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+// Copyright (c) 2006-2012 The Chromium Authors. All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above copyright
+// notice, this list of conditions and the following disclaimer in
+// the documentation and/or other materials provided with the
+// distribution.
+// * Neither the name of Google, Inc. nor the names of its contributors
+// may be used to endorse or promote products derived from this
+// software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+// OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+// AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+// SUCH DAMAGE.
+
+#include "base/basictypes.h"
+
+#include <algorithm>
+#include <cmath>
+#include <limits>
+
+#include "image_operations.h"
+
+#include "base/stack_container.h"
+#include "convolver.h"
+#include "skia/include/core/SkColorPriv.h"
+#include "skia/include/core/SkBitmap.h"
+#include "skia/include/core/SkRect.h"
+#include "skia/include/core/SkFontLCDConfig.h"
+
+namespace skia {
+
+namespace resize {
+
+// TODO(egouriou): Take advantage of periods in the convolution.
+// Practical resizing filters are periodic outside of the border area.
+// For Lanczos, a scaling by a (reduced) factor of p/q (q pixels in the
+// source become p pixels in the destination) will have a period of p.
+// A nice consequence is a period of 1 when downscaling by an integral
+// factor. Downscaling from typical display resolutions is also bound
+// to produce interesting periods as those are chosen to have multiple
+// small factors.
+// 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 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
+ // 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);
+
+ 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;
+
+ StackVector<float, 64> filter_values;
+ StackVector<int16_t, 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.
+ // Note that we base computations on the "center" of the pixels. To see
+ // why, observe that the destination pixel at coordinates (0, 0) in a 5.0x
+ // downscale should "cover" the pixels around the pixel with *its center*
+ // at coordinates (2.5, 2.5) in the source, not those around (0, 0).
+ // Hence we need to scale coordinates (0.5, 0.5), not (0, 0).
+ float src_pixel = (static_cast<float>(dest_subset_i) + 0.5f) * 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. We also need to consider the center of the pixel
+ // when comparing distance against 'src_pixel'. In the 5x downscale
+ // example used above the distance from the center of the filter to
+ // the pixel with coordinates (2, 2) should be 0, because its center
+ // is at (2.5, 2.5).
+ float src_filter_dist =
+ ((static_cast<float>(cur_filter_pixel) + 0.5f) - src_pixel);
+
+ // Since the filter really exists in dest space, map it there.
+ float dest_filter_dist = src_filter_dist * clamped_scale;
+
+ // Compute the filter value at that location.
+ float filter_value = ComputeFilter(method, dest_filter_dist);
+ filter_values->push_back(filter_value);
+
+ filter_sum += filter_value;
+ }
+
+ // The filter must be normalized so that we don't affect the brightness of
+ // the image. Convert to normalized fixed point.
+ int16_t fixed_sum = 0;
+ for (size_t i = 0; i < filter_values->size(); i++) {
+ int16_t 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_t 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()));
+ }
+
+ output->PaddingForSIMD(8);
+}
+
+} // namespace resize
+
+ImageOperations::ResizeMethod ResizeMethodToAlgorithmMethod(
+ ImageOperations::ResizeMethod method) {
+ // Convert any "Quality Method" into an "Algorithm Method"
+ if (method >= ImageOperations::RESIZE_FIRST_ALGORITHM_METHOD &&
+ method <= ImageOperations::RESIZE_LAST_ALGORITHM_METHOD) {
+ return method;
+ }
+ // The call to ImageOperationsGtv::Resize() above took care of
+ // 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:
+ // 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 acceptable trade-off between quality and speed.
+ case ImageOperations::RESIZE_BETTER:
+ return ImageOperations::RESIZE_HAMMING1;
+ default:
+ return ImageOperations::RESIZE_LANCZOS3;
+ }
+}
+
+// Resize ----------------------------------------------------------------------
+
+// static
+SkBitmap ImageOperations::Resize(const SkBitmap& source,
+ ResizeMethod method,
+ int dest_width, int dest_height,
+ const SkIRect& dest_subset,
+ void* dest_pixels /* = nullptr */) {
+ if (method == ImageOperations::RESIZE_SUBPIXEL)
+ return ResizeSubpixel(source, dest_width, dest_height, dest_subset);
+ else
+ return ResizeBasic(source, method, dest_width, dest_height, dest_subset,
+ dest_pixels);
+}
+
+// static
+SkBitmap ImageOperations::ResizeSubpixel(const SkBitmap& source,
+ int dest_width, int dest_height,
+ const SkIRect& dest_subset) {
+ // Currently only works on Linux/BSD because these are the only platforms
+ // where SkFontLCDConfig::GetSubpixelOrder is defined.
+#if defined(XP_UNIX)
+ // Understand the display.
+ const SkFontLCDConfig::LCDOrder order = SkFontLCDConfig::GetSubpixelOrder();
+ const SkFontLCDConfig::LCDOrientation orientation =
+ SkFontLCDConfig::GetSubpixelOrientation();
+
+ // Decide on which dimension, if any, to deploy subpixel rendering.
+ int w = 1;
+ int h = 1;
+ switch (orientation) {
+ case SkFontLCDConfig::kHorizontal_LCDOrientation:
+ w = dest_width < source.width() ? 3 : 1;
+ break;
+ case SkFontLCDConfig::kVertical_LCDOrientation:
+ h = dest_height < source.height() ? 3 : 1;
+ break;
+ }
+
+ // Resize the image.
+ const int width = dest_width * w;
+ const int height = dest_height * h;
+ SkIRect subset = { dest_subset.fLeft, dest_subset.fTop,
+ dest_subset.fLeft + dest_subset.width() * w,
+ dest_subset.fTop + dest_subset.height() * h };
+ SkBitmap img = ResizeBasic(source, ImageOperations::RESIZE_LANCZOS3, width,
+ height, subset);
+ const int row_words = img.rowBytes() / 4;
+ if (w == 1 && h == 1)
+ return img;
+
+ // Render into subpixels.
+ SkBitmap result;
+ SkImageInfo info = SkImageInfo::Make(dest_subset.width(),
+ dest_subset.height(),
+ kBGRA_8888_SkColorType,
+ kPremul_SkAlphaType);
+
+
+ result.allocPixels(info);
+ if (!result.readyToDraw())
+ return img;
+
+ SkAutoLockPixels locker(img);
+ if (!img.readyToDraw())
+ return img;
+
+ uint32_t* src_row = img.getAddr32(0, 0);
+ uint32_t* dst_row = result.getAddr32(0, 0);
+ for (int y = 0; y < dest_subset.height(); y++) {
+ uint32_t* src = src_row;
+ uint32_t* dst = dst_row;
+ for (int x = 0; x < dest_subset.width(); x++, src += w, dst++) {
+ uint8_t r = 0, g = 0, b = 0, a = 0;
+ switch (order) {
+ case SkFontLCDConfig::kRGB_LCDOrder:
+ switch (orientation) {
+ case SkFontLCDConfig::kHorizontal_LCDOrientation:
+ r = SkGetPackedR32(src[0]);
+ g = SkGetPackedG32(src[1]);
+ b = SkGetPackedB32(src[2]);
+ a = SkGetPackedA32(src[1]);
+ break;
+ case SkFontLCDConfig::kVertical_LCDOrientation:
+ r = SkGetPackedR32(src[0 * row_words]);
+ g = SkGetPackedG32(src[1 * row_words]);
+ b = SkGetPackedB32(src[2 * row_words]);
+ a = SkGetPackedA32(src[1 * row_words]);
+ break;
+ }
+ break;
+ case SkFontLCDConfig::kBGR_LCDOrder:
+ switch (orientation) {
+ case SkFontLCDConfig::kHorizontal_LCDOrientation:
+ b = SkGetPackedB32(src[0]);
+ g = SkGetPackedG32(src[1]);
+ r = SkGetPackedR32(src[2]);
+ a = SkGetPackedA32(src[1]);
+ break;
+ case SkFontLCDConfig::kVertical_LCDOrientation:
+ b = SkGetPackedB32(src[0 * row_words]);
+ g = SkGetPackedG32(src[1 * row_words]);
+ r = SkGetPackedR32(src[2 * row_words]);
+ a = SkGetPackedA32(src[1 * row_words]);
+ break;
+ }
+ break;
+ case SkFontLCDConfig::kNONE_LCDOrder:
+ break;
+ }
+ // Premultiplied alpha is very fragile.
+ a = a > r ? a : r;
+ a = a > g ? a : g;
+ a = a > b ? a : b;
+ *dst = SkPackARGB32(a, r, g, b);
+ }
+ src_row += h * row_words;
+ dst_row += result.rowBytes() / 4;
+ }
+ result.setAlphaType(img.alphaType());
+ return result;
+#else
+ return SkBitmap();
+#endif // OS_POSIX && !OS_MACOSX && !defined(OS_ANDROID)
+}
+
+// static
+SkBitmap ImageOperations::ResizeBasic(const SkBitmap& source,
+ ResizeMethod method,
+ int dest_width, int dest_height,
+ const SkIRect& dest_subset,
+ void* dest_pixels /* = nullptr */) {
+ // Ensure that the ResizeMethod enumeration is sound.
+ SkASSERT(((RESIZE_FIRST_QUALITY_METHOD <= method) &&
+ (method <= RESIZE_LAST_QUALITY_METHOD)) ||
+ ((RESIZE_FIRST_ALGORITHM_METHOD <= method) &&
+ (method <= RESIZE_LAST_ALGORITHM_METHOD)));
+
+ // 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_width < 1 || dest_height < 1)
+ return SkBitmap();
+
+ method = ResizeMethodToAlgorithmMethod(method);
+ // Check that we deal with an "algorithm methods" from this point onward.
+ SkASSERT((ImageOperations::RESIZE_FIRST_ALGORITHM_METHOD <= method) &&
+ (method <= ImageOperations::RESIZE_LAST_ALGORITHM_METHOD));
+
+ SkAutoLockPixels locker(source);
+ if (!source.readyToDraw())
+ return SkBitmap();
+
+ 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
+ // referring to the old data.
+ const uint8_t* source_subset =
+ reinterpret_cast<const uint8_t*>(source.getPixels());
+
+ // Convolve into the result.
+ SkBitmap result;
+ SkImageInfo info = SkImageInfo::Make(dest_subset.width(),
+ dest_subset.height(),
+ kBGRA_8888_SkColorType,
+ kPremul_SkAlphaType);
+
+ if (dest_pixels) {
+ result.installPixels(info, dest_pixels, info.minRowBytes());
+ } else {
+ result.allocPixels(info);
+ }
+
+ if (!result.readyToDraw())
+ return SkBitmap();
+
+ BGRAConvolve2D(source_subset, static_cast<int>(source.rowBytes()),
+ !source.isOpaque(), x_filter, y_filter,
+ static_cast<int>(result.rowBytes()),
+ static_cast<unsigned char*>(result.getPixels()));
+
+ // Preserve the "opaque" flag for use as an optimization later.
+ result.setAlphaType(source.alphaType());
+
+ return result;
+}
+
+// static
+SkBitmap ImageOperations::Resize(const SkBitmap& source,
+ ResizeMethod method,
+ int dest_width, int dest_height,
+ void* dest_pixels /* = nullptr */) {
+ SkIRect dest_subset = { 0, 0, dest_width, dest_height };
+ return Resize(source, method, dest_width, dest_height, dest_subset,
+ dest_pixels);
+}
+
+} // namespace skia