[dart:ui] remove expensive index assertion in Vertices.

impeller/display_list/aiks_dl_vertices_unittests.cc

@@ -354,6 +354,30 @@ TEST_P(AiksTest, DrawVerticesPremultipliesColors) {
   ASSERT_TRUE(OpenPlaygroundHere(builder.Build()));
 }
 
+TEST_P(AiksTest, DrawVerticesWithInvalidIndices) {
+  std::vector<SkPoint> positions = {
+      SkPoint::Make(100, 300), SkPoint::Make(200, 100), SkPoint::Make(300, 300),
+      SkPoint::Make(200, 500)};
+  std::vector<uint16_t> indices = {0, 1, 2, 0, 2, 3, 99, 100, 101};
+
+  auto vertices = flutter::DlVertices::Make(
+      flutter::DlVertexMode::kTriangles, positions.size(), positions.data(),
+      /*texture_coordinates=*/nullptr, /*colors=*/nullptr, indices.size(),
+      indices.data());
+
+  EXPECT_EQ(vertices->bounds(), SkRect::MakeLTRB(100, 100, 300, 500));
+
+  flutter::DisplayListBuilder builder;
+  flutter::DlPaint paint;
+  paint.setBlendMode(flutter::DlBlendMode::kSrcOver);
+  paint.setColor(flutter::DlColor::kRed());
+
+  builder.DrawRect(SkRect::MakeLTRB(0, 0, 400, 400), paint);
+  builder.DrawVertices(vertices, flutter::DlBlendMode::kSrc, paint);
+
+  ASSERT_TRUE(OpenPlaygroundHere(builder.Build()));
+}
+
 // All four vertices should form a solid red rectangle with no gaps.
 // The blur rectangle drawn under them should not be visible.
 TEST_P(AiksTest, DrawVerticesTextureCoordinatesWithFragmentShader) {

lib/ui/painting.dart

@@ -4762,17 +4762,20 @@ base class Vertices extends NativeFieldWrapperClass1 {
     if (textureCoordinates != null && textureCoordinates.length != positions.length) {
       throw ArgumentError('"positions" and "textureCoordinates" lengths must match.');
     }
-    if (indices != null) {
-      for (int index = 0; index < indices.length; index += 1) {
-        if (indices[index] >= positions.length) {
-          throw ArgumentError(
-            '"indices" values must be valid indices in the positions list '
-            '(i.e. numbers in the range 0..${positions.length - 1}), '
-            'but indices[$index] is ${indices[index]}, which is too big.',
-          );
+    assert(() {
+      if (indices != null) {
+        for (int index = 0; index < indices.length; index += 1) {
+          if (indices[index] >= positions.length) {
+            throw ArgumentError(
+              '"indices" values must be valid indices in the positions list '
+              '(i.e. numbers in the range 0..${positions.length - 1}), '
+              'but indices[$index] is ${indices[index]}, which is too big.',
+            );
+          }
         }
       }
-    }
+      return true;
+    }());
     final Float32List encodedPositions = _encodePointList(positions);
     final Float32List? encodedTextureCoordinates = (textureCoordinates != null)
       ? _encodePointList(textureCoordinates)
@@ -4849,17 +4852,20 @@ base class Vertices extends NativeFieldWrapperClass1 {
     if (textureCoordinates != null && textureCoordinates.length != positions.length) {
       throw ArgumentError('"positions" and "textureCoordinates" lengths must match.');
     }
-    if (indices != null) {
-      for (int index = 0; index < indices.length; index += 1) {
-        if (indices[index] * 2 >= positions.length) {
-          throw ArgumentError(
-            '"indices" values must be valid indices in the positions list '
-            '(i.e. numbers in the range 0..${positions.length ~/ 2 - 1}), '
-            'but indices[$index] is ${indices[index]}, which is too big.',
-          );
+    assert(() {
+      if (indices != null) {
+        for (int index = 0; index < indices.length; index += 1) {
+          if (indices[index] * 2 >= positions.length) {
+            throw ArgumentError(
+              '"indices" values must be valid indices in the positions list '
+              '(i.e. numbers in the range 0..${positions.length ~/ 2 - 1}), '
+              'but indices[$index] is ${indices[index]}, which is too big.',
+            );
+          }
         }
       }
-    }
+      return true;
+    }());
     if (!_init(this, mode.index, positions, textureCoordinates, colors, indices)) {
       throw ArgumentError('Invalid configuration for vertices.');
     }

testing/dart/painting_test.dart

@@ -34,6 +34,12 @@ void main() {
   });
 
   test('Vertices.raw checks', () {
+    bool assertsEnabled = false;
+    assert(() {
+      assertsEnabled = true;
+      return true;
+    }());
+
     try {
       Vertices.raw(
         VertexMode.triangles,
@@ -43,6 +49,8 @@ void main() {
     } on ArgumentError catch (e) {
       expect('$e', 'Invalid argument(s): "positions" must have an even number of entries (each coordinate is an x,y pair).');
     }
+
+    Object? indicesError;
     try {
       Vertices.raw(
         VertexMode.triangles,
@@ -51,8 +59,14 @@ void main() {
       );
       throw 'Vertices.raw did not throw the expected error.';
     } on ArgumentError catch (e) {
-      expect('$e', 'Invalid argument(s): "indices" values must be valid indices in the positions list (i.e. numbers in the range 0..2), but indices[2] is 5, which is too big.');
+      indicesError = e;
     }
+    if (assertsEnabled) {
+      expect('$indicesError', 'Invalid argument(s): "indices" values must be valid indices in the positions list (i.e. numbers in the range 0..2), but indices[2] is 5, which is too big.');
+    } else {
+      expect(indicesError, null);
+    }
+
     Vertices.raw( // This one does not throw.
       VertexMode.triangles,
       Float32List.fromList(const <double>[0.0, 0.0]),

testing/impeller_golden_tests_output.txt

@@ -593,6 +593,9 @@ impeller_Play_AiksTest_DrawVerticesSolidColorTrianglesWithoutIndices_Vulkan.png
 impeller_Play_AiksTest_DrawVerticesTextureCoordinatesWithFragmentShader_Metal.png
 impeller_Play_AiksTest_DrawVerticesTextureCoordinatesWithFragmentShader_OpenGLES.png
 impeller_Play_AiksTest_DrawVerticesTextureCoordinatesWithFragmentShader_Vulkan.png
+impeller_Play_AiksTest_DrawVerticesWithInvalidIndices_Metal.png
+impeller_Play_AiksTest_DrawVerticesWithInvalidIndices_OpenGLES.png
+impeller_Play_AiksTest_DrawVerticesWithInvalidIndices_Vulkan.png
 impeller_Play_AiksTest_EmptySaveLayerIgnoresPaint_Metal.png
 impeller_Play_AiksTest_EmptySaveLayerIgnoresPaint_OpenGLES.png
 impeller_Play_AiksTest_EmptySaveLayerIgnoresPaint_Vulkan.png