SkMatrixConvolutionImageFilter.h revision a469c28c3c16214733a25201a286970f57b3d944 
1/*
2 * Copyright 2012 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#ifndef SkMatrixConvolutionImageFilter_DEFINED
9#define SkMatrixConvolutionImageFilter_DEFINED
10
11#include "SkSingleInputImageFilter.h"
12#include "SkScalar.h"
13#include "SkSize.h"
14#include "SkPoint.h"
15
16/*! \class SkMatrixConvolutionImageFilter
17    Matrix convolution image filter.  This filter applies an NxM image
18    processing kernel to a given input image.  This can be used to produce
19    effects such as sharpening, blurring, edge detection, etc.
20 */
21
22class SK_API SkMatrixConvolutionImageFilter : public SkSingleInputImageFilter {
23public:
24    /*! \enum TileMode */
25    enum TileMode {
26      kClamp_TileMode,         /*!< Clamp to the image's edge pixels. */
27      kRepeat_TileMode,        /*!< Wrap around to the image's opposite edge. */
28      kClampToBlack_TileMode,  /*!< Fill with transparent black. */
29    };
30
31    /** Construct a matrix convolution image filter.
32        @param kernelSize  The kernel size in pixels, in each dimension (N by M).
33        @param kernel      The image processing kernel.  Must contain N * M
34                           elements, in row order.
35        @param gain        A scale factor applied to each pixel after
36                           convolution.  This can be used to normalize the
37                           kernel, if it does not sum to 1.
38        @param bias        A bias factor added to each pixel after convolution.
39        @param target      An offset applied to each pixel coordinate before
40                           convolution.  This can be used to center the kernel
41                           over the image (e.g., a 3x3 kernel should have a
42                           target of {1, 1}).
43        @param tileMode    How accesses outside the image are treated.  (@see
44                           TileMode).
45        @param convolveAlpha  If true, all channels are convolved.  If false,
46                           only the RGB channels are convolved, and
47                           alpha is copied from the source image.
48        @param input       The input image filter.  If NULL, the src bitmap
49                           passed to filterImage() is used instead.
50    */
51
52    SkMatrixConvolutionImageFilter(const SkISize& kernelSize, const SkScalar* kernel, SkScalar gain, SkScalar bias, const SkIPoint& target, TileMode tileMode, bool convolveAlpha, SkImageFilter* input = NULL);
53    virtual ~SkMatrixConvolutionImageFilter();
54
55    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkMatrixConvolutionImageFilter)
56
57protected:
58    SkMatrixConvolutionImageFilter(SkFlattenableReadBuffer& buffer);
59    virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
60
61    virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
62                               SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;
63
64#if SK_SUPPORT_GPU
65    virtual bool asNewCustomStage(GrEffect** stage, GrTexture*) const SK_OVERRIDE;
66#endif
67
68private:
69    SkISize   fKernelSize;
70    SkScalar* fKernel;
71    SkScalar  fGain;
72    SkScalar  fBias;
73    SkIPoint  fTarget;
74    TileMode  fTileMode;
75    bool      fConvolveAlpha;
76    typedef SkSingleInputImageFilter INHERITED;
77
78    template <class PixelFetcher, bool convolveAlpha>
79    void filterPixels(const SkBitmap& src, SkBitmap* result, const SkIRect& rect);
80    template <class PixelFetcher>
81    void filterPixels(const SkBitmap& src, SkBitmap* result, const SkIRect& rect);
82    void filterInteriorPixels(const SkBitmap& src, SkBitmap* result, const SkIRect& rect);
83    void filterBorderPixels(const SkBitmap& src, SkBitmap* result, const SkIRect& rect);
84};
85
86#endif
87