Fix for issue 1728: raster vs. gpu text draws with the wrong color
The blend mode for LCD text was not set up correctly when using colors with alpha. This takes the color's alpha value
into account when setting up the blending function.
BUG=Skia:1728
R=bsalomon@google.com
Author: jvanverth@google.com
Review URL: https://codereview.chromium.org/45363002
git-svn-id: http://skia.googlecode.com/svn/trunk@11980 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrBitmapTextContext.cpp b/src/gpu/GrBitmapTextContext.cpp
index 7a99f09..737e24b 100755
--- a/src/gpu/GrBitmapTextContext.cpp
+++ b/src/gpu/GrBitmapTextContext.cpp
@@ -12,6 +12,7 @@
#include "GrIndexBuffer.h"
#include "GrTextStrike.h"
#include "GrTextStrike_impl.h"
+#include "SkColorPriv.h"
#include "SkPath.h"
#include "SkRTConf.h"
#include "SkStrokeRec.h"
@@ -22,10 +23,13 @@
SK_CONF_DECLARE(bool, c_DumpFontCache, "gpu.dumpFontCache", false,
"Dump the contents of the font cache before every purge.");
-GrBitmapTextContext::GrBitmapTextContext(GrContext* context, const GrPaint& paint) :
+GrBitmapTextContext::GrBitmapTextContext(GrContext* context, const GrPaint& paint,
+ SkColor color) :
GrTextContext(context, paint) {
fAutoMatrix.setIdentity(fContext, &fPaint);
+ fSkPaintColor = color;
+
fStrike = NULL;
fCurrTexture = NULL;
@@ -39,6 +43,13 @@
this->flushGlyphs();
}
+static inline GrColor skcolor_to_grcolor_nopremultiply(SkColor c) {
+ unsigned r = SkColorGetR(c);
+ unsigned g = SkColorGetG(c);
+ unsigned b = SkColorGetB(c);
+ return GrColorPackRGBA(r, g, b, 0xff);
+}
+
void GrBitmapTextContext::flushGlyphs() {
if (NULL == fDrawTarget) {
return;
@@ -65,12 +76,16 @@
fPaint.numColorStages()) {
GrPrintf("LCD Text will not draw correctly.\n");
}
- // setup blend so that we get mask * paintColor + (1-mask)*dstColor
- drawState->setBlendConstant(fPaint.getColor());
+ // We don't use the GrPaint's color in this case because it's been premultiplied by
+ // alpha. Instead we feed in a non-premultiplied color, and multiply its alpha by
+ // the mask texture color. The end result is that we get
+ // mask*paintAlpha*paintColor + (1-mask*paintAlpha)*dstColor
+ int a = SkColorGetA(fSkPaintColor);
+ // paintAlpha
+ drawState->setColor(SkColorSetARGB(a, a, a, a));
+ // paintColor
+ drawState->setBlendConstant(skcolor_to_grcolor_nopremultiply(fSkPaintColor));
drawState->setBlendFunc(kConstC_GrBlendCoeff, kISC_GrBlendCoeff);
- // don't modulate by the paint's color in the frag since we're
- // already doing it via the blend const.
- drawState->setColor(0xffffffff);
} else {
// set back to normal in case we took LCD path previously.
drawState->setBlendFunc(fPaint.getSrcBlendCoeff(), fPaint.getDstBlendCoeff());
@@ -82,6 +97,7 @@
fDrawTarget->drawIndexedInstances(kTriangles_GrPrimitiveType,
nGlyphs,
4, 6);
+
fDrawTarget->resetVertexSource();
fVertices = NULL;
fMaxVertices = 0;