image/AnimationSurfaceProvider.h
author Henri Sivonen <hsivonen@hsivonen.fi>
Fri, 06 Jul 2018 10:44:43 +0300
changeset 489140 4ef0f163fdeb9afeddd87b37bfd987298c038542
parent 477002 c67a6f1315b49a4faeec778709ab0d3a956a57dd
child 496601 587e01daa080af33c43fe71edf307e02c5a97eb2
permissions -rw-r--r--
Bug 1402247 - Use encoding_rs for XPCOM string encoding conversions. r=Nika,erahm,froydnj. Correctness improvements: * UTF errors are handled safely per spec instead of dangerously truncating strings. * There are fewer converter implementations. Performance improvements: * The old code did exact buffer length math, which meant doing UTF math twice on each input string (once for length calculation and another time for conversion). Exact length math is more complicated when handling errors properly, which the old code didn't do. The new code does UTF math on the string content only once (when converting) but risks allocating more than once. There are heuristics in place to lower the probability of reallocation in cases where the double math avoidance isn't enough of a saving to absorb an allocation and memcpy. * Previously, in UTF-16 <-> UTF-8 conversions, an ASCII prefix was optimized but a single non-ASCII code point pessimized the rest of the string. The new code tries to get back on the fast ASCII path. * UTF-16 to Latin1 conversion guarantees less about handling of out-of-range input to eliminate an operation from the inner loop on x86/x86_64. * When assigning to a pre-existing string, the new code tries to reuse the old buffer instead of first releasing the old buffer and then allocating a new one. * When reallocating from the new code, the memcpy covers only the data that is part of the logical length of the old string instead of memcpying the whole capacity. (For old callers old excess memcpy behavior is preserved due to bogus callers. See bug 1472113.) * UTF-8 strings in XPConnect that are in the Latin1 range are passed to SpiderMonkey as Latin1. New features: * Conversion between UTF-8 and Latin1 is added in order to enable faster future interop between Rust code (or otherwise UTF-8-using code) and text node and SpiderMonkey code that uses Latin1. MozReview-Commit-ID: JaJuExfILM9

/* -*- 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 http://mozilla.org/MPL/2.0/. */

/**
 * An ISurfaceProvider for animated images.
 */

#ifndef mozilla_image_AnimationSurfaceProvider_h
#define mozilla_image_AnimationSurfaceProvider_h

#include "FrameAnimator.h"
#include "IDecodingTask.h"
#include "ISurfaceProvider.h"
#include "AnimationFrameBuffer.h"

namespace mozilla {
namespace image {

/**
 * An ISurfaceProvider that manages the decoding of animated images and
 * dynamically generates surfaces for the current playback state of the
 * animation.
 */
class AnimationSurfaceProvider final
  : public ISurfaceProvider
  , public IDecodingTask
{
public:
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(AnimationSurfaceProvider, override)

  AnimationSurfaceProvider(NotNull<RasterImage*> aImage,
                           const SurfaceKey& aSurfaceKey,
                           NotNull<Decoder*> aDecoder,
                           size_t aCurrentFrame);


  //////////////////////////////////////////////////////////////////////////////
  // ISurfaceProvider implementation.
  //////////////////////////////////////////////////////////////////////////////

public:
  // We use the ISurfaceProvider constructor of DrawableSurface to indicate that
  // our surfaces are computed lazily.
  DrawableSurface Surface() override { return DrawableSurface(WrapNotNull(this)); }

  bool IsFinished() const override;
  bool IsFullyDecoded() const override;
  size_t LogicalSizeInBytes() const override;
  void AddSizeOfExcludingThis(MallocSizeOf aMallocSizeOf,
                              size_t& aHeapSizeOut,
                              size_t& aNonHeapSizeOut,
                              size_t& aExtHandlesOut) override;
  void Reset() override;
  void Advance(size_t aFrame) override;

protected:
  DrawableFrameRef DrawableRef(size_t aFrame) override;
  RawAccessFrameRef RawAccessRef(size_t aFrame) override;

  // Animation frames are always locked. This is because we only want to release
  // their memory atomically (due to the surface cache discarding them). If they
  // were unlocked, the OS could end up releasing the memory of random frames
  // from the middle of the animation, which is not worth the complexity of
  // dealing with.
  bool IsLocked() const override { return true; }
  void SetLocked(bool) override { }


  //////////////////////////////////////////////////////////////////////////////
  // IDecodingTask implementation.
  //////////////////////////////////////////////////////////////////////////////

public:
  void Run() override;
  bool ShouldPreferSyncRun() const override;

  // Full decodes are low priority compared to metadata decodes because they
  // don't block layout or page load.
  TaskPriority Priority() const override { return TaskPriority::eLow; }

private:
  virtual ~AnimationSurfaceProvider();

  void DropImageReference();
  void AnnounceSurfaceAvailable();
  void FinishDecoding();

  // @returns Whether or not we should continue decoding.
  bool CheckForNewFrameAtYield();

  // @returns Whether or not we should restart decoding.
  bool CheckForNewFrameAtTerminalState();

  /// The image associated with our decoder.
  RefPtr<RasterImage> mImage;

  /// A mutex to protect mDecoder. Always taken before mFramesMutex.
  mutable Mutex mDecodingMutex;

  /// The decoder used to decode this animation.
  RefPtr<Decoder> mDecoder;

  /// A mutex to protect mFrames. Always taken after mDecodingMutex.
  mutable Mutex mFramesMutex;

  /// The frames of this animation, in order.
  AnimationFrameBuffer mFrames;
};

} // namespace image
} // namespace mozilla

#endif // mozilla_image_AnimationSurfaceProvider_h