diff options
Diffstat (limited to 'gfx/2d/image_operations.cpp')
| -rw-r--r-- | gfx/2d/image_operations.cpp | 252 |
1 files changed, 47 insertions, 205 deletions
diff --git a/gfx/2d/image_operations.cpp b/gfx/2d/image_operations.cpp index 532be2d98..59861bb9b 100644 --- a/gfx/2d/image_operations.cpp +++ b/gfx/2d/image_operations.cpp @@ -35,7 +35,6 @@ #include "image_operations.h" -#include "nsAlgorithm.h" #include "base/stack_container.h" #include "convolver.h" #include "skia/SkColorPriv.h" @@ -45,184 +44,7 @@ namespace skia { -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) -} - -// Evaluates the Hamming filter of the given filter size window for the given -// position. -// -// The filter covers [-filter_size, +filter_size]. Outside of this window -// the value of the function is 0. Inside of the window, the value is sinus -// cardinal multiplied by a recentered Hamming function. The traditional -// Hamming formula for a window of size N and n ranging in [0, N-1] is: -// hamming(n) = 0.54 - 0.46 * cos(2 * pi * n / (N-1))) -// In our case we want the function centered for x == 0 and at its minimum -// on both ends of the window (x == +/- filter_size), hence the adjusted -// formula: -// hamming(x) = (0.54 - -// 0.46 * cos(2 * pi * (x - filter_size)/ (2 * filter_size))) -// = 0.54 - 0.46 * cos(pi * x / filter_size - pi) -// = 0.54 + 0.46 * cos(pi * x / filter_size) -float EvalHamming(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 sinc discontinuity at the origin. - const float xpi = x * static_cast<float>(M_PI); - - return ((sin(xpi) / xpi) * // sinc(x) - (0.54f + 0.46f * cos(xpi / filter_size))); // hamming(x) -} - -// ResizeFilter ---------------------------------------------------------------- - -// Encapsulates computation and storage of the filters required for one complete -// resize operation. -class ResizeFilter { - public: - ResizeFilter(ImageOperations::ResizeMethod method, - int src_full_width, int src_full_height, - int dest_width, int dest_height, - const SkIRect& dest_subset); - - // Returns the filled filter values. - const ConvolutionFilter1D& x_filter() { return x_filter_; } - const ConvolutionFilter1D& 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_HAMMING1: - // The Hamming filter takes as much space in the source image in - // each direction as the size of the window = 1 for Hamming1. - return 1.0f; - case ImageOperations::RESIZE_LANCZOS2: - // The Lanczos filter takes as much space in the source image in - // each direction as the size of the window = 2 for Lanczos2. - return 2.0f; - 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: - 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, - ConvolutionFilter1D* 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_HAMMING1: - return EvalHamming(1, pos); - case ImageOperations::RESIZE_LANCZOS2: - return EvalLanczos(2, pos); - case ImageOperations::RESIZE_LANCZOS3: - return EvalLanczos(3, pos); - default: - return 0; - } - } - - ImageOperations::ResizeMethod method_; - - // 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. - SkIRect out_bounds_; - - ConvolutionFilter1D x_filter_; - ConvolutionFilter1D y_filter_; - - DISALLOW_COPY_AND_ASSIGN(ResizeFilter); -}; - -ResizeFilter::ResizeFilter(ImageOperations::ResizeMethod method, - int src_full_width, int src_full_height, - int dest_width, int dest_height, - const SkIRect& dest_subset) - : method_(method), - out_bounds_(dest_subset) { - // method_ will only ever refer to an "algorithm method". - SkASSERT((ImageOperations::RESIZE_FIRST_ALGORITHM_METHOD <= method) && - (method <= ImageOperations::RESIZE_LAST_ALGORITHM_METHOD)); - - float scale_x = static_cast<float>(dest_width) / - static_cast<float>(src_full_width); - float scale_y = static_cast<float>(dest_height) / - static_cast<float>(src_full_height); - - x_filter_support_ = GetFilterSupport(scale_x); - y_filter_support_ = GetFilterSupport(scale_y); - - // 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_width, dest_subset.fLeft, dest_subset.width(), - scale_x, src_x_support, &x_filter_); - ComputeFilters(src_full_height, dest_subset.fTop, dest_subset.height(), - scale_y, src_y_support, &y_filter_); -} +namespace resize { // TODO(egouriou): Take advantage of periods in the convolution. // Practical resizing filters are periodic outside of the border area. @@ -235,10 +57,16 @@ ResizeFilter::ResizeFilter(ImageOperations::ResizeMethod method, // Small periods reduce computational load and improve cache usage if // the coefficients can be shared. For periods of 1 we can consider // loading the factors only once outside the borders. -void ResizeFilter::ComputeFilters(int src_size, - int dest_subset_lo, int dest_subset_size, - float scale, float src_support, - ConvolutionFilter1D* output) { +void ComputeFilters(ImageOperations::ResizeMethod method, + int src_size, int dst_size, + int dest_subset_lo, int dest_subset_size, + ConvolutionFilter1D* output) { + // method_ will only ever refer to an "algorithm method". + SkASSERT((ImageOperations::RESIZE_FIRST_ALGORITHM_METHOD <= method) && + (method <= ImageOperations::RESIZE_LAST_ALGORITHM_METHOD)); + + float scale = static_cast<float>(dst_size) / static_cast<float>(src_size); + 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 @@ -248,6 +76,8 @@ void ResizeFilter::ComputeFilters(int src_size, // some computations. float clamped_scale = std::min(1.0f, scale); + float src_support = GetFilterSupport(method, clamped_scale) / clamped_scale; + // Speed up the divisions below by turning them into multiplies. float inv_scale = 1.0f / scale; @@ -294,7 +124,7 @@ void ResizeFilter::ComputeFilters(int src_size, float dest_filter_dist = src_filter_dist * clamped_scale; // Compute the filter value at that location. - float filter_value = ComputeFilter(dest_filter_dist); + float filter_value = ComputeFilter(method, dest_filter_dist); filter_values->push_back(filter_value); filter_sum += filter_value; @@ -325,6 +155,8 @@ void ResizeFilter::ComputeFilters(int src_size, output->PaddingForSIMD(8); } +} + ImageOperations::ResizeMethod ResizeMethodToAlgorithmMethod( ImageOperations::ResizeMethod method) { // Convert any "Quality Method" into an "Algorithm Method" @@ -336,22 +168,24 @@ ImageOperations::ResizeMethod ResizeMethodToAlgorithmMethod( // GPU-acceleration in the cases where it is possible. So now we just // pick the appropriate software method for each resize quality. switch (method) { + // Users of RESIZE_GOOD are willing to trade a lot of quality to + // get speed, allowing the use of linear resampling to get hardware + // acceleration (SRB). Hence any of our "good" software filters + // will be acceptable, and we use the fastest one, Hamming-1. case ImageOperations::RESIZE_GOOD: - // In visual tests we see that Hamming-1 is not as good as + // Users of RESIZE_BETTER are willing to trade some quality in order + // to improve performance, but are guaranteed not to devolve to a linear + // resampling. In visual tests we see that Hamming-1 is not as good as // Lanczos-2, however it is about 40% faster and Lanczos-2 itself is // about 30% faster than Lanczos-3. The use of Hamming-1 has been deemed - // an unacceptable trade-off between quality and speed due to the limited - // pixel space it operates in before switching to HQ scaling becomes - // necessary to retain fidelity of images. + // an acceptable trade-off between quality and speed. case ImageOperations::RESIZE_BETTER: - return ImageOperations::RESIZE_LANCZOS2; + return ImageOperations::RESIZE_HAMMING1; default: return ImageOperations::RESIZE_LANCZOS3; } } -} // namespace - // Resize ---------------------------------------------------------------------- // static @@ -405,9 +239,13 @@ SkBitmap ImageOperations::ResizeSubpixel(const SkBitmap& source, // Render into subpixels. SkBitmap result; - result.setConfig(SkBitmap::kARGB_8888_Config, dest_subset.width(), - dest_subset.height()); - result.allocPixels(); + SkImageInfo info = SkImageInfo::Make(dest_subset.width(), + dest_subset.height(), + kBGRA_8888_SkColorType, + kPremul_SkAlphaType); + + + result.allocPixels(info); if (!result.readyToDraw()) return img; @@ -467,7 +305,7 @@ SkBitmap ImageOperations::ResizeSubpixel(const SkBitmap& source, src_row += h * row_words; dst_row += result.rowBytes() / 4; } - result.setIsOpaque(img.isOpaque()); + result.setAlphaType(img.alphaType()); return result; #else return SkBitmap(); @@ -501,8 +339,11 @@ SkBitmap ImageOperations::ResizeBasic(const SkBitmap& source, if (!source.readyToDraw()) return SkBitmap(); - ResizeFilter filter(method, source.width(), source.height(), - dest_width, dest_height, dest_subset); + ConvolutionFilter1D x_filter; + ConvolutionFilter1D y_filter; + + resize::ComputeFilters(method, source.width(), dest_width, dest_subset.fLeft, dest_subset.width(), &x_filter); + resize::ComputeFilters(method, source.height(), dest_height, dest_subset.fTop, dest_subset.height(), &y_filter); // Get a source bitmap encompassing this touched area. We construct the // offsets and row strides such that it looks like a new bitmap, while @@ -512,26 +353,27 @@ SkBitmap ImageOperations::ResizeBasic(const SkBitmap& source, // Convolve into the result. SkBitmap result; - result.setConfig(SkBitmap::kARGB_8888_Config, - dest_subset.width(), dest_subset.height()); + SkImageInfo info = SkImageInfo::Make(dest_subset.width(), + dest_subset.height(), + kBGRA_8888_SkColorType, + kPremul_SkAlphaType); if (dest_pixels) { - result.setPixels(dest_pixels); + result.installPixels(info, dest_pixels, info.minRowBytes()); } else { - result.allocPixels(); + result.allocPixels(info); } if (!result.readyToDraw()) return SkBitmap(); BGRAConvolve2D(source_subset, static_cast<int>(source.rowBytes()), - !source.isOpaque(), filter.x_filter(), filter.y_filter(), + !source.isOpaque(), x_filter, y_filter, static_cast<int>(result.rowBytes()), - static_cast<unsigned char*>(result.getPixels()), - /* sse = */ false); + static_cast<unsigned char*>(result.getPixels())); // Preserve the "opaque" flag for use as an optimization later. - result.setIsOpaque(source.isOpaque()); + result.setAlphaType(source.alphaType()); return result; } |