Further filter/clear <SkPaint>.setDither(true), this time in DlSkPaintDispatchHelper

display_list/skia/dl_sk_paint_dispatcher.cc

@@ -41,6 +41,17 @@ void DlSkPaintDispatchHelper::setAntiAlias(bool aa) {
   paint_.setAntiAlias(aa);
 }
 void DlSkPaintDispatchHelper::setDither(bool dither) {
+  // On the Impeller backend, we will only support dithering of *gradients*,
+  // and it will be enabled by default (without the option to disable it).
+  // Until Skia support is completely removed, we only want to respect the
+  // dither flag for gradients (otherwise it will also apply to, for example,
+  // images, which is not supported in Impeller).
+  //
+  // See https://github.com/flutter/flutter/issues/112498.
+  if (dither && !color_source_gradient_) {
+    return;
+  }
+
   paint_.setDither(dither);
 }
 void DlSkPaintDispatchHelper::setInvertColors(bool invert) {
@@ -73,6 +84,18 @@ void DlSkPaintDispatchHelper::setBlendMode(DlBlendMode mode) {
   paint_.setBlendMode(ToSk(mode));
 }
 void DlSkPaintDispatchHelper::setColorSource(const DlColorSource* source) {
+  // On the Impeller backend, we will only support dithering of *gradients*,
+  // and it will be enabled by default (without the option to disable it).
+  // Until Skia support is completely removed, we only want to respect the
+  // dither flag for gradients (otherwise it will also apply to, for example,
+  // images, which is not supported in Impeller).
+  //
+  // See https://github.com/flutter/flutter/issues/112498.
+  color_source_gradient_ = source->isGradient();
+  if (!color_source_gradient_) {
+    paint_.setDither(false);
+  }
+
   paint_.setShader(ToSk(source));
 }
 void DlSkPaintDispatchHelper::setImageFilter(const DlImageFilter* filter) {

display_list/skia/dl_sk_paint_dispatcher.h

@@ -57,6 +57,7 @@ class DlSkPaintDispatchHelper : public virtual DlOpReceiver {
 
  private:
   SkPaint paint_;
+  bool color_source_gradient_ = false;
   bool invert_colors_ = false;
   sk_sp<SkColorFilter> sk_color_filter_;
 

display_list/skia/dl_sk_paint_dispatcher_unittests.cc

@@ -31,5 +31,20 @@ TEST(DisplayListUtils, OverRestore) {
   helper.restore();
 }
 
+// https://github.com/flutter/flutter/issues/132860.
+TEST(DisplayListUtils, SetDitherIgnoredIfColorSourceNotGradient) {
+  MockDispatchHelper helper;
+  helper.setDither(true);
+  EXPECT_FALSE(helper.paint().isDither());
+}
+
+// https://github.com/flutter/flutter/issues/132860.
+TEST(DisplayListUtils, SetColorSourceClearsDitherIfNotGradient) {
+  MockDispatchHelper helper;
+  helper.setDither(true);
+  helper.setColorSource(nullptr);
+  EXPECT_FALSE(helper.paint().isDither());
+}
+
 }  // namespace testing
 }  // namespace flutter