Move convolver, image_operations, and skia_utils from base/gfx to skia/ext....

base/gfx/convolver.h

-// Copyright (c) 2006-2008 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 BASE_GFX_CONVOLVER_H__
-#define BASE_GFX_CONVOLVER_H__
-
-#include <vector>
-
-#include "base/basictypes.h"
-
-// avoid confusion with Mac OS X's math library (Carbon)
-#if defined(OS_MACOSX)
-#undef FloatToFixed
-#endif
-
-namespace gfx {
-
-// 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 convolusion by first convolving each row by one
-// ConvolusionFilter1D, then convolving each column by another one.
-//
-// Entries are stored in fixed point, shifted left by kShiftBits.
-class ConvolusionFilter1D {
- public:
-  // The number of bits that fixed point values are shifted by.
-  enum { kShiftBits = 14 };
-
-  ConvolusionFilter1D() : max_filter_(0) {
-  }
-
-  // Convert between floating point and our fixed point representation.
-  static inline int16 FloatToFixed(float f) {
-    return static_cast<int16>(f * (1 << kShiftBits));
-  }
-  static inline unsigned char FixedToChar(int16 x) {
-    return static_cast<unsigned char>(x >> kShiftBits);
-  }
-
-  // Returns the maximum pixel span of a filter.
-  int max_filter() const { return max_filter_; }
-
-  // Returns the number of filters in this filter. This is the dimension of the
-  // output image.
-  int num_values() const { return static_cast<int>(filters_.size()); }
-
-  // Appends the given list of scaling values for generating a given output
-  // pixel. |filter_offset| 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 |filter_length| pixels.
-  //
-  // You will probably want to make sure your input is normalized (that is,
-  // all entries in |filter_values| sub to one) to prevent affecting the overall
-  // brighness of the image.
-  //
-  // The filter_length must be > 0.
-  //
-  // This version will automatically convert your input to fixed point.
-  void AddFilter(int filter_offset,
-                 const float* filter_values,
-                 int filter_length);
-
-  // Same as the above version, but the input is already fixed point.
-  void AddFilter(int filter_offset,
-                 const int16* filter_values,
-                 int filter_length);
-
-  // Retrieves a filter for the given |value_offset|, 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 |filter_length| values in this array.
-  inline const int16* FilterForValue(int value_offset,
-                                     int* filter_offset,
-                                     int* filter_length) const {
-    const FilterInstance& filter = filters_[value_offset];
-    *filter_offset = filter.offset;
-    *filter_length = filter.length;
-    return &filter_values_[filter.data_location];
-  }
-
- private:
-  struct FilterInstance {
-    // Offset within filter_values for this instance of the filter.
-    int data_location;
-
-    // Distance from the left of the filter to the center. IN PIXELS
-    int offset;
-
-    // Number of values in this filter instance.
-    int length;
-  };
-
-  // Stores the information for each filter added to this class.
-  std::vector<FilterInstance> filters_;
-
-  // 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.
-  std::vector<int16> filter_values_;
-
-  // The maximum size of any filter we've added.
-  int max_filter_;
-};
-
-// Does a two-dimensional convolusion 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 |source_byte_row_stride| 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.num_values() * yfilter.num_values() pixels. It will be
-// in rows of exactly xfilter.num_values() * 4 bytes.
-//
-// |source_has_alpha| 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).
-void BGRAConvolve2D(const uint8* source_data,
-                    int source_byte_row_stride,
-                    bool source_has_alpha,
-                    const ConvolusionFilter1D& xfilter,
-                    const ConvolusionFilter1D& yfilter,
-                    uint8* output);
-
-}  // namespace gfx
-
-#endif  // BASE_GFX_CONVOLVER_H__
-