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/GradientCache.cpp b/libs/hwui/GradientCache.cpp
index dceb285..d4d0c99 100644
--- a/libs/hwui/GradientCache.cpp
+++ b/libs/hwui/GradientCache.cpp
@@ -189,9 +189,9 @@
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 @@
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 @@
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 @@
currentPos++;
- end.setUnPreMultiplied(colors[currentPos]);
+ end.set(colors[currentPos]);
distance = positions[currentPos] - startPos;
}