Implement srcRect and dstRect functionality in SkBitmapSource. This is required for the "preserveAs…

src/effects/SkTileImageFilter.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkTileImageFilter.h"
 #include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkDevice.h"
 #include "SkFlattenableBuffers.h"
 #include "SkMatrix.h"
 #include "SkPaint.h"
 #include "SkShader.h"
 #include "SkValidationUtils.h"
 
 bool SkTileImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
                                       SkBitmap* dst, SkIPoint* offset) {
     SkBitmap source = src;
     SkImageFilter* input = getInput(0);
     SkIPoint localOffset = SkIPoint::Make(0, 0);
     if (input && !input->filterImage(proxy, src, ctm, &source, &localOffset)) {
         return false;
     }
 
-    int w = SkScalarTruncToInt(fDstRect.width());
-    int h = SkScalarTruncToInt(fDstRect.height());
+    SkRect dstRect;
+    ctm.mapRect(&dstRect, fDstRect);
+    int w = SkScalarCeilToInt(dstRect.width());
+    int h = SkScalarCeilToInt(dstRect.height());
     if (!fSrcRect.width() || !fSrcRect.height() || !w || !h) {
         return false;
     }
 
-    SkIRect srcRect;
-    fSrcRect.roundOut(&srcRect);
+    SkRect srcRect;
+    ctm.mapRect(&srcRect, fSrcRect);
+    SkIRect srcIRect;
+    srcRect.roundOut(&srcIRect);
     SkBitmap subset;
-    if (!source.extractSubset(&subset, srcRect)) {
+    SkIRect bounds;
+    source.getBounds(&bounds);
+    if (!srcIRect.intersect(bounds)) {
+        return true;
+    } else if (!source.extractSubset(&subset, srcIRect)) {
         return false;
     }
 
     SkAutoTUnref<SkBaseDevice> device(proxy->createDevice(w, h));
     if (NULL == device.get()) {
         return false;
     }
-    SkIRect bounds;
-    source.getBounds(&bounds);
     SkCanvas canvas(device);
     SkPaint paint;
     paint.setXfermodeMode(SkXfermode::kSrc_Mode);
 
     SkAutoTUnref<SkShader> shader(SkShader::CreateBitmapShader(subset,
                                   SkShader::kRepeat_TileMode, SkShader::kRepeat_TileMode));
     paint.setShader(shader);
-    SkRect dstRect = fDstRect;
     dstRect.offset(SkIntToScalar(localOffset.fX), SkIntToScalar(localOffset.fY));
     canvas.drawRect(dstRect, paint);
     *dst = device->accessBitmap(false);
     return true;
 }
 
 SkTileImageFilter::SkTileImageFilter(SkFlattenableReadBuffer& buffer)
   : INHERITED(1, buffer) {
     buffer.readRect(&fSrcRect);
     buffer.readRect(&fDstRect);
     buffer.validate(buffer.isValid() && SkIsValidRect(fSrcRect) && SkIsValidRect(fDstRect));
 }
 
 void SkTileImageFilter::flatten(SkFlattenableWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
     buffer.writeRect(fSrcRect);
     buffer.writeRect(fDstRect);
 }