gecko-dev/gfx/layers/PaintThread.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

#ifndef MOZILLA_LAYERS_PAINTTHREAD_H
#define MOZILLA_LAYERS_PAINTTHREAD_H

#include "base/platform_thread.h"
#include "mozilla/RefPtr.h"
#include "mozilla/StaticPtr.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/layers/TextureClient.h"
#include "RotatedBuffer.h"
#include "nsThreadUtils.h"

namespace mozilla {
namespace gfx {
class DrawTarget;
class DrawTargetCapture;
};

namespace layers {

// Holds the key parts from a RotatedBuffer::PaintState
// required to draw the captured paint state
class CapturedPaintState {
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CapturedPaintState)
public:
  CapturedPaintState(nsIntRegion& aRegionToDraw,
                     gfx::DrawTarget* aTargetDual,
                     gfx::DrawTarget* aTarget,
                     gfx::DrawTarget* aTargetOnWhite,
                     const gfx::Matrix& aTargetTransform,
                     SurfaceMode aSurfaceMode,
                     gfxContentType aContentType)
  : mRegionToDraw(aRegionToDraw)
  , mTargetDual(aTargetDual)
  , mTarget(aTarget)
  , mTargetOnWhite(aTargetOnWhite)
  , mTargetTransform(aTargetTransform)
  , mSurfaceMode(aSurfaceMode)
  , mContentType(aContentType)
  {}

  nsIntRegion mRegionToDraw;
  RefPtr<TextureClient> mTextureClient;
  RefPtr<TextureClient> mTextureClientOnWhite;
  RefPtr<gfx::DrawTargetCapture> mCapture;
  RefPtr<gfx::DrawTarget> mTargetDual;
  RefPtr<gfx::DrawTarget> mTarget;
  RefPtr<gfx::DrawTarget> mTargetOnWhite;
  gfx::Matrix mTargetTransform;
  SurfaceMode mSurfaceMode;
  gfxContentType mContentType;

protected:
  virtual ~CapturedPaintState() {}
};

// Holds the key operations for a ContentClient to prepare
// its buffers for painting
class CapturedBufferState final {
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CapturedBufferState)
public:
  struct Copy {
    Copy(RefPtr<RotatedBuffer> aSource,
         RefPtr<RotatedBuffer> aDestination,
         gfx::IntRect aBounds)
      : mSource(aSource)
      , mDestination(aDestination)
      , mBounds(aBounds)
    {}

    bool CopyBuffer();

    RefPtr<RotatedBuffer> mSource;
    RefPtr<RotatedBuffer> mDestination;
    gfx::IntRect mBounds;
  };

  struct Unrotate {
    Unrotate(RotatedBuffer::Parameters aParameters,
             RefPtr<RotatedBuffer> aBuffer)
      : mParameters(aParameters)
      , mBuffer(aBuffer)
    {}

    bool UnrotateBuffer();

    RotatedBuffer::Parameters mParameters;
    RefPtr<RotatedBuffer> mBuffer;
  };

  /**
   * Prepares the rotated buffers for painting by copying a previous frame
   * into the buffer and/or unrotating the pixels and returns whether the
   * operations were successful. If this fails a new buffer should be created
   * for the frame.
   */
  bool PrepareBuffer();

  Maybe<Copy> mBufferCopy;
  Maybe<Unrotate> mBufferUnrotate;

protected:
  ~CapturedBufferState() {}
};

typedef bool (*PrepDrawTargetForPaintingCallback)(CapturedPaintState* aPaintState);

class CompositorBridgeChild;

class PaintThread final
{
  friend void DestroyPaintThread(UniquePtr<PaintThread>&& aPaintThread);

public:
  static void Start();
  static void Shutdown();
  static PaintThread* Get();

  // Helper for asserts.
  static bool IsOnPaintThread();

  // Must be called on the main thread. Signifies that a new layer transaction
  // is beginning. This must be called immediately after FlushAsyncPaints, and
  // before any new painting occurs, as there can't be any async paints queued
  // or running while this is executing.
  void BeginLayerTransaction();

  void PaintContents(CapturedPaintState* aState,
                     PrepDrawTargetForPaintingCallback aCallback);

  // Must be called on the main thread. Signifies that the current
  // batch of CapturedPaintStates* for PaintContents have been recorded
  // and the main thread is finished recording this layer.
  void EndLayer();

  // Must be called on the main thread. Signifies that the current
  // layer tree transaction has been finished and any async paints
  // for it have been queued on the paint thread. This MUST be called
  // at the end of a layer transaction as it will be used to do an optional
  // texture sync and then unblock the main thread if it is waiting to paint
  // a new frame.
  void EndLayerTransaction(SyncObjectClient* aSyncObject);

  // Sync Runnables need threads to be ref counted,
  // But this thread lives through the whole process.
  // We're only temporarily using sync runnables so
  // Override release/addref but don't do anything.
  void Release();
  void AddRef();

private:
  PaintThread();

  bool Init();
  void ShutdownOnPaintThread();
  void InitOnPaintThread();

  void AsyncPaintContents(CompositorBridgeChild* aBridge,
                          CapturedPaintState* aState,
                          PrepDrawTargetForPaintingCallback aCallback);
  void AsyncEndLayer();
  void AsyncEndLayerTransaction(CompositorBridgeChild* aBridge,
                                SyncObjectClient* aSyncObject);

  static StaticAutoPtr<PaintThread> sSingleton;
  static StaticRefPtr<nsIThread> sThread;
  static PlatformThreadId sThreadId;

  bool mInAsyncPaintGroup;

  // This shouldn't be very many elements, so a list should be fine.
  // Should only be accessed on the paint thread.
  nsTArray<RefPtr<gfx::DrawTarget>> mDrawTargetsToFlush;
};

} // namespace layers
} // namespace mozilla

#endif