blink::Color: Ensure that FromRGB and FromRGBA be constexpr

This is required to convert several locations in blink/renderer/core
from using the implicit blink::Color constructor from RGBA32.

Also update a missed implicit conversion in
CanvasRenderingContext2DState and GraphicsContext.

Bug: 1351544
Change-Id: I4ae5a98bfabdd6c0d5c1ba0f25bddf4ff0ca89c2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3825960
Commit-Queue: ccameron chromium <ccameron@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1033999}

third_party/blink/renderer/modules/canvas/canvas2d/canvas_rendering_context_2d_state.cc

@@ -571,7 +571,7 @@ sk_sp<SkDrawLooper>& CanvasRenderingContext2DState::ShadowOnlyDrawLooper()
   if (!shadow_only_draw_looper_) {
     DrawLooperBuilder draw_looper_builder;
     draw_looper_builder.AddShadow(shadow_offset_, ClampTo<float>(shadow_blur_),
-                                  shadow_color_,
+                                  Color::FromSkColor(shadow_color_),
                                   DrawLooperBuilder::kShadowIgnoresTransforms,
                                   DrawLooperBuilder::kShadowRespectsAlpha);
     shadow_only_draw_looper_ = draw_looper_builder.DetachDrawLooper();
@@ -584,7 +584,7 @@ CanvasRenderingContext2DState::ShadowAndForegroundDrawLooper() const {
   if (!shadow_and_foreground_draw_looper_) {
     DrawLooperBuilder draw_looper_builder;
     draw_looper_builder.AddShadow(shadow_offset_, ClampTo<float>(shadow_blur_),
-                                  shadow_color_,
+                                  Color::FromSkColor(shadow_color_),
                                   DrawLooperBuilder::kShadowIgnoresTransforms,
                                   DrawLooperBuilder::kShadowRespectsAlpha);
     draw_looper_builder.AddUnmodifiedContent();

third_party/blink/renderer/platform/graphics/color.cc

@@ -304,8 +304,8 @@ Color::operator SkColor() const {
 
 Color Color::Light() const {
   // Hardcode this common case for speed.
-  if (color_ == kBlack)
-    return kLightenedBlack;
+  if (color_ == kBlack.color_)
+    return Color(kLightenedBlack);
 
   const float scale_factor = nextafterf(256.0f, 0.0f);
 
@@ -327,8 +327,8 @@ Color Color::Light() const {
 
 Color Color::Dark() const {
   // Hardcode this common case for speed.
-  if (color_ == kWhite)
-    return kDarkenedWhite;
+  if (color_ == kWhite.color_)
+    return Color(kDarkenedWhite);
 
   const float scale_factor = nextafterf(256.0f, 0.0f);
 
@@ -346,7 +346,7 @@ Color Color::Dark() const {
 Color Color::CombineWithAlpha(float other_alpha) const {
   RGBA32 rgb_only = Rgb() & 0x00FFFFFF;
   float override_alpha = (Alpha() / 255.f) * other_alpha;
-  return rgb_only | ColorFloatToRGBAByte(override_alpha) << 24;
+  return Color(rgb_only | ColorFloatToRGBAByte(override_alpha) << 24);
 }
 
 Color Color::Blend(const Color& source) const {

third_party/blink/renderer/platform/graphics/color.h

@@ -106,12 +106,14 @@ class PLATFORM_EXPORT Color {
 
   // Create a color using rgb() syntax.
   static constexpr Color FromRGB(int r, int g, int b) {
-    return Color(MakeRGB(r, g, b));
+    return Color(0xFF000000 | ClampInt(r) << 16 | ClampInt(g) << 8 |
+                 ClampInt(b));
   }
 
   // Create a color using rgba() syntax.
   static constexpr Color FromRGBA(int r, int g, int b, int a) {
-    return Color(MakeRGBA(r, g, b, a));
+    return Color(ClampInt(a) << 24 | ClampInt(r) << 16 | ClampInt(g) << 8 |
+                 ClampInt(b));
   }
 
   // Create a color using the hsl() syntax.
@@ -127,7 +129,7 @@ class PLATFORM_EXPORT Color {
   // TODO(crbug.com/1308932): These three functions are just helpers for while
   // we're converting platform/graphics to float color.
   static Color FromSkColor4f(SkColor4f fc) {
-    return MakeRGBA32FromFloats(fc.fR, fc.fG, fc.fB, fc.fA);
+    return Color(MakeRGBA32FromFloats(fc.fR, fc.fG, fc.fB, fc.fA));
   }
   static constexpr Color FromSkColor(SkColor color) { return Color(color); }
   static constexpr Color FromRGBA32(RGBA32 color) { return Color(color); }
@@ -189,6 +191,9 @@ class PLATFORM_EXPORT Color {
   static const Color kTransparent;
 
  private:
+  static constexpr int ClampInt(int x) {
+    return x < 0 ? 0 : (x > 255 ? 255 : x);
+  }
   void GetHueMaxMin(double&, double&, double&) const;
 
   RGBA32 color_;

third_party/blink/renderer/platform/graphics/graphics_context.cc

@@ -96,8 +96,8 @@ Color DarkModeColor(GraphicsContext& context,
   if (auto_dark_mode.enabled) {
     // TODO(https://crbug.com/1351544): DarkModeFilter should operate on
     // SkColor4f, not SkColor.
-    return context.GetDarkModeFilter()->InvertColorIfNeeded(
-        SkColor(color), auto_dark_mode.role);
+    return Color::FromSkColor(context.GetDarkModeFilter()->InvertColorIfNeeded(
+        SkColor(color), auto_dark_mode.role));
   }
   return color;
 }