Implement support for expanding crop rects in image filters

src/core/SkImageFilter.cpp

Index: src/core/SkImageFilter.cpp
diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index 6613f09b93b7fd0ba2f06aa3ebe7db4ed04f89fd..2be66e787c5c6efba9148de9884c3e26a85b012f 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -8,6 +8,7 @@
 #include "SkImageFilter.h"
 
 #include "SkBitmap.h"
+#include "SkDevice.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkRect.h"
@@ -155,9 +156,7 @@ bool SkImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const Cont
     }
     GrTexture* srcTexture = input.getTexture();
     SkIRect bounds;
-    src.getBounds(&bounds);
-    bounds.offset(srcOffset);
-    if (!this->applyCropRect(&bounds, ctx.ctm())) {
+    if (!this->applyCropRect(ctx, proxy, input, &srcOffset, &bounds, &input)) {
         return false;
     }
     SkRect srcRect = SkRect::Make(bounds);
@@ -196,18 +195,60 @@ bool SkImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const Cont
 #endif
 }
 
-bool SkImageFilter::applyCropRect(SkIRect* rect, const SkMatrix& matrix) const {
+bool SkImageFilter::applyCropRect(const Context& ctx, const SkBitmap& src,
+                                  const SkIPoint& srcOffset, SkIRect* bounds) const {
+    SkIRect srcBounds;
+    src.getBounds(&srcBounds);
+    srcBounds.offset(srcOffset);
     SkRect cropRect;
-    matrix.mapRect(&cropRect, fCropRect.rect());
+    ctx.ctm().mapRect(&cropRect, fCropRect.rect());
     SkIRect cropRectI;
     cropRect.roundOut(&cropRectI);
     uint32_t flags = fCropRect.flags();
-    // If the original crop rect edges were unset, max out the new crop edges
-    if (!(flags & CropRect::kHasLeft_CropEdge)) cropRectI.fLeft = SK_MinS32;
-    if (!(flags & CropRect::kHasTop_CropEdge)) cropRectI.fTop = SK_MinS32;
-    if (!(flags & CropRect::kHasRight_CropEdge)) cropRectI.fRight = SK_MaxS32;
-    if (!(flags & CropRect::kHasBottom_CropEdge)) cropRectI.fBottom = SK_MaxS32;
-    return rect->intersect(cropRectI);
+    if (flags & CropRect::kHasLeft_CropEdge) srcBounds.fLeft = cropRectI.fLeft;
+    if (flags & CropRect::kHasTop_CropEdge) srcBounds.fTop = cropRectI.fTop;
+    if (flags & CropRect::kHasRight_CropEdge) srcBounds.fRight = cropRectI.fRight;
+    if (flags & CropRect::kHasBottom_CropEdge) srcBounds.fBottom = cropRectI.fBottom;
+    if (!srcBounds.intersect(ctx.clipBounds())) {
+        return false;
+    }
+    *bounds = srcBounds;
+    return true;
+}
+
+bool SkImageFilter::applyCropRect(const Context& ctx, Proxy* proxy, const SkBitmap& src,
+                                  SkIPoint* srcOffset, SkIRect* bounds, SkBitmap* dst) const {
+    SkIRect srcBounds;
+    src.getBounds(&srcBounds);
+    srcBounds.offset(*srcOffset);
+    SkRect cropRect;
+    ctx.ctm().mapRect(&cropRect, fCropRect.rect());
+    SkIRect cropRectI;
+    cropRect.roundOut(&cropRectI);
+    uint32_t flags = fCropRect.flags();
+    *bounds = srcBounds;
+    if (flags & CropRect::kHasLeft_CropEdge) bounds->fLeft = cropRectI.fLeft;
+    if (flags & CropRect::kHasTop_CropEdge) bounds->fTop = cropRectI.fTop;
+    if (flags & CropRect::kHasRight_CropEdge) bounds->fRight = cropRectI.fRight;
+    if (flags & CropRect::kHasBottom_CropEdge) bounds->fBottom = cropRectI.fBottom;
+    if (!bounds->intersect(ctx.clipBounds())) {
+        return false;
+    }
+    if (srcBounds.contains(*bounds)) {
+        *dst = src;
+        return true;
+    } else {
+        SkAutoTUnref<SkBaseDevice> device(proxy->createDevice(bounds->width(), bounds->height()));
+        if (!device) {
+            return false;
+        }
+        SkCanvas canvas(device);
+        canvas.clear(0x00000000);
+        canvas.drawBitmap(src, srcOffset->x() - bounds->x(), srcOffset->y() - bounds->y());
+        *srcOffset = SkIPoint::Make(bounds->x(), bounds->y());
+        *dst = device->accessBitmap(false);
+        return true;
+    }
 }
 
 bool SkImageFilter::onFilterBounds(const SkIRect& src, const SkMatrix& ctm,