image/ISurfaceProvider.h
author Kartikaya Gupta <kgupta@mozilla.com>
Thu, 15 Mar 2018 15:25:09 -0400
changeset 408344 a27ceb86fbd002b8aafd2f6377c315c11254af0c
parent 405768 32b33a66cf6b224b155f93115b555eff8bc22988
child 420278 c67a6f1315b49a4faeec778709ab0d3a956a57dd
permissions -rw-r--r--
Bug 1445662 - Remove ProcessTouchVelocity from PAPZCTreeManager.ipdl. r=rhunt This function is never actually called over IPDL. It is called directly on the concrete APZCTreeManager instance by the AndroidDynamicToolbarAnimator code, both of which live in the compositor. So we don't need to expose this method on IAPZCTreeManager or over PAPZCTreeManager.

/* -*- 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 interface for objects which can either store a surface or dynamically
 * generate one, and various implementations.
 */

#ifndef mozilla_image_ISurfaceProvider_h
#define mozilla_image_ISurfaceProvider_h

#include "mozilla/Attributes.h"
#include "mozilla/Maybe.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/NotNull.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/Variant.h"
#include "mozilla/gfx/2D.h"

#include "imgFrame.h"
#include "SurfaceCache.h"

namespace mozilla {
namespace image {

class CachedSurface;
class DrawableSurface;

/**
 * An interface for objects which can either store a surface or dynamically
 * generate one.
 */
class ISurfaceProvider
{
public:
  // Subclasses may or may not be XPCOM classes, so we just require that they
  // implement AddRef and Release.
  NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING

  /// @return key data used for identifying which image this ISurfaceProvider is
  /// associated with in the surface cache.
  ImageKey GetImageKey() const { return mImageKey; }

  /// @return key data used to uniquely identify this ISurfaceProvider's cache
  /// entry in the surface cache.
  const SurfaceKey& GetSurfaceKey() const { return mSurfaceKey; }

  /// @return a (potentially lazily computed) drawable reference to a surface.
  virtual DrawableSurface Surface();

  /// @return true if DrawableRef() will return a completely decoded surface.
  virtual bool IsFinished() const = 0;

  /// @return true if the underlying decoder is currently fully decoded. For
  /// animated images, this means that at least every frame has been decoded
  /// at least once. It does not guarantee that all of the frames are present,
  /// as the surface provider has the option to discard as it deems necessary.
  virtual bool IsFullyDecoded() const { return IsFinished(); }

  /// @return the number of bytes of memory this ISurfaceProvider is expected to
  /// require. Optimizations may result in lower real memory usage. Trivial
  /// overhead is ignored. Because this value is used in bookkeeping, it's
  /// important that it be constant over the lifetime of this object.
  virtual size_t LogicalSizeInBytes() const = 0;

  /// @return the actual number of bytes of memory this ISurfaceProvider is
  /// using. May vary over the lifetime of the ISurfaceProvider. The default
  /// implementation is appropriate for static ISurfaceProviders.
  virtual void AddSizeOfExcludingThis(MallocSizeOf aMallocSizeOf,
                                      size_t& aHeapSizeOut,
                                      size_t& aNonHeapSizeOut,
                                      size_t& aExtHandlesOut)
  {
    DrawableFrameRef ref = DrawableRef(/* aFrame = */ 0);
    if (!ref) {
      return;
    }

    ref->AddSizeOfExcludingThis(aMallocSizeOf, aHeapSizeOut,
                                aNonHeapSizeOut, aExtHandlesOut);
  }

  virtual void Reset() { }
  virtual void Advance(size_t aFrame) { }

  /// @return the availability state of this ISurfaceProvider, which indicates
  /// whether DrawableRef() could successfully return a surface. Should only be
  /// called from SurfaceCache code as it relies on SurfaceCache for
  /// synchronization.
  AvailabilityState& Availability() { return mAvailability; }
  const AvailabilityState& Availability() const { return mAvailability; }

protected:
  ISurfaceProvider(const ImageKey aImageKey,
                   const SurfaceKey& aSurfaceKey,
                   AvailabilityState aAvailability)
    : mImageKey(aImageKey)
    , mSurfaceKey(aSurfaceKey)
    , mAvailability(aAvailability)
  {
    MOZ_ASSERT(aImageKey, "Must have a valid image key");
  }

  virtual ~ISurfaceProvider() { }

  /// @return an eagerly computed drawable reference to a surface. For
  /// dynamically generated animation surfaces, @aFrame specifies the 0-based
  /// index of the desired frame.
  virtual DrawableFrameRef DrawableRef(size_t aFrame) = 0;

  /// @return true if this ISurfaceProvider is locked. (@see SetLocked())
  /// Should only be called from SurfaceCache code as it relies on SurfaceCache
  /// for synchronization.
  virtual bool IsLocked() const = 0;

  /// If @aLocked is true, hint that this ISurfaceProvider is in use and it
  /// should avoid releasing its resources. Should only be called from
  /// SurfaceCache code as it relies on SurfaceCache for synchronization.
  virtual void SetLocked(bool aLocked) = 0;

private:
  friend class CachedSurface;
  friend class DrawableSurface;

  const ImageKey mImageKey;
  const SurfaceKey mSurfaceKey;
  AvailabilityState mAvailability;
};


/**
 * A reference to a surface (stored in an imgFrame) that holds the surface in
 * memory, guaranteeing that it can be drawn. If you have a DrawableSurface
 * |surf| and |if (surf)| returns true, then calls to |surf->Draw()| and
 * |surf->GetSourceSurface()| are guaranteed to succeed.
 *
 * Note that the surface may be computed lazily, so a DrawableSurface should not
 * be dereferenced (i.e., operator->() should not be called) until you're
 * sure that you want to draw it.
 */
class MOZ_STACK_CLASS DrawableSurface final
{
public:
  DrawableSurface() : mHaveSurface(false) { }

  explicit DrawableSurface(DrawableFrameRef&& aDrawableRef)
    : mDrawableRef(Move(aDrawableRef))
    , mHaveSurface(bool(mDrawableRef))
  { }

  explicit DrawableSurface(NotNull<ISurfaceProvider*> aProvider)
    : mProvider(aProvider)
    , mHaveSurface(true)
  { }

  DrawableSurface(DrawableSurface&& aOther)
    : mDrawableRef(Move(aOther.mDrawableRef))
    , mProvider(Move(aOther.mProvider))
    , mHaveSurface(aOther.mHaveSurface)
  {
    aOther.mHaveSurface = false;
  }

  DrawableSurface& operator=(DrawableSurface&& aOther)
  {
    MOZ_ASSERT(this != &aOther, "Self-moves are prohibited");
    mDrawableRef = Move(aOther.mDrawableRef);
    mProvider = Move(aOther.mProvider);
    mHaveSurface = aOther.mHaveSurface;
    aOther.mHaveSurface = false;
    return *this;
  }

  /**
   * If this DrawableSurface is dynamically generated from an animation, attempt
   * to seek to frame @aFrame, where @aFrame is a 0-based index into the frames
   * of the animation. Otherwise, nothing will blow up at runtime, but we assert
   * in debug builds, since calling this in an unexpected situation probably
   * indicates a bug.
   *
   * @return a successful result if we could obtain frame @aFrame. Note that
   * |mHaveSurface| being true means that we're guaranteed to have *some* frame,
   * so the caller can dereference this DrawableSurface even if Seek() fails,
   * but while nothing will blow up, the frame won't be the one they expect.
   */
  nsresult Seek(size_t aFrame)
  {
    MOZ_ASSERT(mHaveSurface, "Trying to seek an empty DrawableSurface?");

    if (!mProvider) {
      MOZ_ASSERT_UNREACHABLE("Trying to seek a static DrawableSurface?");
      return NS_ERROR_FAILURE;
    }

    mDrawableRef = mProvider->DrawableRef(aFrame);

    return mDrawableRef ? NS_OK : NS_ERROR_FAILURE;
  }

  void Reset()
  {
    if (!mProvider) {
      MOZ_ASSERT_UNREACHABLE("Trying to reset a static DrawableSurface?");
      return;
    }

    mProvider->Reset();
  }

  void Advance(size_t aFrame)
  {
    if (!mProvider) {
      MOZ_ASSERT_UNREACHABLE("Trying to advance a static DrawableSurface?");
      return;
    }

    mProvider->Advance(aFrame);
  }

  bool IsFullyDecoded() const
  {
    if (!mProvider) {
      MOZ_ASSERT_UNREACHABLE("Trying to check decoding state of a static DrawableSurface?");
      return false;
    }

    return mProvider->IsFullyDecoded();
  }

  explicit operator bool() const { return mHaveSurface; }
  imgFrame* operator->() { return DrawableRef().get(); }

private:
  DrawableSurface(const DrawableSurface& aOther) = delete;
  DrawableSurface& operator=(const DrawableSurface& aOther) = delete;

  DrawableFrameRef& DrawableRef()
  {
    MOZ_ASSERT(mHaveSurface);

    // If we weren't created with a DrawableFrameRef directly, we should've been
    // created with an ISurfaceProvider which can give us one. Note that if
    // Seek() has been called, we'll already have a DrawableFrameRef, so we
    // won't need to get one here.
    if (!mDrawableRef) {
      MOZ_ASSERT(mProvider);
      mDrawableRef = mProvider->DrawableRef(/* aFrame = */ 0);
    }

    MOZ_ASSERT(mDrawableRef);
    return mDrawableRef;
  }

  DrawableFrameRef mDrawableRef;
  RefPtr<ISurfaceProvider> mProvider;
  bool mHaveSurface;
};


// Surface() is implemented here so that DrawableSurface's definition is
// visible. This default implementation eagerly obtains a DrawableFrameRef for
// the first frame and is intended for static ISurfaceProviders.
inline DrawableSurface
ISurfaceProvider::Surface()
{
  return DrawableSurface(DrawableRef(/* aFrame = */ 0));
}


/**
 * An ISurfaceProvider that stores a single surface.
 */
class SimpleSurfaceProvider final : public ISurfaceProvider
{
public:
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(SimpleSurfaceProvider, override)

  SimpleSurfaceProvider(const ImageKey aImageKey,
                        const SurfaceKey& aSurfaceKey,
                        NotNull<imgFrame*> aSurface)
    : ISurfaceProvider(aImageKey, aSurfaceKey,
                       AvailabilityState::StartAvailable())
    , mSurface(aSurface)
  {
    MOZ_ASSERT(aSurfaceKey.Size() == mSurface->GetSize());
  }

  bool IsFinished() const override { return mSurface->IsFinished(); }

  size_t LogicalSizeInBytes() const override
  {
    gfx::IntSize size = mSurface->GetSize();
    return size.width * size.height * mSurface->GetBytesPerPixel();
  }

protected:
  DrawableFrameRef DrawableRef(size_t aFrame) override
  {
    MOZ_ASSERT(aFrame == 0,
               "Requesting an animation frame from a SimpleSurfaceProvider?");
    return mSurface->DrawableRef();
  }

  bool IsLocked() const override { return bool(mLockRef); }

  void SetLocked(bool aLocked) override
  {
    if (aLocked == IsLocked()) {
      return;  // Nothing changed.
    }

    // If we're locked, hold a DrawableFrameRef to |mSurface|, which will keep
    // any volatile buffer it owns in memory.
    mLockRef = aLocked ? mSurface->DrawableRef()
                       : DrawableFrameRef();
  }

private:
  virtual ~SimpleSurfaceProvider() { }

  NotNull<RefPtr<imgFrame>> mSurface;
  DrawableFrameRef mLockRef;
};

} // namespace image
} // namespace mozilla

#endif // mozilla_image_ISurfaceProvider_h