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

src/effects/SkTileImageFilter.cpp

Index: src/effects/SkTileImageFilter.cpp
diff --git a/src/effects/SkTileImageFilter.cpp b/src/effects/SkTileImageFilter.cpp
index c5eace0b74ddd598311af434bb9128cc30437a82..73e5304adb3db2f8a0a87908a5f3e1b0c0d76030 100644
--- a/src/effects/SkTileImageFilter.cpp
+++ b/src/effects/SkTileImageFilter.cpp
@@ -24,16 +24,24 @@ bool SkTileImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& src, const S
         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;
     }
 
@@ -41,8 +49,6 @@ bool SkTileImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& src, const S
     if (NULL == device.get()) {
         return false;
     }
-    SkIRect bounds;
-    source.getBounds(&bounds);
     SkCanvas canvas(device);
     SkPaint paint;
     paint.setXfermodeMode(SkXfermode::kSrc_Mode);
@@ -50,7 +56,6 @@ bool SkTileImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& src, const S
     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);