skia2/include/effects/SkBitmapSource.h
senorblanco@chromium.org c4b12f19a4 Implement correct clipping for image filters.
Image filters in Skia currently clip the size of the the offscreen
bitmap used for filtering to the device clip bounds. This means that
any pixel-moving filter (e.g., blur) has edge artifacts at the clip
boundaries. This is problematic for tiling, where a single SkPicture
is played back with a clip set to the tile boundaries.

By implementing the onFilterBounds() traversal, and using it in
saveLayer() when a filter is present, we can clip the layer to the
expanded clip rect. Note that this requires that the traversal be
performed in reverse as compared to computeFastBounds().  (It's also
done in device space, unlike computeFastBounds()).

New test imagefiltersclipped tests pixel-moving filters when clipped
by various clip rects.
New test imageblurtiled tests tiled (compositor-style) rendering of
blurred text. There should be no artifacts at the tile boundaries.

BUG=337831
R=reed@google.com

Review URL: https://codereview.chromium.org/23011012

git-svn-id: http://skia.googlecode.com/svn/trunk@13323 2bbb7eff-a529-9590-31e7-b0007b416f81
2014-02-05 17:51:22 +00:00

36 lines
1.1 KiB
C++

/*
* Copyright 2012 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.
*/
#ifndef SkBitmapSource_DEFINED
#define SkBitmapSource_DEFINED
#include "SkImageFilter.h"
#include "SkBitmap.h"
class SK_API SkBitmapSource : public SkImageFilter {
public:
explicit SkBitmapSource(const SkBitmap& bitmap);
SkBitmapSource(const SkBitmap& bitmap, const SkRect& srcRect, const SkRect& dstRect);
virtual void computeFastBounds(const SkRect& src, SkRect* dst) const SK_OVERRIDE;
SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkBitmapSource)
protected:
explicit SkBitmapSource(SkReadBuffer& buffer);
virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
SkBitmap* result, SkIPoint* offset) SK_OVERRIDE;
virtual bool onFilterBounds(const SkIRect& src, const SkMatrix& ctm, SkIRect* dst) const SK_OVERRIDE;
private:
SkBitmap fBitmap;
SkRect fSrcRect, fDstRect;
typedef SkImageFilter INHERITED;
};
#endif