gecko-dev/gfx/layers/Compositor.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_COMPOSITOR_H
#define MOZILLA_GFX_COMPOSITOR_H

#include "Units.h"                           // for ScreenPoint
#include "mozilla/Assertions.h"              // for MOZ_ASSERT, etc
#include "mozilla/RefPtr.h"                  // for already_AddRefed, RefCounted
#include "mozilla/gfx/2D.h"                  // for DrawTarget
#include "mozilla/gfx/MatrixFwd.h"           // for Matrix, Matrix4x4
#include "mozilla/gfx/Point.h"               // for IntSize, Point
#include "mozilla/gfx/Polygon.h"             // for Polygon
#include "mozilla/gfx/Rect.h"                // for Rect, IntRect
#include "mozilla/gfx/Types.h"               // for Float
#include "mozilla/gfx/Triangle.h"            // for Triangle, TexturedTriangle
#include "mozilla/layers/CompositorTypes.h"  // for DiagnosticTypes, etc
#include "mozilla/layers/LayersTypes.h"      // for LayersBackend
#include "mozilla/layers/TextureSourceProvider.h"
#include "mozilla/widget/CompositorWidget.h"
#include "nsISupportsImpl.h"  // for MOZ_COUNT_CTOR, etc
#include "nsRegion.h"
#include <vector>
#include "mozilla/WidgetUtils.h"

/**
 * Different elements of a web pages are rendered into separate "layers" before
 * they are flattened into the final image that is brought to the screen.
 * See Layers.h for more informations about layers and why we use retained
 * structures.
 * Most of the documentation for layers is directly in the source code in the
 * form of doc comments. An overview can also be found in the the wiki:
 * https://wiki.mozilla.org/Gecko:Overview#Graphics
 *
 *
 * # Main interfaces and abstractions
 *
 *  - Layer, ShadowableLayer and LayerComposite
 *    (see Layers.h and ipc/ShadowLayers.h)
 *  - CompositableClient and CompositableHost
 *    (client/CompositableClient.h composite/CompositableHost.h)
 *  - TextureClient and TextureHost
 *    (client/TextureClient.h composite/TextureHost.h)
 *  - TextureSource
 *    (composite/TextureHost.h)
 *  - Forwarders
 *    (ipc/CompositableForwarder.h ipc/ShadowLayers.h)
 *  - Compositor
 *    (this file)
 *  - IPDL protocols
 *    (.ipdl files under the gfx/layers/ipc directory)
 *
 * The *Client and Shadowable* classes are always used on the content thread.
 * Forwarders are always used on the content thread.
 * The *Host and Shadow* classes are always used on the compositor thread.
 * Compositors, TextureSource, and Effects are always used on the compositor
 * thread.
 * Most enums and constants are declared in LayersTypes.h and CompositorTypes.h.
 *
 *
 * # Texture transfer
 *
 * Most layer classes own a Compositable plus some extra information like
 * transforms and clip rects. They are platform independent.
 * Compositable classes manipulate Texture objects and are reponsible for
 * things like tiling, buffer rotation or double buffering. Compositables
 * are also platform-independent. Examples of compositable classes are:
 *  - ImageClient
 *  - CanvasClient
 *  - ContentHost
 *  - etc.
 * Texture classes (TextureClient and TextureHost) are thin abstractions over
 * platform-dependent texture memory. They are maniplulated by compositables
 * and don't know about buffer rotations and such. The purposes of TextureClient
 * and TextureHost are to synchronize, serialize and deserialize texture data.
 * TextureHosts provide access to TextureSources that are views on the
 * Texture data providing the necessary api for Compositor backend to composite
 * them.
 *
 * Compositable and Texture clients and hosts are created using factory methods.
 * They should only be created by using their constructor in exceptional
 * circumstances. The factory methods are located:
 *    TextureClient       - CompositableClient::CreateTextureClient
 *    TextureHost         - TextureHost::CreateTextureHost, which calls a
 *                          platform-specific function, e.g.,
 * CreateTextureHostOGL CompositableClient  - in the appropriate subclass, e.g.,
 *                          CanvasClient::CreateCanvasClient
 *    CompositableHost    - CompositableHost::Create
 *
 *
 * # IPDL
 *
 * If off-main-thread compositing (OMTC) is enabled, compositing is performed
 * in a dedicated thread. In some setups compositing happens in a dedicated
 * process. Documentation may refer to either the compositor thread or the
 * compositor process.
 * See explanations in ShadowLayers.h.
 *
 *
 * # Backend implementations
 *
 * Compositor backends like OpenGL or flavours of D3D live in their own
 * directory under gfx/layers/. To add a new backend, implement at least the
 * following interfaces:
 * - Compositor (ex. CompositorOGL)
 * - TextureHost (ex. SurfaceTextureHost)
 * Depending on the type of data that needs to be serialized, you may need to
 * add specific TextureClient implementations.
 */

class nsIWidget;

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

namespace layers {

struct Effect;
struct EffectChain;
class Image;
class Layer;
class TextureSource;
class DataTextureSource;
class CompositingRenderTarget;
class CompositorBridgeParent;
class LayerManagerComposite;
class CompositorOGL;
class CompositorD3D11;
class BasicCompositor;
class TextureReadLock;
struct GPUStats;
class AsyncReadbackBuffer;
class RecordedFrame;

enum SurfaceInitMode { INIT_MODE_NONE, INIT_MODE_CLEAR };

/**
 * Common interface for compositor backends.
 *
 * Compositor provides a cross-platform interface to a set of operations for
 * compositing quads. Compositor knows nothing about the layer tree. It must be
 * told everything about each composited quad - contents, location, transform,
 * opacity, etc.
 *
 * In theory it should be possible for different widgets to use the same
 * compositor. In practice, we use one compositor per window.
 *
 * # Usage
 *
 * For an example of a user of Compositor, see LayerManagerComposite.
 *
 * Initialization: create a Compositor object, call Initialize().
 *
 * Destruction: destroy any resources associated with the compositor, call
 * Destroy(), delete the Compositor object.
 *
 * Composition:
 *  call BeginFrame,
 *  for each quad to be composited:
 *    call MakeCurrent if necessary (not necessary if no other context has been
 *      made current),
 *    take care of any texture upload required to composite the quad, this step
 *      is backend-dependent,
 *    construct an EffectChain for the quad,
 *    call DrawQuad,
 *  call EndFrame.
 *
 * By default, the compositor will render to the screen, to render to a target,
 * call SetTargetContext or SetRenderTarget, the latter with a target created
 * by CreateRenderTarget or CreateRenderTargetFromSource.
 *
 * The target and viewport methods can be called before any DrawQuad call and
 * affect any subsequent DrawQuad calls.
 */
class Compositor : public TextureSourceProvider {
 protected:
  virtual ~Compositor();

 public:
  explicit Compositor(widget::CompositorWidget* aWidget,
                      CompositorBridgeParent* aParent = nullptr);

  virtual bool Initialize(nsCString* const out_failureReason) = 0;
  void Destroy() override;
  bool IsDestroyed() const { return mIsDestroyed; }

  virtual void DetachWidget() { mWidget = nullptr; }

  /**
   * Request a texture host identifier that may be used for creating textures
   * across process or thread boundaries that are compatible with this
   * compositor.
   */
  virtual TextureFactoryIdentifier GetTextureFactoryIdentifier() = 0;

  /**
   * Properties of the compositor.
   */
  virtual bool CanUseCanvasLayerForSize(const gfx::IntSize& aSize) = 0;

  /**
   * Set the target for rendering. Results will have been written to aTarget by
   * the time that EndFrame returns.
   *
   * If this method is not used, or we pass in nullptr, we target the
   * compositor's usual swap chain and render to the screen.
   */
  void SetTargetContext(gfx::DrawTarget* aTarget, const gfx::IntRect& aRect) {
    mTarget = aTarget;
    mTargetBounds = aRect;
  }
  gfx::DrawTarget* GetTargetContext() const { return mTarget; }
  void ClearTargetContext() { mTarget = nullptr; }

  typedef uint32_t MakeCurrentFlags;
  static const MakeCurrentFlags ForceMakeCurrent = 0x1;
  /**
   * Make this compositor's rendering context the current context for the
   * underlying graphics API. This may be a global operation, depending on the
   * API. Our context will remain the current one until someone else changes it.
   *
   * Clients of the compositor should call this at the start of the compositing
   * process, it might be required by texture uploads etc.
   *
   * If aFlags == ForceMakeCurrent then we will (re-)set our context on the
   * underlying API even if it is already the current context.
   */
  virtual void MakeCurrent(MakeCurrentFlags aFlags = 0) = 0;

  /**
   * Creates a Surface that can be used as a rendering target by this
   * compositor.
   */
  virtual already_AddRefed<CompositingRenderTarget> CreateRenderTarget(
      const gfx::IntRect& aRect, SurfaceInitMode aInit) = 0;

  /**
   * Creates a Surface that can be used as a rendering target by this
   * compositor, and initializes the surface by copying from aSource.
   * If aSource is null, then the current screen buffer is used as source.
   *
   * aSourcePoint specifies the point in aSource to copy data from.
   */
  virtual already_AddRefed<CompositingRenderTarget>
  CreateRenderTargetFromSource(const gfx::IntRect& aRect,
                               const CompositingRenderTarget* aSource,
                               const gfx::IntPoint& aSourcePoint) = 0;

  /**
   * Grab a snapshot of aSource and store it in aDest, so that the pixels can
   * be read on the CPU by mapping aDest at some point in the future.
   * aSource and aDest must have the same size.
   * If this is a GPU compositor, this call must not block on the GPU.
   * Returns whether the operation was successful.
   */
  virtual bool ReadbackRenderTarget(CompositingRenderTarget* aSource,
                                    AsyncReadbackBuffer* aDest) {
    return false;
  }

  /**
   * Create an AsyncReadbackBuffer of the specified size. Can return null.
   */
  virtual already_AddRefed<AsyncReadbackBuffer> CreateAsyncReadbackBuffer(
      const gfx::IntSize& aSize) {
    return nullptr;
  }

  /**
   * Draw a part of aSource into the current render target.
   * Scaling is done with linear filtering.
   * Returns whether the operation was successful.
   */
  virtual bool BlitRenderTarget(CompositingRenderTarget* aSource,
                                const gfx::IntSize& aSourceSize,
                                const gfx::IntSize& aDestSize) {
    return false;
  }

  /**
   * Sets the given surface as the target for subsequent calls to DrawQuad.
   * Passing null as aSurface sets the screen as the target.
   */
  virtual void SetRenderTarget(CompositingRenderTarget* aSurface) = 0;

  /**
   * Returns the current target for rendering. Will return null if we are
   * rendering to the screen.
   */
  virtual already_AddRefed<CompositingRenderTarget> GetCurrentRenderTarget()
      const = 0;

  /**
   * Returns a render target which contains the entire window's drawing.
   * On platforms where no such render target is used during compositing (e.g.
   * with buffered BasicCompositor, where only the invalid area is drawn to a
   * render target), this will return null.
   */
  virtual already_AddRefed<CompositingRenderTarget> GetWindowRenderTarget()
      const {
    return nullptr;
  }

  /**
   * Mostly the compositor will pull the size from a widget and this method will
   * be ignored, but compositor implementations are free to use it if they like.
   */
  virtual void SetDestinationSurfaceSize(const gfx::IntSize& aSize) = 0;

  /**
   * Declare an offset to use when rendering layers. This will be ignored when
   * rendering to a target instead of the screen.
   */
  virtual void SetScreenRenderOffset(const ScreenPoint& aOffset) = 0;

  void DrawGeometry(const gfx::Rect& aRect, const gfx::IntRect& aClipRect,
                    const EffectChain& aEffectChain, gfx::Float aOpacity,
                    const gfx::Matrix4x4& aTransform,
                    const gfx::Rect& aVisibleRect,
                    const Maybe<gfx::Polygon>& aGeometry);

  void DrawGeometry(const gfx::Rect& aRect, const gfx::IntRect& aClipRect,
                    const EffectChain& aEffectChain, gfx::Float aOpacity,
                    const gfx::Matrix4x4& aTransform,
                    const Maybe<gfx::Polygon>& aGeometry) {
    DrawGeometry(aRect, aClipRect, aEffectChain, aOpacity, aTransform, aRect,
                 aGeometry);
  }

  /**
   * Tell the compositor to draw a quad. What to do draw and how it is
   * drawn is specified by aEffectChain. aRect is the quad to draw, in user
   * space. aTransform transforms from user space to screen space. If texture
   * coords are required, these will be in the primary effect in the effect
   * chain. aVisibleRect is used to determine which edges should be antialiased,
   * without applying the effect to the inner edges of a tiled layer.
   */
  virtual void DrawQuad(const gfx::Rect& aRect, const gfx::IntRect& aClipRect,
                        const EffectChain& aEffectChain, gfx::Float aOpacity,
                        const gfx::Matrix4x4& aTransform,
                        const gfx::Rect& aVisibleRect) = 0;

  /**
   * Overload of DrawQuad, with aVisibleRect defaulted to the value of aRect.
   * Use this when you are drawing a single quad that is not part of a tiled
   * layer.
   */
  void DrawQuad(const gfx::Rect& aRect, const gfx::IntRect& aClipRect,
                const EffectChain& aEffectChain, gfx::Float aOpacity,
                const gfx::Matrix4x4& aTransform) {
    DrawQuad(aRect, aClipRect, aEffectChain, aOpacity, aTransform, aRect);
  }

  virtual void DrawTriangle(const gfx::TexturedTriangle& aTriangle,
                            const gfx::IntRect& aClipRect,
                            const EffectChain& aEffectChain,
                            gfx::Float aOpacity,
                            const gfx::Matrix4x4& aTransform,
                            const gfx::Rect& aVisibleRect) {
    MOZ_CRASH(
        "Compositor::DrawTriangle is not implemented for the current "
        "platform!");
  }

  virtual bool SupportsLayerGeometry() const { return false; }

  /**
   * Draw an unfilled solid color rect. Typically used for debugging overlays.
   */
  void SlowDrawRect(const gfx::Rect& aRect, const gfx::Color& color,
                    const gfx::IntRect& aClipRect = gfx::IntRect(),
                    const gfx::Matrix4x4& aTransform = gfx::Matrix4x4(),
                    int aStrokeWidth = 1);

  /**
   * Draw a solid color filled rect. This is a simple DrawQuad helper.
   */
  void FillRect(const gfx::Rect& aRect, const gfx::Color& color,
                const gfx::IntRect& aClipRect = gfx::IntRect(),
                const gfx::Matrix4x4& aTransform = gfx::Matrix4x4());

  void SetClearColor(const gfx::Color& aColor) { mClearColor = aColor; }

  void SetDefaultClearColor(const gfx::Color& aColor) {
    mDefaultClearColor = aColor;
  }

  void SetClearColorToDefault() { mClearColor = mDefaultClearColor; }

  /*
   * Clear aRect on current render target.
   */
  virtual void ClearRect(const gfx::Rect& aRect) = 0;

  /**
   * Start a new frame.
   *
   * aInvalidRect is the invalid region of the screen; it can be ignored for
   * compositors where the performance for compositing the entire window is
   * sufficient.
   *
   * aClipRectIn is the clip rect for the window in window space (optional).
   * aTransform is the transform from user space to window space.
   * aRenderBounds bounding rect for rendering, in user space.
   *
   * If aClipRectIn is null, this method sets *aClipRectOut to the clip rect
   * actually used for rendering (if aClipRectIn is non-null, we will use that
   * for the clip rect).
   *
   * If aRenderBoundsOut is non-null, it will be set to the render bounds
   * actually used by the compositor in window space. If aRenderBoundsOut
   * is returned empty, composition should be aborted.
   *
   * If aOpaque is true, then all of aInvalidRegion will be drawn to with
   * opaque content.
   */
  virtual void BeginFrame(const nsIntRegion& aInvalidRegion,
                          const gfx::IntRect* aClipRectIn,
                          const gfx::IntRect& aRenderBounds,
                          const nsIntRegion& aOpaqueRegion,
                          gfx::IntRect* aClipRectOut = nullptr,
                          gfx::IntRect* aRenderBoundsOut = nullptr) = 0;

  /**
   * Notification that we've finished issuing draw commands for normal
   * layers (as opposed to the diagnostic overlay which comes after).
   */
  virtual void NormalDrawingDone() {}

  /**
   * Flush the current frame to the screen and tidy up.
   *
   * Derived class overriding this should call Compositor::EndFrame.
   */
  virtual void EndFrame();

  virtual void CancelFrame(bool aNeedFlush = true) { ReadUnlockTextures(); }

  /**
   * Whether textures created by this compositor can receive partial updates.
   */
  virtual bool SupportsPartialTextureUpdate() = 0;

  void SetDiagnosticTypes(DiagnosticTypes aDiagnostics) {
    mDiagnosticTypes = aDiagnostics;
  }

  DiagnosticTypes GetDiagnosticTypes() const { return mDiagnosticTypes; }

  void DrawDiagnostics(DiagnosticFlags aFlags, const gfx::Rect& visibleRect,
                       const gfx::IntRect& aClipRect,
                       const gfx::Matrix4x4& transform,
                       uint32_t aFlashCounter = DIAGNOSTIC_FLASH_COUNTER_MAX);

  void DrawDiagnostics(DiagnosticFlags aFlags, const nsIntRegion& visibleRegion,
                       const gfx::IntRect& aClipRect,
                       const gfx::Matrix4x4& transform,
                       uint32_t aFlashCounter = DIAGNOSTIC_FLASH_COUNTER_MAX);

#ifdef MOZ_DUMP_PAINTING
  virtual const char* Name() const = 0;
#endif  // MOZ_DUMP_PAINTING

  virtual LayersBackend GetBackendType() const = 0;

  virtual CompositorD3D11* AsCompositorD3D11() { return nullptr; }
  virtual BasicCompositor* AsBasicCompositor() { return nullptr; }

  Compositor* AsCompositor() override { return this; }

  TimeStamp GetLastCompositionEndTime() const override {
    return mLastCompositionEndTime;
  }

  void UnlockAfterComposition(TextureHost* aTexture) override;
  bool NotifyNotUsedAfterComposition(TextureHost* aTextureHost) override;

  /**
   * Notify the compositor that composition is being paused. This allows the
   * compositor to temporarily release any resources.
   * Between calling Pause and Resume, compositing may fail.
   */
  virtual void Pause() {}
  /**
   * Notify the compositor that composition is being resumed. The compositor
   * regain any resources it requires for compositing.
   * Returns true if succeeded.
   */
  virtual bool Resume() { return true; }

  /**
   * Call before rendering begins to ensure the compositor is ready to
   * composite. Returns false if rendering should be aborted.
   */
  virtual bool Ready() { return true; }

  virtual void ForcePresent() {}

  virtual bool IsPendingComposite() { return false; }

  virtual void FinishPendingComposite() {}

  widget::CompositorWidget* GetWidget() const { return mWidget; }

  // Return statistics for the most recent frame we computed statistics for.
  virtual void GetFrameStats(GPUStats* aStats);

  ScreenRotation GetScreenRotation() const { return mScreenRotation; }
  void SetScreenRotation(ScreenRotation aRotation) {
    mScreenRotation = aRotation;
  }

  // A stale Compositor has no CompositorBridgeParent; it will not process
  // frames and should not be used.
  void SetInvalid();
  bool IsValid() const override;
  CompositorBridgeParent* GetCompositorBridgeParent() const { return mParent; }

  /**
   * Request the compositor to allow recording its frames.
   *
   * This is a noop on |CompositorOGL|.
   */
  virtual void RequestAllowFrameRecording(bool aWillRecord) {}

  /**
   * Record the current frame for readback by the |CompositionRecorder|.
   *
   * If this compositor does not support this feature, a null pointer is
   * returned instead.
   */
  already_AddRefed<RecordedFrame> RecordFrame(const TimeStamp& aTimeStamp);

 protected:
  void DrawDiagnosticsInternal(DiagnosticFlags aFlags,
                               const gfx::Rect& aVisibleRect,
                               const gfx::IntRect& aClipRect,
                               const gfx::Matrix4x4& transform,
                               uint32_t aFlashCounter);

  bool ShouldDrawDiagnostics(DiagnosticFlags);

  /**
   * Given a layer rect, clip, and transform, compute the area of the backdrop
   * that needs to be copied for mix-blending. The output transform translates
   * from 0..1 space into the backdrop rect space.
   *
   * The transformed layer quad is also optionally returned - this is the same
   * as the result rect, before rounding.
   */
  gfx::IntRect ComputeBackdropCopyRect(const gfx::Rect& aRect,
                                       const gfx::IntRect& aClipRect,
                                       const gfx::Matrix4x4& aTransform,
                                       gfx::Matrix4x4* aOutTransform,
                                       gfx::Rect* aOutLayerQuad = nullptr);

  gfx::IntRect ComputeBackdropCopyRect(const gfx::Triangle& aTriangle,
                                       const gfx::IntRect& aClipRect,
                                       const gfx::Matrix4x4& aTransform,
                                       gfx::Matrix4x4* aOutTransform,
                                       gfx::Rect* aOutLayerQuad = nullptr);

  virtual void DrawTriangles(const nsTArray<gfx::TexturedTriangle>& aTriangles,
                             const gfx::Rect& aRect,
                             const gfx::IntRect& aClipRect,
                             const EffectChain& aEffectChain,
                             gfx::Float aOpacity,
                             const gfx::Matrix4x4& aTransform,
                             const gfx::Rect& aVisibleRect);

  virtual void DrawPolygon(const gfx::Polygon& aPolygon, const gfx::Rect& aRect,
                           const gfx::IntRect& aClipRect,
                           const EffectChain& aEffectChain, gfx::Float aOpacity,
                           const gfx::Matrix4x4& aTransform,
                           const gfx::Rect& aVisibleRect);

  /**
   * Last Composition end time.
   */
  TimeStamp mLastCompositionEndTime;

  DiagnosticTypes mDiagnosticTypes;
  CompositorBridgeParent* mParent;

  /**
   * We keep track of the total number of pixels filled as we composite the
   * current frame. This value is an approximation and is not accurate,
   * especially in the presence of transforms.
   */
  size_t mPixelsPerFrame;
  size_t mPixelsFilled;

  ScreenRotation mScreenRotation;

  RefPtr<gfx::DrawTarget> mTarget;
  gfx::IntRect mTargetBounds;

  widget::CompositorWidget* mWidget;

  bool mIsDestroyed;

  gfx::Color mClearColor;
  gfx::Color mDefaultClearColor;

 private:
  static LayersBackend sBackend;
};

// Returns the number of rects. (Up to 4)
typedef gfx::Rect decomposedRectArrayT[4];
size_t DecomposeIntoNoRepeatRects(const gfx::Rect& aRect,
                                  const gfx::Rect& aTexCoordRect,
                                  decomposedRectArrayT* aLayerRects,
                                  decomposedRectArrayT* aTextureRects);

static inline bool BlendOpIsMixBlendMode(gfx::CompositionOp aOp) {
  switch (aOp) {
    case gfx::CompositionOp::OP_MULTIPLY:
    case gfx::CompositionOp::OP_SCREEN:
    case gfx::CompositionOp::OP_OVERLAY:
    case gfx::CompositionOp::OP_DARKEN:
    case gfx::CompositionOp::OP_LIGHTEN:
    case gfx::CompositionOp::OP_COLOR_DODGE:
    case gfx::CompositionOp::OP_COLOR_BURN:
    case gfx::CompositionOp::OP_HARD_LIGHT:
    case gfx::CompositionOp::OP_SOFT_LIGHT:
    case gfx::CompositionOp::OP_DIFFERENCE:
    case gfx::CompositionOp::OP_EXCLUSION:
    case gfx::CompositionOp::OP_HUE:
    case gfx::CompositionOp::OP_SATURATION:
    case gfx::CompositionOp::OP_COLOR:
    case gfx::CompositionOp::OP_LUMINOSITY:
      return true;
    default:
      return false;
  }
}

class AsyncReadbackBuffer {
 public:
  NS_INLINE_DECL_REFCOUNTING(AsyncReadbackBuffer)

  gfx::IntSize GetSize() const { return mSize; }
  virtual bool MapAndCopyInto(gfx::DataSourceSurface* aSurface,
                              const gfx::IntSize& aReadSize) const = 0;

 protected:
  explicit AsyncReadbackBuffer(const gfx::IntSize& aSize) : mSize(aSize) {}
  virtual ~AsyncReadbackBuffer() = default;

  gfx::IntSize mSize;
};

struct TexturedVertex {
  float position[2];
  float texCoords[2];
};

nsTArray<TexturedVertex> TexturedTrianglesToVertexArray(
    const nsTArray<gfx::TexturedTriangle>& aTriangles);

}  // namespace layers
}  // namespace mozilla

#endif /* MOZILLA_GFX_COMPOSITOR_H */