1 files changed, 73 insertions, 0 deletions
diff --git a/dom/canvas/ImageUtils.h b/dom/canvas/ImageUtils.h
new file mode 100644
index 000000000..b64c33704
--- /dev/null
+++ b/dom/canvas/ImageUtils.h
@@ -0,0 +1,73 @@
+/* -*- 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_ImageBitmapFormatUtils_h
+#define mozilla_dom_ImageBitmapFormatUtils_h
+
+#include "mozilla/UniquePtr.h"
+#include "nsTArrayForwardDeclare.h"
+
+namespace mozilla {
+
+namespace layers {
+class Image;
+}
+
+class ErrorResult;
+
+namespace dom {
+
+struct ChannelPixelLayout;
+enum class ImageBitmapFormat : uint32_t;
+
+typedef nsTArray<ChannelPixelLayout> ImagePixelLayout;
+
+/*
+ * ImageUtils is a wrapper around layers::Image. It provides three unified
+ * methods to all sub-classes of layers::Image, which are:
+ *
+ * (1) GetFormat() converts the image's format into ImageBitmapFormat enum.
+ * (2) GetBufferLength() returns the number of bytes that are used to store
+ *     the image's underlying raw data.
+ * (3) MapDataInto() writes the image's underlying raw data into a given
+ *     ArrayBuffer in the given format. (If the given format is different from
+ *     the existing format, the ImageUtils uses the ImageBitmapFormatUtils to
+ *     performa color conversion.)
+ *
+ * In theory, the functionalities of this class could be merged into the
+ * interface of layers::Image. However, this is designed as a isolated wrapper
+ * because we don't want to pollute the layers::Image's interface with methods
+ * that are only meaningful to the ImageBitmap.
+ */
+class ImageUtils
+{
+public:
+  class Impl;
+  ImageUtils() = delete;
+  ImageUtils(const ImageUtils&) = delete;
+  ImageUtils(ImageUtils&&) = delete;
+  ImageUtils& operator=(const ImageUtils&) = delete;
+  ImageUtils& operator=(ImageUtils&&) = delete;
+
+  explicit ImageUtils(layers::Image* aImage);
+  ~ImageUtils();
+
+  ImageBitmapFormat GetFormat() const;
+
+  uint32_t GetBufferLength() const;
+
+  UniquePtr<ImagePixelLayout>
+  MapDataInto(uint8_t* aBuffer, uint32_t aOffset, uint32_t aBufferLength,
+              ImageBitmapFormat aFormat, ErrorResult& aRv) const;
+
+protected:
+  Impl* mImpl;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_ImageBitmapFormatUtils_h */