Implement correct clipping for image filters.

src/core/SkCanvas.cpp

 
 /*
  * Copyright 2008 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 "SkCanvas.h"
@@ skipping 773 matching lines @@
 #else
     return SkBitmap::kARGB_8888_Config; // default answer
 #endif
 }
 
 static bool bounds_affects_clip(SkCanvas::SaveFlags flags) {
     return (flags & SkCanvas::kClipToLayer_SaveFlag) != 0;
 }
 
 bool SkCanvas::clipRectBounds(const SkRect* bounds, SaveFlags flags,
-                               SkIRect* intersection) {
+                               SkIRect* intersection, const SkImageFilter* imageFilter) {
     SkIRect clipBounds;
+    SkRegion::Op op = SkRegion::kIntersect_Op;
     if (!this->getClipDeviceBounds(&clipBounds)) {
         return false;
     }
+
+    if (imageFilter) {
+        imageFilter->filterBounds(clipBounds, *fMCRec->fMatrix, &clipBounds);
+        // Filters may grow the bounds beyond the device bounds.
+        op = SkRegion::kReplace_Op;
+    }
     SkIRect ir;
     if (NULL != bounds) {
         SkRect r;
 
         this->getTotalMatrix().mapRect(&r, *bounds);
         r.roundOut(&ir);
         // early exit if the layer's bounds are clipped out
         if (!ir.intersect(clipBounds)) {
             if (bounds_affects_clip(flags)) {
                 fMCRec->fRasterClip->setEmpty();
             }
             return false;
         }
     } else {    // no user bounds, so just use the clip
         ir = clipBounds;
     }
 
-    fClipStack.clipDevRect(ir, SkRegion::kIntersect_Op);
+    fClipStack.clipDevRect(ir, op);
 
     // early exit if the clip is now empty
     if (bounds_affects_clip(flags) &&
-        !fMCRec->fRasterClip->op(ir, SkRegion::kIntersect_Op)) {
+        !fMCRec->fRasterClip->op(ir, op)) {
         return false;
     }
 
     if (intersection) {
         *intersection = ir;
     }
     return true;
 }
 
 int SkCanvas::saveLayer(const SkRect* bounds, const SkPaint* paint,
                         SaveFlags flags) {
     return this->internalSaveLayer(bounds, paint, flags, false);
 }
 
 int SkCanvas::internalSaveLayer(const SkRect* bounds, const SkPaint* paint,
                                 SaveFlags flags, bool justForImageFilter) {
     // do this before we create the layer. We don't call the public save() since
     // that would invoke a possibly overridden virtual
     int count = this->internalSave(flags);
 
     fDeviceCMDirty = true;
 
     SkIRect ir;
-    if (!this->clipRectBounds(bounds, flags, &ir)) {
+    if (!this->clipRectBounds(bounds, flags, &ir, paint ? paint->getImageFilter() : NULL)) {
         return count;
     }
 
     // Kill the imagefilter if our device doesn't allow it
     SkLazyPaint lazyP;
     if (paint && paint->getImageFilter()) {
         if (!this->getTopDevice()->allowImageFilter(paint->getImageFilter())) {
             if (justForImageFilter) {
                 // early exit if the layer was just for the imageFilter
                 return count;
@@ skipping 1363 matching lines @@
     return *paint;
 }
 
 const SkRegion& SkCanvas::LayerIter::clip() const { return fImpl->getClip(); }
 int SkCanvas::LayerIter::x() const { return fImpl->getX(); }
 int SkCanvas::LayerIter::y() const { return fImpl->getY(); }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 SkCanvas::ClipVisitor::~ClipVisitor() { }