Changes DlColor to support wide gamut colors (#54473)

ci/licenses_golden/licenses_flutter

@@ -42320,6 +42320,7 @@ ORIGIN: ../../../flutter/display_list/dl_builder.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/display_list/dl_builder.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/display_list/dl_canvas.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/display_list/dl_canvas.h + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/display_list/dl_color.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/display_list/dl_color.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/display_list/dl_op_flags.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/display_list/dl_op_flags.h + ../../../flutter/LICENSE
@@ -45199,6 +45200,7 @@ FILE: ../../../flutter/display_list/dl_builder.cc
 FILE: ../../../flutter/display_list/dl_builder.h
 FILE: ../../../flutter/display_list/dl_canvas.cc
 FILE: ../../../flutter/display_list/dl_canvas.h
+FILE: ../../../flutter/display_list/dl_color.cc
 FILE: ../../../flutter/display_list/dl_color.h
 FILE: ../../../flutter/display_list/dl_op_flags.cc
 FILE: ../../../flutter/display_list/dl_op_flags.h

display_list/BUILD.gn

@@ -35,6 +35,7 @@ source_set("display_list") {
     "dl_builder.h",
     "dl_canvas.cc",
     "dl_canvas.h",
+    "dl_color.cc",
     "dl_color.h",
     "dl_op_flags.cc",
     "dl_op_flags.h",

display_list/display_list_unittests.cc

@@ -1847,7 +1847,7 @@ TEST_F(DisplayListTest, FlutterSvgIssue661BoundsWereEmpty) {
   // This is the more practical result. The bounds are "almost" 0,0,100x100
   EXPECT_EQ(display_list->bounds().roundOut(), SkIRect::MakeWH(100, 100));
   EXPECT_EQ(display_list->op_count(), 19u);
-  EXPECT_EQ(display_list->bytes(), sizeof(DisplayList) + 408u);
+  EXPECT_EQ(display_list->bytes(), sizeof(DisplayList) + 424u);
   EXPECT_EQ(display_list->total_depth(), 3u);
 }
 

display_list/dl_builder.h

@@ -805,7 +805,7 @@ class DisplayListBuilder final : public virtual DlCanvas,
 
   // kAnyColor is a non-opaque and non-transparent color that will not
   // trigger any short-circuit tests about the results of a blend.
-  static constexpr DlColor kAnyColor = DlColor::kMidGrey().withAlpha(0x80);
+  static constexpr DlColor kAnyColor = DlColor::kMidGrey().withAlphaF(0.5f);
   static_assert(!kAnyColor.isOpaque());
   static_assert(!kAnyColor.isTransparent());
   static DlColor GetEffectiveColor(const DlPaint& paint,

display_list/dl_color.cc

@@ -0,0 +1,75 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/display_list/dl_color.h"
+
+namespace flutter {
+
+namespace {
+const std::array<DlScalar, 12> kP3ToSrgb = {
+    1.306671048092539,  -0.298061942172353,
+    0.213228303487995,  -0.213580156254466,  //
+    -0.117390025596251, 1.127722006101976,
+    0.109727644608938,  -0.109450321455370,  //
+    0.214813187718391,  0.054268702864647,
+    1.406898424029350,  -0.364892765879631};
+
+DlColor transform(const DlColor& color,
+                  const std::array<DlScalar, 12>& matrix,
+                  DlColorSpace color_space) {
+  return DlColor(color.getAlphaF(),
+                 matrix[0] * color.getRedF() +        //
+                     matrix[1] * color.getGreenF() +  //
+                     matrix[2] * color.getBlueF() +   //
+                     matrix[3],                       //
+                 matrix[4] * color.getRedF() +        //
+                     matrix[5] * color.getGreenF() +  //
+                     matrix[6] * color.getBlueF() +   //
+                     matrix[7],                       //
+                 matrix[8] * color.getRedF() +        //
+                     matrix[9] * color.getGreenF() +  //
+                     matrix[10] * color.getBlueF() +  //
+                     matrix[11],                      //
+                 color_space);
+}
+}  // namespace
+
+DlColor DlColor::withColorSpace(DlColorSpace color_space) const {
+  switch (color_space_) {
+    case DlColorSpace::kSRGB:
+      switch (color_space) {
+        case DlColorSpace::kSRGB:
+          return *this;
+        case DlColorSpace::kExtendedSRGB:
+          return DlColor(alpha_, red_, green_, blue_,
+                         DlColorSpace::kExtendedSRGB);
+        case DlColorSpace::kDisplayP3:
+          FML_CHECK(false) << "not implemented";
+          return *this;
+      }
+    case DlColorSpace::kExtendedSRGB:
+      switch (color_space) {
+        case DlColorSpace::kSRGB:
+          FML_CHECK(false) << "not implemented";
+          return *this;
+        case DlColorSpace::kExtendedSRGB:
+          return *this;
+        case DlColorSpace::kDisplayP3:
+          FML_CHECK(false) << "not implemented";
+          return *this;
+      }
+    case DlColorSpace::kDisplayP3:
+      switch (color_space) {
+        case DlColorSpace::kSRGB:
+          FML_CHECK(false) << "not implemented";
+          return *this;
+        case DlColorSpace::kExtendedSRGB:
+          return transform(*this, kP3ToSrgb, DlColorSpace::kExtendedSRGB);
+        case DlColorSpace::kDisplayP3:
+          return *this;
+      }
+  }
+}
+
+}  // namespace flutter

display_list/dl_color.h

@@ -9,10 +9,39 @@
 
 namespace flutter {
 
+// These should match the enumerations defined in //lib/ui/painting.dart.
+enum class DlColorSpace { kSRGB = 0, kExtendedSRGB = 1, kDisplayP3 = 2 };
+
+/// A representation of a color.
+///
+/// The color belongs to a DlColorSpace. Using deprecated integer data accessors
+/// on colors not in the kSRGB colorspace can lead to data loss. Using the
+/// floating point accessors and constructors that were added for wide-gamut
+/// support are preferred.
 struct DlColor {
  public:
-  constexpr DlColor() : argb_(0xFF000000) {}
-  constexpr explicit DlColor(uint32_t argb) : argb_(argb) {}
+  constexpr DlColor()
+      : alpha_(1.f),
+        red_(0.f),
+        green_(0.f),
+        blue_(0.f),
+        color_space_(DlColorSpace::kSRGB) {}
+  constexpr explicit DlColor(uint32_t argb)
+      : alpha_(toF((argb >> 24) & 0xff)),
+        red_(toF((argb >> 16) & 0xff)),
+        green_(toF((argb >> 8) & 0xff)),
+        blue_(toF((argb >> 0) & 0xff)),
+        color_space_(DlColorSpace::kSRGB) {}
+  constexpr DlColor(DlScalar alpha,
+                    DlScalar red,
+                    DlScalar green,
+                    DlScalar blue,
+                    DlColorSpace colorspace)
+      : alpha_(alpha),
+        red_(red),
+        green_(green),
+        blue_(blue),
+        color_space_(colorspace) {}
 
   /// @brief Construct a 32 bit color from floating point R, G, B, and A color
   /// channels.
@@ -29,10 +58,7 @@ struct DlColor {
                                 DlScalar r,
                                 DlScalar g,
                                 DlScalar b) {
-    return DlColor(toC(a) << 24 |  //
-                   toC(r) << 16 |  //
-                   toC(g) << 8 |   //
-                   toC(b));
+    return DlColor(a, r, g, b, DlColorSpace::kSRGB);
   }
 
   static constexpr uint8_t toAlpha(DlScalar opacity) { return toC(opacity); }
@@ -66,58 +92,106 @@ struct DlColor {
   static constexpr DlColor kOrangeRed()          {return DlColor(0xFFFF4500);};
   // clang-format on
 
-  constexpr bool isOpaque() const { return getAlpha() == 0xFF; }
-  constexpr bool isTransparent() const { return getAlpha() == 0; }
-
-  constexpr int getAlpha() const { return argb_ >> 24; }
-  constexpr int getRed() const { return (argb_ >> 16) & 0xFF; }
-  constexpr int getGreen() const { return (argb_ >> 8) & 0xFF; }
-  constexpr int getBlue() const { return argb_ & 0xFF; }
-
-  constexpr DlScalar getAlphaF() const { return toF(getAlpha()); }
-  constexpr DlScalar getRedF() const { return toF(getRed()); }
-  constexpr DlScalar getGreenF() const { return toF(getGreen()); }
-  constexpr DlScalar getBlueF() const { return toF(getBlue()); }
-
-  constexpr uint32_t premultipliedArgb() const {
-    if (isOpaque()) {
-      return argb_;
-    }
-    DlScalar f = getAlphaF();
-    return (argb_ & 0xFF000000) |       //
-           toC(getRedF() * f) << 16 |   //
-           toC(getGreenF() * f) << 8 |  //
-           toC(getBlueF() * f);
-  }
+  constexpr bool isOpaque() const { return alpha_ >= 1.f; }
+  constexpr bool isTransparent() const { return alpha_ <= 0.f; }
+
+  ///\deprecated Use floating point accessors to avoid data loss when using wide
+  /// gamut colors.
+  constexpr int getAlpha() const { return toC(alpha_); }
+  ///\deprecated Use floating point accessors to avoid data loss when using wide
+  /// gamut colors.
+  constexpr int getRed() const { return toC(red_); }
+  ///\deprecated Use floating point accessors to avoid data loss when using wide
+  /// gamut colors.
+  constexpr int getGreen() const { return toC(green_); }
+  ///\deprecated Use floating point accessors to avoid data loss when using wide
+  /// gamut colors.
+  constexpr int getBlue() const { return toC(blue_); }
+
+  constexpr DlScalar getAlphaF() const { return alpha_; }
+  constexpr DlScalar getRedF() const { return red_; }
+  constexpr DlScalar getGreenF() const { return green_; }
+  constexpr DlScalar getBlueF() const { return blue_; }
+
+  constexpr DlColorSpace getColorSpace() const { return color_space_; }
 
   constexpr DlColor withAlpha(uint8_t alpha) const {  //
-    return DlColor((argb_ & 0x00FFFFFF) | (alpha << 24));
+    return DlColor((argb() & 0x00FFFFFF) | (alpha << 24));
   }
   constexpr DlColor withRed(uint8_t red) const {  //
-    return DlColor((argb_ & 0xFF00FFFF) | (red << 16));
+    return DlColor((argb() & 0xFF00FFFF) | (red << 16));
   }
   constexpr DlColor withGreen(uint8_t green) const {  //
-    return DlColor((argb_ & 0xFFFF00FF) | (green << 8));
+    return DlColor((argb() & 0xFFFF00FF) | (green << 8));
   }
   constexpr DlColor withBlue(uint8_t blue) const {  //
-    return DlColor((argb_ & 0xFFFFFF00) | (blue << 0));
+    return DlColor((argb() & 0xFFFFFF00) | (blue << 0));
+  }
+  constexpr DlColor withAlphaF(float alpha) const {  //
+    return DlColor(alpha, red_, green_, blue_, color_space_);
+  }
+  constexpr DlColor withRedF(float red) const {  //
+    return DlColor(alpha_, red, green_, blue_, color_space_);
+  }
+  constexpr DlColor withGreenF(float green) const {  //
+    return DlColor(alpha_, red_, green, blue_, color_space_);
   }
+  constexpr DlColor withBlueF(float blue) const {  //
+    return DlColor(alpha_, red_, green_, blue, color_space_);
+  }
+  /// Performs a colorspace transformation.
+  ///
+  /// This isn't just a replacement of the color space field, the new color
+  /// components are calculated.
+  DlColor withColorSpace(DlColorSpace color_space) const;
 
   constexpr DlColor modulateOpacity(DlScalar opacity) const {
     return opacity <= 0   ? withAlpha(0)
            : opacity >= 1 ? *this
                           : withAlpha(round(getAlpha() * opacity));
   }
 
-  constexpr uint32_t argb() const { return argb_; }
+  ///\deprecated Use floating point accessors to avoid data loss when using wide
+  /// gamut colors.
+  constexpr uint32_t argb() const {
+    return toC(alpha_) << 24 |  //
+           toC(red_) << 16 |    //
+           toC(green_) << 8 |   //
+           toC(blue_) << 0;
+  }
 
-  bool operator==(DlColor const& other) const { return argb_ == other.argb_; }
-  bool operator!=(DlColor const& other) const { return argb_ != other.argb_; }
-  bool operator==(uint32_t const& other) const { return argb_ == other; }
-  bool operator!=(uint32_t const& other) const { return argb_ != other; }
+  /// Checks that no difference in color components exceeds the delta.
+  ///
+  /// This doesn't check against the actual distance between the colors in some
+  /// space.
+  bool isClose(DlColor const& other, DlScalar delta = 1.0f / 256.0f) {
+    return color_space_ == other.color_space_ &&
+           std::abs(alpha_ - other.alpha_) < delta &&
+           std::abs(red_ - other.red_) < delta &&
+           std::abs(green_ - other.green_) < delta &&
+           std::abs(blue_ - other.blue_) < delta;
+  }
+  bool operator==(DlColor const& other) const {
+    return alpha_ == other.alpha_ && red_ == other.red_ &&
+           green_ == other.green_ && blue_ == other.blue_ &&
+           color_space_ == other.color_space_;
+  }
+  bool operator!=(DlColor const& other) const {
+    return !this->operator==(other);
+  }
+  bool operator==(uint32_t const& other) const {
+    return argb() == other && color_space_ == DlColorSpace::kSRGB;
+  }
+  bool operator!=(uint32_t const& other) const {
+    return !this->operator==(other);
+  }
 
  private:
-  uint32_t argb_;
+  DlScalar alpha_;
+  DlScalar red_;
+  DlScalar green_;
+  DlScalar blue_;
+  DlColorSpace color_space_;
 
   static constexpr DlScalar toF(uint8_t comp) { return comp * (1.0f / 255); }
   static constexpr uint8_t toC(DlScalar fComp) { return round(fComp * 255); }