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Fix HWUI/Skia Gradients to premultiply the colors prior to interpolation

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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
This commit is contained in:
Derek Sollenberger
2017-03-31 12:09:24 -04:00
parent 3f2bbcbe92
commit 669b15a935
4 changed files with 32 additions and 32 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
core/jni/android/graphics/Shader.cpp
View File

@@ -10,6 +10,14 @@
using namespace android::uirenderer;
/**
* By default Skia gradients will interpolate their colors in unpremul space
* and then premultiply each of the results. We must set this flag to preserve
* backwards compatiblity by premultiplying the colors of the gradient first,
* and then interpolating between them.
*/
static const uint32_t sGradientShaderFlags = SkGradientShader::kInterpolateColorsInPremul_Flag;
static void ThrowIAE_IfNull(JNIEnv* env, void* ptr) {
if (NULL == ptr) {
doThrowIAE(env);
@@ -89,7 +97,7 @@ static jlong LinearGradient_create1(JNIEnv* env, jobject o, jlong matrixPtr,
SkShader* shader = SkGradientShader::MakeLinear(pts,
reinterpret_cast<const SkColor*>(colorValues), pos, count,
static_cast<SkShader::TileMode>(tileMode), /* flags */ 0, matrix).release();
static_cast<SkShader::TileMode>(tileMode), sGradientShaderFlags, matrix).release();
env->ReleaseIntArrayElements(colorArray, const_cast<jint*>(colorValues), JNI_ABORT);
ThrowIAE_IfNull(env, shader);
@@ -109,7 +117,7 @@ static jlong LinearGradient_create2(JNIEnv* env, jobject o, jlong matrixPtr,
colors[1] = color1;
SkShader* s = SkGradientShader::MakeLinear(pts, colors, NULL, 2,
(SkShader::TileMode)tileMode, /* flags */ 0, matrix).release();
static_cast<SkShader::TileMode>(tileMode), sGradientShaderFlags, matrix).release();
ThrowIAE_IfNull(env, s);
return reinterpret_cast<jlong>(s);
@@ -135,7 +143,7 @@ static jlong RadialGradient_create1(JNIEnv* env, jobject, jlong matrixPtr, jfloa
SkShader* shader = SkGradientShader::MakeRadial(center, radius,
reinterpret_cast<const SkColor*>(colorValues), pos, count,
static_cast<SkShader::TileMode>(tileMode), /* flags */ 0, matrix).release();
static_cast<SkShader::TileMode>(tileMode), sGradientShaderFlags, matrix).release();
env->ReleaseIntArrayElements(colorArray, const_cast<jint*>(colorValues),
JNI_ABORT);
@@ -154,7 +162,7 @@ static jlong RadialGradient_create2(JNIEnv* env, jobject, jlong matrixPtr, jfloa
colors[1] = color1;
SkShader* s = SkGradientShader::MakeRadial(center, radius, colors, NULL, 2,
(SkShader::TileMode)tileMode, /* flags */ 0, matrix).release();
static_cast<SkShader::TileMode>(tileMode), sGradientShaderFlags, matrix).release();
ThrowIAE_IfNull(env, s);
return reinterpret_cast<jlong>(s);
}
@@ -174,8 +182,8 @@ static jlong SweepGradient_create1(JNIEnv* env, jobject, jlong matrixPtr, jfloat
#error Need to convert float array to SkScalar array before calling the following function.
#endif
SkShader* shader = SkGradientShader::MakeSweep(x, y,
reinterpret_cast<const SkColor*>(colors), pos, count, /* flags */ 0, matrix).release();
SkShader* shader = SkGradientShader::MakeSweep(x, y, reinterpret_cast<const SkColor*>(colors),
pos, count, sGradientShaderFlags, matrix).release();
env->ReleaseIntArrayElements(jcolors, const_cast<jint*>(colors),
JNI_ABORT);
ThrowIAE_IfNull(env, shader);
@@ -189,7 +197,7 @@ static jlong SweepGradient_create2(JNIEnv* env, jobject, jlong matrixPtr, jfloat
colors[0] = color0;
colors[1] = color1;
SkShader* s = SkGradientShader::MakeSweep(x, y, colors, NULL, 2,
/* flags */ 0, matrix).release();
sGradientShaderFlags, matrix).release();
ThrowIAE_IfNull(env, s);
return reinterpret_cast<jlong>(s);
}

24
libs/hwui/GradientCache.cpp
View File

@@ -189,9 +189,9 @@ void GradientCache::mixBytes(const FloatColor& start, const FloatColor& end,
float amount, uint8_t*& dst) const {
float oppAmount = 1.0f - amount;
float a = start.a * oppAmount + end.a * amount;
*dst++ = uint8_t(a * OECF(start.r * oppAmount + end.r * amount) * 255.0f);
*dst++ = uint8_t(a * OECF(start.g * oppAmount + end.g * amount) * 255.0f);
*dst++ = uint8_t(a * OECF(start.b * oppAmount + end.b * amount) * 255.0f);
*dst++ = uint8_t(OECF(start.r * oppAmount + end.r * amount) * 255.0f);
*dst++ = uint8_t(OECF(start.g * oppAmount + end.g * amount) * 255.0f);
*dst++ = uint8_t(OECF(start.b * oppAmount + end.b * amount) * 255.0f);
*dst++ = uint8_t(a * 255.0f);
}
@@ -202,13 +202,13 @@ void GradientCache::mixFloats(const FloatColor& start, const FloatColor& end,
float* d = (float*) dst;
#ifdef ANDROID_ENABLE_LINEAR_BLENDING
// We want to stay linear
*d++ = a * (start.r * oppAmount + end.r * amount);
*d++ = a * (start.g * oppAmount + end.g * amount);
*d++ = a * (start.b * oppAmount + end.b * amount);
*d++ = (start.r * oppAmount + end.r * amount);
*d++ = (start.g * oppAmount + end.g * amount);
*d++ = (start.b * oppAmount + end.b * amount);
#else
*d++ = a * OECF(start.r * oppAmount + end.r * amount);
*d++ = a * OECF(start.g * oppAmount + end.g * amount);
*d++ = a * OECF(start.b * oppAmount + end.b * amount);
*d++ = OECF(start.r * oppAmount + end.r * amount);
*d++ = OECF(start.g * oppAmount + end.g * amount);
*d++ = OECF(start.b * oppAmount + end.b * amount);
#endif
*d++ = a;
dst += 4 * sizeof(float);
@@ -229,10 +229,10 @@ void GradientCache::generateTexture(uint32_t* colors, float* positions,
ChannelMixer mix = gMixers[mUseFloatTexture];
FloatColor start;
start.setUnPreMultiplied(colors[0]);
start.set(colors[0]);
FloatColor end;
end.setUnPreMultiplied(colors[1]);
end.set(colors[1]);
int currentPos = 1;
float startPos = positions[0];
@@ -247,7 +247,7 @@ void GradientCache::generateTexture(uint32_t* colors, float* positions,
currentPos++;
end.setUnPreMultiplied(colors[currentPos]);
end.set(colors[currentPos]);
distance = positions[currentPos] - startPos;
}

14
libs/hwui/ProgramCache.cpp
View File

@@ -295,10 +295,6 @@ const char* gFS_GradientPreamble[2] = {
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 @@ const char* gFS_GradientPreamble[2] = {
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 @@ const char* gFS_Main_FetchGradient[6] = {
// 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";

4
libs/hwui/SkiaShader.cpp
View File

@@ -173,8 +173,8 @@ bool tryStoreGradient(Caches& caches, const SkShader& shader, const Matrix4 mode
outData->gradientSampler = 0;
outData->gradientTexture = nullptr;
outData->startColor.setUnPreMultiplied(gradInfo.fColors[0]);
outData->endColor.setUnPreMultiplied(gradInfo.fColors[1]);
outData->startColor.set(gradInfo.fColors[0]);
outData->endColor.set(gradInfo.fColors[1]);
}
return true;