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| 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #ifndef SKIA_EXT_CONVOLVER_H_ | |
| 6 #define SKIA_EXT_CONVOLVER_H_ | |
| 7 | |
| 8 #include <cmath> | |
| 9 #include <vector> | |
| 10 | |
| 11 #include "base/basictypes.h" | |
| 12 #include "third_party/skia/include/core/SkSize.h" | |
| 13 #include "third_party/skia/include/core/SkTypes.h" | |
| 14 | |
| 15 // We can build SSE2 optimized versions for all x86 CPUs | |
| 16 // except when building for the IOS emulator. | |
| 17 #if defined(ARCH_CPU_X86_FAMILY) && !defined(OS_IOS) | |
| 18 #define SIMD_SSE2 1 | |
| 19 #define SIMD_PADDING 8 // 8 * int16 | |
| 20 #endif | |
| 21 | |
| 22 #if defined (ARCH_CPU_MIPS_FAMILY) && \ | |
| 23 defined(__mips_dsp) && (__mips_dsp_rev >= 2) | |
| 24 #define SIMD_MIPS_DSPR2 1 | |
| 25 #endif | |
| 26 // avoid confusion with Mac OS X's math library (Carbon) | |
| 27 #if defined(__APPLE__) | |
| 28 #undef FloatToFixed | |
| 29 #undef FixedToFloat | |
| 30 #endif | |
| 31 | |
| 32 namespace skia { | |
| 33 | |
| 34 // Represents a filter in one dimension. Each output pixel has one entry in this | |
| 35 // object for the filter values contributing to it. You build up the filter | |
| 36 // list by calling AddFilter for each output pixel (in order). | |
| 37 // | |
| 38 // We do 2-dimensional convolution by first convolving each row by one | |
| 39 // ConvolutionFilter1D, then convolving each column by another one. | |
| 40 // | |
| 41 // Entries are stored in fixed point, shifted left by kShiftBits. | |
| 42 class ConvolutionFilter1D { | |
| 43 public: | |
| 44 typedef short Fixed; | |
| 45 | |
| 46 // The number of bits that fixed point values are shifted by. | |
| 47 enum { kShiftBits = 14 }; | |
| 48 | |
| 49 SK_API ConvolutionFilter1D(); | |
| 50 SK_API ~ConvolutionFilter1D(); | |
| 51 | |
| 52 // Convert between floating point and our fixed point representation. | |
| 53 static Fixed FloatToFixed(float f) { | |
| 54 return static_cast<Fixed>(f * (1 << kShiftBits)); | |
| 55 } | |
| 56 static unsigned char FixedToChar(Fixed x) { | |
| 57 return static_cast<unsigned char>(x >> kShiftBits); | |
| 58 } | |
| 59 static float FixedToFloat(Fixed x) { | |
| 60 // The cast relies on Fixed being a short, implying that on | |
| 61 // the platforms we care about all (16) bits will fit into | |
| 62 // the mantissa of a (32-bit) float. | |
| 63 static_assert(sizeof(Fixed) == 2, | |
| 64 "fixed type should fit in float mantissa"); | |
| 65 float raw = static_cast<float>(x); | |
| 66 return ldexpf(raw, -kShiftBits); | |
| 67 } | |
| 68 | |
| 69 // Returns the maximum pixel span of a filter. | |
| 70 int max_filter() const { return max_filter_; } | |
| 71 | |
| 72 // Returns the number of filters in this filter. This is the dimension of the | |
| 73 // output image. | |
| 74 int num_values() const { return static_cast<int>(filters_.size()); } | |
| 75 | |
| 76 // Appends the given list of scaling values for generating a given output | |
| 77 // pixel. |filter_offset| is the distance from the edge of the image to where | |
| 78 // the scaling factors start. The scaling factors apply to the source pixels | |
| 79 // starting from this position, and going for the next |filter_length| pixels. | |
| 80 // | |
| 81 // You will probably want to make sure your input is normalized (that is, | |
| 82 // all entries in |filter_values| sub to one) to prevent affecting the overall | |
| 83 // brighness of the image. | |
| 84 // | |
| 85 // The filter_length must be > 0. | |
| 86 // | |
| 87 // This version will automatically convert your input to fixed point. | |
| 88 SK_API void AddFilter(int filter_offset, | |
| 89 const float* filter_values, | |
| 90 int filter_length); | |
| 91 | |
| 92 // Same as the above version, but the input is already fixed point. | |
| 93 void AddFilter(int filter_offset, | |
| 94 const Fixed* filter_values, | |
| 95 int filter_length); | |
| 96 | |
| 97 // Retrieves a filter for the given |value_offset|, a position in the output | |
| 98 // image in the direction we're convolving. The offset and length of the | |
| 99 // filter values are put into the corresponding out arguments (see AddFilter | |
| 100 // above for what these mean), and a pointer to the first scaling factor is | |
| 101 // returned. There will be |filter_length| values in this array. | |
| 102 inline const Fixed* FilterForValue(int value_offset, | |
| 103 int* filter_offset, | |
| 104 int* filter_length) const { | |
| 105 const FilterInstance& filter = filters_[value_offset]; | |
| 106 *filter_offset = filter.offset; | |
| 107 *filter_length = filter.trimmed_length; | |
| 108 if (filter.trimmed_length == 0) { | |
| 109 return NULL; | |
| 110 } | |
| 111 return &filter_values_[filter.data_location]; | |
| 112 } | |
| 113 | |
| 114 // Retrieves the filter for the offset 0, presumed to be the one and only. | |
| 115 // The offset and length of the filter values are put into the corresponding | |
| 116 // out arguments (see AddFilter). Note that |filter_legth| and | |
| 117 // |specified_filter_length| may be different if leading/trailing zeros of the | |
| 118 // original floating point form were clipped. | |
| 119 // There will be |filter_length| values in the return array. | |
| 120 // Returns NULL if the filter is 0-length (for instance when all floating | |
| 121 // point values passed to AddFilter were clipped to 0). | |
| 122 SK_API const Fixed* GetSingleFilter(int* specified_filter_length, | |
| 123 int* filter_offset, | |
| 124 int* filter_length) const; | |
| 125 | |
| 126 inline void PaddingForSIMD() { | |
| 127 // Padding |padding_count| of more dummy coefficients after the coefficients | |
| 128 // of last filter to prevent SIMD instructions which load 8 or 16 bytes | |
| 129 // together to access invalid memory areas. We are not trying to align the | |
| 130 // coefficients right now due to the opaqueness of <vector> implementation. | |
| 131 // This has to be done after all |AddFilter| calls. | |
| 132 #ifdef SIMD_PADDING | |
| 133 for (int i = 0; i < SIMD_PADDING; ++i) | |
| 134 filter_values_.push_back(static_cast<Fixed>(0)); | |
| 135 #endif | |
| 136 } | |
| 137 | |
| 138 private: | |
| 139 struct FilterInstance { | |
| 140 // Offset within filter_values for this instance of the filter. | |
| 141 int data_location; | |
| 142 | |
| 143 // Distance from the left of the filter to the center. IN PIXELS | |
| 144 int offset; | |
| 145 | |
| 146 // Number of values in this filter instance. | |
| 147 int trimmed_length; | |
| 148 | |
| 149 // Filter length as specified. Note that this may be different from | |
| 150 // 'trimmed_length' if leading/trailing zeros of the original floating | |
| 151 // point form were clipped differently on each tail. | |
| 152 int length; | |
| 153 }; | |
| 154 | |
| 155 // Stores the information for each filter added to this class. | |
| 156 std::vector<FilterInstance> filters_; | |
| 157 | |
| 158 // We store all the filter values in this flat list, indexed by | |
| 159 // |FilterInstance.data_location| to avoid the mallocs required for storing | |
| 160 // each one separately. | |
| 161 std::vector<Fixed> filter_values_; | |
| 162 | |
| 163 // The maximum size of any filter we've added. | |
| 164 int max_filter_; | |
| 165 }; | |
| 166 | |
| 167 // Does a two-dimensional convolution on the given source image. | |
| 168 // | |
| 169 // It is assumed the source pixel offsets referenced in the input filters | |
| 170 // reference only valid pixels, so the source image size is not required. Each | |
| 171 // row of the source image starts |source_byte_row_stride| after the previous | |
| 172 // one (this allows you to have rows with some padding at the end). | |
| 173 // | |
| 174 // The result will be put into the given output buffer. The destination image | |
| 175 // size will be xfilter.num_values() * yfilter.num_values() pixels. It will be | |
| 176 // in rows of exactly xfilter.num_values() * 4 bytes. | |
| 177 // | |
| 178 // |source_has_alpha| is a hint that allows us to avoid doing computations on | |
| 179 // the alpha channel if the image is opaque. If you don't know, set this to | |
| 180 // true and it will work properly, but setting this to false will be a few | |
| 181 // percent faster if you know the image is opaque. | |
| 182 // | |
| 183 // The layout in memory is assumed to be 4-bytes per pixel in B-G-R-A order | |
| 184 // (this is ARGB when loaded into 32-bit words on a little-endian machine). | |
| 185 SK_API void BGRAConvolve2D(const unsigned char* source_data, | |
| 186 int source_byte_row_stride, | |
| 187 bool source_has_alpha, | |
| 188 const ConvolutionFilter1D& xfilter, | |
| 189 const ConvolutionFilter1D& yfilter, | |
| 190 int output_byte_row_stride, | |
| 191 unsigned char* output, | |
| 192 bool use_simd_if_possible); | |
| 193 | |
| 194 // Does a 1D convolution of the given source image along the X dimension on | |
| 195 // a single channel of the bitmap. | |
| 196 // | |
| 197 // The function uses the same convolution kernel for each pixel. That kernel | |
| 198 // must be added to |filter| at offset 0. This is a most straightforward | |
| 199 // implementation of convolution, intended chiefly for development purposes. | |
| 200 SK_API void SingleChannelConvolveX1D(const unsigned char* source_data, | |
| 201 int source_byte_row_stride, | |
| 202 int input_channel_index, | |
| 203 int input_channel_count, | |
| 204 const ConvolutionFilter1D& filter, | |
| 205 const SkISize& image_size, | |
| 206 unsigned char* output, | |
| 207 int output_byte_row_stride, | |
| 208 int output_channel_index, | |
| 209 int output_channel_count, | |
| 210 bool absolute_values); | |
| 211 | |
| 212 // Does a 1D convolution of the given source image along the Y dimension on | |
| 213 // a single channel of the bitmap. | |
| 214 SK_API void SingleChannelConvolveY1D(const unsigned char* source_data, | |
| 215 int source_byte_row_stride, | |
| 216 int input_channel_index, | |
| 217 int input_channel_count, | |
| 218 const ConvolutionFilter1D& filter, | |
| 219 const SkISize& image_size, | |
| 220 unsigned char* output, | |
| 221 int output_byte_row_stride, | |
| 222 int output_channel_index, | |
| 223 int output_channel_count, | |
| 224 bool absolute_values); | |
| 225 | |
| 226 // Set up the |filter| instance with a gaussian kernel. |kernel_sigma| is the | |
| 227 // parameter of gaussian. If |derivative| is true, the kernel will be that of | |
| 228 // the first derivative. Intended for use with the two routines above. | |
| 229 SK_API void SetUpGaussianConvolutionKernel(ConvolutionFilter1D* filter, | |
| 230 float kernel_sigma, | |
| 231 bool derivative); | |
| 232 | |
| 233 } // namespace skia | |
| 234 | |
| 235 #endif // SKIA_EXT_CONVOLVER_H_ | |
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Chromium Code Reviews
Issue 1519243002:
Remove many unused files from //skia/ext (Closed)
Base URL: git@github.com:domokit/mojo.git@master