michael@0: // Copyright (c) 2006-2012 The Chromium Authors. All rights reserved.
michael@0: //
michael@0: // Redistribution and use in source and binary forms, with or without
michael@0: // modification, are permitted provided that the following conditions
michael@0: // are met:
michael@0: //  * Redistributions of source code must retain the above copyright
michael@0: //    notice, this list of conditions and the following disclaimer.
michael@0: //  * Redistributions in binary form must reproduce the above copyright
michael@0: //    notice, this list of conditions and the following disclaimer in
michael@0: //    the documentation and/or other materials provided with the
michael@0: //    distribution.
michael@0: //  * Neither the name of Google, Inc. nor the names of its contributors
michael@0: //    may be used to endorse or promote products derived from this
michael@0: //    software without specific prior written permission.
michael@0: //
michael@0: // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
michael@0: // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
michael@0: // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
michael@0: // FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
michael@0: // COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
michael@0: // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
michael@0: // BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
michael@0: // OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
michael@0: // AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
michael@0: // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
michael@0: // OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
michael@0: // SUCH DAMAGE.
michael@0: 
michael@0: #include "base/basictypes.h"
michael@0: 
michael@0: #define _USE_MATH_DEFINES
michael@0: #include <algorithm>
michael@0: #include <cmath>
michael@0: #include <limits>
michael@0: 
michael@0: #include "image_operations.h"
michael@0: 
michael@0: #include "base/stack_container.h"
michael@0: #include "convolver.h"
michael@0: #include "skia/SkColorPriv.h"
michael@0: #include "skia/SkBitmap.h"
michael@0: #include "skia/SkRect.h"
michael@0: #include "skia/SkFontHost.h"
michael@0: 
michael@0: namespace skia {
michael@0: 
michael@0: namespace {
michael@0: 
michael@0: // Returns the ceiling/floor as an integer.
michael@0: inline int CeilInt(float val) {
michael@0:   return static_cast<int>(ceil(val));
michael@0: }
michael@0: inline int FloorInt(float val) {
michael@0:   return static_cast<int>(floor(val));
michael@0: }
michael@0: 
michael@0: // Filter function computation -------------------------------------------------
michael@0: 
michael@0: // Evaluates the box filter, which goes from -0.5 to +0.5.
michael@0: float EvalBox(float x) {
michael@0:   return (x >= -0.5f && x < 0.5f) ? 1.0f : 0.0f;
michael@0: }
michael@0: 
michael@0: // Evaluates the Lanczos filter of the given filter size window for the given
michael@0: // position.
michael@0: //
michael@0: // |filter_size| is the width of the filter (the "window"), outside of which
michael@0: // the value of the function is 0. Inside of the window, the value is the
michael@0: // normalized sinc function:
michael@0: //   lanczos(x) = sinc(x) * sinc(x / filter_size);
michael@0: // where
michael@0: //   sinc(x) = sin(pi*x) / (pi*x);
michael@0: float EvalLanczos(int filter_size, float x) {
michael@0:   if (x <= -filter_size || x >= filter_size)
michael@0:     return 0.0f;  // Outside of the window.
michael@0:   if (x > -std::numeric_limits<float>::epsilon() &&
michael@0:       x < std::numeric_limits<float>::epsilon())
michael@0:     return 1.0f;  // Special case the discontinuity at the origin.
michael@0:   float xpi = x * static_cast<float>(M_PI);
michael@0:   return (sin(xpi) / xpi) *  // sinc(x)
michael@0:           sin(xpi / filter_size) / (xpi / filter_size);  // sinc(x/filter_size)
michael@0: }
michael@0: 
michael@0: // Evaluates the Hamming filter of the given filter size window for the given
michael@0: // position.
michael@0: //
michael@0: // The filter covers [-filter_size, +filter_size]. Outside of this window
michael@0: // the value of the function is 0. Inside of the window, the value is sinus
michael@0: // cardinal multiplied by a recentered Hamming function. The traditional
michael@0: // Hamming formula for a window of size N and n ranging in [0, N-1] is:
michael@0: //   hamming(n) = 0.54 - 0.46 * cos(2 * pi * n / (N-1)))
michael@0: // In our case we want the function centered for x == 0 and at its minimum
michael@0: // on both ends of the window (x == +/- filter_size), hence the adjusted
michael@0: // formula:
michael@0: //   hamming(x) = (0.54 -
michael@0: //                 0.46 * cos(2 * pi * (x - filter_size)/ (2 * filter_size)))
michael@0: //              = 0.54 - 0.46 * cos(pi * x / filter_size - pi)
michael@0: //              = 0.54 + 0.46 * cos(pi * x / filter_size)
michael@0: float EvalHamming(int filter_size, float x) {
michael@0:   if (x <= -filter_size || x >= filter_size)
michael@0:     return 0.0f;  // Outside of the window.
michael@0:   if (x > -std::numeric_limits<float>::epsilon() &&
michael@0:       x < std::numeric_limits<float>::epsilon())
michael@0:     return 1.0f;  // Special case the sinc discontinuity at the origin.
michael@0:   const float xpi = x * static_cast<float>(M_PI);
michael@0: 
michael@0:   return ((sin(xpi) / xpi) *  // sinc(x)
michael@0:           (0.54f + 0.46f * cos(xpi / filter_size)));  // hamming(x)
michael@0: }
michael@0: 
michael@0: // ResizeFilter ----------------------------------------------------------------
michael@0: 
michael@0: // Encapsulates computation and storage of the filters required for one complete
michael@0: // resize operation.
michael@0: class ResizeFilter {
michael@0:  public:
michael@0:   ResizeFilter(ImageOperations::ResizeMethod method,
michael@0:                int src_full_width, int src_full_height,
michael@0:                int dest_width, int dest_height,
michael@0:                const SkIRect& dest_subset);
michael@0: 
michael@0:   // Returns the filled filter values.
michael@0:   const ConvolutionFilter1D& x_filter() { return x_filter_; }
michael@0:   const ConvolutionFilter1D& y_filter() { return y_filter_; }
michael@0: 
michael@0:  private:
michael@0:   // Returns the number of pixels that the filer spans, in filter space (the
michael@0:   // destination image).
michael@0:   float GetFilterSupport(float scale) {
michael@0:     switch (method_) {
michael@0:       case ImageOperations::RESIZE_BOX:
michael@0:         // The box filter just scales with the image scaling.
michael@0:         return 0.5f;  // Only want one side of the filter = /2.
michael@0:       case ImageOperations::RESIZE_HAMMING1:
michael@0:         // The Hamming filter takes as much space in the source image in
michael@0:         // each direction as the size of the window = 1 for Hamming1.
michael@0:         return 1.0f;
michael@0:       case ImageOperations::RESIZE_LANCZOS2:
michael@0:         // The Lanczos filter takes as much space in the source image in
michael@0:         // each direction as the size of the window = 2 for Lanczos2.
michael@0:         return 2.0f;
michael@0:       case ImageOperations::RESIZE_LANCZOS3:
michael@0:         // The Lanczos filter takes as much space in the source image in
michael@0:         // each direction as the size of the window = 3 for Lanczos3.
michael@0:         return 3.0f;
michael@0:       default:
michael@0:         return 1.0f;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   // Computes one set of filters either horizontally or vertically. The caller
michael@0:   // will specify the "min" and "max" rather than the bottom/top and
michael@0:   // right/bottom so that the same code can be re-used in each dimension.
michael@0:   //
michael@0:   // |src_depend_lo| and |src_depend_size| gives the range for the source
michael@0:   // depend rectangle (horizontally or vertically at the caller's discretion
michael@0:   // -- see above for what this means).
michael@0:   //
michael@0:   // Likewise, the range of destination values to compute and the scale factor
michael@0:   // for the transform is also specified.
michael@0:   void ComputeFilters(int src_size,
michael@0:                       int dest_subset_lo, int dest_subset_size,
michael@0:                       float scale, float src_support,
michael@0:                       ConvolutionFilter1D* output);
michael@0: 
michael@0:   // Computes the filter value given the coordinate in filter space.
michael@0:   inline float ComputeFilter(float pos) {
michael@0:     switch (method_) {
michael@0:       case ImageOperations::RESIZE_BOX:
michael@0:         return EvalBox(pos);
michael@0:       case ImageOperations::RESIZE_HAMMING1:
michael@0:         return EvalHamming(1, pos);
michael@0:       case ImageOperations::RESIZE_LANCZOS2:
michael@0:         return EvalLanczos(2, pos);
michael@0:       case ImageOperations::RESIZE_LANCZOS3:
michael@0:         return EvalLanczos(3, pos);
michael@0:       default:
michael@0:         return 0;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   ImageOperations::ResizeMethod method_;
michael@0: 
michael@0:   // Size of the filter support on one side only in the destination space.
michael@0:   // See GetFilterSupport.
michael@0:   float x_filter_support_;
michael@0:   float y_filter_support_;
michael@0: 
michael@0:   // Subset of scaled destination bitmap to compute.
michael@0:   SkIRect out_bounds_;
michael@0: 
michael@0:   ConvolutionFilter1D x_filter_;
michael@0:   ConvolutionFilter1D y_filter_;
michael@0: 
michael@0:   DISALLOW_COPY_AND_ASSIGN(ResizeFilter);
michael@0: };
michael@0: 
michael@0: ResizeFilter::ResizeFilter(ImageOperations::ResizeMethod method,
michael@0:                            int src_full_width, int src_full_height,
michael@0:                            int dest_width, int dest_height,
michael@0:                            const SkIRect& dest_subset)
michael@0:     : method_(method),
michael@0:       out_bounds_(dest_subset) {
michael@0:   // method_ will only ever refer to an "algorithm method".
michael@0:   SkASSERT((ImageOperations::RESIZE_FIRST_ALGORITHM_METHOD <= method) &&
michael@0:            (method <= ImageOperations::RESIZE_LAST_ALGORITHM_METHOD));
michael@0: 
michael@0:   float scale_x = static_cast<float>(dest_width) /
michael@0:                   static_cast<float>(src_full_width);
michael@0:   float scale_y = static_cast<float>(dest_height) /
michael@0:                   static_cast<float>(src_full_height);
michael@0: 
michael@0:   x_filter_support_ = GetFilterSupport(scale_x);
michael@0:   y_filter_support_ = GetFilterSupport(scale_y);
michael@0: 
michael@0:   // Support of the filter in source space.
michael@0:   float src_x_support = x_filter_support_ / scale_x;
michael@0:   float src_y_support = y_filter_support_ / scale_y;
michael@0: 
michael@0:   ComputeFilters(src_full_width, dest_subset.fLeft, dest_subset.width(),
michael@0:                  scale_x, src_x_support, &x_filter_);
michael@0:   ComputeFilters(src_full_height, dest_subset.fTop, dest_subset.height(),
michael@0:                  scale_y, src_y_support, &y_filter_);
michael@0: }
michael@0: 
michael@0: // TODO(egouriou): Take advantage of periods in the convolution.
michael@0: // Practical resizing filters are periodic outside of the border area.
michael@0: // For Lanczos, a scaling by a (reduced) factor of p/q (q pixels in the
michael@0: // source become p pixels in the destination) will have a period of p.
michael@0: // A nice consequence is a period of 1 when downscaling by an integral
michael@0: // factor. Downscaling from typical display resolutions is also bound
michael@0: // to produce interesting periods as those are chosen to have multiple
michael@0: // small factors.
michael@0: // Small periods reduce computational load and improve cache usage if
michael@0: // the coefficients can be shared. For periods of 1 we can consider
michael@0: // loading the factors only once outside the borders.
michael@0: void ResizeFilter::ComputeFilters(int src_size,
michael@0:                                   int dest_subset_lo, int dest_subset_size,
michael@0:                                   float scale, float src_support,
michael@0:                                   ConvolutionFilter1D* output) {
michael@0:   int dest_subset_hi = dest_subset_lo + dest_subset_size;  // [lo, hi)
michael@0: 
michael@0:   // When we're doing a magnification, the scale will be larger than one. This
michael@0:   // means the destination pixels are much smaller than the source pixels, and
michael@0:   // that the range covered by the filter won't necessarily cover any source
michael@0:   // pixel boundaries. Therefore, we use these clamped values (max of 1) for
michael@0:   // some computations.
michael@0:   float clamped_scale = std::min(1.0f, scale);
michael@0: 
michael@0:   // Speed up the divisions below by turning them into multiplies.
michael@0:   float inv_scale = 1.0f / scale;
michael@0: 
michael@0:   StackVector<float, 64> filter_values;
michael@0:   StackVector<int16_t, 64> fixed_filter_values;
michael@0: 
michael@0:   // Loop over all pixels in the output range. We will generate one set of
michael@0:   // filter values for each one. Those values will tell us how to blend the
michael@0:   // source pixels to compute the destination pixel.
michael@0:   for (int dest_subset_i = dest_subset_lo; dest_subset_i < dest_subset_hi;
michael@0:        dest_subset_i++) {
michael@0:     // Reset the arrays. We don't declare them inside so they can re-use the
michael@0:     // same malloc-ed buffer.
michael@0:     filter_values->clear();
michael@0:     fixed_filter_values->clear();
michael@0: 
michael@0:     // This is the pixel in the source directly under the pixel in the dest.
michael@0:     // Note that we base computations on the "center" of the pixels. To see
michael@0:     // why, observe that the destination pixel at coordinates (0, 0) in a 5.0x
michael@0:     // downscale should "cover" the pixels around the pixel with *its center*
michael@0:     // at coordinates (2.5, 2.5) in the source, not those around (0, 0).
michael@0:     // Hence we need to scale coordinates (0.5, 0.5), not (0, 0).
michael@0:     float src_pixel = (static_cast<float>(dest_subset_i) + 0.5f) * inv_scale;
michael@0: 
michael@0:     // Compute the (inclusive) range of source pixels the filter covers.
michael@0:     int src_begin = std::max(0, FloorInt(src_pixel - src_support));
michael@0:     int src_end = std::min(src_size - 1, CeilInt(src_pixel + src_support));
michael@0: 
michael@0:     // Compute the unnormalized filter value at each location of the source
michael@0:     // it covers.
michael@0:     float filter_sum = 0.0f;  // Sub of the filter values for normalizing.
michael@0:     for (int cur_filter_pixel = src_begin; cur_filter_pixel <= src_end;
michael@0:          cur_filter_pixel++) {
michael@0:       // Distance from the center of the filter, this is the filter coordinate
michael@0:       // in source space. We also need to consider the center of the pixel
michael@0:       // when comparing distance against 'src_pixel'. In the 5x downscale
michael@0:       // example used above the distance from the center of the filter to
michael@0:       // the pixel with coordinates (2, 2) should be 0, because its center
michael@0:       // is at (2.5, 2.5).
michael@0:       float src_filter_dist =
michael@0:            ((static_cast<float>(cur_filter_pixel) + 0.5f) - src_pixel);
michael@0: 
michael@0:       // Since the filter really exists in dest space, map it there.
michael@0:       float dest_filter_dist = src_filter_dist * clamped_scale;
michael@0: 
michael@0:       // Compute the filter value at that location.
michael@0:       float filter_value = ComputeFilter(dest_filter_dist);
michael@0:       filter_values->push_back(filter_value);
michael@0: 
michael@0:       filter_sum += filter_value;
michael@0:     }
michael@0: 
michael@0:     // The filter must be normalized so that we don't affect the brightness of
michael@0:     // the image. Convert to normalized fixed point.
michael@0:     int16_t fixed_sum = 0;
michael@0:     for (size_t i = 0; i < filter_values->size(); i++) {
michael@0:       int16_t cur_fixed = output->FloatToFixed(filter_values[i] / filter_sum);
michael@0:       fixed_sum += cur_fixed;
michael@0:       fixed_filter_values->push_back(cur_fixed);
michael@0:     }
michael@0: 
michael@0:     // The conversion to fixed point will leave some rounding errors, which
michael@0:     // we add back in to avoid affecting the brightness of the image. We
michael@0:     // arbitrarily add this to the center of the filter array (this won't always
michael@0:     // be the center of the filter function since it could get clipped on the
michael@0:     // edges, but it doesn't matter enough to worry about that case).
michael@0:     int16_t leftovers = output->FloatToFixed(1.0f) - fixed_sum;
michael@0:     fixed_filter_values[fixed_filter_values->size() / 2] += leftovers;
michael@0: 
michael@0:     // Now it's ready to go.
michael@0:     output->AddFilter(src_begin, &fixed_filter_values[0],
michael@0:                       static_cast<int>(fixed_filter_values->size()));
michael@0:   }
michael@0: 
michael@0:   output->PaddingForSIMD(8);
michael@0: }
michael@0: 
michael@0: ImageOperations::ResizeMethod ResizeMethodToAlgorithmMethod(
michael@0:     ImageOperations::ResizeMethod method) {
michael@0:   // Convert any "Quality Method" into an "Algorithm Method"
michael@0:   if (method >= ImageOperations::RESIZE_FIRST_ALGORITHM_METHOD &&
michael@0:       method <= ImageOperations::RESIZE_LAST_ALGORITHM_METHOD) {
michael@0:     return method;
michael@0:   }
michael@0:   // The call to ImageOperationsGtv::Resize() above took care of
michael@0:   // GPU-acceleration in the cases where it is possible. So now we just
michael@0:   // pick the appropriate software method for each resize quality.
michael@0:   switch (method) {
michael@0:     // Users of RESIZE_GOOD are willing to trade a lot of quality to
michael@0:     // get speed, allowing the use of linear resampling to get hardware
michael@0:     // acceleration (SRB). Hence any of our "good" software filters
michael@0:     // will be acceptable, and we use the fastest one, Hamming-1.
michael@0:     case ImageOperations::RESIZE_GOOD:
michael@0:       // Users of RESIZE_BETTER are willing to trade some quality in order
michael@0:       // to improve performance, but are guaranteed not to devolve to a linear
michael@0:       // resampling. In visual tests we see that Hamming-1 is not as good as
michael@0:       // Lanczos-2, however it is about 40% faster and Lanczos-2 itself is
michael@0:       // about 30% faster than Lanczos-3. The use of Hamming-1 has been deemed
michael@0:       // an acceptable trade-off between quality and speed.
michael@0:     case ImageOperations::RESIZE_BETTER:
michael@0:       return ImageOperations::RESIZE_HAMMING1;
michael@0:     default:
michael@0:       return ImageOperations::RESIZE_LANCZOS3;
michael@0:   }
michael@0: }
michael@0: 
michael@0: }  // namespace
michael@0: 
michael@0: // Resize ----------------------------------------------------------------------
michael@0: 
michael@0: // static
michael@0: SkBitmap ImageOperations::Resize(const SkBitmap& source,
michael@0:                                  ResizeMethod method,
michael@0:                                  int dest_width, int dest_height,
michael@0:                                  const SkIRect& dest_subset,
michael@0:                                  void* dest_pixels /* = nullptr */) {
michael@0:   if (method == ImageOperations::RESIZE_SUBPIXEL)
michael@0:     return ResizeSubpixel(source, dest_width, dest_height, dest_subset);
michael@0:   else
michael@0:     return ResizeBasic(source, method, dest_width, dest_height, dest_subset,
michael@0:                        dest_pixels);
michael@0: }
michael@0: 
michael@0: // static
michael@0: SkBitmap ImageOperations::ResizeSubpixel(const SkBitmap& source,
michael@0:                                          int dest_width, int dest_height,
michael@0:                                          const SkIRect& dest_subset) {
michael@0:   // Currently only works on Linux/BSD because these are the only platforms
michael@0:   // where SkFontHost::GetSubpixelOrder is defined.
michael@0: #if defined(XP_UNIX)
michael@0:   // Understand the display.
michael@0:   const SkFontHost::LCDOrder order = SkFontHost::GetSubpixelOrder();
michael@0:   const SkFontHost::LCDOrientation orientation =
michael@0:       SkFontHost::GetSubpixelOrientation();
michael@0: 
michael@0:   // Decide on which dimension, if any, to deploy subpixel rendering.
michael@0:   int w = 1;
michael@0:   int h = 1;
michael@0:   switch (orientation) {
michael@0:     case SkFontHost::kHorizontal_LCDOrientation:
michael@0:       w = dest_width < source.width() ? 3 : 1;
michael@0:       break;
michael@0:     case SkFontHost::kVertical_LCDOrientation:
michael@0:       h = dest_height < source.height() ? 3 : 1;
michael@0:       break;
michael@0:   }
michael@0: 
michael@0:   // Resize the image.
michael@0:   const int width = dest_width * w;
michael@0:   const int height = dest_height * h;
michael@0:   SkIRect subset = { dest_subset.fLeft, dest_subset.fTop,
michael@0:                      dest_subset.fLeft + dest_subset.width() * w,
michael@0:                      dest_subset.fTop + dest_subset.height() * h };
michael@0:   SkBitmap img = ResizeBasic(source, ImageOperations::RESIZE_LANCZOS3, width,
michael@0:                              height, subset);
michael@0:   const int row_words = img.rowBytes() / 4;
michael@0:   if (w == 1 && h == 1)
michael@0:     return img;
michael@0: 
michael@0:   // Render into subpixels.
michael@0:   SkBitmap result;
michael@0:   result.setConfig(SkBitmap::kARGB_8888_Config, dest_subset.width(),
michael@0:                    dest_subset.height());
michael@0:   result.allocPixels();
michael@0:   if (!result.readyToDraw())
michael@0:     return img;
michael@0: 
michael@0:   SkAutoLockPixels locker(img);
michael@0:   if (!img.readyToDraw())
michael@0:     return img;
michael@0: 
michael@0:   uint32_t* src_row = img.getAddr32(0, 0);
michael@0:   uint32_t* dst_row = result.getAddr32(0, 0);
michael@0:   for (int y = 0; y < dest_subset.height(); y++) {
michael@0:     uint32_t* src = src_row;
michael@0:     uint32_t* dst = dst_row;
michael@0:     for (int x = 0; x < dest_subset.width(); x++, src += w, dst++) {
michael@0:       uint8_t r = 0, g = 0, b = 0, a = 0;
michael@0:       switch (order) {
michael@0:         case SkFontHost::kRGB_LCDOrder:
michael@0:           switch (orientation) {
michael@0:             case SkFontHost::kHorizontal_LCDOrientation:
michael@0:               r = SkGetPackedR32(src[0]);
michael@0:               g = SkGetPackedG32(src[1]);
michael@0:               b = SkGetPackedB32(src[2]);
michael@0:               a = SkGetPackedA32(src[1]);
michael@0:               break;
michael@0:             case SkFontHost::kVertical_LCDOrientation:
michael@0:               r = SkGetPackedR32(src[0 * row_words]);
michael@0:               g = SkGetPackedG32(src[1 * row_words]);
michael@0:               b = SkGetPackedB32(src[2 * row_words]);
michael@0:               a = SkGetPackedA32(src[1 * row_words]);
michael@0:               break;
michael@0:           }
michael@0:           break;
michael@0:         case SkFontHost::kBGR_LCDOrder:
michael@0:           switch (orientation) {
michael@0:             case SkFontHost::kHorizontal_LCDOrientation:
michael@0:               b = SkGetPackedB32(src[0]);
michael@0:               g = SkGetPackedG32(src[1]);
michael@0:               r = SkGetPackedR32(src[2]);
michael@0:               a = SkGetPackedA32(src[1]);
michael@0:               break;
michael@0:             case SkFontHost::kVertical_LCDOrientation:
michael@0:               b = SkGetPackedB32(src[0 * row_words]);
michael@0:               g = SkGetPackedG32(src[1 * row_words]);
michael@0:               r = SkGetPackedR32(src[2 * row_words]);
michael@0:               a = SkGetPackedA32(src[1 * row_words]);
michael@0:               break;
michael@0:           }
michael@0:           break;
michael@0:         case SkFontHost::kNONE_LCDOrder:
michael@0:           break;
michael@0:       }
michael@0:       // Premultiplied alpha is very fragile.
michael@0:       a = a > r ? a : r;
michael@0:       a = a > g ? a : g;
michael@0:       a = a > b ? a : b;
michael@0:       *dst = SkPackARGB32(a, r, g, b);
michael@0:     }
michael@0:     src_row += h * row_words;
michael@0:     dst_row += result.rowBytes() / 4;
michael@0:   }
michael@0:   result.setAlphaType(img.alphaType());
michael@0:   return result;
michael@0: #else
michael@0:   return SkBitmap();
michael@0: #endif  // OS_POSIX && !OS_MACOSX && !defined(OS_ANDROID)
michael@0: }
michael@0: 
michael@0: // static
michael@0: SkBitmap ImageOperations::ResizeBasic(const SkBitmap& source,
michael@0:                                       ResizeMethod method,
michael@0:                                       int dest_width, int dest_height,
michael@0:                                       const SkIRect& dest_subset,
michael@0:                                       void* dest_pixels /* = nullptr */) {
michael@0:   // Ensure that the ResizeMethod enumeration is sound.
michael@0:   SkASSERT(((RESIZE_FIRST_QUALITY_METHOD <= method) &&
michael@0:             (method <= RESIZE_LAST_QUALITY_METHOD)) ||
michael@0:            ((RESIZE_FIRST_ALGORITHM_METHOD <= method) &&
michael@0:             (method <= RESIZE_LAST_ALGORITHM_METHOD)));
michael@0: 
michael@0:   // If the size of source or destination is 0, i.e. 0x0, 0xN or Nx0, just
michael@0:   // return empty.
michael@0:   if (source.width() < 1 || source.height() < 1 ||
michael@0:       dest_width < 1 || dest_height < 1)
michael@0:     return SkBitmap();
michael@0: 
michael@0:   method = ResizeMethodToAlgorithmMethod(method);
michael@0:   // Check that we deal with an "algorithm methods" from this point onward.
michael@0:   SkASSERT((ImageOperations::RESIZE_FIRST_ALGORITHM_METHOD <= method) &&
michael@0:            (method <= ImageOperations::RESIZE_LAST_ALGORITHM_METHOD));
michael@0: 
michael@0:   SkAutoLockPixels locker(source);
michael@0:   if (!source.readyToDraw())
michael@0:       return SkBitmap();
michael@0: 
michael@0:   ResizeFilter filter(method, source.width(), source.height(),
michael@0:                       dest_width, dest_height, dest_subset);
michael@0: 
michael@0:   // Get a source bitmap encompassing this touched area. We construct the
michael@0:   // offsets and row strides such that it looks like a new bitmap, while
michael@0:   // referring to the old data.
michael@0:   const uint8_t* source_subset =
michael@0:       reinterpret_cast<const uint8_t*>(source.getPixels());
michael@0: 
michael@0:   // Convolve into the result.
michael@0:   SkBitmap result;
michael@0:   result.setConfig(SkBitmap::kARGB_8888_Config,
michael@0:                    dest_subset.width(), dest_subset.height());
michael@0: 
michael@0:   if (dest_pixels) {
michael@0:     result.setPixels(dest_pixels);
michael@0:   } else {
michael@0:     result.allocPixels();
michael@0:   }
michael@0: 
michael@0:   if (!result.readyToDraw())
michael@0:     return SkBitmap();
michael@0: 
michael@0:   BGRAConvolve2D(source_subset, static_cast<int>(source.rowBytes()),
michael@0:                  !source.isOpaque(), filter.x_filter(), filter.y_filter(),
michael@0:                  static_cast<int>(result.rowBytes()),
michael@0:                  static_cast<unsigned char*>(result.getPixels()),
michael@0:                  /* sse = */ false);
michael@0: 
michael@0:   // Preserve the "opaque" flag for use as an optimization later.
michael@0:   result.setAlphaType(source.alphaType());
michael@0: 
michael@0:   return result;
michael@0: }
michael@0: 
michael@0: // static
michael@0: SkBitmap ImageOperations::Resize(const SkBitmap& source,
michael@0:                                  ResizeMethod method,
michael@0:                                  int dest_width, int dest_height,
michael@0:                                  void* dest_pixels /* = nullptr */) {
michael@0:   SkIRect dest_subset = { 0, 0, dest_width, dest_height };
michael@0:   return Resize(source, method, dest_width, dest_height, dest_subset,
michael@0:                 dest_pixels);
michael@0: }
michael@0: 
michael@0: }  // namespace skia