gecko-dev/gfx/layers/client/ContentClient.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_GFX_CONTENTCLIENT_H
#define MOZILLA_GFX_CONTENTCLIENT_H

#include <stdint.h>         // for uint32_t
#include "RotatedBuffer.h"  // for RotatedBuffer, etc
#include "gfxTypes.h"
#include "gfxPlatform.h"                        // for gfxPlatform
#include "mozilla/Assertions.h"                 // for MOZ_CRASH
#include "mozilla/Attributes.h"                 // for override
#include "mozilla/RefPtr.h"                     // for RefPtr, already_AddRefed
#include "mozilla/gfx/Point.h"                  // for IntSize
#include "mozilla/layers/CompositableClient.h"  // for CompositableClient
#include "mozilla/layers/CompositableForwarder.h"
#include "mozilla/layers/CompositorTypes.h"  // for TextureInfo, etc
#include "mozilla/layers/ISurfaceAllocator.h"
#include "mozilla/layers/LayersSurfaces.h"  // for SurfaceDescriptor
#include "mozilla/layers/LayersTypes.h"     // for TextureDumpMode
#include "mozilla/layers/TextureClient.h"   // for TextureClient
#include "mozilla/layers/PaintThread.h"     // for PaintTask
#include "mozilla/Maybe.h"                  // for Maybe
#include "mozilla/mozalloc.h"               // for operator delete
#include "mozilla/UniquePtr.h"              // for UniquePtr
#include "ReadbackProcessor.h"              // For ReadbackProcessor::Update
#include "nsCOMPtr.h"                       // for already_AddRefed
#include "nsPoint.h"                        // for nsIntPoint
#include "nsRect.h"                         // for mozilla::gfx::IntRect
#include "nsRegion.h"                       // for nsIntRegion
#include "nsTArray.h"                       // for nsTArray

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

namespace layers {

class PaintedLayer;

/**
 * A compositable client for PaintedLayers. These are different to Image/Canvas
 * clients due to sending a valid region across IPC and because we do a lot more
 * optimisation work, encapsulated in RotatedBuffers.
 *
 * We use content clients for OMTC and non-OMTC, basic rendering so that
 * BasicPaintedLayer has only one interface to deal with. We support single and
 * double buffered flavours. For tiled layers, we do not use a ContentClient
 * although we do have a ContentHost, and we do use texture clients and texture
 * hosts.
 *
 * The interface presented by ContentClient is used by the BasicPaintedLayer
 * methods - PaintThebes, which is the same for MT and OMTC, and PaintBuffer
 * which is different (the OMTC one does a little more).
 */
class ContentClient : public CompositableClient {
 public:
  typedef gfxContentType ContentType;

  /**
   * Creates, configures, and returns a new content client. If necessary, a
   * message will be sent to the compositor to create a corresponding content
   * host.
   */
  static already_AddRefed<ContentClient> CreateContentClient(
      CompositableForwarder* aFwd);

  /**
   * Controls the size of the backing buffer of this.
   * - SizedToVisibleBounds: the backing buffer is exactly the same
   *   size as the bounds of PaintedLayer's visible region
   * - ContainsVisibleBounds: the backing buffer is large enough to
   *   fit visible bounds.  May be larger.
   */
  enum BufferSizePolicy { SizedToVisibleBounds, ContainsVisibleBounds };

  ContentClient(CompositableForwarder* aForwarder,
                BufferSizePolicy aBufferSizePolicy)
      : CompositableClient(aForwarder), mBufferSizePolicy(aBufferSizePolicy) {}

  virtual void PrintInfo(std::stringstream& aStream, const char* aPrefix);

  virtual void Clear();

  /**
   * This is returned by BeginPaint. The caller should draw into mTarget.
   * mRegionToDraw must be drawn. mRegionToInvalidate has been invalidated
   * by ContentClient and must be redrawn on the screen.
   * mRegionToInvalidate is set when the buffer has changed from
   * opaque to transparent or vice versa, since the details of rendering can
   * depend on the buffer type.
   */
  struct PaintState {
    PaintState()
        : mRegionToDraw(),
          mRegionToInvalidate(),
          mMode(SurfaceMode::SURFACE_NONE),
          mClip(DrawRegionClip::NONE),
          mContentType(gfxContentType::SENTINEL),
          mAsyncPaint(false),
          mAsyncTask(nullptr) {}

    nsIntRegion mRegionToDraw;
    nsIntRegion mRegionToInvalidate;
    SurfaceMode mMode;
    DrawRegionClip mClip;
    gfxContentType mContentType;
    bool mAsyncPaint;
    UniquePtr<PaintTask> mAsyncTask;
  };

  enum {
    PAINT_WILL_RESAMPLE = 0x01,
    PAINT_NO_ROTATION = 0x02,
    PAINT_CAN_DRAW_ROTATED = 0x04,
    PAINT_ASYNC = 0x08,
  };

  /**
   * Start a drawing operation. This returns a PaintState describing what
   * needs to be drawn to bring the buffer up to date in the visible region.
   * This queries aLayer to get the currently valid and visible regions.
   * The returned mTarget may be null if mRegionToDraw is empty.
   * Otherwise it must not be null.
   * mRegionToInvalidate will contain mRegionToDraw.
   * @param aFlags when PAINT_WILL_RESAMPLE is passed, this indicates that
   * buffer will be resampled when rendering (i.e the effective transform
   * combined with the scale for the resolution is not just an integer
   * translation). This will disable buffer rotation (since we don't want
   * to resample across the rotation boundary) and will ensure that we
   * make the entire buffer contents valid (since we don't want to sample
   * invalid pixels outside the visible region, if the visible region doesn't
   * fill the buffer bounds).
   * PAINT_CAN_DRAW_ROTATED can be passed if the caller supports drawing
   * rotated content that crosses the physical buffer boundary. The caller
   * will need to call BorrowDrawTargetForPainting multiple times to achieve
   * this.
   */
  virtual PaintState BeginPaint(PaintedLayer* aLayer, uint32_t aFlags);
  virtual void EndPaint(
      PaintState& aPaintState,
      nsTArray<ReadbackProcessor::Update>* aReadbackUpdates = nullptr);

  /**
   * Fetch a DrawTarget for rendering. The DrawTarget remains owned by
   * this. See notes on BorrowDrawTargetForQuadrantUpdate.
   * May return null. If the return value is non-null, it must be
   * 'un-borrowed' using ReturnDrawTarget.
   *
   * If PAINT_CAN_DRAW_ROTATED was specified for BeginPaint, then the caller
   * must call this function repeatedly (with an iterator) until it returns
   * nullptr. The caller should draw the mDrawRegion of the iterator instead
   * of mRegionToDraw in the PaintState.
   *
   * @param aPaintState Paint state data returned by a call to BeginPaint
   * @param aIter Paint state iterator. Only required if PAINT_CAN_DRAW_ROTATED
   * was specified to BeginPaint.
   */
  virtual gfx::DrawTarget* BorrowDrawTargetForPainting(
      PaintState& aPaintState, RotatedBuffer::DrawIterator* aIter = nullptr);

  void ReturnDrawTarget(gfx::DrawTarget*& aReturned);

  enum {
    BUFFER_COMPONENT_ALPHA = 0x02  // Dual buffers should be created for drawing
                                   // with component alpha.
  };

 protected:
  struct BufferDecision {
    nsIntRegion mNeededRegion;
    nsIntRegion mValidRegion;
    gfx::IntRect mBufferRect;
    SurfaceMode mBufferMode;
    gfxContentType mBufferContentType;
    bool mCanReuseBuffer;
    bool mCanKeepBufferContents;
  };

  /**
   * Decide whether we can keep our current buffer and its contents,
   * and return a struct containing the regions to paint, invalidate,
   * the new buffer rect, surface mode, and content type.
   */
  BufferDecision CalculateBufferForPaint(PaintedLayer* aLayer, uint32_t aFlags);

  static bool ValidBufferSize(BufferSizePolicy aPolicy,
                              const gfx::IntSize& aBufferSize,
                              const gfx::IntSize& aVisibleBoundsSize);

  /**
   * Any actions that should be performed at the last moment before we begin
   * rendering the next frame. I.e., after we calculate what we will draw,
   * but before we rotate the buffer and possibly create new buffers.
   * aRegionToDraw is the region which is guaranteed to be overwritten when
   * drawing the next frame.
   */
  virtual void FinalizeFrame(PaintState& aPaintState) {}

  virtual RefPtr<RotatedBuffer> GetFrontBuffer() const { return mBuffer; }

  /**
   * Create a new rotated buffer for the specified content type, buffer rect,
   * and buffer flags.
   */
  virtual RefPtr<RotatedBuffer> CreateBuffer(gfxContentType aType,
                                             const gfx::IntRect& aRect,
                                             uint32_t aFlags) = 0;

  RefPtr<RotatedBuffer> mBuffer;
  BufferSizePolicy mBufferSizePolicy;
};

// Thin wrapper around DrawTargetRotatedBuffer, for on-mtc
class ContentClientBasic final : public ContentClient {
 public:
  explicit ContentClientBasic(gfx::BackendType aBackend);

  void DrawTo(PaintedLayer* aLayer, gfx::DrawTarget* aTarget, float aOpacity,
              gfx::CompositionOp aOp, gfx::SourceSurface* aMask,
              const gfx::Matrix* aMaskTransform);

  TextureInfo GetTextureInfo() const override {
    MOZ_CRASH("GFX: Should not be called on non-remote ContentClient");
  }

 protected:
  RefPtr<RotatedBuffer> CreateBuffer(gfxContentType aType,
                                     const gfx::IntRect& aRect,
                                     uint32_t aFlags) override;

 private:
  gfx::BackendType mBackend;
};

/**
 * A ContentClient backed by a RemoteRotatedBuffer.
 *
 * When using a ContentClientRemoteBuffer, SurfaceDescriptors are created on
 * the rendering side and destroyed on the compositing side. They are only
 * passed from one side to the other when the TextureClient/Hosts are created.
 * *Ownership* of the SurfaceDescriptor moves from the rendering side to the
 * compositing side with the create message (send from CreateBuffer) which
 * tells the compositor that TextureClients have been created and that the
 * compositor should assign the corresponding TextureHosts to our corresponding
 * ContentHost.
 *
 * If the size or type of our buffer(s) change(s), then we simply destroy and
 * create them.
 */
class ContentClientRemoteBuffer : public ContentClient {
 public:
  explicit ContentClientRemoteBuffer(CompositableForwarder* aForwarder)
      : ContentClient(aForwarder, ContainsVisibleBounds), mIsNewBuffer(false) {}

  void Dump(std::stringstream& aStream, const char* aPrefix = "",
            bool aDumpHtml = false,
            TextureDumpMode aCompress = TextureDumpMode::Compress) override;

  void EndPaint(
      PaintState& aPaintState,
      nsTArray<ReadbackProcessor::Update>* aReadbackUpdates = nullptr) override;

  void Updated(const nsIntRegion& aRegionToDraw,
               const nsIntRegion& aVisibleRegion);

  TextureFlags ExtraTextureFlags() const {
    return TextureFlags::IMMEDIATE_UPLOAD;
  }

 protected:
  /**
   * Called when we have been updated and should swap references to our
   * buffers.
   */
  virtual void SwapBuffers(const nsIntRegion& aFrontUpdatedRegion) {}

  virtual nsIntRegion GetUpdatedRegion(const nsIntRegion& aRegionToDraw,
                                       const nsIntRegion& aVisibleRegion);

  RefPtr<RotatedBuffer> CreateBuffer(gfxContentType aType,
                                     const gfx::IntRect& aRect,
                                     uint32_t aFlags) override;

  RefPtr<RotatedBuffer> CreateBufferInternal(const gfx::IntRect& aRect,
                                             gfx::SurfaceFormat aFormat,
                                             TextureFlags aFlags);

  RemoteRotatedBuffer* GetRemoteBuffer() const {
    return static_cast<RemoteRotatedBuffer*>(mBuffer.get());
  }

  bool mIsNewBuffer;
};

/**
 * A double buffered ContentClientRemoteBuffer. mBuffer is the back buffer,
 * which we draw into. mFrontBuffer is the front buffer which we may read from,
 * but not write to, when the compositor does not have the 'soft' lock.
 *
 * The ContentHost keeps a reference to both corresponding texture hosts, in
 * response to our UpdateTextureRegion message, the compositor swaps its
 * references.
 */
class ContentClientDoubleBuffered : public ContentClientRemoteBuffer {
 public:
  explicit ContentClientDoubleBuffered(CompositableForwarder* aFwd)
      : ContentClientRemoteBuffer(aFwd), mFrontAndBackBufferDiffer(false) {}

  void Dump(std::stringstream& aStream, const char* aPrefix = "",
            bool aDumpHtml = false,
            TextureDumpMode aCompress = TextureDumpMode::Compress) override;

  void Clear() override;

  void SwapBuffers(const nsIntRegion& aFrontUpdatedRegion) override;

  PaintState BeginPaint(PaintedLayer* aLayer, uint32_t aFlags) override;

  void FinalizeFrame(PaintState& aPaintState) override;

  RefPtr<RotatedBuffer> GetFrontBuffer() const override { return mFrontBuffer; }

  TextureInfo GetTextureInfo() const override {
    return TextureInfo(CompositableType::CONTENT_DOUBLE, mTextureFlags);
  }

 private:
  void EnsureBackBufferIfFrontBuffer();

  RefPtr<RemoteRotatedBuffer> mFrontBuffer;
  nsIntRegion mFrontUpdatedRegion;
  bool mFrontAndBackBufferDiffer;
};

/**
 * A single buffered ContentClientRemoteBuffer. We have a single
 * TextureClient/Host which we update and then send a message to the
 * compositor that we are done updating. It is not safe for the compositor
 * to use the corresponding TextureHost's memory directly, it must upload
 * it to video memory of some kind. We are free to modify the TextureClient
 * once we receive reply from the compositor.
 */
class ContentClientSingleBuffered : public ContentClientRemoteBuffer {
 public:
  explicit ContentClientSingleBuffered(CompositableForwarder* aFwd)
      : ContentClientRemoteBuffer(aFwd) {}

  TextureInfo GetTextureInfo() const override {
    return TextureInfo(CompositableType::CONTENT_SINGLE,
                       mTextureFlags | ExtraTextureFlags());
  }
};

}  // namespace layers
}  // namespace mozilla

#endif