The external view embedder used by the generic embedder API. This class acts a proxy between the rasterizer and the embedder when the rasterizer is rendering into multiple layers. It asks the embedder for the render targets for the various layers the rasterizer is rendering into, recycles the render targets as necessary and converts rasterizer specific metadata into an embedder friendly format so that it can present the layers on-screen. More...

#include <embedder_external_view_embedder.h>

Inheritance diagram for flutter::EmbedderExternalViewEmbedder:

Public Types
using	CreateRenderTargetCallback = std::function< std::unique_ptr< EmbedderRenderTarget >(GrDirectContext *context, const std::shared_ptr< impeller::AiksContext > &aiks_context, const FlutterBackingStoreConfig &config)>

using	PresentCallback = std::function< bool(FlutterViewId view_id, const std::vector< const FlutterLayer * > &layers)>

using	SurfaceTransformationCallback = std::function< SkMatrix(void)>

Public Member Functions
	EmbedderExternalViewEmbedder (bool avoid_backing_store_cache, const CreateRenderTargetCallback &create_render_target_callback, const PresentCallback &present_callback)
	Creates an external view embedder used by the generic embedder API.

	~EmbedderExternalViewEmbedder () override
	Collects the external view embedder.

void	CollectView (int64_t view_id) override

void	SetSurfaceTransformationCallback (SurfaceTransformationCallback surface_transformation_callback)
	Sets the surface transformation callback used by the external view embedder to ask the platform for the per frame root surface transformation.

Public Member Functions inherited from flutter::ExternalViewEmbedder
	ExternalViewEmbedder ()=default

virtual	~ExternalViewEmbedder ()=default

virtual PostPrerollResult	PostPrerollAction (const fml::RefPtr< fml::RasterThreadMerger > &raster_thread_merger)

virtual void	EndFrame (bool should_resubmit_frame, const fml::RefPtr< fml::RasterThreadMerger > &raster_thread_merger)

virtual bool	SupportsDynamicThreadMerging ()

virtual void	Teardown ()

void	SetUsedThisFrame (bool used_this_frame)

bool	GetUsedThisFrame () const

virtual void	PushVisitedPlatformView (int64_t platform_view_id)

virtual void	PushFilterToVisitedPlatformViews (const std::shared_ptr< const DlImageFilter > &filter, const SkRect &filter_rect)

Private Member Functions
void	CancelFrame () override

void	BeginFrame (GrDirectContext *context, const fml::RefPtr< fml::RasterThreadMerger > &raster_thread_merger) override

void	PrepareFlutterView (SkISize frame_size, double device_pixel_ratio) override

void	PrerollCompositeEmbeddedView (int64_t view_id, std::unique_ptr< EmbeddedViewParams > params) override

DlCanvas *	CompositeEmbeddedView (int64_t view_id) override

void	SubmitFlutterView (int64_t flutter_view_id, GrDirectContext *context, const std::shared_ptr< impeller::AiksContext > &aiks_context, std::unique_ptr< SurfaceFrame > frame) override

DlCanvas *	GetRootCanvas () override

Detailed Description

The external view embedder used by the generic embedder API. This class acts a proxy between the rasterizer and the embedder when the rasterizer is rendering into multiple layers. It asks the embedder for the render targets for the various layers the rasterizer is rendering into, recycles the render targets as necessary and converts rasterizer specific metadata into an embedder friendly format so that it can present the layers on-screen.

Definition at line 30 of file embedder_external_view_embedder.h.

Member Typedef Documentation

◆ CreateRenderTargetCallback

using flutter::EmbedderExternalViewEmbedder::CreateRenderTargetCallback = std::function<std::unique_ptr<EmbedderRenderTarget>( GrDirectContext* context, const std::shared_ptr<impeller::AiksContext>& aiks_context, const FlutterBackingStoreConfig& config)>

Definition at line 32 of file embedder_external_view_embedder.h.

◆ PresentCallback

using flutter::EmbedderExternalViewEmbedder::PresentCallback = std::function<bool(FlutterViewId view_id, const std::vector<const FlutterLayer*>& layers)>

Definition at line 37 of file embedder_external_view_embedder.h.

◆ SurfaceTransformationCallback

using flutter::EmbedderExternalViewEmbedder::SurfaceTransformationCallback = std::function<SkMatrix(void)>

Definition at line 40 of file embedder_external_view_embedder.h.

Constructor & Destructor Documentation

◆ EmbedderExternalViewEmbedder()

flutter::EmbedderExternalViewEmbedder::EmbedderExternalViewEmbedder	(	bool	avoid_backing_store_cache,
		const CreateRenderTargetCallback &	create_render_target_callback,
		const PresentCallback &	present_callback
	)

Creates an external view embedder used by the generic embedder API.

Parameters

[in]	avoid_backing_store_cache	If set, create_render_target_callback will beinvoked every frame for every engine composited layer. The result will not cached.
[in]	create_render_target_callback	The render target callback used to request the render target for a layer.
[in]	present_callback	The callback used to forward a collection of layers (backed by fulfilled render targets) to the embedder for presentation.

Definition at line 19 of file embedder_external_view_embedder.cc.

    : avoid_backing_store_cache_(avoid_backing_store_cache),
      create_render_target_callback_(create_render_target_callback),
      present_callback_(present_callback) {
  FML_DCHECK(create_render_target_callback_);
  FML_DCHECK(present_callback_);
}

◆ ~EmbedderExternalViewEmbedder()

flutter::EmbedderExternalViewEmbedder::~EmbedderExternalViewEmbedder ( )

overridedefault

Collects the external view embedder.

Member Function Documentation

◆ BeginFrame()

void flutter::EmbedderExternalViewEmbedder::BeginFrame	(	GrDirectContext *	context,
		const fml::RefPtr< fml::RasterThreadMerger > &	raster_thread_merger
	)

overrideprivatevirtual

Implements flutter::ExternalViewEmbedder.

Definition at line 60 of file embedder_external_view_embedder.cc.

62 {}

◆ CancelFrame()

void flutter::EmbedderExternalViewEmbedder::CancelFrame ( )

overrideprivatevirtual

Implements flutter::ExternalViewEmbedder.

Definition at line 55 of file embedder_external_view_embedder.cc.

                                               {
  Reset();
}

◆ CollectView()

void flutter::EmbedderExternalViewEmbedder::CollectView ( int64_t view_id )

overridevirtual

Reimplemented from flutter::ExternalViewEmbedder.

Definition at line 32 of file embedder_external_view_embedder.cc.

                                                              {
  render_target_caches_.erase(view_id);
}

◆ CompositeEmbeddedView()

DlCanvas * flutter::EmbedderExternalViewEmbedder::CompositeEmbeddedView ( int64_t view_id )

overrideprivatevirtual

Implements flutter::ExternalViewEmbedder.

Definition at line 109 of file embedder_external_view_embedder.cc.

                                                                             {
  auto vid = EmbedderExternalView::ViewIdentifier(view_id);
  auto found = pending_views_.find(vid);
  if (found == pending_views_.end()) {
    FML_DCHECK(false) << "Attempted to composite a view that was not "
                         "pre-rolled.";
    return nullptr;
  }
  return found->second->GetCanvas();
}

◆ GetRootCanvas()

DlCanvas * flutter::EmbedderExternalViewEmbedder::GetRootCanvas ( )

overrideprivatevirtual

Implements flutter::ExternalViewEmbedder.

Definition at line 96 of file embedder_external_view_embedder.cc.

                                                      {
  auto found = pending_views_.find(kRootViewIdentifier);
  if (found == pending_views_.end()) {
    FML_DLOG(WARNING)
        << "No root canvas could be found. This is extremely unlikely and "
           "indicates that the external view embedder did not receive the "
           "notification to begin the frame.";
    return nullptr;
  }
  return found->second->GetCanvas();
}

◆ PrepareFlutterView()

void flutter::EmbedderExternalViewEmbedder::PrepareFlutterView	(	SkISize	frame_size,
		double	device_pixel_ratio
	)

overrideprivatevirtual

Implements flutter::ExternalViewEmbedder.

Definition at line 65 of file embedder_external_view_embedder.cc.

                               {
  Reset();
 
  pending_frame_size_ = frame_size;
  pending_device_pixel_ratio_ = device_pixel_ratio;
  pending_surface_transformation_ = GetSurfaceTransformation();
 
  pending_views_[kRootViewIdentifier] = std::make_unique<EmbedderExternalView>(
      pending_frame_size_, pending_surface_transformation_);
  composition_order_.push_back(kRootViewIdentifier);
}

◆ PrerollCompositeEmbeddedView()

void flutter::EmbedderExternalViewEmbedder::PrerollCompositeEmbeddedView	(	int64_t	view_id,
		std::unique_ptr< EmbeddedViewParams >	params
	)

overrideprivatevirtual

Implements flutter::ExternalViewEmbedder.

Definition at line 80 of file embedder_external_view_embedder.cc.

                                              {
  auto vid = EmbedderExternalView::ViewIdentifier(view_id);
  FML_DCHECK(pending_views_.count(vid) == 0);
 
  pending_views_[vid] = std::make_unique<EmbedderExternalView>(
      pending_frame_size_,              // frame size
      pending_surface_transformation_,  // surface xformation
      vid,                              // view identifier
      std::move(params)                 // embedded view params
  );
  composition_order_.push_back(vid);
}

◆ SetSurfaceTransformationCallback()

void flutter::EmbedderExternalViewEmbedder::SetSurfaceTransformationCallback ( SurfaceTransformationCallback surface_transformation_callback )

Sets the surface transformation callback used by the external view embedder to ask the platform for the per frame root surface transformation.

Parameters

[in] surface_transformation_callback The surface transformation callback

Definition at line 36 of file embedder_external_view_embedder.cc.

                                                                   {
  surface_transformation_callback_ = std::move(surface_transformation_callback);
}

◆ SubmitFlutterView()

void flutter::EmbedderExternalViewEmbedder::SubmitFlutterView	(	int64_t	flutter_view_id,
		GrDirectContext *	context,
		const std::shared_ptr< impeller::AiksContext > &	aiks_context,
		std::unique_ptr< SurfaceFrame >	frame
	)

overrideprivatevirtual

Reimplemented from flutter::ExternalViewEmbedder.

Definition at line 421 of file embedder_external_view_embedder.cc.

                                       {
  // The unordered_map render_target_cache creates a new entry if the view ID is
  // unrecognized.
  EmbedderRenderTargetCache& render_target_cache =
      render_target_caches_[flutter_view_id];
  SkRect _rect = SkRect::MakeIWH(pending_frame_size_.width(),
                                 pending_frame_size_.height());
  pending_surface_transformation_.mapRect(&_rect);
 
  LayerBuilder builder(SkISize::Make(_rect.width(), _rect.height()));
 
  for (auto view_id : composition_order_) {
    auto& view = pending_views_[view_id];
    builder.AddExternalView(view.get());
  }
 
  builder.PrepareBackingStore([&](const SkISize& frame_size) {
    if (!avoid_backing_store_cache_) {
      std::unique_ptr<EmbedderRenderTarget> target =
          render_target_cache.GetRenderTarget(
              EmbedderExternalView::RenderTargetDescriptor(frame_size));
      if (target != nullptr) {
        return target;
      }
    }
    auto config = MakeBackingStoreConfig(flutter_view_id, frame_size);
    return create_render_target_callback_(context, aiks_context, config);
  });
 
  // This is where unused render targets will be collected. Control may flow
  // to the embedder. Here, the embedder has the opportunity to trample on the
  // OpenGL context.
  //
  // For optimum performance, we should tell the render target cache to clear
  // its unused entries before allocating new ones. This collection step
  // before allocating new render targets ameliorates peak memory usage within
  // the frame. But, this causes an issue in a known internal embedder. To
  // work around this issue while that embedder migrates, collection of render
  // targets is deferred after the presentation.
  //
  // @warning: Embedder may trample on our OpenGL context here.
  auto deferred_cleanup_render_targets =
      render_target_cache.ClearAllRenderTargetsInCache();
 
  // The OpenGL context could have been trampled by the embedder at this point
  // as it attempted to collect old render targets and create new ones. Tell
  // Skia to not rely on existing bindings.
  if (context) {
    context->resetContext(kAll_GrBackendState);
  }
 
  builder.Render();
 
  // We are going to be transferring control back over to the embedder there
  // the context may be trampled upon again. Flush all operations to the
  // underlying rendering API.
  //
  // @warning: Embedder may trample on our OpenGL context here.
  if (context) {
    context->flushAndSubmit();
  }
 
  {
    auto presentation_time_optional = frame->submit_info().presentation_time;
    uint64_t presentation_time =
        presentation_time_optional.has_value()
            ? presentation_time_optional->ToEpochDelta().ToNanoseconds()
            : 0;
 
    // Submit the scribbled layer to the embedder for presentation.
    //
    // @warning: Embedder may trample on our OpenGL context here.
    EmbedderLayers presented_layers(
        pending_frame_size_, pending_device_pixel_ratio_,
        pending_surface_transformation_, presentation_time);
 
    builder.PushLayers(presented_layers);
 
    presented_layers.InvokePresentCallback(flutter_view_id, present_callback_);
  }
 
  // See why this is necessary in the comment where this collection in
  // realized.
  //
  // @warning: Embedder may trample on our OpenGL context here.
  deferred_cleanup_render_targets.clear();
 
  auto render_targets = builder.ClearAndCollectRenderTargets();
  for (auto& render_target : render_targets) {
    if (!avoid_backing_store_cache_) {
      render_target_cache.CacheRenderTarget(std::move(render_target));
    }
  }
 
  frame->Submit();
}

The documentation for this class was generated from the following files:

shell/platform/embedder/embedder_external_view_embedder.h
shell/platform/embedder/embedder_external_view_embedder.cc

Public Types

Public Member Functions

Private Member Functions

Detailed Description

Member Typedef Documentation

◆ CreateRenderTargetCallback

◆ PresentCallback

◆ SurfaceTransformationCallback

Constructor & Destructor Documentation

◆ EmbedderExternalViewEmbedder()

◆ ~EmbedderExternalViewEmbedder()

Member Function Documentation

◆ BeginFrame()

◆ CancelFrame()

◆ CollectView()

◆ CompositeEmbeddedView()

◆ GetRootCanvas()

◆ PrepareFlutterView()

◆ PrerollCompositeEmbeddedView()

◆ SetSurfaceTransformationCallback()

◆ SubmitFlutterView()