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

base/gfx/image_operations.cc

Index: base/gfx/image_operations.cc
===================================================================
--- base/gfx/image_operations.cc	(revision 6142)
+++ base/gfx/image_operations.cc	(working copy)
@@ -1,362 +0,0 @@
-// 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.
-//
-#define _USE_MATH_DEFINES
-#include <cmath>
-#include <limits>
-#include <vector>
-
-#include "base/gfx/image_operations.h"
-
-#include "base/gfx/convolver.h"
-#include "base/gfx/rect.h"
-#include "base/gfx/size.h"
-#include "base/logging.h"
-#include "base/stack_container.h"
-#include "SkBitmap.h"
-
-namespace gfx {
-
-namespace {
-
-// Returns the ceiling/floor as an integer.
-inline int CeilInt(float val) {
-  return static_cast<int>(ceil(val));
-}
-inline int FloorInt(float val) {
-  return static_cast<int>(floor(val));
-}
-
-// Filter function computation -------------------------------------------------
-
-// Evaluates the box filter, which goes from -0.5 to +0.5.
-float EvalBox(float x) {
-  return (x >= -0.5f && x < 0.5f) ? 1.0f : 0.0f;
-}
-
-// Evaluates the Lanczos filter of the given filter size window for the given
-// position.
-//
-// |filter_size| is the width of the filter (the "window"), outside of which
-// the value of the function is 0. Inside of the window, the value is the
-// normalized sinc function:
-//   lanczos(x) = sinc(x) * sinc(x / filter_size);
-// where
-//   sinc(x) = sin(pi*x) / (pi*x);
-float EvalLanczos(int filter_size, float x) {
-  if (x <= -filter_size || x >= filter_size)
-    return 0.0f;  // Outside of the window.
-  if (x > -std::numeric_limits<float>::epsilon() &&
-      x < std::numeric_limits<float>::epsilon())
-    return 1.0f;  // Special case the discontinuity at the origin.
-  float xpi = x * static_cast<float>(M_PI);
-  return (sin(xpi) / xpi) *  // sinc(x)
-          sin(xpi / filter_size) / (xpi / filter_size);  // sinc(x/filter_size)
-}
-
-// ResizeFilter ----------------------------------------------------------------
-
-// Encapsulates computation and storage of the filters required for one complete
-// resize operation.
-class ResizeFilter {
- public:
-  ResizeFilter(ImageOperations::ResizeMethod method,
-               const Size& src_full_size,
-               const Size& dest_size,
-               const Rect& dest_subset);
-
-  // Returns the bounds in the input bitmap of data that is used in the output.
-  // The filter offsets are within this rectangle.
-  const Rect& src_depend() { return src_depend_; }
-
-  // Returns the filled filter values.
-  const ConvolusionFilter1D& x_filter() { return x_filter_; }
-  const ConvolusionFilter1D& y_filter() { return y_filter_; }
-
- private:
-  // Returns the number of pixels that the filer spans, in filter space (the
-  // destination image).
-  float GetFilterSupport(float scale) {
-    switch (method_) {
-      case ImageOperations::RESIZE_BOX:
-        // The box filter just scales with the image scaling.
-        return 0.5f;  // Only want one side of the filter = /2.
-      case ImageOperations::RESIZE_LANCZOS3:
-        // The lanczos filter takes as much space in the source image in
-        // each direction as the size of the window = 3 for Lanczos3.
-        return 3.0f;
-      default:
-        NOTREACHED();
-        return 1.0f;
-    }
-  }
-
-  // Computes one set of filters either horizontally or vertically. The caller
-  // will specify the "min" and "max" rather than the bottom/top and
-  // right/bottom so that the same code can be re-used in each dimension.
-  //
-  // |src_depend_lo| and |src_depend_size| gives the range for the source
-  // depend rectangle (horizontally or vertically at the caller's discretion
-  // -- see above for what this means).
-  //
-  // Likewise, the range of destination values to compute and the scale factor
-  // for the transform is also specified.
-  void ComputeFilters(int src_size,
-                      int dest_subset_lo, int dest_subset_size,
-                      float scale, float src_support,
-                      ConvolusionFilter1D* output);
-
-  // Computes the filter value given the coordinate in filter space.
-  inline float ComputeFilter(float pos) {
-    switch (method_) {
-      case ImageOperations::RESIZE_BOX:
-        return EvalBox(pos);
-      case ImageOperations::RESIZE_LANCZOS3:
-        return EvalLanczos(3, pos);
-      default:
-        NOTREACHED();
-        return 0;
-    }
-  }
-
-  ImageOperations::ResizeMethod method_;
-
-  // Subset of source the filters will touch.
-  Rect src_depend_;
-
-  // Size of the filter support on one side only in the destination space.
-  // See GetFilterSupport.
-  float x_filter_support_;
-  float y_filter_support_;
-
-  // Subset of scaled destination bitmap to compute.
-  Rect out_bounds_;
-
-  ConvolusionFilter1D x_filter_;
-  ConvolusionFilter1D y_filter_;
-
-  DISALLOW_EVIL_CONSTRUCTORS(ResizeFilter);
-};
-
-ResizeFilter::ResizeFilter(ImageOperations::ResizeMethod method,
-                           const Size& src_full_size,
-                           const Size& dest_size,
-                           const Rect& dest_subset)
-    : method_(method),
-      out_bounds_(dest_subset) {
-  float scale_x = static_cast<float>(dest_size.width()) /
-                  static_cast<float>(src_full_size.width());
-  float scale_y = static_cast<float>(dest_size.height()) /
-                  static_cast<float>(src_full_size.height());
-
-  x_filter_support_ = GetFilterSupport(scale_x);
-  y_filter_support_ = GetFilterSupport(scale_y);
-
-  gfx::Rect src_full(0, 0, src_full_size.width(), src_full_size.height());
-  gfx::Rect dest_full(0, 0,
-                      static_cast<int>(src_full_size.width() * scale_x + 0.5),
-                      static_cast<int>(src_full_size.height() * scale_y + 0.5));
-
-  // Support of the filter in source space.
-  float src_x_support = x_filter_support_ / scale_x;
-  float src_y_support = y_filter_support_ / scale_y;
-
-  ComputeFilters(src_full_size.width(), dest_subset.x(), dest_subset.width(),
-                 scale_x, src_x_support, &x_filter_);
-  ComputeFilters(src_full_size.height(), dest_subset.y(), dest_subset.height(),
-                 scale_y, src_y_support, &y_filter_);
-}
-
-void ResizeFilter::ComputeFilters(int src_size,
-                                  int dest_subset_lo, int dest_subset_size,
-                                  float scale, float src_support,
-                                  ConvolusionFilter1D* output) {
-  int dest_subset_hi = dest_subset_lo + dest_subset_size;  // [lo, hi)
-
-  // When we're doing a magnification, the scale will be larger than one. This
-  // means the destination pixels are much smaller than the source pixels, and
-  // that the range covered by the filter won't necessarily cover any source
-  // pixel boundaries. Therefore, we use these clamped values (max of 1) for
-  // some computations.
-  float clamped_scale = std::min(1.0f, scale);
-
-  // Speed up the divisions below by turning them into multiplies.
-  float inv_scale = 1.0f / scale;
-
-  StackVector<float, 64> filter_values;
-  StackVector<int16, 64> fixed_filter_values;
-
-  // Loop over all pixels in the output range. We will generate one set of
-  // filter values for each one. Those values will tell us how to blend the
-  // source pixels to compute the destination pixel.
-  for (int dest_subset_i = dest_subset_lo; dest_subset_i < dest_subset_hi;
-       dest_subset_i++) {
-    // Reset the arrays. We don't declare them inside so they can re-use the
-    // same malloc-ed buffer.
-    filter_values->clear();
-    fixed_filter_values->clear();
-
-    // This is the pixel in the source directly under the pixel in the dest.
-    float src_pixel = dest_subset_i * inv_scale;
-
-    // Compute the (inclusive) range of source pixels the filter covers.
-    int src_begin = std::max(0, FloorInt(src_pixel - src_support));
-    int src_end = std::min(src_size - 1, CeilInt(src_pixel + src_support));
-
-    // Compute the unnormalized filter value at each location of the source
-    // it covers.
-    float filter_sum = 0.0f;  // Sub of the filter values for normalizing.
-    for (int cur_filter_pixel = src_begin; cur_filter_pixel <= src_end;
-         cur_filter_pixel++) {
-      // Distance from the center of the filter, this is the filter coordinate
-      // in source space.
-      float src_filter_pos = cur_filter_pixel - src_pixel;
-
-      // Since the filter really exists in dest space, map it there.
-      float dest_filter_pos = src_filter_pos * clamped_scale;
-
-      // Compute the filter value at that location.
-      float filter_value = ComputeFilter(dest_filter_pos);
-      filter_values->push_back(filter_value);
-
-      filter_sum += filter_value;
-    }
-    DCHECK(!filter_values->empty()) << "We should always get a filter!";
-
-    // The filter must be normalized so that we don't affect the brightness of
-    // the image. Convert to normalized fixed point.
-    int16 fixed_sum = 0;
-    for (size_t i = 0; i < filter_values->size(); i++) {
-      int16 cur_fixed = output->FloatToFixed(filter_values[i] / filter_sum);
-      fixed_sum += cur_fixed;
-      fixed_filter_values->push_back(cur_fixed);
-    }
-
-    // The conversion to fixed point will leave some rounding errors, which
-    // we add back in to avoid affecting the brightness of the image. We
-    // arbitrarily add this to the center of the filter array (this won't always
-    // be the center of the filter function since it could get clipped on the
-    // edges, but it doesn't matter enough to worry about that case).
-    int16 leftovers = output->FloatToFixed(1.0f) - fixed_sum;
-    fixed_filter_values[fixed_filter_values->size() / 2] += leftovers;
-
-    // Now it's ready to go.
-    output->AddFilter(src_begin, &fixed_filter_values[0],
-                      static_cast<int>(fixed_filter_values->size()));
-  }
-}
-
-}  // namespace
-
-// Resize ----------------------------------------------------------------------
-
-// static
-SkBitmap ImageOperations::Resize(const SkBitmap& source,
-                                 ResizeMethod method,
-                                 const Size& dest_size,
-                                 const Rect& dest_subset) {
-  DCHECK(Rect(dest_size.width(), dest_size.height()).Contains(dest_subset)) <<
-      "The supplied subset does not fall within the destination image.";
-
-  // If the size of source or destination is 0, i.e. 0x0, 0xN or Nx0, just
-  // return empty
-  if (source.width() < 1 || source.height() < 1 ||
-      dest_size.width() < 1 || dest_size.height() < 1)
-      return SkBitmap();
-
-  SkAutoLockPixels locker(source);
-
-  ResizeFilter filter(method, Size(source.width(), source.height()),
-                      dest_size, dest_subset);
-
-  // Get a source bitmap encompassing this touched area. We construct the
-  // offsets and row strides such that it looks like a new bitmap, while
-  // referring to the old data.
-  const uint8* source_subset =
-      reinterpret_cast<const uint8*>(source.getPixels());
-
-  // Convolve into the result.
-  SkBitmap result;
-  result.setConfig(SkBitmap::kARGB_8888_Config,
-                   dest_subset.width(), dest_subset.height());
-  result.allocPixels();
-  BGRAConvolve2D(source_subset, static_cast<int>(source.rowBytes()),
-                 !source.isOpaque(), filter.x_filter(), filter.y_filter(),
-                 static_cast<unsigned char*>(result.getPixels()));
-
-  // Preserve the "opaque" flag for use as an optimization later.
-  result.setIsOpaque(source.isOpaque());
-
-  return result;
-}
-
-// static
-SkBitmap ImageOperations::Resize(const SkBitmap& source,
-                                 ResizeMethod method,
-                                 const Size& dest_size) {
-  Rect dest_subset(0, 0, dest_size.width(), dest_size.height());
-  return Resize(source, method, dest_size, dest_subset);
-}
-
-// static
-SkBitmap ImageOperations::CreateBlendedBitmap(const SkBitmap& first,
-                                              const SkBitmap& second,
-                                              double alpha) {
-  DCHECK(alpha <= 1 && alpha >= 0);
-  DCHECK(first.width() == second.width());
-  DCHECK(first.height() == second.height());
-  DCHECK(first.bytesPerPixel() == second.bytesPerPixel());
-  DCHECK(first.config() == SkBitmap::kARGB_8888_Config);
-
-  // Optimize for case where we won't need to blend anything.
-  static const double alpha_min = 1.0 / 255;
-  static const double alpha_max = 254.0 / 255;
-  if (alpha < alpha_min) {
-    return first;
-  } else if (alpha > alpha_max) {
-    return second;
-  }
-
-  SkAutoLockPixels lock_first(first);
-  SkAutoLockPixels lock_second(second);
-
-  SkBitmap blended;
-  blended.setConfig(SkBitmap::kARGB_8888_Config, first.width(),
-                    first.height(), 0);
-  blended.allocPixels();
-  blended.eraseARGB(0, 0, 0, 0);
-
-  double first_alpha = 1 - alpha;
-
-  for (int y = 0; y < first.height(); y++) {
-    uint32* first_row = first.getAddr32(0, y);
-    uint32* second_row = second.getAddr32(0, y);
-    uint32* dst_row = blended.getAddr32(0, y);
-
-    for (int x = 0; x < first.width(); x++) {
-      uint32 first_pixel = first_row[x];
-      uint32 second_pixel = second_row[x];
-
-      int a = static_cast<int>(
-          SkColorGetA(first_pixel) * first_alpha +
-          SkColorGetA(second_pixel) * alpha);
-      int r = static_cast<int>(
-          SkColorGetR(first_pixel) * first_alpha +
-          SkColorGetR(second_pixel) * alpha);
-      int g = static_cast<int>(
-          SkColorGetG(first_pixel) * first_alpha +
-          SkColorGetG(second_pixel) * alpha);
-      int b = static_cast<int>(
-          SkColorGetB(first_pixel) * first_alpha +
-          SkColorGetB(second_pixel) * alpha);
-
-      dst_row[x] = SkColorSetARGB(a, r, g, b);
-    }
-  }
-
-  return blended;
-}
-
-}  // namespace gfx
-