flutter::SingleFrameCodec Class Reference

#include <single_frame_codec.h>

Inheritance diagram for flutter::SingleFrameCodec:

Public Member Functions
	SingleFrameCodec (const fml::RefPtr< ImageDescriptor > &descriptor, uint32_t target_width, uint32_t target_height)
	~SingleFrameCodec () override
int	frameCount () const override
int	repetitionCount () const override
Dart_Handle	getNextFrame (Dart_Handle args) override
Public Member Functions inherited from flutter::Codec
virtual int	frameCount () const =0
virtual int	repetitionCount () const =0
virtual Dart_Handle	getNextFrame (Dart_Handle callback_handle)=0
void	dispose ()
Public Member Functions inherited from flutter::RefCountedDartWrappable< Codec >
virtual void	RetainDartWrappableReference () const override
virtual void	ReleaseDartWrappableReference () const override
Public Member Functions inherited from fml::RefCountedThreadSafe< Codec >
void	Release () const
Public Member Functions inherited from fml::internal::RefCountedThreadSafeBase
void	AddRef () const
bool	HasOneRef () const
void	AssertHasOneRef () const
Public Member Functions inherited from tonic::DartWrappable
	DartWrappable ()
virtual const DartWrapperInfo &	GetDartWrapperInfo () const =0
virtual void	RetainDartWrappableReference () const =0
virtual void	ReleaseDartWrappableReference () const =0
Dart_Handle	CreateDartWrapper (DartState *dart_state)
void	AssociateWithDartWrapper (Dart_Handle wrappable)
void	ClearDartWrapper ()
Dart_WeakPersistentHandle	dart_wrapper () const

Additional Inherited Members
Public Types inherited from tonic::DartWrappable
enum	DartNativeFields { kPeerIndex , kNumberOfNativeFields }
Protected Member Functions inherited from fml::RefCountedThreadSafe< Codec >
	RefCountedThreadSafe ()
	~RefCountedThreadSafe ()
Protected Member Functions inherited from fml::internal::RefCountedThreadSafeBase
	RefCountedThreadSafeBase ()
	~RefCountedThreadSafeBase ()
bool	Release () const
void	Adopt ()
Protected Member Functions inherited from tonic::DartWrappable
virtual	~DartWrappable ()
Static Protected Member Functions inherited from tonic::DartWrappable
static Dart_PersistentHandle	GetTypeForWrapper (tonic::DartState *dart_state, const tonic::DartWrapperInfo &wrapper_info)

Detailed Description

Definition at line 16 of file single_frame_codec.h.

Constructor & Destructor Documentation

SingleFrameCodec()

flutter::SingleFrameCodec::SingleFrameCodec	(	const fml::RefPtr< ImageDescriptor > &	descriptor,
		uint32_t	target_width,
		uint32_t	target_height
	)

Definition at line 12 of file single_frame_codec.cc.

    : descriptor_(descriptor),
      target_width_(target_width),
      target_height_(target_height) {}

~SingleFrameCodec()

flutter::SingleFrameCodec::~SingleFrameCodec ( )

overridedefault

Member Function Documentation

frameCount()

int flutter::SingleFrameCodec::frameCount ( ) const

overridevirtual

Implements flutter::Codec.

Definition at line 22 of file single_frame_codec.cc.

                                       {
  return 1;
}

getNextFrame()

Dart_Handle flutter::SingleFrameCodec::getNextFrame ( Dart_Handle  args )

overridevirtual

Implements flutter::Codec.

Definition at line 30 of file single_frame_codec.cc.

                                                                      {
  if (!Dart_IsClosure(callback_handle)) {
    return tonic::ToDart("Callback must be a function");
  }
 
  if (status_ == Status::kComplete) {
    if (!cached_image_->image()) {
      return tonic::ToDart("Decoded image has been disposed");
    }
    tonic::DartInvoke(callback_handle, {tonic::ToDart(cached_image_),
                                        tonic::ToDart(0), tonic::ToDart("")});
    return Dart_Null();
  }
 
  // This has to be valid because this method is called from Dart.
  auto dart_state = UIDartState::Current();
 
  pending_callbacks_.emplace_back(dart_state, callback_handle);
 
  if (status_ == Status::kInProgress) {
    // Another call to getNextFrame is in progress and will invoke the
    // pending callbacks when decoding completes.
    return Dart_Null();
  }
 
  auto decoder = dart_state->GetImageDecoder();
 
  if (!decoder) {
    return tonic::ToDart(
        "Failed to access the internal image decoder "
        "registry on this isolate. Please file a bug on "
        "https://github.com/flutter/flutter/issues.");
  }
 
  // The SingleFrameCodec must be deleted on the UI thread.  Allocate a RefPtr
  // on the heap to ensure that the SingleFrameCodec remains alive until the
  // decoder callback is invoked on the UI thread.  The callback can then
  // drop the reference.
  fml::RefPtr<SingleFrameCodec>* raw_codec_ref =
      new fml::RefPtr<SingleFrameCodec>(this);
 
  decoder->Decode(
      descriptor_, target_width_, target_height_,
      [raw_codec_ref](auto image, auto decode_error) {
        std::unique_ptr<fml::RefPtr<SingleFrameCodec>> codec_ref(raw_codec_ref);
        fml::RefPtr<SingleFrameCodec> codec(std::move(*codec_ref));
 
        auto state = codec->pending_callbacks_.front().dart_state().lock();
 
        if (!state) {
          // This is probably because the isolate has been terminated before the
          // image could be decoded.
 
          return;
        }
 
        tonic::DartState::Scope scope(state.get());
 
        if (image) {
          auto canvas_image = fml::MakeRefCounted<CanvasImage>();
          canvas_image->set_image(std::move(image));
 
          codec->cached_image_ = std::move(canvas_image);
        }
 
        // The cached frame is now available and should be returned to any
        // future callers.
        codec->status_ = Status::kComplete;
 
        // Invoke any callbacks that were provided before the frame was decoded.
        for (const tonic::DartPersistentValue& callback :
             codec->pending_callbacks_) {
          tonic::DartInvoke(callback.value(),
                            {tonic::ToDart(codec->cached_image_),
                             tonic::ToDart(0), tonic::ToDart(decode_error)});
        }
        codec->pending_callbacks_.clear();
      });
 
  // The encoded data is no longer needed now that it has been handed off
  // to the decoder.
  descriptor_ = nullptr;
 
  status_ = Status::kInProgress;
 
  return Dart_Null();
}

repetitionCount()

int flutter::SingleFrameCodec::repetitionCount ( ) const

overridevirtual

Implements flutter::Codec.

Definition at line 26 of file single_frame_codec.cc.

                                            {
  return 0;
}

---

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

• lib/ui/painting/single_frame_codec.h
• lib/ui/painting/single_frame_codec.cc