Implements a matrix convolution filter (raster path only). The filtering loop
is templated on the tiling mode for speed: interior pixels are unconditionally
fetched; border pixels apply the appropriate tiling mode before fetching. It
handles target, bias, divisor (as gain), and edge modes (named to be more
skia-like). It does not handle the "preserveAlpha" semantics of
feConvolveMatrix, nor "kernelUnitLength".
git-svn-id: http://skia.googlecode.com/svn/trunk@5592 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/effects/SkMatrixConvolutionImageFilter.h b/include/effects/SkMatrixConvolutionImageFilter.h
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+++ b/include/effects/SkMatrixConvolutionImageFilter.h
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+/*
+ * 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 "SkSingleInputImageFilter.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 SkMatrixConvolutionImageFilter : public SkSingleInputImageFilter {
+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 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, 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;
+
+private:
+ SkISize fKernelSize;
+ SkScalar* fKernel;
+ SkScalar fGain;
+ SkScalar fBias;
+ SkIPoint fTarget;
+ TileMode fTileMode;
+ typedef SkSingleInputImageFilter INHERITED;
+
+ 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