Use SkXfermode as public facing enum for GrPorterDuffXP

src/gpu/SkGpuDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGpuDevice.h"
 
 #include "effects/GrBicubicEffect.h"
 #include "effects/GrDashingEffect.h"
-#include "effects/GrPorterDuffXferProcessor.h"
 #include "effects/GrTextureDomain.h"
 #include "effects/GrSimpleTextureEffect.h"
 
 #include "GrContext.h"
 #include "GrBitmapTextContext.h"
 #include "GrDistanceFieldTextContext.h"
 #include "GrLayerHoister.h"
 #include "GrRecordReplaceDraw.h"
 #include "GrStrokeInfo.h"
 #include "GrTracing.h"
@@ skipping 649 matching lines @@
     SkRect clipRect = SkRect::MakeWH(maskRect.width(), maskRect.height());
 
     GrContext::AutoRenderTarget art(context, mask->asRenderTarget());
     GrContext::AutoClip ac(context, clipRect);
 
     context->clear(NULL, 0x0, true, mask->asRenderTarget());
 
     GrPaint tempPaint;
     if (doAA) {
         tempPaint.setAntiAlias(true);
-        // AA uses the "coverage" stages on GrDrawTarget. Coverage with a dst
-        // blend coeff of zero requires dual source blending support in order
-        // to properly blend partially covered pixels. This means the AA
-        // code path may not be taken. So we use a dst blend coeff of ISA. We
-        // could special case AA draws to a dst surface with known alpha=0 to
-        // use a zero dst coeff when dual source blending isn't available.
-        tempPaint.setPorterDuffXPFactory(kOne_GrBlendCoeff, kISC_GrBlendCoeff);
+        tempPaint.setCoverageSetOpXPFactory(SkRegion::kUnion_Op);

[bsalomon, 2015/02/14 20:45:59]

I know we spent time figuring out that this is union, but now I realize that the
old code was trying to draw with replace, but to avoid triggering dsb/dst-copy
it was using union. Since the dst was cleared to zero union is equivalent to
replace. Might as well use replace.

[bsalomon, 2015/02/17 13:58:13]

Also, we should install this XP unconditionally. It was guarded by doAA only
because this code had to try to be too smart in the pre-XP days by knowing that
aa could trigger coverage stages and therefore present blending challenges in
src mode.

[egdaniel, 2015/02/17 14:43:01]

Do we still want to set aa on the paint? Should it be tempPaint.setAA(doAA)?

     }
 
     // Draw the mask into maskTexture with the path's top-left at the origin using tempPaint.
     SkMatrix translate;
     translate.setTranslate(-maskRect.fLeft, -maskRect.fTop);
     context->drawPath(tempPaint, translate, devPath, strokeInfo);
     return mask;
 }
 
 SkBitmap wrap_texture(GrTexture* texture) {
@@ skipping 1205 matching lines @@
 #endif
 }
 
 SkImageFilter::Cache* SkGpuDevice::getImageFilterCache() {
     // We always return a transient cache, so it is freed after each
     // filter traversal.
     return SkImageFilter::Cache::Create(kDefaultImageFilterCacheSize);
 }
 
 #endif