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Commit 73821c8d authored Sep 16, 2014 by Chris Craik

Handle premultiplication correctly for ColorMatrixColorFilters

bug:17405627

Previously, the input content to the color matrix computation was left
premultiplied. Since the color matrix could reduce the alpha channel,
the alpha was re-multiplied, but this was incomplete, and incorrect.

Instead, apply the color matrix in unpremultiplied space.

Change-Id: I87b8e03d2e228e6ded81f7bbfea952605d7a095c

parent c1e1550b

libs/hwui/ProgramCache.cpp

+3 −1

Original line number	Diff line number	Diff line
		@@ -327,8 +327,10 @@ const char* gFS_Main_ApplyColorOp[3] = {
		// None
		"",
		// Matrix
		" fragColor.rgb /= (fragColor.a + 0.0019);\n" // un-premultiply
		" fragColor *= colorMatrix;\n"
		" fragColor += colorMatrixVector;\n",
		" fragColor += colorMatrixVector;\n"
		" fragColor.rgb *= (fragColor.a + 0.0019);\n", // re-premultiply
		// PorterDuff
		" fragColor = blendColors(colorBlend, fragColor);\n"
		};

libs/hwui/Renderer.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -70,6 +70,7 @@ public:
		// TODO: move to a method on android:Paint
		static inline bool paintWillNotDraw(const SkPaint& paint) {
		return paint.getAlpha() == 0
		&& !paint.getColorFilter()
		&& getXfermode(paint.getXfermode()) != SkXfermode::kClear_Mode;
		}

		@@ -77,6 +78,7 @@ public:
		static inline bool paintWillNotDrawText(const SkPaint& paint) {
		return paint.getAlpha() == 0
		&& paint.getLooper() == NULL
		&& !paint.getColorFilter()
		&& getXfermode(paint.getXfermode()) == SkXfermode::kSrcOver_Mode;
		}
		// ----------------------------------------------------------------------------