[display] Build on_page_change with build_callback_automation and compile it out when unused (#20456)

esphome/components/display/__init__.py

@@ -21,7 +21,6 @@ from esphome.const import (
     CONF_PAGES,
     CONF_ROTATION,
     CONF_TO,
-    CONF_TRIGGER_ID,
     CONF_UPDATE_INTERVAL,
     CONF_WIDTH,
     SCHEDULER_DONT_RUN,
@@ -39,14 +38,13 @@ DisplayPage = display_ns.class_("DisplayPage")
 DisplayPagePtr = DisplayPage.operator("ptr")
 DisplayRef = Display.operator("ref")
 DisplayPageShowAction = display_ns.class_("DisplayPageShowAction", automation.Action)
-DisplayOnPageChangeTrigger = display_ns.class_(
-    "DisplayOnPageChangeTrigger", automation.Trigger
-)
 
 CONF_ON_PAGE_CHANGE = "on_page_change"
 CONF_SHOW_TEST_CARD = "show_test_card"
 CONF_UNSPECIFIED = "unspecified"
 
+_request_page_change_slot = cg.slot_counter("DISPLAY_PAGE_CHANGE_CALLBACK_COUNT")
+
 DISPLAY_ROTATIONS = {
     0: display_ns.DISPLAY_ROTATION_0_DEGREES,
     90: display_ns.DISPLAY_ROTATION_90_DEGREES,
@@ -99,9 +97,6 @@ FULL_DISPLAY_SCHEMA = BASIC_DISPLAY_SCHEMA.extend(
         ),
         cv.Optional(CONF_ON_PAGE_CHANGE): automation.validate_automation(
             {
-                cv.GenerateID(CONF_TRIGGER_ID): cv.declare_id(
-                    DisplayOnPageChangeTrigger
-                ),
                 cv.Optional(CONF_FROM): cv.use_id(DisplayPage),
                 cv.Optional(CONF_TO): cv.use_id(DisplayPage),
             }
@@ -137,15 +132,18 @@ async def setup_display_core_(var, config):
             pages.append(page)
         cg.add(var.set_pages(pages))
     for conf in config.get(CONF_ON_PAGE_CHANGE, []):
-        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        if CONF_FROM in conf:
-            page = await cg.get_variable(conf[CONF_FROM])
-            cg.add(trigger.set_from(page))
-        if CONF_TO in conf:
-            page = await cg.get_variable(conf[CONF_TO])
-            cg.add(trigger.set_to(page))
-        await automation.build_automation(
-            trigger, [(DisplayPagePtr, "from"), (DisplayPagePtr, "to")], conf
+        _request_page_change_slot(str(var))
+        checks = []
+        for key, name in ((CONF_FROM, "from"), (CONF_TO, "to")):
+            if (page_id := conf.get(key)) is not None:
+                page = await cg.get_variable(page_id)
+                checks.append(f"{name} == ::{page}")
+        await automation.build_callback_automation(
+            var,
+            "add_on_page_change_callback",
+            [(DisplayPagePtr, "from"), (DisplayPagePtr, "to")],
+            conf,
+            when=" && ".join(checks) or None,
         )
     if config.get(CONF_SHOW_TEST_CARD):
         cg.add(var.show_test_card())

esphome/components/display/display.cpp

@@ -678,12 +678,14 @@ void Display::set_pages(std::vector<DisplayPage *> pages) {
 }
 
 void Display::show_page(DisplayPage *page) {
-  this->previous_page_ = this->page_;
+#ifdef DISPLAY_PAGE_CHANGE_CALLBACK_COUNT
+  DisplayPage *previous = this->page_;
   this->page_ = page;
-  if (this->previous_page_ != this->page_) {
-    for (auto *t : on_page_change_triggers_)
-      t->process(this->previous_page_, this->page_);
-  }
+  if (previous != page)
+    this->page_change_callback_.call(previous, page);
+#else
+  this->page_ = page;
+#endif
 }
 
 void Display::do_update_() {
@@ -700,11 +702,6 @@ void Display::do_update_() {
   this->clear_clipping_();
 }
 
-void DisplayOnPageChangeTrigger::process(DisplayPage *from, DisplayPage *to) {
-  if ((this->from_ == nullptr || this->from_ == from) && (this->to_ == nullptr || this->to_ == to))
-    this->trigger(from, to);
-}
-
 void Display::strftime(int x, int y, BaseFont *font, Color color, Color background, TextAlign align, const char *format,
                        ESPTime time) {
   char buffer[64];

esphome/components/display/display.h

@@ -7,6 +7,8 @@
 
 #include "esphome/core/color.h"
 #include "esphome/core/automation.h"
+#include "esphome/core/defines.h"
+#include "esphome/core/helpers.h"
 #include "esphome/core/time.h"
 #include "esphome/core/log.h"
 #include "display_color_utils.h"
@@ -173,7 +175,6 @@ enum RegularPolygonDrawing {
 
 class Display;
 class DisplayPage;
-class DisplayOnPageChangeTrigger;
 
 /** Optimized display writer that uses function pointers for stateless lambdas.
  *
@@ -702,7 +703,11 @@ class Display : public PollingComponent {
 
   const DisplayPage *get_active_page() const { return this->page_; }
 
-  void add_on_page_change_trigger(DisplayOnPageChangeTrigger *t) { this->on_page_change_triggers_.push_back(t); }
+#ifdef DISPLAY_PAGE_CHANGE_CALLBACK_COUNT
+  template<typename F> void add_on_page_change_callback(F &&callback) {
+    this->page_change_callback_.add(std::forward<F>(callback));
+  }
+#endif
 
   /// Internal method to set the display rotation with.
   virtual void set_rotation(DisplayRotation rotation);
@@ -809,8 +814,9 @@ class Display : public PollingComponent {
   DisplayRotation rotation_{DISPLAY_ROTATION_0_DEGREES};
   display_writer_t writer_{};
   DisplayPage *page_{nullptr};
-  DisplayPage *previous_page_{nullptr};
-  std::vector<DisplayOnPageChangeTrigger *> on_page_change_triggers_;
+#ifdef DISPLAY_PAGE_CHANGE_CALLBACK_COUNT
+  StaticCallbackManager<DISPLAY_PAGE_CHANGE_CALLBACK_COUNT, void(DisplayPage *, DisplayPage *)> page_change_callback_;
+#endif
   bool auto_clear_enabled_{true};
   std::vector<Rect> clipping_rectangle_;
   uint8_t wdt_pixel_counter_{0};
@@ -850,18 +856,6 @@ template<typename... Ts> class DisplayPageShowAction final : public Action<Ts...
   }
 };
 
-class DisplayOnPageChangeTrigger final : public Trigger<DisplayPage *, DisplayPage *> {
- public:
-  explicit DisplayOnPageChangeTrigger(Display *parent) { parent->add_on_page_change_trigger(this); }
-  void process(DisplayPage *from, DisplayPage *to);
-  void set_from(DisplayPage *p) { this->from_ = p; }
-  void set_to(DisplayPage *p) { this->to_ = p; }
-
- protected:
-  DisplayPage *from_{nullptr};
-  DisplayPage *to_{nullptr};
-};
-
 const LogString *text_align_to_string(TextAlign textalign);
 
 }  // namespace esphome::display

esphome/core/defines.h

@@ -63,6 +63,7 @@
 #define USE_DEEP_SLEEP_ON_WAKE
 #define USE_DEVICES
 #define USE_DISPLAY
+#define DISPLAY_PAGE_CHANGE_CALLBACK_COUNT 1
 #define USE_ENTITY_DEVICE_CLASS
 #define USE_ENTITY_ICON
 #define USE_ENTITY_UNIT_OF_MEASUREMENT