tor-browser

ISurfaceProvider.h (11730B)

---

/* -*- 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/gfx/2D.h"
#include "mozilla/image/WebRenderImageProvider.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 WebRenderImageProvider {
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 drawable reference to a surface.
 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;

 typedef imgFrame::AddSizeOfCbData AddSizeOfCbData;
 typedef imgFrame::AddSizeOfCb AddSizeOfCb;

 /// @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,
                                     const AddSizeOfCb& aCallback) {
   DrawableFrameRef ref = DrawableRef(/* aFrame = */ 0);
   if (!ref) {
     return;
   }

   ref->AddSizeOfExcludingThis(aMallocSizeOf, aCallback);
 }

 virtual void Reset() {}
 virtual void Advance(size_t aFrame) {}
 virtual bool MayAdvance() const { return false; }
 virtual void MarkMayAdvance() {}

 /// @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)
     : WebRenderImageProvider(aImageKey),
       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 an imgFrame at the 0-based index of the desired frame, as
 /// specified by @aFrame. Only applies for animated images.
 virtual already_AddRefed<imgFrame> GetFrame(size_t aFrame) {
   MOZ_ASSERT_UNREACHABLE("Surface provider does not support direct access!");
   return nullptr;
 }

 /// @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(NotNull<ISurfaceProvider*> aProvider)
     : mProvider(aProvider), mHaveSurface(true) {}

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

 DrawableSurface& operator=(DrawableSurface&& aOther) {
   MOZ_ASSERT(this != &aOther, "Self-moves are prohibited");
   mDrawableRef = std::move(aOther.mDrawableRef);
   mProvider = std::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;
 }

 already_AddRefed<imgFrame> GetFrame(size_t aFrame) {
   MOZ_ASSERT(mHaveSurface, "Trying to get on an empty DrawableSurface?");

   if (!mProvider) {
     MOZ_ASSERT_UNREACHABLE("Trying to get on a static DrawableSurface?");
     return nullptr;
   }

   return mProvider->GetFrame(aFrame);
 }

 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 MayAdvance() const {
   if (!mProvider) {
     MOZ_ASSERT_UNREACHABLE("Trying to advance a static DrawableSurface?");
     return false;
   }

   return mProvider->MayAdvance();
 }

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

   mProvider->MarkMayAdvance();
 }

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

   return mProvider->IsFullyDecoded();
 }

 void TakeProvider(WebRenderImageProvider** aOutProvider) {
   mProvider.forget(aOutProvider);
 }

 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.
inline DrawableSurface ISurfaceProvider::Surface() {
 return DrawableSurface(WrapNotNull(this));
}

/**
* 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();
 }

 nsresult UpdateKey(layers::RenderRootStateManager* aManager,
                    wr::IpcResourceUpdateQueue& aResources,
                    wr::ImageKey& aKey) override;

 void InvalidateSurface() override;

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;
 bool mDirty = false;
};

}  // namespace image
}  // namespace mozilla

#endif  // mozilla_image_ISurfaceProvider_h