added sweep gradient

Author: gaaclarke

lib/ui/painting.dart

@@ -4664,7 +4664,7 @@ base class Gradient extends Shader {
        assert(matrix4 == null || _matrix4IsValid(matrix4)),
        super._() {
     _validateColorStops(colors, colorStops);
-    final Int32List colorsBuffer = _encodeColorList(colors);
+    final Float32List colorsBuffer = _encodeWideColorList(colors);
     final Float32List? colorStopsBuffer = colorStops == null ? null : Float32List.fromList(colorStops);
     _constructor();
     _initSweep(center.dx, center.dy, colorsBuffer, colorStopsBuffer, tileMode.index, startAngle, endAngle, matrix4);
@@ -4703,7 +4703,7 @@ base class Gradient extends Shader {
   external void _initSweep(
       double centerX,
       double centerY,
-      Int32List colors,
+      Float32List colors,
       Float32List? colorStops,
       int tileMode,
       double startAngle,

lib/ui/painting/gradient.cc

@@ -101,13 +101,13 @@ void CanvasGradient::initRadial(double center_x,
 
 void CanvasGradient::initSweep(double center_x,
                                double center_y,
-                               const tonic::Int32List& colors,
+                               const tonic::Float32List& colors,
                                const tonic::Float32List& color_stops,
                                DlTileMode tile_mode,
                                double start_angle,
                                double end_angle,
                                const tonic::Float64List& matrix4) {
-  FML_DCHECK(colors.num_elements() == color_stops.num_elements() ||
+  FML_DCHECK(colors.num_elements() == (color_stops.num_elements() * 4) ||
              color_stops.data() == nullptr);
 
   static_assert(sizeof(SkColor) == sizeof(int32_t),
@@ -121,16 +121,20 @@ void CanvasGradient::initSweep(double center_x,
 
   std::vector<DlColor> dl_colors;
   dl_colors.reserve(colors.num_elements());
-  for (int i = 0; i < colors.num_elements(); ++i) {
-    dl_colors.emplace_back(DlColor(colors[i]));
+  for (int i = 0; i < colors.num_elements(); i += 4) {
+    DlScalar a = colors[i + 0];
+    DlScalar r = colors[i + 1];
+    DlScalar g = colors[i + 2];
+    DlScalar b = colors[i + 3];
+    dl_colors.emplace_back(DlColor(a, r, g, b, DlColorSpace::kExtendedSRGB));
   }
 
   dl_shader_ = DlColorSource::MakeSweep(
       SkPoint::Make(SafeNarrow(center_x), SafeNarrow(center_y)),
       SafeNarrow(start_angle) * 180.0f / static_cast<float>(M_PI),
       SafeNarrow(end_angle) * 180.0f / static_cast<float>(M_PI),
-      colors.num_elements(), dl_colors.data(), color_stops.data(), tile_mode,
-      has_matrix ? &sk_matrix : nullptr);
+      color_stops.num_elements(), dl_colors.data(), color_stops.data(),
+      tile_mode, has_matrix ? &sk_matrix : nullptr);
   // Just a sanity check, all gradient shaders should be thread-safe
   FML_DCHECK(dl_shader_->isUIThreadSafe());
 }

lib/ui/painting/gradient.h

@@ -36,7 +36,7 @@ class CanvasGradient : public Shader {
 
   void initSweep(double center_x,
                  double center_y,
-                 const tonic::Int32List& colors,
+                 const tonic::Float32List& colors,
                  const tonic::Float32List& color_stops,
                  DlTileMode tile_mode,
                  double start_angle,