[light] Shrink LightState by 12 bytes per light (#19711)

tests/benchmarks/components/light/__init__.py

@@ -1,5 +1,5 @@
 import esphome.codegen as cg
-from esphome.components.light import generate_gamma_table
+from esphome.components.light import gamma_table_initializer
 from tests.testing_helpers import ComponentManifestOverride
 
 
@@ -12,15 +12,13 @@ def override_manifest(manifest: ComponentManifestOverride) -> None:
     async def to_code(config):
         await original_to_code(config)
         cg.add_define("USE_LIGHT_GAMMA_LUT")
-        # Use the light component's own generate_gamma_table() so the
+        # Use the light component's own gamma_table_initializer() so the
         # benchmark stays in sync with any formula changes.
-        forward = generate_gamma_table(2.8)
-        values = ", ".join(f"0x{int(v):04X}" for v in forward)
-        # Use extern-visible (non-static) array so the benchmark .cpp
-        # can reference it via extern declaration.
+        # Extern-visible (non-static) so the benchmark .cpp can reference it.
         cg.add_global(
             cg.RawStatement(
-                f"extern const uint16_t bench_gamma_2_8_fwd[256] PROGMEM = {{{values}}};"
+                "extern const esphome::light::GammaTable bench_gamma_2_8 PROGMEM = "
+                f"{gamma_table_initializer(2.8)};"
             )
         )
 

tests/benchmarks/components/light/bench_light_call.cpp

@@ -4,8 +4,8 @@
 #include "esphome/components/light/light_state.h"
 
 // Gamma 2.8 forward LUT generated by the light component's Python codegen
-// (see tests/benchmarks/components/light/__init__.py which calls generate_gamma_table())
-extern const uint16_t bench_gamma_2_8_fwd[256];
+// (see tests/benchmarks/components/light/__init__.py which calls gamma_table_initializer())
+extern const esphome::light::GammaTable bench_gamma_2_8;
 
 namespace esphome::benchmarks {
 
@@ -37,8 +37,7 @@ static void setup_rgbww_light(BenchLightOutput &output, TestLightState &light) {
   output.traits_.set_max_mireds(500.0f);
   light.configure("test_light");
   light.set_default_transition_length(0);
-  light.set_gamma_correct(2.8f);
-  light.set_gamma_table(bench_gamma_2_8_fwd);
+  light.set_gamma_table(&bench_gamma_2_8);
 }
 
 // --- LightCall::perform() with instant RGB color change (Home Assistant API path) ---

tests/component_tests/light/test_light_state_layout.py

@@ -0,0 +1,37 @@
+"""Limits and flash layout that let LightState stay small."""
+
+import pytest
+
+from esphome import config_validation as cv
+from esphome.components.light.effects import (
+    MAX_EFFECTS,
+    MONOCHROMATIC_EFFECTS,
+    validate_effects,
+)
+
+
+def _effects(count: int) -> list[dict[str, dict[str, str]]]:
+    return [{"pulse": {"name": f"Pulse {i}"}} for i in range(count)]
+
+
+def test_rejects_more_effects_than_the_index_holds() -> None:
+    with pytest.raises(cv.Invalid, match=f"at most {MAX_EFFECTS} effects"):
+        validate_effects(MONOCHROMATIC_EFFECTS)(_effects(MAX_EFFECTS + 1))
+
+
+def test_accepts_a_normal_effect_list() -> None:
+    assert len(validate_effects(MONOCHROMATIC_EFFECTS)(_effects(3))) == 3
+
+
+def test_gamma_table_initializer_holds_the_lut_then_gamma_times_100() -> None:
+    from esphome.components.light import gamma_table_initializer, generate_gamma_table
+
+    init = gamma_table_initializer(2.8)
+    lut = ", ".join(f"0x{int(v):04X}" for v in generate_gamma_table(2.8))
+    assert init == f"{{{{{lut}}}, 280}}"
+
+
+def test_gamma_table_initializer_saturates_gamma_that_overflows_uint16() -> None:
+    from esphome.components.light import gamma_table_initializer
+
+    assert gamma_table_initializer(1000.0).endswith(", 65535}")

tests/components/light/__init__.py

@@ -8,6 +8,8 @@ def override_manifest(manifest: ComponentManifestOverride) -> None:
         cg.add_define("USE_WEBSERVER")
         # api_connection.cpp reports the port whenever USE_WEBSERVER is set
         cg.add_define("USE_WEBSERVER_PORT", 80)
+        # The gamma table and its stored gamma are behind this define
+        cg.add_define("USE_LIGHT_GAMMA_LUT")
 
     manifest.to_code = to_code_testing
     manifest.dependencies = manifest.dependencies + ["json"]

tests/components/light/common.yaml

@@ -254,6 +254,7 @@ light:
       state: INITIAL
       brightness: INITIAL
   - platform: monochromatic
+    flash_transition_length: 100ms
     id: test_monochromatic_light
     name: Monochromatic Light
     output: test_ledc_1

tests/components/light/test_light_state.cpp

@@ -0,0 +1,68 @@
+#include <gtest/gtest.h>
+
+#include "esphome/components/light/light_effect.h"
+#include "esphome/components/light/light_output.h"
+#include "esphome/components/light/light_state.h"
+
+namespace esphome::light::testing {
+
+namespace {
+
+class BrightnessOutput : public LightOutput {
+ public:
+  LightTraits get_traits() override {
+    LightTraits traits;
+    traits.set_supported_color_modes({ColorMode::BRIGHTNESS});
+    return traits;
+  }
+  void write_state(LightState *state) override {}
+};
+
+class NoopEffect : public LightEffect {
+ public:
+  using LightEffect::LightEffect;
+  void apply() override {}
+};
+
+// start_effect_() is where the uint32_t index is narrowed to the stored uint16_t.
+class TestableLightState : public LightState {
+ public:
+  using LightState::LightState;
+  using LightState::start_effect_;
+};
+
+}  // namespace
+
+// add_effects() is public, so an external component can exceed the codegen cap on effect count;
+// an index the uint16_t can't hold must be ignored rather than wrap onto another effect.
+TEST(LightStateEffect, IndexAboveUint16IsIgnoredAndKeepsTheActiveEffect) {
+  BrightnessOutput output;
+  TestableLightState state(&output);
+  NoopEffect effect("Noop");
+  state.add_effects({&effect});
+
+  state.start_effect_(1);
+  ASSERT_EQ(state.get_current_effect_index(), 1u);
+
+  state.start_effect_(0x10000u);  // unchecked narrowing wraps this to 0, which stops the effect
+  EXPECT_EQ(state.get_current_effect_index(), 1u);
+}
+
+// get_gamma_correct() reads the gamma codegen stores after the lookup table, rounded to two decimals.
+TEST(LightStateGamma, ReadsTheGammaStoredWithTheTable) {
+  static constexpr GammaTable TABLE{{}, 280};
+  BrightnessOutput output;
+  LightState state(&output);
+  state.set_gamma_table(&TABLE);
+  EXPECT_FLOAT_EQ(state.get_gamma_correct(), 2.8f);
+  EXPECT_EQ(state.get_gamma_table(), TABLE.lut);
+}
+
+TEST(LightStateGamma, IsZeroWithoutATable) {
+  BrightnessOutput output;
+  LightState state(&output);
+  EXPECT_FLOAT_EQ(state.get_gamma_correct(), 0.0f);
+  EXPECT_EQ(state.get_gamma_table(), nullptr);
+}
+
+}  // namespace esphome::light::testing