Bounds fixes for SkXfermodeImageFilter:

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"
@@ skipping 43 matching lines @@
     if (backgroundInput &&
         !backgroundInput->filterImage(proxy, src, ctm, &background, &backgroundOffset)) {
         return false;
     }
     SkIPoint foregroundOffset = SkIPoint::Make(0, 0);
     if (foregroundInput &&
         !foregroundInput->filterImage(proxy, src, ctm, &foreground, &foregroundOffset)) {
         return false;
     }
 
-    SkIRect bounds;
+    SkIRect bounds, foregroundBounds;
     background.getBounds(&bounds);
+    bounds.offset(backgroundOffset);
+    foreground.getBounds(&foregroundBounds);
+    foregroundBounds.offset(foregroundOffset);
+    bounds.join(foregroundBounds);
     if (!applyCropRect(&bounds, ctm)) {
         return false;
     }
-    backgroundOffset.fX -= bounds.left();
-    backgroundOffset.fY -= bounds.top();
-    foregroundOffset.fX -= bounds.left();
-    foregroundOffset.fY -= bounds.top();
 
     SkAutoTUnref<SkBaseDevice> device(proxy->createDevice(bounds.width(), bounds.height()));
     if (NULL == device.get()) {
         return false;
     }
     SkCanvas canvas(device);
+    canvas.translate(SkIntToScalar(-bounds.left()), SkIntToScalar(-bounds.top()));
     SkPaint paint;
     paint.setXfermodeMode(SkXfermode::kSrc_Mode);
     canvas.drawBitmap(background, SkIntToScalar(backgroundOffset.fX),
                       SkIntToScalar(backgroundOffset.fY), &paint);
     paint.setXfermode(fMode);
     canvas.drawBitmap(foreground, SkIntToScalar(foregroundOffset.fX),
                       SkIntToScalar(foregroundOffset.fY), &paint);
+    canvas.clipRect(SkRect::Make(foregroundBounds), SkRegion::kDifference_Op);
+    paint.setColor(SK_ColorTRANSPARENT);
+    canvas.drawPaint(paint);
     *dst = device->accessBitmap(false);
     offset->fX += bounds.left();
     offset->fY += bounds.top();
     return true;
 }
 
 #if SK_SUPPORT_GPU
 
 bool SkXfermodeImageFilter::filterImageGPU(Proxy* proxy,
                                            const SkBitmap& src,
@@ skipping 56 matching lines @@
         foregroundPaint.setBlendFunc(sk_blend_to_grblend(sm), sk_blend_to_grblend(dm));
         foregroundPaint.addColorTextureEffect(foregroundTex, foregroundMatrix);
         context->drawRect(foregroundPaint, srcRect);
     }
     offset->fX += backgroundOffset.fX;
     offset->fY += backgroundOffset.fY;
     return SkImageFilterUtils::WrapTexture(dst, src.width(), src.height(), result);
 }
 
 #endif