[Impeller] CoverGeometry transforms its bounds.

impeller/aiks/aiks_unittests.cc

@@ -2911,6 +2911,36 @@ TEST_P(AiksTest, CanRenderClippedRuntimeEffects) {
   ASSERT_TRUE(OpenPlaygroundHere(canvas.EndRecordingAsPicture()));
 }
 
+TEST_P(AiksTest, DrawPaintTransformsBounds) {
+  if (GetParam() != PlaygroundBackend::kMetal) {
+    GTEST_SKIP_("This backend doesn't support runtime effects.");
+  }
+
+  auto runtime_stage = OpenAssetAsRuntimeStage("gradient.frag.iplr");
+  ASSERT_TRUE(runtime_stage->IsDirty());
+
+  struct FragUniforms {
+    Size size;
+  } frag_uniforms = {.size = Size::MakeWH(400, 400)};
+  auto uniform_data = std::make_shared<std::vector<uint8_t>>();
+  uniform_data->resize(sizeof(FragUniforms));
+  memcpy(uniform_data->data(), &frag_uniforms, sizeof(FragUniforms));
+
+  std::vector<RuntimeEffectContents::TextureInput> texture_inputs;
+
+  Paint paint;
+  paint.color_source = ColorSource::MakeRuntimeEffect(
+      runtime_stage, uniform_data, texture_inputs);
+
+  Canvas canvas;
+  canvas.Save();
+  canvas.Scale(GetContentScale());
+  canvas.DrawPaint(paint);
+  canvas.Restore();
+
+  ASSERT_TRUE(OpenPlaygroundHere(canvas.EndRecordingAsPicture()));
+}
+
 TEST_P(AiksTest, CanDrawPoints) {
   std::vector<Point> points = {
       {0, 0},      //

impeller/entity/geometry/cover_geometry.cc

@@ -23,13 +23,16 @@ GeometryResult CoverGeometry::GetPositionBuffer(const ContentContext& renderer,
       .vertex_buffer =
           {
               .vertex_buffer = host_buffer.Emplace(
-                  rect.GetPoints().data(), 8 * sizeof(float), alignof(float)),
+                  rect.GetTransformedPoints(entity.GetTransformation().Invert())
+                      .data(),
+                  8 * sizeof(float), alignof(float)),
               .index_buffer = host_buffer.Emplace(
                   kRectIndicies, 4 * sizeof(uint16_t), alignof(uint16_t)),
               .vertex_count = 4,
               .index_type = IndexType::k16bit,
           },
-      .transform = Matrix::MakeOrthographic(pass.GetRenderTargetSize()),
+      .transform = Matrix::MakeOrthographic(pass.GetRenderTargetSize()) *
+                   entity.GetTransformation(),
       .prevent_overdraw = false,
   };
 }

impeller/fixtures/BUILD.gn

@@ -57,6 +57,7 @@ impellerc("runtime_stages") {
   shaders = [
     "ink_sparkle.frag",
     "runtime_stage_example.frag",
+    "gradient.frag",
   ]
   sl_file_extension = "iplr"
   shader_target_flag = "--runtime-stage-metal"

impeller/fixtures/gradient.frag

@@ -0,0 +1,10 @@
+#include <flutter/runtime_effect.glsl>
+
+uniform vec2 uSize;
+
+out vec4 fragColor;
+
+void main() {
+  float v = FlutterFragCoord().y / uSize.y;
+  fragColor = vec4(v, v, v, 1);
+}