Implement bounds traversals for tile and matrix convolution filters.

Add a new GM that exercises tiled drawing all pixel-moving filters
(and some non-pixel-moving ones) and compares it against non-tiled
drawing of the same filters. Fixing this test revealed that tile and
matrix convolution filters had no onFilterBounds() traversals
(test-driven development FTW). Tile requires (conservatively) the
bounds to include the whole source rect, since it may end up in the
result. Matrix convolution requires the bounds to be offset by the
kernel size and target.

R=reed@google.com
BUG=skia:

Review URL: https://codereview.chromium.org/258243005

git-svn-id: http://skia.googlecode.com/svn/trunk@14432 2bbb7eff-a529-9590-31e7-b0007b416f81

2 files changed, 24 insertions, 0 deletions

diff --git a/src/effects/SkMatrixConvolutionImageFilter.cpp b/src/effects/SkMatrixConvolutionImageFilter.cpp
index 878cbae795..3c9fc87787 100644
--- a/src/effects/SkMatrixConvolutionImageFilter.cpp
+++ b/src/effects/SkMatrixConvolutionImageFilter.cpp
@@ -306,6 +306,19 @@ bool SkMatrixConvolutionImageFilter::onFilterImage(Proxy* proxy,
     return true;
 }
 
+bool SkMatrixConvolutionImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,
+                                                    SkIRect* dst) const {
+    SkIRect bounds = src;
+    bounds.fRight += fKernelSize.width() - 1;
+    bounds.fBottom += fKernelSize.height() - 1;
+    bounds.offset(-fKernelOffset);
+    if (getInput(0) && !getInput(0)->filterBounds(bounds, ctm, &bounds)) {
+        return false;
+    }
+    *dst = bounds;
+    return true;
+}
+
 #if SK_SUPPORT_GPU
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/src/effects/SkTileImageFilter.cpp b/src/effects/SkTileImageFilter.cpp
index f3bad76345..73c0a581e9 100644
--- a/src/effects/SkTileImageFilter.cpp
+++ b/src/effects/SkTileImageFilter.cpp
@@ -75,6 +75,17 @@ bool SkTileImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& src,
     return true;
 }
 
+bool SkTileImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,
+                                       SkIRect* dst) const {
+    SkRect srcRect;
+    ctm.mapRect(&srcRect, fSrcRect);
+    SkIRect srcIRect;
+    srcRect.roundOut(&srcIRect);
+    srcIRect.join(src);
+    *dst = srcIRect;
+    return true;
+}
+
 SkTileImageFilter::SkTileImageFilter(SkReadBuffer& buffer)
   : INHERITED(1, buffer) {
     buffer.readRect(&fSrcRect);