Fix HWUI/Skia Gradients to premultiply the colors prior to interpolation
This is fixed in Skia by passing the appropriate flag when the shader is
generated. The fix in HWUI is to reverse the premultiplication and
interpolation steps.
Test: bit CtsUiRenderingTestCases:.testclasses.ShaderTests
Bug: 34323783
Change-Id: I3417141949f62fcc696b6d8213a4b446d7d0cbf8
diff --git a/libs/hwui/ProgramCache.cpp b/libs/hwui/ProgramCache.cpp
index 1f78e09..d0f0949 100644
--- a/libs/hwui/ProgramCache.cpp
+++ b/libs/hwui/ProgramCache.cpp
@@ -295,10 +295,6 @@
vec4 dither(const vec4 color) {
return color + (triangleNoise(gl_FragCoord.xy * screenSize.xy) / 255.0);
}
- vec4 gradientMix(const vec4 a, const vec4 b, float v) {
- vec4 c = mix(a, b, v);
- return vec4(c.rgb * c.a, c.a);
- }
)__SHADER__",
// sRGB framebuffer
R"__SHADER__(
@@ -306,10 +302,6 @@
vec3 dithered = sqrt(color.rgb) + (triangleNoise(gl_FragCoord.xy * screenSize.xy) / 255.0);
return vec4(dithered * dithered, color.a);
}
- vec4 gradientMixMix(const vec4 a, const vec4 b, float v) {
- vec4 c = mix(a, b, v);
- return vec4(c.rgb * c.a, c.a);
- }
)__SHADER__",
};
@@ -364,19 +356,19 @@
// Linear
" vec4 gradientColor = texture2D(gradientSampler, linear);\n",
- " vec4 gradientColor = gradientMix(startColor, endColor, clamp(linear, 0.0, 1.0));\n",
+ " vec4 gradientColor = mix(startColor, endColor, clamp(linear, 0.0, 1.0));\n",
// Circular
" vec4 gradientColor = texture2D(gradientSampler, vec2(length(circular), 0.5));\n",
- " vec4 gradientColor = gradientMix(startColor, endColor, clamp(length(circular), 0.0, 1.0));\n",
+ " vec4 gradientColor = mix(startColor, endColor, clamp(length(circular), 0.0, 1.0));\n",
// Sweep
" highp float index = atan(sweep.y, sweep.x) * 0.15915494309; // inv(2 * PI)\n"
" vec4 gradientColor = texture2D(gradientSampler, vec2(index - floor(index), 0.5));\n",
" highp float index = atan(sweep.y, sweep.x) * 0.15915494309; // inv(2 * PI)\n"
- " vec4 gradientColor = gradientMix(startColor, endColor, clamp(index - floor(index), 0.0, 1.0));\n"
+ " vec4 gradientColor = mix(startColor, endColor, clamp(index - floor(index), 0.0, 1.0));\n"
};
const char* gFS_Main_FetchBitmap =
" vec4 bitmapColor = colorConvert(texture2D(bitmapSampler, outBitmapTexCoords));\n";