_all(img, JPEG_GRADIENT, sizeof(JPEG_GRADIENT)));
+    EXPECT_EQ(img.get_width(), size);
+    EXPECT_EQ(static_cast<JpegDecoder *>(img.decoder())->get_scale(), scale) << size << "x" << size;
+  }
 }
 
 // Every scaled direct decode must equal the unscaled one sampled through the boundary table,
@@ -427,7 +518,8 @@ TEST(RuntimeImageDecoder, JpegDirectRgb565ScalesBySourcePixelSpans) {
   TestableRuntimeImage full(JPEG, image::IMAGE_TYPE_RGB565, false, 8, 8);
   ASSERT_TRUE(decode_all(full, JPEG_GRADIENT, sizeof(JPEG_GRADIENT)));
 
-  for (int size : {4, 6, 16}) {
+  // Sizes JPEGDEC cannot reach by scaling, so the full size decode is spread over the buffer
+  for (int size : {5, 6, 16}) {
     TestableRuntimeImage scaled(JPEG, image::IMAGE_TYPE_RGB565, false, size, size);
     ASSERT_TRUE(decode_all(scaled, JPEG_GRADIENT, sizeof(JPEG_GRADIENT)));
     ASSERT_EQ(scaled.get_width(), size);

tests/components/runtime_image/test_jpeg_source.cpp

@@ -5,6 +5,7 @@
 #include <vector>
 
 #include "esphome/components/runtime_image/image_decoder.h"
+#include "esphome/components/runtime_image/jpeg_decoder.h"
 #include "esphome/components/runtime_image/runtime_image.h"
 
 #ifdef USE_RUNTIME_IMAGE_JPEG
@@ -178,6 +179,7 @@ class SourceImage : public RuntimeImage {
   explicit SourceImage(image::ImageType type = image::IMAGE_TYPE_RGB, int width = 0, int height = 0)
       : RuntimeImage(JPEG, type, image::TRANSPARENCY_OPAQUE, nullptr, false, width, height) {}
   size_t decoded_bytes() const { return this->decoded_bytes_; }
+  int scale() const { return static_cast<const JpegDecoder *>(this->decoder_.get())->get_scale(); }
 };
 
 /// The file in memory; fails reads once fail_at bytes have been read
@@ -291,6 +293,23 @@ TEST(JpegSourceDecode, SteppedDirectRgb565MatchesFedDecode) {
   EXPECT_EQ(pixels(stepped), pixels(fed));
 }
 
+// decodeBegin() is given the same reduced scale as decode(), and decodeRows() keeps it for every step
+TEST(JpegSourceDecode, SteppedScaledDecodeMatchesFedDecode) {
+  for (auto type : {image::IMAGE_TYPE_RGB565, image::IMAGE_TYPE_RGB}) {
+    // 24x20 is half of 48x40, so JPEGDEC decodes at 1/2 size
+    SourceImage fed(type, 24, 20);
+    ASSERT_TRUE(decode_fed(fed));
+    ASSERT_EQ(fed.scale(), 2);
+
+    SourceImage stepped(type, 24, 20);
+    MemorySource source(JPEG_ROWS, sizeof(JPEG_ROWS));
+    int steps;
+    ASSERT_EQ(decode_stepped(stepped, source, steps), DECODE_STEP_DONE);
+    ASSERT_EQ(stepped.scale(), 2);
+    EXPECT_EQ(pixels(stepped), pixels(fed)) << "image type " << type;
+  }
+}
+
 TEST(JpegSourceDecode, WaitsForDataThatHasNotArrived) {
   SourceImage fed;
   ASSERT_TRUE(decode_fed(fed));

tests/integration/fixtures/uart_mock_ld2412.yaml

@@ -30,7 +30,7 @@ uart_mock:
     # Target state: 0x03 (moving + still)
     # detection_distance = 100 (LD2412 computes from moving target when MOVE_BITMASK set)
     #
-    # Frame layout (23 bytes):
+    # Frame layout (24 bytes):
     #   [0-3]   F4 F3 F2 F1 = data frame header
     #   [4-5]   0D 00       = length 13
     #   [6]     02          = data type (normal)
@@ -41,9 +41,10 @@ uart_mock:
     #   [12-13] 78 00       = still distance 120 (0x0078)
     #   [14]    19          = still energy 25
     #   [15-16] 64 00       = detect distance bytes (ignored by LD2412 code)
-    #   [17]    55          = data footer marker
-    #   [18]    00          = CRC/check
-    #   [19-22] F8 F7 F6 F5 = data frame footer
+    #   [17]    00          = padding
+    #   [18]    55          = data footer marker
+    #   [19]    00          = CRC/check
+    #   [20-23] F8 F7 F6 F5 = data frame footer
     - delay: 100ms
       inject_rx:
         [
@@ -56,6 +57,7 @@ uart_mock:
           0x78, 0x00,
           0x19,
           0x64, 0x00,
+          0x00,
           0x55, 0x00,
           0xF8, 0xF7, 0xF6, 0xF5,
         ]
@@ -67,13 +69,17 @@ uart_mock:
       inject_rx: [0xDE, 0xAD, 0xBE, 0xEF, 0x00, 0x11, 0x22]
 
     # Phase 3 (t=400ms): Truncated frame (header + partial data, no footer)
-    # Starts with a valid data frame header, so the parser waits for the 23 bytes its length announces.
+    # Starts with valid data frame header so parser accepts it.
+    # After this, buffer_pos_ = 8.
     - delay: 100ms
       inject_rx: [0xF4, 0xF3, 0xF2, 0xF1, 0x0D, 0x00, 0x02, 0xAA]
 
-    # Phase 4 (t=600ms): 60 bytes of 0xFF
-    # The first 15 complete the truncated frame's 23 bytes without its footer, so it is dropped
-    # with an 'Invalid length' warning; the rest cannot start a header and are dropped too.
+    # Phase 4 (t=600ms): Overflow - inject 60 bytes of 0xFF (MAX_LINE_LENGTH=54)
+    # Buffer has 8 bytes from phase 3 (garbage in phase 2 was rejected).
+    # Overflow math: buffer_pos_ starts at 8, overflow triggers when
+    # buffer_pos_ reaches 53 (MAX_LINE_LENGTH - 1). Need 45 more bytes to
+    # fill positions 8-52, then byte 46 triggers overflow. After overflow,
+    # buffer_pos_ = 0 and remaining 0xFF bytes are rejected (don't match header).
     - delay: 200ms
       inject_rx:
         [
@@ -85,8 +91,8 @@ uart_mock:
           0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
         ]
 
-    # Phase 5 (t=700ms): Valid frame after the garbage - recovery test
-    # The buffer is empty again, so this valid frame should parse correctly.
+    # Phase 5 (t=700ms): Valid frame after overflow - recovery test
+    # Buffer was reset by overflow. This valid frame should parse correctly.
     # Moving target: 50cm, energy 100
     # Still target: 75cm, energy 80
     # detection_distance = 50 (moving target distance, since MOVE_BITMASK set)
@@ -102,72 +108,7 @@ uart_mock:
           0x4B, 0x00,
           0x50,
           0x32, 0x00,
-          0x55, 0x00,
-          0xF8, 0xF7, 0xF6, 0xF5,
-        ]
-
-    # Phase 6 (t=3200ms): Values that spell the command footer 04 03 02 01
-    # Moving distance 772 (0x0304), moving energy 2, still distance 1: bytes 9 to 12 are the
-    # command frame footer, which must not end the frame early.
-    # Still energy 5, detection_distance = 772 (moving target distance, since MOVE_BITMASK set).
-    # The sensors hold and throttle values for a second, so the gap lets the phase 5 states
-    # reach the test before these replace them.
-    - delay: 2500ms
-      inject_rx:
-        [
-          0xF4, 0xF3, 0xF2, 0xF1,
-          0x0D, 0x00,
-          0x02, 0xAA,
-          0x03,
-          0x04, 0x03,
-          0x02,
-          0x01, 0x00,
-          0x05,
-          0x04, 0x03,
-          0x55, 0x00,
-          0xF8, 0xF7, 0xF6, 0xF5,
-        ]
-
-    # Phase 7 (t=5700ms): Truncated frame merged with a complete one
-    # The eight header bytes announce a 23 byte frame, so its window takes in the first 15 bytes of
-    # the valid frame that follows. The merged frame has no footer where the count says, so it is
-    # dropped and the bytes after its header are replayed, which recovers the valid frame.
-    # Moving distance 400, moving energy 7, still distance 200, still energy 9, detection_distance = 400
-    - delay: 2500ms
-      inject_rx:
-        [
-          0xF4, 0xF3, 0xF2, 0xF1, 0x0D, 0x00, 0x02, 0xAA,
-          0xF4, 0xF3, 0xF2, 0xF1,
-          0x0D, 0x00,
-          0x02, 0xAA,
-          0x03,
-          0x90, 0x01,
-          0x07,
-          0xC8, 0x00,
-          0x09,
-          0x90, 0x01,
-          0x55, 0x00,
-          0xF8, 0xF7, 0xF6, 0xF5,
-        ]
-
-    # Phase 8 (t=8200ms): Impossible counts, then a complete frame
-    # A command header counting 0xFFF6 bytes (65536 in total, which must not wrap to 0) and one counting
-    # 0xFFFF are each dropped as soon as the count arrives, and the valid frame after them is parsed.
-    # Moving distance 600, moving energy 11, still distance 300, still energy 13, detection distance 600
-    - delay: 2500ms
-      inject_rx:
-        [
-          0xFD, 0xFC, 0xFB, 0xFA, 0xF6, 0xFF,
-          0xFD, 0xFC, 0xFB, 0xFA, 0xFF, 0xFF,
-          0xF4, 0xF3, 0xF2, 0xF1,
-          0x0D, 0x00,
-          0x02, 0xAA,
-          0x03,
-          0x58, 0x02,
-          0x0B,
-          0x2C, 0x01,
-          0x0D,
-          0x58, 0x02,
+          0x00,
           0x55, 0x00,
           0xF8, 0xF7, 0xF6, 0xF5,
         ]

tests/integration/fixtures/uart_mock_ld2412_short_answers.yaml

@@ -1,88 +0,0 @@
-esphome:
-  name: uart-mock-ld2412-short-answers
-
-host:
-api:
-  batch_delay: 0ms  # Disable batching to receive all state updates
-logger:
-  level: VERBOSE
-
-external_components:
-  - source:
-      type: local
-      path: EXTERNAL_COMPONENT_PATH
-
-# Dummy uart entry to satisfy ld2412's DEPENDENCIES = ["uart"]
-# The actual UART bus used is the uart_mock component below
-uart:
-  baud_rate: 115200
-  port: /dev/null
-
-# Answers cut short, so the footer sits where their values would be, each followed by a whole one
-uart_mock:
-  id: mock_uart
-  baud_rate: 256000
-  auto_start: false
-  injections:
-    # Version answer cut after two version bytes
-    - delay: 100ms
-      inject_rx:
-        [
-          0xFD, 0xFC, 0xFB, 0xFA, 0x08, 0x00, 0xA0, 0x01, 0x00, 0x00,
-          0x00, 0x01, 0x07, 0x02,
-          0x04, 0x03, 0x02, 0x01,
-        ]
-
-    # Basic configuration answer cut after the minimum gate 7
-    - delay: 100ms
-      inject_rx:
-        [
-          0xFD, 0xFC, 0xFB, 0xFA, 0x05, 0x00, 0x12, 0x01, 0x00, 0x00,
-          0x07,
-          0x04, 0x03, 0x02, 0x01,
-        ]
-
-    # Whole version answer: firmware type 1, version 2.07.22062416
-    - delay: 100ms
-      inject_rx:
-        [
-          0xFD, 0xFC, 0xFB, 0xFA, 0x0C, 0x00, 0xA0, 0x01, 0x00, 0x00,
-          0x00, 0x01, 0x07, 0x02, 0x16, 0x24, 0x06, 0x22,
-          0x04, 0x03, 0x02, 0x01,
-        ]
-
-    # Whole basic configuration answer: gates 3 to 9, timeout 10 s, output pin level low
-    - delay: 100ms
-      inject_rx:
-        [
-          0xFD, 0xFC, 0xFB, 0xFA, 0x09, 0x00, 0x12, 0x01, 0x00, 0x00,
-          0x03, 0x09, 0x0A, 0x00, 0x01,
-          0x04, 0x03, 0x02, 0x01,
-        ]
-
-ld2412:
-  id: ld2412_dev
-  uart_id: mock_uart
-
-number:
-  - platform: ld2412
-    ld2412_id: ld2412_dev
-    min_distance_gate:
-      name: "Min Distance Gate"
-    max_distance_gate:
-      name: "Max Distance Gate"
-    timeout:
-      name: "Timeout"
-
-text_sensor:
-  - platform: ld2412
-    ld2412_id: ld2412_dev
-    version:
-      name: "Version"
-
-button:
-  - platform: template
-    name: "Start Scenario"
-    id: start_scenario_btn
-    on_press:
-      - lambda: 'id(mock_uart).start_scenario();'

tests/integration/fixtures/uart_mock_ld2412_truncated_answer.yaml

@@ -37,7 +37,7 @@ uart_mock:
           0x04, 0x00,  # length 4
           0xFE, 0x01,  # answer to command 0x00FE
           0x00, 0x00,  # status: success
-          0x04, 0x03, 0x02, 0x01,  # its footer; the 28 bytes the answer announced hold no footer, so it is dropped
+          0x04, 0x03, 0x02, 0x01,  # its footer; the merged 40-byte frame gets dropped
         ]
   # A complete answer after setup proves the parser recovered
   injections:

tests/integration/test_uart_mock_ld2412.py

@@ -5,12 +5,9 @@ test_uart_mock_ld2412 (normal mode):
   1. Happy path - valid data frame publishes correct sensor values
   2. Garbage resilience - random bytes don't crash the component
   3. Truncated frame handling - partial frame doesn't corrupt state
-  4. Truncated frame recovery - the frame is dropped once its length is reached
-  5. Post-garbage parsing - the next valid frame is parsed correctly
-  6. Footer bytes in the values - a frame whose values spell the command footer is parsed whole
-  7. Replay after a drop - a valid frame caught inside a dropped frame's window is still parsed
-  8. Impossible counts - a length field of 0xFFF6 or 0xFFFF is dropped and the next frame is parsed
-  9. TX logging - verifies LD2412 sends expected setup commands
+  4. Buffer overflow recovery - overflow resets the parser
+  5. Post-overflow parsing - next valid frame after overflow is parsed correctly
+  6. TX logging - verifies LD2412 sends expected setup commands
 
 test_uart_mock_ld2412_engineering (engineering mode):
   1. Engineering mode frames with per-gate energy data and light sensor
@@ -27,7 +24,6 @@ test_uart_mock_ld2412_engineering_truncated (truncated engineering mode):
 The gate threshold tests (footer_in_payload, truncated_answer, requery_after_giveup) cover
 answers that hold the frame footer or are truncated, writes that fill the gates without a
 number from the module's values, and writes held back until the module reports them.
-test_uart_mock_ld2412_short_answers: answers cut short publish nothing, the whole ones after them do.
 """
 
 from __future__ import annotations
@@ -43,7 +39,6 @@ from aioesphomeapi import (
     EntityState,
     NumberInfo,
     NumberState,
-    TextSensorState,
 )
 import pytest
 
@@ -144,7 +139,7 @@ async def test_uart_mock_ld2412(
     run_compiled: RunCompiledFunction,
     api_client_connected: APIClientConnectedFactory,
 ) -> None:
-    """Test LD2412 data parsing with happy path, garbage, a truncated frame, and recovery."""
+    """Test LD2412 data parsing with happy path, garbage, overflow, and recovery."""
     waiter = LineWaiter()
 
     collector = SensorStateCollector(
@@ -170,22 +165,6 @@ async def test_uart_mock_ld2412(
             and pytest.approx(100.0) in collector.sensor_states["moving_energy"]
             and pytest.approx(80.0) in collector.sensor_states["still_energy"]
             and pytest.approx(50.0) in collector.sensor_states["detection_distance"]
-            and pytest.approx(772.0) in collector.sensor_states["moving_distance"]
-            and pytest.approx(400.0) in collector.sensor_states["moving_distance"]
-            # Every value asserted below, so no state can still be in flight when the waiter fires
-            and pytest.approx(2.0) in collector.sensor_states["moving_energy"]
-            and pytest.approx(1.0) in collector.sensor_states["still_distance"]
-            and pytest.approx(5.0) in collector.sensor_states["still_energy"]
-            and pytest.approx(772.0) in collector.sensor_states["detection_distance"]
-            and pytest.approx(7.0) in collector.sensor_states["moving_energy"]
-            and pytest.approx(200.0) in collector.sensor_states["still_distance"]
-            and pytest.approx(9.0) in collector.sensor_states["still_energy"]
-            and pytest.approx(400.0) in collector.sensor_states["detection_distance"]
-            and pytest.approx(600.0) in collector.sensor_states["moving_distance"]
-            and pytest.approx(11.0) in collector.sensor_states["moving_energy"]
-            and pytest.approx(300.0) in collector.sensor_states["still_distance"]
-            and pytest.approx(13.0) in collector.sensor_states["still_energy"]
-            and pytest.approx(600.0) in collector.sensor_states["detection_distance"]
         )
     )
 
@@ -213,17 +192,17 @@ async def test_uart_mock_ld2412(
         assert collector.sensor_states["detection_distance"][0] == pytest.approx(100.0)
 
         # Wait for the recovery frame (Phase 5) to be parsed
-        # This proves the component survived garbage + truncated frame + filler bytes
+        # This proves the component survived garbage + truncated + overflow
         await wait_or_fail(
             recovery_received,
-            15.0,
+            3.0,
             "Timeout waiting for recovery frame",
             sensor_states=collector.sensor_states,
         )
 
-        # Verify the truncated frame was dropped with a warning
-        assert any("Invalid length" in line for line in waiter.lines), (
-            "Expected 'Invalid length' warning in logs"
+        # Verify overflow warning was logged
+        assert any("Max command length exceeded" in line for line in waiter.lines), (
+            "Expected 'Max command length exceeded' warning in logs"
         )
 
         # Verify LD2412 sent setup commands (TX logging)
@@ -245,27 +224,6 @@ async def test_uart_mock_ld2412(
         assert pytest.approx(80.0) in collector.sensor_states["still_energy"]
         assert pytest.approx(50.0) in collector.sensor_states["detection_distance"]
 
-        # Phase 6: the values 04 03 02 01 did not end the frame early
-        assert pytest.approx(772.0) in collector.sensor_states["moving_distance"]
-        assert pytest.approx(2.0) in collector.sensor_states["moving_energy"]
-        assert pytest.approx(1.0) in collector.sensor_states["still_distance"]
-        assert pytest.approx(5.0) in collector.sensor_states["still_energy"]
-        assert pytest.approx(772.0) in collector.sensor_states["detection_distance"]
-
-        # Phase 7: the valid frame inside the dropped frame's window was replayed and parsed
-        assert pytest.approx(400.0) in collector.sensor_states["moving_distance"]
-        assert pytest.approx(7.0) in collector.sensor_states["moving_energy"]
-        assert pytest.approx(200.0) in collector.sensor_states["still_distance"]
-        assert pytest.approx(9.0) in collector.sensor_states["still_energy"]
-        assert pytest.approx(400.0) in collector.sensor_states["detection_distance"]
-
-        # Phase 8: both impossible counts were dropped and the frame after them was parsed
-        assert pytest.approx(600.0) in collector.sensor_states["moving_distance"]
-        assert pytest.approx(11.0) in collector.sensor_states["moving_energy"]
-        assert pytest.approx(300.0) in collector.sensor_states["still_distance"]
-        assert pytest.approx(13.0) in collector.sensor_states["still_energy"]
-        assert pytest.approx(600.0) in collector.sensor_states["detection_distance"]
-
         # Verify binary sensors detected targets (from Phase 1 frame)
         assert collector.binary_states["has_target"][0] is True
         assert collector.binary_states["has_moving_target"][0] is True
@@ -573,7 +531,7 @@ async def test_uart_mock_ld2412_truncated_answer(
 
         try:
             _, gate_0_state, gate_5_state = await asyncio.gather(
-                waiter.wait_for("Invalid length", timeout=5.0),
+                waiter.wait_for("Dropping gate threshold answer", timeout=5.0),
                 gate_0_read,
                 gate_5_read,
             )
@@ -695,56 +653,3 @@ async def test_uart_mock_ld2412_requery_after_giveup(
         assert gate_0_state.state == pytest.approx(25.0)
         assert gate_5_values
         assert all(value == pytest.approx(30.0) for value in gate_5_values)
-
-
-@pytest.mark.asyncio
-async def test_uart_mock_ld2412_short_answers(
-    yaml_config: str,
-    run_compiled: RunCompiledFunction,
-    api_client_connected: APIClientConnectedFactory,
-) -> None:
-    """Test that answers cut short publish nothing and the whole answers after them do."""
-    loop = asyncio.get_running_loop()
-    # Number object_id: the value from the whole basic configuration answer
-    expected = {"min_distance_gate": 3.0, "max_distance_gate": 8.0, "timeout": 10.0}
-    number_states: dict[str, list[float]] = {name: [] for name in expected}
-    version_states: list[str] = []
-    key_to_name: dict[int, str] = {}
-    all_received = loop.create_future()
-
-    def on_state(state: EntityState) -> None:
-        if isinstance(state, TextSensorState) and not state.missing_state:
-            version_states.append(state.state)
-        elif (
-            isinstance(state, NumberState)
-            and not state.missing_state
-            and (name := key_to_name.get(state.key)) is not None
-        ):
-            number_states[name].append(state.state)
-        if not all_received.done() and version_states and all(number_states.values()):
-            all_received.set_result(True)
-
-    async with (
-        run_compiled(yaml_config),
-        api_client_connected() as client,
-    ):
-        entities, _ = await client.list_entities_services()
-        key_to_name.update(
-            {require_entity(entities, name, NumberInfo).key: name for name in expected}
-        )
-        await _wait_initial(client, entities, on_state)
-
-        start_btn = require_entity(entities, "start_scenario", ButtonInfo)
-        client.button_command(start_btn.key)
-
-        await wait_or_fail(
-            all_received,
-            5.0,
-            "Timeout waiting for the whole answers",
-            number_states=number_states,
-            version_states=version_states,
-        )
-        # Each entity saw exactly one value, the one from the whole answer
-        assert version_states == ["2.07.22062416"]
-        for name, value in expected.items():
-            assert number_states[name] == pytest.approx([value]), name