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/* -*- 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 */
#ifndef mozilla_layers_NativeLayerCA_h
#define mozilla_layers_NativeLayerCA_h
#include <IOSurface/IOSurface.h>
#include <deque>
#include <unordered_map>
#include <ostream>
#include "mozilla/Mutex.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/gfx/MacIOSurface.h"
#include "mozilla/layers/NativeLayer.h"
#include "CFTypeRefPtr.h"
#include "nsRegion.h"
#include "nsISupportsImpl.h"
#ifdef __OBJC__
@class CALayer;
typedef void CALayer;
namespace mozilla {
namespace gl {
class GLContextCGL;
class MozFramebuffer;
} // namespace gl
namespace wr {
class RenderMacIOSurfaceTextureHost;
} // namespace wr
namespace layers {
class NativeLayerRootSnapshotterCA;
class SurfacePoolHandleCA;
enum class VideoLowPowerType {
// These must be kept synchronized with the telemetry histogram enums.
NotVideo, // Never emitted as telemetry. No video is visible.
LowPower, // As best we can tell, we are in the "detached",
// low-power compositing mode. We don't use "Success"
// because of name collision with telemetry generation.
FailMultipleVideo, // There is more than one video visible.
FailWindowed, // The window is not fullscreen.
FailOverlaid, // Something is on top of the video (likely captions).
FailBacking, // The layer behind the video is not full-coverage black.
FailMacOSVersion, // macOS version does not meet requirements.
FailPref, // Pref is not set.
FailSurface, // Surface is not eligible.
FailEnqueue, // Enqueueing the video didn't work.
// NativeLayerRootCA is the CoreAnimation implementation of the NativeLayerRoot
// interface. A NativeLayerRootCA is created by the widget around an existing
// CALayer with a call to CreateForCALayer - this CALayer is the root of the
// "onscreen" representation of this layer tree.
// All methods can be called from any thread, there is internal locking.
// All effects from mutating methods are buffered locally and don't modify the
// underlying CoreAnimation layers until CommitToScreen() is called. This
// ensures that the modifications happen on the right thread.
// More specifically: During normal operation, screen updates are driven from a
// compositing thread. On this thread, the layers are created / destroyed, their
// contents are painted, and the result is committed to the screen. However,
// there are some scenarios that need to involve the main thread, most notably
// window resizing: During a window resize, we still need the drawing part to
// happen on the compositing thread, but the modifications to the underlying
// CALayers need to happen on the main thread, once compositing is done.
// NativeLayerRootCA + NativeLayerCA create and maintain *two* CALayer tree
// representations: An "onscreen" representation and an "offscreen"
// representation. These representations are updated via calls to
// CommitToScreen() and CommitOffscreen(), respectively. The reason for having
// two representations is the following: Our implementation of the snapshotter
// API uses CARenderer, which lets us render the composited result of our layer
// tree into a GPU buffer. But CARenderer requires "ownership" of the rendered
// CALayers in the sense that it associates the CALayers with a local
// "CAContext". A CALayer can only be associated with one CAContext at any time.
// If we wanted te render our *onscreen* CALayers with CARenderer, we would need
// to remove them from the window, reparent them to the CARenderer, render them,
// and then put them back into the window. This would lead to a visible flashing
// effect. To solve this problem, we build two CALayer representations, so that
// one representation can stay inside the window and the other can stay attached
// to the CARenderer.
class NativeLayerRootCA : public NativeLayerRoot {
static already_AddRefed<NativeLayerRootCA> CreateForCALayer(CALayer* aLayer);
virtual NativeLayerRootCA* AsNativeLayerRootCA() override { return this; }
// Can be called on any thread at any point. Returns whether comitting was
// successful. Will return false if called off the main thread while
// off-main-thread commits are suspended.
bool CommitToScreen() override;
void CommitOffscreen();
void OnNativeLayerRootSnapshotterDestroyed(
NativeLayerRootSnapshotterCA* aNativeLayerRootSnapshotter);
// Enters a mode during which CommitToScreen(), when called on a non-main
// thread, will not apply any updates to the CALayer tree.
void SuspendOffMainThreadCommits();
// Exits the mode entered by SuspendOffMainThreadCommits().
// Returns true if the last CommitToScreen() was canceled due to suspension,
// indicating that another call to CommitToScreen() is needed.
bool UnsuspendOffMainThreadCommits();
bool AreOffMainThreadCommitsSuspended();
void DumpLayerTreeToFile(const char* aPath);
enum class WhichRepresentation : uint8_t { ONSCREEN, OFFSCREEN };
// Overridden methods
already_AddRefed<NativeLayer> CreateLayer(
const gfx::IntSize& aSize, bool aIsOpaque,
SurfacePoolHandle* aSurfacePoolHandle) override;
void AppendLayer(NativeLayer* aLayer) override;
void RemoveLayer(NativeLayer* aLayer) override;
void SetLayers(const nsTArray<RefPtr<NativeLayer>>& aLayers) override;
UniquePtr<NativeLayerRootSnapshotter> CreateSnapshotter() override;
void SetBackingScale(float aBackingScale);
float BackingScale();
already_AddRefed<NativeLayer> CreateLayerForExternalTexture(
bool aIsOpaque) override;
already_AddRefed<NativeLayer> CreateLayerForColor(
gfx::DeviceColor aColor) override;
void SetWindowIsFullscreen(bool aFullscreen);
VideoLowPowerType CheckVideoLowPower();
explicit NativeLayerRootCA(CALayer* aLayer);
~NativeLayerRootCA() override;
struct Representation {
explicit Representation(CALayer* aRootCALayer);
void Commit(WhichRepresentation aRepresentation,
const nsTArray<RefPtr<NativeLayerCA>>& aSublayers,
bool aWindowIsFullscreen);
CALayer* mRootCALayer = nullptr; // strong
bool mMutatedLayerStructure = false;
template <typename F>
void ForAllRepresentations(F aFn);
Mutex mMutex MOZ_UNANNOTATED; // protects all other fields
Representation mOnscreenRepresentation;
Representation mOffscreenRepresentation;
NativeLayerRootSnapshotterCA* mWeakSnapshotter = nullptr;
nsTArray<RefPtr<NativeLayerCA>> mSublayers; // in z-order
float mBackingScale = 1.0f;
bool mMutated = false;
// While mOffMainThreadCommitsSuspended is true, no commits
// should happen on a non-main thread, because they might race with
// main-thread driven updates such as window shape changes, and cause
// glitches.
bool mOffMainThreadCommitsSuspended = false;
// Set to true if CommitToScreen() was aborted because of commit suspension.
// Set to false when CommitToScreen() completes successfully. When true,
// indicates that CommitToScreen() needs to be called at the next available
// opportunity.
bool mCommitPending = false;
// Updated by the layer's view's window to match the fullscreen state
// of that window.
bool mWindowIsFullscreen = false;
// How many times have we committed since the last time we emitted
// telemetry?
unsigned int mTelemetryCommitCount = 0;
static const unsigned int TELEMETRY_COMMIT_PERIOD =
600; // 10 seconds at 60fps
class RenderSourceNLRS;
class NativeLayerRootSnapshotterCA final : public NativeLayerRootSnapshotter {
static UniquePtr<NativeLayerRootSnapshotterCA> Create(
NativeLayerRootCA* aLayerRoot, CALayer* aRootCALayer);
virtual ~NativeLayerRootSnapshotterCA();
bool ReadbackPixels(const gfx::IntSize& aReadbackSize,
gfx::SurfaceFormat aReadbackFormat,
const Range<uint8_t>& aReadbackBuffer) override;
already_AddRefed<profiler_screenshots::RenderSource> GetWindowContents(
const gfx::IntSize& aWindowSize) override;
already_AddRefed<profiler_screenshots::DownscaleTarget> CreateDownscaleTarget(
const gfx::IntSize& aSize) override;
CreateAsyncReadbackBuffer(const gfx::IntSize& aSize) override;
NativeLayerRootSnapshotterCA(NativeLayerRootCA* aLayerRoot,
RefPtr<gl::GLContext>&& aGL,
CALayer* aRootCALayer);
void UpdateSnapshot(const gfx::IntSize& aSize);
RefPtr<NativeLayerRootCA> mLayerRoot;
RefPtr<gl::GLContext> mGL;
// Can be null. Created and updated in UpdateSnapshot.
RefPtr<RenderSourceNLRS> mSnapshot;
CARenderer* mRenderer = nullptr; // strong
// NativeLayerCA wraps a CALayer and lets you draw to it. It ensures that only
// fully-drawn frames make their way to the screen, by maintaining a swap chain
// of IOSurfaces.
// All calls to mutating methods are buffered, and don't take effect on the
// underlying CoreAnimation layers until ApplyChanges() is called.
// The two most important methods are NextSurface and NotifySurfaceReady:
// NextSurface takes an available surface from the swap chain or creates a new
// surface if necessary. This surface can then be drawn to. Once drawing is
// finished, NotifySurfaceReady marks the surface as ready. This surface is
// committed to the layer during the next call to ApplyChanges().
// The swap chain keeps track of invalid areas within the surfaces.
class NativeLayerCA : public NativeLayer {
virtual NativeLayerCA* AsNativeLayerCA() override { return this; }
// Overridden methods
gfx::IntSize GetSize() override;
void SetPosition(const gfx::IntPoint& aPosition) override;
gfx::IntPoint GetPosition() override;
void SetTransform(const gfx::Matrix4x4& aTransform) override;
gfx::Matrix4x4 GetTransform() override;
gfx::IntRect GetRect() override;
void SetSamplingFilter(gfx::SamplingFilter aSamplingFilter) override;
RefPtr<gfx::DrawTarget> NextSurfaceAsDrawTarget(
const gfx::IntRect& aDisplayRect, const gfx::IntRegion& aUpdateRegion,
gfx::BackendType aBackendType) override;
Maybe<GLuint> NextSurfaceAsFramebuffer(const gfx::IntRect& aDisplayRect,
const gfx::IntRegion& aUpdateRegion,
bool aNeedsDepth) override;
void NotifySurfaceReady() override;
void DiscardBackbuffers() override;
bool IsOpaque() override;
void SetClipRect(const Maybe<gfx::IntRect>& aClipRect) override;
Maybe<gfx::IntRect> ClipRect() override;
gfx::IntRect CurrentSurfaceDisplayRect() override;
void SetSurfaceIsFlipped(bool aIsFlipped) override;
bool SurfaceIsFlipped() override;
void DumpLayer(std::ostream& aOutputStream);
void AttachExternalImage(wr::RenderTextureHost* aExternalImage) override;
void SetRootWindowIsFullscreen(bool aFullscreen);
friend class NativeLayerRootCA;
NativeLayerCA(const gfx::IntSize& aSize, bool aIsOpaque,
SurfacePoolHandleCA* aSurfacePoolHandle);
explicit NativeLayerCA(bool aIsOpaque);
explicit NativeLayerCA(gfx::DeviceColor aColor);
~NativeLayerCA() override;
// Gets the next surface for drawing from our swap chain and stores it in
// mInProgressSurface. Returns whether this was successful.
// mInProgressSurface is guaranteed to be not in use by the window server.
// After a call to NextSurface, NextSurface must not be called again until
// after NotifySurfaceReady has been called. Can be called on any thread. When
// used from multiple threads, callers need to make sure that they still only
// call NextSurface and NotifySurfaceReady alternatingly and not in any other
// order.
bool NextSurface(const MutexAutoLock& aProofOfLock);
// To be called by NativeLayerRootCA:
typedef NativeLayerRootCA::WhichRepresentation WhichRepresentation;
CALayer* UnderlyingCALayer(WhichRepresentation aRepresentation);
enum class UpdateType {
None, // Order is important. Each enum must fully encompass the
OnlyVideo, // work implied by the previous enums.
UpdateType HasUpdate(WhichRepresentation aRepresentation);
bool WillUpdateAffectLayers(WhichRepresentation aRepresentation);
bool ApplyChanges(WhichRepresentation aRepresentation, UpdateType aUpdate);
void SetBackingScale(float aBackingScale);
// Invalidates the specified region in all surfaces that are tracked by this
// layer.
void InvalidateRegionThroughoutSwapchain(const MutexAutoLock& aProofOfLock,
const gfx::IntRegion& aRegion);
// Invalidate aUpdateRegion and make sure that mInProgressSurface retains any
// valid content from the previous surface outside of aUpdateRegion, so that
// only aUpdateRegion needs to be drawn. If content needs to be copied,
// aCopyFn is called to do the copying.
// aCopyFn: Fn(CFTypeRefPtr<IOSurfaceRef> aValidSourceIOSurface,
// const gfx::IntRegion& aCopyRegion) -> void
template <typename F>
void HandlePartialUpdate(const MutexAutoLock& aProofOfLock,
const gfx::IntRect& aDisplayRect,
const gfx::IntRegion& aUpdateRegion, F&& aCopyFn);
struct SurfaceWithInvalidRegion {
CFTypeRefPtr<IOSurfaceRef> mSurface;
gfx::IntRegion mInvalidRegion;
struct SurfaceWithInvalidRegionAndCheckCount {
SurfaceWithInvalidRegion mEntry;
uint32_t mCheckCount; // The number of calls to IOSurfaceIsInUse
Maybe<SurfaceWithInvalidRegion> GetUnusedSurfaceAndCleanUp(
const MutexAutoLock& aProofOfLock);
bool IsVideo();
bool IsVideoAndLocked(const MutexAutoLock& aProofOfLock);
bool ShouldSpecializeVideo(const MutexAutoLock& aProofOfLock);
bool HasExtent() const { return mHasExtent; }
void SetHasExtent(bool aHasExtent) { mHasExtent = aHasExtent; }
// Wraps one CALayer representation of this NativeLayer.
struct Representation {
CALayer* UnderlyingCALayer() { return mWrappingCALayer; }
bool EnqueueSurface(IOSurfaceRef aSurfaceRef);
// Applies buffered changes to the native CALayers. The contract with the
// caller is as follows: If any of these values have changed since the last
// call to ApplyChanges, mMutated[Field] needs to have been set to true
// before the call. If aUpdate is not All, then a partial update will be
// applied. In such a case, ApplyChanges may not make any changes that
// require a CATransacation, because no transaction will be created. In a
// a partial update, the return value will indicate if all the needed
// changes were able to be applied under these restrictions. A false return
// value indicates an All update is necessary.
bool ApplyChanges(UpdateType aUpdate, const gfx::IntSize& aSize,
bool aIsOpaque, const gfx::IntPoint& aPosition,
const gfx::Matrix4x4& aTransform,
const gfx::IntRect& aDisplayRect,
const Maybe<gfx::IntRect>& aClipRect, float aBackingScale,
bool aSurfaceIsFlipped,
gfx::SamplingFilter aSamplingFilter,
bool aSpecializeVideo,
CFTypeRefPtr<IOSurfaceRef> aFrontSurface,
CFTypeRefPtr<CGColorRef> aColor);
// Return whether any aspects of this layer representation have been mutated
// since the last call to ApplyChanges, i.e. whether ApplyChanges needs to
// be called.
// This is used to optimize away a CATransaction commit if no layers have
// changed.
UpdateType HasUpdate(bool aIsVideo);
// Lazily initialized by first call to ApplyChanges. mWrappingLayer is the
// layer that applies the intersection of mDisplayRect and mClipRect (if
// set), and mContentCALayer is the layer that hosts the IOSurface. We do
// not share clip layers between consecutive NativeLayerCA objects with the
// same clip rect.
CALayer* mWrappingCALayer = nullptr; // strong
CALayer* mContentCALayer = nullptr; // strong
CALayer* mOpaquenessTintLayer = nullptr; // strong
bool mMutatedPosition : 1;
bool mMutatedTransform : 1;
bool mMutatedDisplayRect : 1;
bool mMutatedClipRect : 1;
bool mMutatedBackingScale : 1;
bool mMutatedSize : 1;
bool mMutatedSurfaceIsFlipped : 1;
bool mMutatedFrontSurface : 1;
bool mMutatedSamplingFilter : 1;
bool mMutatedSpecializeVideo : 1;
Representation& GetRepresentation(WhichRepresentation aRepresentation);
template <typename F>
void ForAllRepresentations(F aFn);
// Controls access to all fields of this class.
// Each IOSurface is initially created inside NextSurface.
// The surface stays alive until the recycling mechanism in NextSurface
// determines it is no longer needed (because the swap chain has grown too
// long) or until DiscardBackbuffers() is called or the layer is destroyed.
// During the surface's lifetime, it will continuously move through the fields
// mInProgressSurface, mFrontSurface, and back to front through the mSurfaces
// queue:
// mSurfaces.front()
// ------[NextSurface()]-----> mInProgressSurface
// --[NotifySurfaceReady()]--> mFrontSurface
// --[NotifySurfaceReady()]--> mSurfaces.back() --> .... -->
// mSurfaces.front()
// We mark an IOSurface as "in use" as long as it is either in
// mInProgressSurface. When it is in mFrontSurface or in the mSurfaces queue,
// it is not marked as "in use" by us - but it can be "in use" by the window
// server. Consequently, IOSurfaceIsInUse on a surface from mSurfaces reflects
// whether the window server is still reading from the surface, and we can use
// this indicator to decide when to recycle the surface.
// Users of NativeLayerCA normally proceed in this order:
// 1. Begin a frame by calling NextSurface to get the surface.
// 2. Draw to the surface.
// 3. Mark the surface as done by calling NotifySurfaceReady.
// 4. Call NativeLayerRoot::CommitToScreen(), which calls ApplyChanges()
// during a CATransaction.
// The surface we returned from the most recent call to NextSurface, before
// the matching call to NotifySurfaceReady.
// Will only be Some() between calls to NextSurface and NotifySurfaceReady.
Maybe<SurfaceWithInvalidRegion> mInProgressSurface;
Maybe<gfx::IntRegion> mInProgressUpdateRegion;
Maybe<gfx::IntRect> mInProgressDisplayRect;
// The surface that the most recent call to NotifySurfaceReady was for.
// Will be Some() after the first call to NotifySurfaceReady, for the rest of
// the layer's life time.
Maybe<SurfaceWithInvalidRegion> mFrontSurface;
// The queue of surfaces which make up the rest of our "swap chain".
// mSurfaces.front() is the next surface we'll attempt to use.
// mSurfaces.back() is the one that was used most recently.
std::vector<SurfaceWithInvalidRegionAndCheckCount> mSurfaces;
// Non-null between calls to NextSurfaceAsDrawTarget and NotifySurfaceReady.
RefPtr<MacIOSurface> mInProgressLockedIOSurface;
RefPtr<SurfacePoolHandleCA> mSurfacePoolHandle;
RefPtr<wr::RenderMacIOSurfaceTextureHost> mTextureHost;
Representation mOnscreenRepresentation;
Representation mOffscreenRepresentation;
gfx::IntPoint mPosition;
gfx::Matrix4x4 mTransform;
gfx::IntRect mDisplayRect;
gfx::IntSize mSize;
Maybe<gfx::IntRect> mClipRect;
gfx::SamplingFilter mSamplingFilter = gfx::SamplingFilter::POINT;
float mBackingScale = 1.0f;
bool mSurfaceIsFlipped = false;
CFTypeRefPtr<CGColorRef> mColor;
const bool mIsOpaque = false;
bool mRootWindowIsFullscreen = false;
bool mSpecializeVideo = false;
bool mHasExtent = false;
} // namespace layers
} // namespace mozilla
#endif // mozilla_layers_NativeLayerCA_h