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[Impeller] Fix CPU Porter-Duff blends #43217

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bdero merged 1 commit into from
Jun 26, 2023
Merged

[Impeller] Fix CPU Porter-Duff blends #43217

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13 changes: 7 additions & 6 deletions impeller/aiks/aiks_unittests.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -2085,8 +2085,9 @@ static Picture BlendModeTest(BlendMode blend_mode,
const std::shared_ptr<Image>& src_image,
const std::shared_ptr<Image>& dst_image) {
Color destination_color = Color::CornflowerBlue().WithAlpha(0.75);
auto source_colors =
std::vector<Color>({Color::White(), Color::LimeGreen(), Color::Black()});
auto source_colors = std::vector<Color>({Color::White().WithAlpha(0.75),
Color::LimeGreen().WithAlpha(0.75),
Color::Black().WithAlpha(0.75)});

Canvas canvas;

Expand All @@ -2111,7 +2112,7 @@ static Picture BlendModeTest(BlendMode blend_mode,
// pass.
canvas.SaveLayer({.blend_mode = blend_mode});
{ //
canvas.DrawRect({50, 50, 100, 100}, {.color = color.WithAlpha(0.75)});
canvas.DrawRect({50, 50, 100, 100}, {.color = color});
}
canvas.Restore();
}
Expand All @@ -2135,9 +2136,9 @@ static Picture BlendModeTest(BlendMode blend_mode,
// canvas.DrawPaint({.color = destination_color});
for (auto& color : source_colors) {
// Simply write the CPU blended color to the pass.
canvas.DrawRect({50, 50, 100, 100}, {.color = destination_color.Blend(
color.WithAlpha(0.75), blend_mode),
.blend_mode = BlendMode::kSource});
canvas.DrawRect({50, 50, 100, 100},
{.color = destination_color.Blend(color, blend_mode),
.blend_mode = BlendMode::kSourceOver});
canvas.Translate(Vector2(100, 0));
}
canvas.RestoreToCount(0);
Expand Down
64 changes: 31 additions & 33 deletions impeller/geometry/color.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -123,18 +123,6 @@ Color ColorHSB::ToRGBA() const {
return Color(0, 0, 0, alpha);
}

Color Color::operator+(const Color& c) const {
return Color(Vector4(*this) + Vector4(c));
}

Color Color::operator-(const Color& c) const {
return Color(Vector4(*this) - Vector4(c));
}

Color Color::operator*(Scalar value) const {
return Color(red * value, green * value, blue * value, alpha * value);
}

Color::Color(const ColorHSB& hsbColor) : Color(hsbColor.ToRGBA()) {}

Color::Color(const Vector4& value)
Expand Down Expand Up @@ -218,47 +206,57 @@ Color Color::Blend(const Color& src, BlendMode blend_mode) const {
return dst;
case BlendMode::kSourceOver:
// r = s + (1-sa)*d
return src + dst * (1 - src.alpha);
return (src.Premultiply() + dst.Premultiply() * (1 - src.alpha))
.Unpremultiply();
case BlendMode::kDestinationOver:
// r = d + (1-da)*s
return dst + src * (1 - dst.alpha);
return (dst.Premultiply() + src.Premultiply() * (1 - dst.alpha))
.Unpremultiply();
case BlendMode::kSourceIn:
// r = s * da
return src * dst.alpha;
return (src.Premultiply() * dst.alpha).Unpremultiply();
case BlendMode::kDestinationIn:
// r = d * sa
return dst * src.alpha;
return (dst.Premultiply() * src.alpha).Unpremultiply();
case BlendMode::kSourceOut:
// r = s * ( 1- da)
return src * (1 - dst.alpha);
return (src.Premultiply() * (1 - dst.alpha)).Unpremultiply();
case BlendMode::kDestinationOut:
// r = d * (1-sa)
return dst * (1 - src.alpha);
return (dst.Premultiply() * (1 - src.alpha)).Unpremultiply();
case BlendMode::kSourceATop:
// r = s*da + d*(1-sa)
return src * dst.alpha + dst * (1 - src.alpha);
return (src.Premultiply() * dst.alpha +
dst.Premultiply() * (1 - src.alpha))
.Unpremultiply();
case BlendMode::kDestinationATop:
// r = d*sa + s*(1-da)
return dst * src.alpha + src * (1 - dst.alpha);
return (dst.Premultiply() * src.alpha +
src.Premultiply() * (1 - dst.alpha))
.Unpremultiply();
case BlendMode::kXor:
// r = s*(1-da) + d*(1-sa)
return src * (1 - dst.alpha) + dst * (1 - src.alpha);
return (src.Premultiply() * (1 - dst.alpha) +
dst.Premultiply() * (1 - src.alpha))
.Unpremultiply();
case BlendMode::kPlus:
// r = min(s + d, 1)
return Min(src + dst, 1);
return (Min(src.Premultiply() + dst.Premultiply(), 1)).Unpremultiply();
case BlendMode::kModulate:
// r = s*d
return src * dst;
return (src.Premultiply() * dst.Premultiply()).Unpremultiply();
case BlendMode::kScreen: {
// r = s + d - s*d
return src + dst - src * dst;
auto s = src.Premultiply();
auto d = dst.Premultiply();
return (s + d - s * d).Unpremultiply();
}
case BlendMode::kOverlay:
return apply_rgb_srcover_alpha([&](auto s, auto d) {
if (d * 2 < dst.alpha) {
if (d * 2 <= dst.alpha) {
return 2 * s * d;
}
return src.alpha * dst.alpha - 2 * (dst.alpha - s) * (src.alpha - d);
return src.alpha * dst.alpha - 2 * (dst.alpha - d) * (src.alpha - s);
});
case BlendMode::kDarken: {
return apply_rgb_srcover_alpha([&](auto s, auto d) {
Expand Down Expand Up @@ -313,13 +311,13 @@ Color Color::Blend(const Color& src, BlendMode blend_mode) const {
std::sqrt(dst_rgb.z)), //
dst_rgb, //
0.25);
Color blended =
FromRGB(ComponentChoose(
dst_rgb - (1.0 - 2.0 * src) * dst * (1.0 - dst_rgb), //
dst_rgb + (2.0 * src_rgb - 1.0) * (d - dst_rgb), //
src_rgb, //
0.5),
dst.alpha);
Color blended = FromRGB(
ComponentChoose(
dst_rgb - (1.0 - 2.0 * src_rgb) * dst_rgb * (1.0 - dst_rgb), //
dst_rgb + (2.0 * src_rgb - 1.0) * (d - dst_rgb), //
src_rgb, //
0.5),
dst.alpha);
return blended + dst * (1 - blended.alpha);
}
case BlendMode::kDifference:
Expand Down
74 changes: 64 additions & 10 deletions impeller/geometry/color.h
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,9 @@
#include <cstdlib>
#include <ostream>
#include <type_traits>

#include "impeller/geometry/scalar.h"
#include "impeller/geometry/type_traits.h"

#define IMPELLER_FOR_EACH_BLEND_MODE(V) \
V(Clear) \
Expand Down Expand Up @@ -162,11 +164,51 @@ struct Color {
0xFFFFFFFF;
}

constexpr bool operator==(const Color& c) const {
constexpr inline bool operator==(const Color& c) const {
return ScalarNearlyEqual(red, c.red) && ScalarNearlyEqual(green, c.green) &&
ScalarNearlyEqual(blue, c.blue) && ScalarNearlyEqual(alpha, c.alpha);
}

constexpr inline Color operator+(const Color& c) const {
return {red + c.red, green + c.green, blue + c.blue, alpha + c.alpha};
}

template <class T, class = std::enable_if_t<std::is_arithmetic_v<T>>>
constexpr inline Color operator+(T value) const {
auto v = static_cast<Scalar>(value);
return {red + v, green + v, blue + v, alpha + v};
}

constexpr inline Color operator-(const Color& c) const {
return {red - c.red, green - c.green, blue - c.blue, alpha - c.alpha};
}

template <class T, class = std::enable_if_t<std::is_arithmetic_v<T>>>
constexpr inline Color operator-(T value) const {
auto v = static_cast<Scalar>(value);
return {red - v, green - v, blue - v, alpha - v};
}

constexpr inline Color operator*(const Color& c) const {
return {red * c.red, green * c.green, blue * c.blue, alpha * c.alpha};
}

template <class T, class = std::enable_if_t<std::is_arithmetic_v<T>>>
constexpr inline Color operator*(T value) const {
auto v = static_cast<Scalar>(value);
return {red * v, green * v, blue * v, alpha * v};
}

constexpr inline Color operator/(const Color& c) const {
return {red * c.red, green * c.green, blue * c.blue, alpha * c.alpha};
}

template <class T, class = std::enable_if_t<std::is_arithmetic_v<T>>>
constexpr inline Color operator/(T value) const {
auto v = static_cast<Scalar>(value);
return {red / v, green / v, blue / v, alpha / v};
}

constexpr Color Premultiply() const {
return {red * alpha, green * alpha, blue * alpha, alpha};
}
Expand Down Expand Up @@ -835,20 +877,32 @@ struct Color {
/// premultipled, the conversion output will be incorrect.
Color SRGBToLinear() const;

Color operator*(const Color& c) const {
return Color(red * c.red, green * c.green, blue * c.blue, alpha * c.alpha);
}
constexpr bool IsTransparent() const { return alpha == 0.0f; }

Color operator+(const Color& c) const;
constexpr bool IsOpaque() const { return alpha == 1.0f; }
};

Color operator-(const Color& c) const;
template <class T, class = std::enable_if_t<std::is_arithmetic_v<T>>>
constexpr inline Color operator+(T value, const Color& c) {
return c + static_cast<Scalar>(value);
}

Color operator*(Scalar value) const;
template <class T, class = std::enable_if_t<std::is_arithmetic_v<T>>>
constexpr inline Color operator-(T value, const Color& c) {
auto v = static_cast<Scalar>(value);
return {v - c.red, v - c.green, v - c.blue, v - c.alpha};
}

constexpr bool IsTransparent() const { return alpha == 0.0f; }
template <class T, class = std::enable_if_t<std::is_arithmetic_v<T>>>
constexpr inline Color operator*(T value, const Color& c) {
return c * static_cast<Scalar>(value);
}

constexpr bool IsOpaque() const { return alpha == 1.0f; }
};
template <class T, class = std::enable_if_t<std::is_arithmetic_v<T>>>
constexpr inline Color operator/(T value, const Color& c) {
auto v = static_cast<Scalar>(value);
return {v / c.red, v / c.green, v / c.blue, v / c.alpha};
}

std::string ColorToString(const Color& color);

Expand Down
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