The Tor Browser: gfx/2d/image_operations.h@97036ab72558 (annotated)

gfx/2d/image_operations.h@97036ab72558 (annotated)

gfx/2d/image_operations.h

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 // Copyright (c) 2006-2011 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.
 #ifndef SKIA_EXT_IMAGE_OPERATIONS_H_
 #define SKIA_EXT_IMAGE_OPERATIONS_H_
 #include "skia/SkTypes.h"
 #include "Types.h"
 class SkBitmap;
 struct SkIRect;
 namespace skia {
 class ImageOperations {
  public:
   enum ResizeMethod {
     //
     // Quality Methods
     //
     // Those enumeration values express a desired quality/speed tradeoff.
     // They are translated into an algorithm-specific method that depends
     // on the capabilities (CPU, GPU) of the underlying platform.
     // It is possible for all three methods to be mapped to the same
     // algorithm on a given platform.
     // Good quality resizing. Fastest resizing with acceptable visual quality.
     // This is typically intended for use during interactive layouts
     // where slower platforms may want to trade image quality for large
     // increase in resizing performance.
     //
     // For example the resizing implementation may devolve to linear
     // filtering if this enables GPU acceleration to be used.
     //
     // Note that the underlying resizing method may be determined
     // on the fly based on the parameters for a given resize call.
     // For example an implementation using a GPU-based linear filter
     // in the common case may still use a higher-quality software-based
     // filter in cases where using the GPU would actually be slower - due
     // to too much latency - or impossible - due to image format or size
     // constraints.
     RESIZE_GOOD,
     // Medium quality resizing. Close to high quality resizing (better
     // than linear interpolation) with potentially some quality being
     // traded-off for additional speed compared to RESIZE_BEST.
     //
     // This is intended, for example, for generation of large thumbnails
     // (hundreds of pixels in each dimension) from large sources, where
     // a linear filter would produce too many artifacts but where
     // a RESIZE_HIGH might be too costly time-wise.
     RESIZE_BETTER,
     // High quality resizing. The algorithm is picked to favor image quality.
     RESIZE_BEST,
     //
     // Algorithm-specific enumerations
     //
     // Box filter. This is a weighted average of all of the pixels touching
     // the destination pixel. For enlargement, this is nearest neighbor.
     //
     // You probably don't want this, it is here for testing since it is easy to
     // compute. Use RESIZE_LANCZOS3 instead.
     RESIZE_BOX,
     // 1-cycle Hamming filter. This is tall is the middle and falls off towards
     // the window edges but without going to 0. This is about 40% faster than
     // a 2-cycle Lanczos.
     RESIZE_HAMMING1,
     // 2-cycle Lanczos filter. This is tall in the middle, goes negative on
     // each side, then returns to zero. Does not provide as good a frequency
     // response as a 3-cycle Lanczos but is roughly 30% faster.
     RESIZE_LANCZOS2,
     // 3-cycle Lanczos filter. This is tall in the middle, goes negative on
     // each side, then oscillates 2 more times. It gives nice sharp edges.
     RESIZE_LANCZOS3,
     // Lanczos filter + subpixel interpolation. If subpixel rendering is not
     // appropriate we automatically fall back to Lanczos.
     RESIZE_SUBPIXEL,
     // enum aliases for first and last methods by algorithm or by quality.
     RESIZE_FIRST_QUALITY_METHOD = RESIZE_GOOD,
     RESIZE_LAST_QUALITY_METHOD = RESIZE_BEST,
     RESIZE_FIRST_ALGORITHM_METHOD = RESIZE_BOX,
     RESIZE_LAST_ALGORITHM_METHOD = RESIZE_SUBPIXEL,
   };
   // Resizes the given source bitmap using the specified resize method, so that
   // the entire image is (dest_size) big. The dest_subset is the rectangle in
   // this destination image that should actually be returned.
   //
   // The output image will be (dest_subset.width(), dest_subset.height()). This
   // will save work if you do not need the entire bitmap.
   //
   // The destination subset must be smaller than the destination image.
   static SkBitmap Resize(const SkBitmap& source,
                          ResizeMethod method,
                          int dest_width, int dest_height,
                          const SkIRect& dest_subset,
                          void* dest_pixels = nullptr);
   // Alternate version for resizing and returning the entire bitmap rather than
   // a subset.
   static SkBitmap Resize(const SkBitmap& source,
                          ResizeMethod method,
                          int dest_width, int dest_height,
                          void* dest_pixels = nullptr);
  private:
   ImageOperations();  // Class for scoping only.
   // Supports all methods except RESIZE_SUBPIXEL.
   static SkBitmap ResizeBasic(const SkBitmap& source,
                               ResizeMethod method,
                               int dest_width, int dest_height,
                               const SkIRect& dest_subset,
                               void* dest_pixels = nullptr);
   // Subpixel renderer.
   static SkBitmap ResizeSubpixel(const SkBitmap& source,
                                  int dest_width, int dest_height,
                                  const SkIRect& dest_subset);
 };
 }  // namespace skia
 #endif  // SKIA_EXT_IMAGE_OPERATIONS_H_

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gfx/2d/image_operations.h@97036ab72558 (annotated)

gfx/2d/image_operations.h