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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 */
* An interface for tasks which can execute on the ImageLib DecodePool, and
* various implementations.
#ifndef mozilla_image_IDecodingTask_h
#define mozilla_image_IDecodingTask_h
#include "imgFrame.h"
#include "mozilla/NotNull.h"
#include "mozilla/RefPtr.h"
#include "nsIEventTarget.h"
#include "SourceBuffer.h"
namespace mozilla {
namespace image {
class Decoder;
class RasterImage;
/// A priority hint that DecodePool can use when scheduling an IDecodingTask.
enum class TaskPriority : uint8_t { eLow, eHigh };
* An interface for tasks which can execute on the ImageLib DecodePool.
class IDecodingTask : public IResumable {
/// Run the task.
virtual void Run() = 0;
/// @return true if, given the option, this task prefers to run synchronously.
virtual bool ShouldPreferSyncRun() const = 0;
/// @return a priority hint that DecodePool can use when scheduling this task.
virtual TaskPriority Priority() const = 0;
/// A default implementation of IResumable which resubmits the task to the
/// DecodePool. Subclasses can override this if they need different behavior.
void Resume() override;
virtual ~IDecodingTask() {}
/// Notify @aImage of @aDecoder's progress.
void NotifyProgress(NotNull<RasterImage*> aImage, NotNull<Decoder*> aDecoder);
/// Notify @aImage that @aDecoder has finished.
void NotifyDecodeComplete(NotNull<RasterImage*> aImage,
NotNull<Decoder*> aDecoder);
void EnsureHasEventTarget(NotNull<RasterImage*> aImage);
bool IsOnEventTarget() const;
nsCOMPtr<nsIEventTarget> mEventTarget;
* An IDecodingTask implementation for metadata decodes of images.
class MetadataDecodingTask final : public IDecodingTask {
explicit MetadataDecodingTask(NotNull<Decoder*> aDecoder);
void Run() override;
// Metadata decodes are very fast (since they only need to examine an image's
// header) so there's no reason to refuse to run them synchronously if the
// caller will allow us to.
bool ShouldPreferSyncRun() const override { return true; }
// Metadata decodes run at the highest priority because they block layout and
// page load.
TaskPriority Priority() const override { return TaskPriority::eHigh; }
virtual ~MetadataDecodingTask() {}
/// Mutex protecting access to mDecoder.
NotNull<RefPtr<Decoder>> mDecoder;
* An IDecodingTask implementation for anonymous decoders - that is, decoders
* with no associated Image object.
class AnonymousDecodingTask final : public IDecodingTask {
explicit AnonymousDecodingTask(NotNull<Decoder*> aDecoder, bool aResumable);
void Run() override;
bool ShouldPreferSyncRun() const override { return true; }
TaskPriority Priority() const override { return TaskPriority::eLow; }
void Resume() override;
virtual ~AnonymousDecodingTask() {}
NotNull<RefPtr<Decoder>> mDecoder;
bool mResumable;
} // namespace image
} // namespace mozilla
#endif // mozilla_image_IDecodingTask_h