The Tor Browser: comparison gfx/skia/trunk/src/core/SkConvolver.h

--1:000000000000
+:844ea5384fa3
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+#ifndef SK_CONVOLVER_H
+#define SK_CONVOLVER_H
+#include "SkSize.h"
+#include "SkTypes.h"
+#include "SkTArray.h"
+// avoid confusion with Mac OS X's math library (Carbon)
+#if defined(__APPLE__)
+#undef FloatToConvolutionFixed
+#undef ConvolutionFixedToFloat
+#endif
+// Represents a filter in one dimension. Each output pixel has one entry in this
+// object for the filter values contributing to it. You build up the filter
+// list by calling AddFilter for each output pixel (in order).
+//
+// We do 2-dimensional convolution by first convolving each row by one
+// SkConvolutionFilter1D, then convolving each column by another one.
+//
+// Entries are stored in ConvolutionFixed point, shifted left by kShiftBits.
+class SkConvolutionFilter1D {
+public:
+typedef short ConvolutionFixed;
+// The number of bits that ConvolutionFixed point values are shifted by.
+enum { kShiftBits = 14 };
+SK_API SkConvolutionFilter1D();
+SK_API ~SkConvolutionFilter1D();
+// Convert between floating point and our ConvolutionFixed point representation.
+static ConvolutionFixed FloatToFixed(float f) {
+return static_cast<ConvolutionFixed>(f * (1 << kShiftBits));
+}
+static unsigned char FixedToChar(ConvolutionFixed x) {
+return static_cast<unsigned char>(x >> kShiftBits);
+}
+static float FixedToFloat(ConvolutionFixed x) {
+// The cast relies on ConvolutionFixed being a short, implying that on
+// the platforms we care about all (16) bits will fit into
+// the mantissa of a (32-bit) float.
+SK_COMPILE_ASSERT(sizeof(ConvolutionFixed) == 2, ConvolutionFixed_type_should_fit_in_float_mantissa);
+float raw = static_cast<float>(x);
+return ldexpf(raw, -kShiftBits);
+}
+// Returns the maximum pixel span of a filter.
+int maxFilter() const { return fMaxFilter; }
+// Returns the number of filters in this filter. This is the dimension of the
+// output image.
+int numValues() const { return static_cast<int>(fFilters.count()); }
+// Appends the given list of scaling values for generating a given output
+// pixel. |filterOffset| is the distance from the edge of the image to where
+// the scaling factors start. The scaling factors apply to the source pixels
+// starting from this position, and going for the next |filterLength| pixels.
+//
+// You will probably want to make sure your input is normalized (that is,
+// all entries in |filterValuesg| sub to one) to prevent affecting the overall
+// brighness of the image.
+//
+// The filterLength must be > 0.
+//
+// This version will automatically convert your input to ConvolutionFixed point.
+SK_API void AddFilter(int filterOffset,
+const float* filterValues,
+int filterLength);
+// Same as the above version, but the input is already ConvolutionFixed point.
+void AddFilter(int filterOffset,
+const ConvolutionFixed* filterValues,
+int filterLength);
+// Retrieves a filter for the given |valueOffset|, a position in the output
+// image in the direction we're convolving. The offset and length of the
+// filter values are put into the corresponding out arguments (see AddFilter
+// above for what these mean), and a pointer to the first scaling factor is
+// returned. There will be |filterLength| values in this array.
+inline const ConvolutionFixed* FilterForValue(int valueOffset,
+int* filterOffset,
+int* filterLength) const {
+const FilterInstance& filter = fFilters[valueOffset];
+*filterOffset = filter.fOffset;
+*filterLength = filter.fTrimmedLength;
+if (filter.fTrimmedLength == 0) {
+return NULL;
+}
+return &fFilterValues[filter.fDataLocation];
+}
+// Retrieves the filter for the offset 0, presumed to be the one and only.
+// The offset and length of the filter values are put into the corresponding
+// out arguments (see AddFilter). Note that |filterLegth| and
+// |specifiedFilterLength| may be different if leading/trailing zeros of the
+// original floating point form were clipped.
+// There will be |filterLength| values in the return array.
+// Returns NULL if the filter is 0-length (for instance when all floating
+// point values passed to AddFilter were clipped to 0).
+SK_API const ConvolutionFixed* GetSingleFilter(int* specifiedFilterLength,
+int* filterOffset,
+int* filterLength) const;
+// Add another value to the fFilterValues array -- useful for
+// SIMD padding which happens outside of this class.
+void addFilterValue( ConvolutionFixed val ) {
+fFilterValues.push_back( val );
+}
+private:
+struct FilterInstance {
+// Offset within filterValues for this instance of the filter.
+int fDataLocation;
+// Distance from the left of the filter to the center. IN PIXELS
+int fOffset;
+// Number of values in this filter instance.
+int fTrimmedLength;
+// Filter length as specified. Note that this may be different from
+// 'trimmed_length' if leading/trailing zeros of the original floating
+// point form were clipped differently on each tail.
+int fLength;
+};
+// Stores the information for each filter added to this class.
+SkTArray<FilterInstance> fFilters;
+// We store all the filter values in this flat list, indexed by
+// |FilterInstance.data_location| to avoid the mallocs required for storing
+// each one separately.
+SkTArray<ConvolutionFixed> fFilterValues;
+// The maximum size of any filter we've added.
+int fMaxFilter;
+};
+typedef void (*SkConvolveVertically_pointer)(
+const SkConvolutionFilter1D::ConvolutionFixed* filterValues,
+int filterLength,
+unsigned char* const* sourceDataRows,
+int pixelWidth,
+unsigned char* outRow,
+bool hasAlpha);
+typedef void (*SkConvolve4RowsHorizontally_pointer)(
+const unsigned char* srcData[4],
+const SkConvolutionFilter1D& filter,
+unsigned char* outRow[4]);
+typedef void (*SkConvolveHorizontally_pointer)(
+const unsigned char* srcData,
+const SkConvolutionFilter1D& filter,
+unsigned char* outRow,
+bool hasAlpha);
+typedef void (*SkConvolveFilterPadding_pointer)(
+SkConvolutionFilter1D* filter);
+struct SkConvolutionProcs {
+// This is how many extra pixels may be read by the
+// conolve*horizontally functions.
+int fExtraHorizontalReads;
+SkConvolveVertically_pointer fConvolveVertically;
+SkConvolve4RowsHorizontally_pointer fConvolve4RowsHorizontally;
+SkConvolveHorizontally_pointer fConvolveHorizontally;
+SkConvolveFilterPadding_pointer fApplySIMDPadding;
+};
+// Does a two-dimensional convolution on the given source image.
+//
+// It is assumed the source pixel offsets referenced in the input filters
+// reference only valid pixels, so the source image size is not required. Each
+// row of the source image starts |sourceByteRowStride| after the previous
+// one (this allows you to have rows with some padding at the end).
+//
+// The result will be put into the given output buffer. The destination image
+// size will be xfilter.numValues() * yfilter.numValues() pixels. It will be
+// in rows of exactly xfilter.numValues() * 4 bytes.
+//
+// |sourceHasAlpha| is a hint that allows us to avoid doing computations on
+// the alpha channel if the image is opaque. If you don't know, set this to
+// true and it will work properly, but setting this to false will be a few
+// percent faster if you know the image is opaque.
+//
+// The layout in memory is assumed to be 4-bytes per pixel in B-G-R-A order
+// (this is ARGB when loaded into 32-bit words on a little-endian machine).
+SK_API void BGRAConvolve2D(const unsigned char* sourceData,
+int sourceByteRowStride,
+bool sourceHasAlpha,
+const SkConvolutionFilter1D& xfilter,
+const SkConvolutionFilter1D& yfilter,
+int outputByteRowStride,
+unsigned char* output,
+const SkConvolutionProcs&,
+bool useSimdIfPossible);
+#endif  // SK_CONVOLVER_H

The Tor Browser / file comparison

comparison: gfx/skia/trunk/src/core/SkConvolver.h

gfx/skia/trunk/src/core/SkConvolver.h