Create fragment processor for performing input color blend with child processor

src/effects/SkXfermodeImageFilter.cpp

 /*
  * Copyright 2013 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkXfermodeImageFilter.h"
 #include "SkCanvas.h"
 #include "SkDevice.h"
 #include "SkColorPriv.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkXfermode.h"
 #if SK_SUPPORT_GPU
 #include "GrContext.h"
 #include "GrDrawContext.h"
 #include "effects/GrTextureDomain.h"
+#include "effects/GrSimpleTextureEffect.h"
 #include "SkGr.h"
 #endif
 
 ///////////////////////////////////////////////////////////////////////////////
 
 SkXfermodeImageFilter::SkXfermodeImageFilter(SkXfermode* mode,
                                              SkImageFilter* inputs[2],
                                              const CropRect* cropRect)
   : INHERITED(2, inputs, cropRect), fMode(mode) {
     SkSafeRef(fMode);
@@ skipping 117 matching lines @@
 
     SkBitmap foreground = src;
     SkIPoint foregroundOffset = SkIPoint::Make(0, 0);
     if (this->getInput(1) && 
         !this->getInput(1)->getInputResultGPU(proxy, src, ctx, &foreground, &foregroundOffset)) {
         return false;
     }
     GrTexture* foregroundTex = foreground.getTexture();
     GrContext* context = foregroundTex->getContext();
 
-    GrFragmentProcessor* xferProcessor = nullptr;
+    const GrFragmentProcessor* xferFP = nullptr;
 
     GrSurfaceDesc desc;
     desc.fFlags = kRenderTarget_GrSurfaceFlag;
     desc.fWidth = src.width();
     desc.fHeight = src.height();
     desc.fConfig = kSkia8888_GrPixelConfig;
     SkAutoTUnref<GrTexture> dst(context->textureProvider()->createApproxTexture(desc));
     if (!dst) {
         return false;
     }
 
     GrPaint paint;
-    if (!fMode || !fMode->asFragmentProcessor(&xferProcessor, paint.getProcessorDataManager(),
-                                              backgroundTex)) {
+    SkMatrix bgMatrix;
+    bgMatrix.setIDiv(backgroundTex->width(), backgroundTex->height());
+    SkAutoTUnref<const GrFragmentProcessor> bgFP(
+        GrSimpleTextureEffect::Create(paint.getProcessorDataManager(), backgroundTex, bgMatrix));
+    if (!fMode || !fMode->asFragmentProcessor(&xferFP, paint.getProcessorDataManager(), bgFP)) {
         // canFilterImageGPU() should've taken care of this
         SkASSERT(false);
         return false;
     }
 
     SkMatrix foregroundMatrix = GrCoordTransform::MakeDivByTextureWHMatrix(foregroundTex);
     foregroundMatrix.preTranslate(SkIntToScalar(backgroundOffset.fX-foregroundOffset.fX),
                                   SkIntToScalar(backgroundOffset.fY-foregroundOffset.fY));
 
 
     SkRect srcRect;
     src.getBounds(&srcRect);
 
     SkAutoTUnref<GrFragmentProcessor> foregroundDomain(GrTextureDomainEffect::Create(
         paint.getProcessorDataManager(),
         foregroundTex, foregroundMatrix,
         GrTextureDomain::MakeTexelDomain(foregroundTex, foreground.bounds()),
         GrTextureDomain::kDecal_Mode,
         GrTextureParams::kNone_FilterMode)
     );
 
     paint.addColorFragmentProcessor(foregroundDomain.get());
-    paint.addColorFragmentProcessor(xferProcessor)->unref();
+    if (xferFP) {
+        paint.addColorFragmentProcessor(xferFP)->unref();
+    }
 
     SkAutoTUnref<GrDrawContext> drawContext(context->drawContext());
     if (!drawContext) {
         return false;
     }
 
     drawContext->drawRect(dst->asRenderTarget(), GrClip::WideOpen(), paint, 
                           SkMatrix::I(), srcRect);
 
     offset->fX = backgroundOffset.fX;
     offset->fY = backgroundOffset.fY;
     WrapTexture(dst, src.width(), src.height(), result);
     return true;
 }
 
 #endif