dom/canvas/ImageBitmapUtils.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:set ts=2 sw=2 sts=2 et cindent: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_dom_ImageBitmapUtils_h
   8 #define mozilla_dom_ImageBitmapUtils_h
   9
  10 #include "mozilla/UniquePtr.h"
  11 #include "nsTArrayForwardDeclare.h"
  12
  13 namespace mozilla {
  14
  15 namespace layers {
  16 class Image;
  17 struct PlanarYCbCrData;
  18 }  // namespace layers
  19
  20 namespace dom {
  21
  22 struct ChannelPixelLayout;
  23 template <typename>
  24 class Sequence;
  25
  26 typedef nsTArray<ChannelPixelLayout> ImagePixelLayout;
  27
  28 /*
  29  * This function creates an ImagePixelLayout object which describes the
  30  * default layout of the given ImageBitmapFormat with the given width, height
  31  * and stride.
  32  */
  33 UniquePtr<ImagePixelLayout> CreateDefaultPixelLayout(ImageBitmapFormat aFormat,
  34                                                      uint32_t aWidth,
  35                                                      uint32_t aHeight,
  36                                                      uint32_t aStride);
  37
  38 /*
  39  * This function extracts information from the aImage parameter to customize
  40  * the ImagePixelLayout object, that is, this function creates a customized
  41  * ImagePixelLayout object which exactly describes the pixel layout of the
  42  * given aImage.
  43  */
  44 UniquePtr<ImagePixelLayout> CreatePixelLayoutFromPlanarYCbCrData(
  45     const layers::PlanarYCbCrData* aData);
  46
  47 /*
  48  * Get the number of channels of the given ImageBitmapFormat.
  49  */
  50 uint8_t GetChannelCountOfImageFormat(ImageBitmapFormat aFormat);
  51
  52 /*
  53  * This function always copies the image data in _aSrcBuffer_ into _aDstBuffer_
  54  * and it also performs color conversion if the _aSrcFormat_ and the
  55  * _aDstFormat_ are different.
  56  *
  57  * The source image is stored in the _aSrcBuffer_ and the corresponding pixel
  58  * layout is described by the _aSrcLayout_.
  59  *
  60  * The copied and converted image will be stored in the _aDstBuffer_, which
  61  * should be allocated with enough size before invoking this function and the
  62  * needed size could be found by the CalculateImageBufferSize() method.
  63  *
  64  * The returned ImagePixelLayout object describes the pixel layout of the result
  65  * image and will be null if on failure.
  66  */
  67 UniquePtr<ImagePixelLayout> CopyAndConvertImageData(
  68     ImageBitmapFormat aSrcFormat, const uint8_t* aSrcBuffer,
  69     const ImagePixelLayout* aSrcLayout, ImageBitmapFormat aDstFormat,
  70     uint8_t* aDstBuffer);
  71
  72 /*
  73  * This function tries to find the best ImageBitmapFormat, from the aCandiates,
  74  * which can be converted from the aSrcFormat. The algorithm now merely returns
  75  * the FIRST one, from the aCandidates, which can be converted from the
  76  * aSrcFormat.
  77  *
  78  * TODO: The algorithm should be updated after we implement optimizations for
  79  *       different platforms (different kinds of layers::Image), considering
  80  *       that some conversion might be cheaper through hardware.
  81  */
  82 ImageBitmapFormat FindBestMatchingFromat(
  83     ImageBitmapFormat aSrcFormat,
  84     const Sequence<ImageBitmapFormat>& aCandidates);
  85
  86 }  // namespace dom
  87 }  // namespace mozilla
  88
  89 #endif  // mozilla_dom_ImageBitmapUtils_h