image/ISurfaceProvider.h
author cku <cku@mozilla.com>
Thu, 18 May 2017 22:03:41 +0200
changeset 359088 bbf16eb4f821b2d535826141f9f33f3eb49a54c6
parent 344583 2c135b467344e72465ccf64f1cd24a18ad28f15d
child 404961 6b4514506318e472a8fb6b2b01ebd115dd0b5ded
permissions -rw-r--r--
Bug 1351440 - Part 2. Encapsulate DrawResult and imgIContainer::FLAG_* into imgDrawingParams, and pass it to PaintSVG. r=jwatt The DrawResult return was not in fact anything to do with the success or failure of that method, but was actually passing out a very specific piece of information about the success or failure of any imagelib drawing that may not have occurred under the various PaintSVG calls. The signature of PaintSVG is changed from DrawResult PaintSVG(...., uint32 flags); to void PaintSVG(...., imgDrawingParams& aPackage); imgDrawingParams wraps DrawResult and imgIContainer::FLAG_* as a pack, pass through PaintSVG to imagelib draw calls under beneath. MozReview-Commit-ID: IOq2evUAOQF

/* -*- 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 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& aSharedHandlesOut)
  {
    DrawableFrameRef ref = DrawableRef(/* aFrame = */ 0);
    if (!ref) {
      return;
    }

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

  /// @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;
  }

  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