1 files changed, 99 insertions, 0 deletions
diff --git a/dom/canvas/ImageBitmapUtils.h b/dom/canvas/ImageBitmapUtils.h
new file mode 100644
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--- /dev/null
+++ b/dom/canvas/ImageBitmapUtils.h
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_ImageBitmapUtils_h
+#define mozilla_dom_ImageBitmapUtils_h
+
+#include "mozilla/UniquePtr.h"
+#include "nsTArrayForwardDeclare.h"
+
+namespace mozilla {
+
+namespace layers {
+class Image;
+struct PlanarYCbCrData;
+}
+
+namespace dom {
+
+struct ChannelPixelLayout;
+template<typename> class Sequence;
+
+typedef nsTArray<ChannelPixelLayout> ImagePixelLayout;
+
+/*
+ * This function creates an ImagePixelLayout object which describes the
+ * default layout of the given ImageBitmapFormat with the given width, height
+ * and stride.
+ */
+UniquePtr<ImagePixelLayout>
+CreateDefaultPixelLayout(ImageBitmapFormat aFormat,
+                         uint32_t aWidth, uint32_t aHeight, uint32_t aStride);
+
+/*
+ * This function extracts information from the aImage parameter to customize
+ * the ImagePixelLayout object, that is, this function creates a customized
+ * ImagePixelLayout object which exactly describes the pixel layout of the
+ * given aImage.
+ */
+UniquePtr<ImagePixelLayout>
+CreatePixelLayoutFromPlanarYCbCrData(const layers::PlanarYCbCrData* aData);
+
+/*
+ * Get the number of channels of the given ImageBitmapFormat.
+ */
+uint8_t
+GetChannelCountOfImageFormat(ImageBitmapFormat aFormat);
+
+/*
+ * Get the needed buffer size to store the image data in the given
+ * ImageBitmapFormat with the given width and height.
+ */
+uint32_t
+CalculateImageBufferSize(ImageBitmapFormat aFormat,
+                         uint32_t aWidth, uint32_t aHeight);
+
+/*
+ * This function always copies the image data in _aSrcBuffer_ into _aDstBuffer_
+ * and it also performs color conversion if the _aSrcFormat_ and the
+ * _aDstFormat_ are different.
+ *
+ * The source image is stored in the _aSrcBuffer_ and the corresponding pixel
+ * layout is described by the _aSrcLayout_.
+ *
+ * The copied and converted image will be stored in the _aDstBuffer_, which
+ * should be allocated with enough size before invoking this function and the
+ * needed size could be found by the CalculateImageBufferSize() method.
+ *
+ * The returned ImagePixelLayout object describes the pixel layout of the result
+ * image and will be null if on failure.
+ */
+UniquePtr<ImagePixelLayout>
+CopyAndConvertImageData(ImageBitmapFormat aSrcFormat,
+                        const uint8_t* aSrcBuffer,
+                        const ImagePixelLayout* aSrcLayout,
+                        ImageBitmapFormat aDstFormat,
+                        uint8_t* aDstBuffer);
+
+/*
+ * This function tries to find the best ImageBitmapFormat, from the aCandiates,
+ * which can be converted from the aSrcFormat. The algorithm now merely returns
+ * the FIRST one, from the aCandidates, which can be converted from the
+ * aSrcFormat.
+ *
+ * TODO: The algorithm should be updated after we implement optimizations for
+ *       different platforms (different kinds of layers::Image), considering
+ *       that some conversion might be cheaper through hardware.
+ */
+ImageBitmapFormat
+FindBestMatchingFromat(ImageBitmapFormat aSrcFormat,
+                       const Sequence<ImageBitmapFormat>& aCandidates);
+
+} // namespace dom
+} // namespace mozilla
+
+
+#endif // mozilla_dom_ImageBitmapUtils_h