include/effects/SkMatrixConvolutionImageFilter.h

/*
 * 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 SkMatrixConvolutionImageFilter_DEFINED
#define SkMatrixConvolutionImageFilter_DEFINED

#include "SkImageFilter.h"
#include "SkScalar.h"
#include "SkSize.h"
#include "SkPoint.h"

/*! \class SkMatrixConvolutionImageFilter
    Matrix convolution image filter.  This filter applies an NxM image
    processing kernel to a given input image.  This can be used to produce
    effects such as sharpening, blurring, edge detection, etc.
 */

class SK_API SkMatrixConvolutionImageFilter : public SkImageFilter {
public:
    /*! \enum TileMode */
    enum TileMode {
      kClamp_TileMode,         /*!< Clamp to the image's edge pixels. */
      kRepeat_TileMode,        /*!< Wrap around to the image's opposite edge. */
      kClampToBlack_TileMode,  /*!< Fill with transparent black. */
    };

    /** Construct a matrix convolution image filter.
        @param kernelSize  The kernel size in pixels, in each dimension (N by M).
        @param kernel      The image processing kernel.  Must contain N * M
                           elements, in row order.
        @param gain        A scale factor applied to each pixel after
                           convolution.  This can be used to normalize the
                           kernel, if it does not sum to 1.
        @param bias        A bias factor added to each pixel after convolution.
        @param target      An offset applied to each pixel coordinate before
                           convolution.  This can be used to center the kernel
                           over the image (e.g., a 3x3 kernel should have a
                           target of {1, 1}).
        @param tileMode    How accesses outside the image are treated.  (@see
                           TileMode).
        @param convolveAlpha  If true, all channels are convolved.  If false,
                           only the RGB channels are convolved, and
                           alpha is copied from the source image.
        @param input       The input image filter.  If NULL, the src bitmap
                           passed to filterImage() is used instead.
    */

    SkMatrixConvolutionImageFilter(const SkISize& kernelSize, const SkScalar* kernel, SkScalar gain, SkScalar bias, const SkIPoint& target, TileMode tileMode, bool convolveAlpha, SkImageFilter* input = NULL);
    virtual ~SkMatrixConvolutionImageFilter();

    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkMatrixConvolutionImageFilter)

protected:
    SkMatrixConvolutionImageFilter(SkFlattenableReadBuffer& buffer);
    virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;

    virtual bool onFilterImage(Proxy*, const SkBitmap& src, const SkMatrix&,
                               SkBitmap* result, SkIPoint* loc) SK_OVERRIDE;

#if SK_SUPPORT_GPU
    virtual bool asNewEffect(GrEffectRef**, GrTexture*) const SK_OVERRIDE;
#endif

private:
    SkISize   fKernelSize;
    SkScalar* fKernel;
    SkScalar  fGain;
    SkScalar  fBias;
    SkIPoint  fTarget;
    TileMode  fTileMode;
    bool      fConvolveAlpha;
    typedef SkImageFilter INHERITED;

    template <class PixelFetcher, bool convolveAlpha>
    void filterPixels(const SkBitmap& src, SkBitmap* result, const SkIRect& rect);
    template <class PixelFetcher>
    void filterPixels(const SkBitmap& src, SkBitmap* result, const SkIRect& rect);
    void filterInteriorPixels(const SkBitmap& src, SkBitmap* result, const SkIRect& rect);
    void filterBorderPixels(const SkBitmap& src, SkBitmap* result, const SkIRect& rect);
};

#endif