[Impeller] Add the paint color to the key of the text shadow cache (flutter#177140)

Fixes flutter#176146

Author: jason-simmons

engine/src/flutter/impeller/display_list/BUILD.gn

@@ -114,6 +114,7 @@ template("display_list_unittests_component") {
     deps += [
       ":display_list",
       "../playground:playground_test",
+      "//flutter/display_list/testing:display_list_testing",
       "//flutter/impeller/golden_tests:screenshot",
       "//flutter/txt",
     ]

engine/src/flutter/impeller/display_list/aiks_dl_text_unittests.cc

@@ -11,6 +11,7 @@
 #include "flutter/display_list/effects/dl_color_source.h"
 #include "flutter/display_list/effects/dl_mask_filter.h"
 #include "flutter/display_list/geometry/dl_path_builder.h"
+#include "flutter/display_list/testing/dl_test_snippets.h"
 #include "flutter/fml/build_config.h"
 #include "flutter/impeller/display_list/aiks_unittests.h"
 #include "flutter/testing/testing.h"
@@ -834,6 +835,44 @@ TEST_P(AiksTest, MultipleTextWithShadowCache) {
             5u);
 }
 
+TEST_P(AiksTest, MultipleColorWithShadowCache) {
+  DisplayListBuilder builder;
+  builder.Scale(GetContentScale().x, GetContentScale().y);
+  DlPaint paint;
+  paint.setColor(DlColor::kWhite());
+  builder.DrawPaint(paint);
+
+  AiksContext aiks_context(GetContext(),
+                           std::make_shared<TypographerContextSkia>());
+  // Cache empty
+  EXPECT_EQ(aiks_context.GetContentContext()
+                .GetTextShadowCache()
+                .GetCacheSizeForTesting(),
+            0u);
+
+  SkFont sk_font = flutter::testing::CreateTestFontOfSize(12);
+
+  std::array<DlColor, 4> colors{DlColor::kRed(), DlColor::kGreen(),
+                                DlColor::kBlue(), DlColor::kRed()};
+  for (const auto& color : colors) {
+    ASSERT_TRUE(RenderTextInCanvasSkia(
+        GetContext(), builder, "A", kFontFixture,
+        TextRenderOptions{
+            .color = color,
+            .filter = DlBlurMaskFilter::Make(DlBlurStyle::kNormal, 4)},
+        sk_font));
+  }
+
+  DisplayListToTexture(builder.Build(), {400, 400}, aiks_context);
+
+  // The count of cache entries should match the number of distinct colors
+  // in the list.  Repeated usage of a color should not add to the cache.
+  EXPECT_EQ(aiks_context.GetContentContext()
+                .GetTextShadowCache()
+                .GetCacheSizeForTesting(),
+            3u);
+}
+
 TEST_P(AiksTest, SingleIconShadowTest) {
   DisplayListBuilder builder;
   builder.Scale(GetContentScale().x, GetContentScale().y);

engine/src/flutter/impeller/display_list/canvas.cc

@@ -1649,7 +1649,8 @@ bool Canvas::AttemptBlurredTextOptimization(
       /*p_identifier=*/identifier,
       /*p_is_single_glyph=*/maybe_glyph.has_value(),
       /*p_font=*/text_frame->GetFont(),
-      /*p_sigma=*/paint.mask_blur_descriptor->sigma);
+      /*p_sigma=*/paint.mask_blur_descriptor->sigma,
+      /*p_color=*/paint.color);
 
   std::optional<Entity> result = renderer_.GetTextShadowCache().Lookup(
       renderer_, entity, filter, cache_key);

engine/src/flutter/impeller/entity/contents/text_shadow_cache.cc

@@ -19,13 +19,15 @@ TextShadowCache::TextShadowCacheKey::TextShadowCacheKey(Scalar p_max_basis,
                                                         int64_t p_identifier,
                                                         bool p_is_single_glyph,
                                                         const Font& p_font,
-                                                        Sigma p_sigma)
+                                                        Sigma p_sigma,
+                                                        Color p_color)
     : max_basis(p_max_basis),
       identifier(p_identifier),
       is_single_glyph(p_is_single_glyph),
       font(p_font),
       rounded_sigma(Rational(std::round(p_sigma.sigma * kMaxSigmaDenominator),
-                             kMaxSigmaDenominator)) {}
+                             kMaxSigmaDenominator)),
+      color(p_color) {}
 
 void TextShadowCache::MarkFrameStart() {
   for (auto& entry : entries_) {

engine/src/flutter/impeller/entity/contents/text_shadow_cache.h

@@ -41,18 +41,21 @@ class TextShadowCache {
     bool is_single_glyph;
     Font font;
     Rational rounded_sigma;
+    Color color;
 
     TextShadowCacheKey(Scalar p_max_basis,
                        int64_t p_identifier,
                        bool p_is_single_glyph,
                        const Font& p_font,
-                       Sigma p_sigma);
+                       Sigma p_sigma,
+                       Color p_color);
 
     struct Hash {
       std::size_t operator()(const TextShadowCacheKey& key) const {
         return fml::HashCombine(key.max_basis, key.identifier,
                                 key.is_single_glyph, key.font.GetHash(),
-                                key.rounded_sigma.GetHash());
+                                key.rounded_sigma.GetHash(),
+                                key.color.ToARGB());
       }
     };
 
@@ -63,7 +66,7 @@ class TextShadowCache {
                lhs.identifier == rhs.identifier &&
                lhs.is_single_glyph == rhs.is_single_glyph &&
                lhs.font.IsEqual(rhs.font) &&
-               lhs.rounded_sigma == rhs.rounded_sigma;
+               lhs.rounded_sigma == rhs.rounded_sigma && lhs.color == rhs.color;
       }
     };
   };