embedder

README

embedder

This package wraps the Flutter embedder API in Go and adds some helper functions to work with it. This package does NOT contain any platform specific code (glfw, etc.) and may eventualy be used for platforms other than the ones targeted by go-flutter right now. Note that this package does not promise a stable API: types, functions, methods may all change in a breaking way.

Build

To build this package set the CGO_LDFLAGS and run go build. For example:

export CGO_LDFLAGS="-L/home/${HOME}/.cache/hover/engine/linux/"
go build

This works if hover has cached the flutter engine for the local user.

Documentation

Overview

Package embedder wraps the Flutter Embedder C API to Go.

The package contains some GLFW specific implementation helpers. These may be removed in the future.

If you wish to publish a Flutter application to desktop, you shouldn't use this package directly. Instead, use the go-flutter package. There is NO compatibility promise on this package (embedder). Breaking changes can and will occur.

Index

• func CountFlutterEngines() int
• func FlutterEngineFlushPendingTasksNow()
• type FlutterEngine
  • func FlutterEngineByIndex(index int) (engine *FlutterEngine)
  • func NewFlutterEngine() *FlutterEngine
  • func (flu *FlutterEngine) Index() int
  • func (flu *FlutterEngine) Run(userData unsafe.Pointer, vmArgs []string) Result
  • func (flu *FlutterEngine) SendPlatformMessage(msg *PlatformMessage) Result
  • func (flu *FlutterEngine) SendPlatformMessageResponse(responseTo PlatformMessageResponseHandle, encodedMessage []byte) Result
  • func (flu *FlutterEngine) SendPointerEvent(event PointerEvent) Result
  • func (flu *FlutterEngine) SendWindowMetricsEvent(event WindowMetricsEvent) Result
  • func (flu *FlutterEngine) Shutdown() Result
• type PlatformMessage
  • func (p PlatformMessage) ExpectsResponse() bool
• type PlatformMessageResponseHandle
• type PointerEvent
• type PointerPhase
• type PointerSignalKind
• type Result
• type WindowMetricsEvent

Functions

func CountFlutterEngines

func CountFlutterEngines() int

CountFlutterEngines return the number of engines registered in this embedder.

func FlutterEngineFlushPendingTasksNow

func FlutterEngineFlushPendingTasksNow()

FlutterEngineFlushPendingTasksNow flush tasks on a message loop not controlled by the Flutter engine.

deprecated soon.

Types

type FlutterEngine

type FlutterEngine struct {
	// Flutter Engine.
	Engine C.FlutterEngine

	// GL callback functions
	GLMakeCurrent         func() bool
	GLClearCurrent        func() bool
	GLPresent             func() bool
	GLFboCallback         func() int32
	GLMakeResourceCurrent func() bool
	GLProcResolver        func(procName string) unsafe.Pointer

	// platform message callback function
	PlatfromMessage func(message *PlatformMessage)

	// Engine arguments
	AssetsPath  string
	IcuDataPath string
	// contains filtered or unexported fields
}

FlutterEngine corresponds to the C.FlutterEngine with his associated callback's method.

func FlutterEngineByIndex

func FlutterEngineByIndex(index int) (engine *FlutterEngine)

FlutterEngineByIndex returns an existing FlutterEngine by its index in this embedder. Deprecated 2019-04-05, this is not used by go-flutter anymore and may be removed in the future.

func NewFlutterEngine

func NewFlutterEngine() *FlutterEngine

NewFlutterEngine creates an empty FlutterEngine and assigns it an index for global lookup.

func (*FlutterEngine) Index

func (flu *FlutterEngine) Index() int

Index returns the index of the engine in the global flutterEngines slice Deprecated 2019-04-05, this is not used by go-flutter anymore and may be removed in the future.

func (*FlutterEngine) Run

func (flu *FlutterEngine) Run(userData unsafe.Pointer, vmArgs []string) Result

Run launches the Flutter Engine in a background thread.

func (*FlutterEngine) SendPlatformMessage

func (flu *FlutterEngine) SendPlatformMessage(msg *PlatformMessage) Result

SendPlatformMessage is used to send a PlatformMessage to the Flutter engine.

func (*FlutterEngine) SendPlatformMessageResponse

func (flu *FlutterEngine) SendPlatformMessageResponse(
	responseTo PlatformMessageResponseHandle,
	encodedMessage []byte,
) Result

SendPlatformMessageResponse is used to send a message to the Flutter side using the correct ResponseHandle.

func (*FlutterEngine) SendPointerEvent

func (flu *FlutterEngine) SendPointerEvent(event PointerEvent) Result

SendPointerEvent is used to send an PointerEvent to the Flutter engine.

func (*FlutterEngine) SendWindowMetricsEvent

func (flu *FlutterEngine) SendWindowMetricsEvent(event WindowMetricsEvent) Result

SendWindowMetricsEvent is used to send a WindowMetricsEvent to the Flutter Engine.

func (*FlutterEngine) Shutdown

func (flu *FlutterEngine) Shutdown() Result

Shutdown stops the Flutter engine.

type PlatformMessage

type PlatformMessage struct {
	Channel string
	Message []byte

	// ResponseHandle is only set when receiving a platform message.
	// https://github.com/flutter/flutter/issues/18852
	ResponseHandle PlatformMessageResponseHandle
}

PlatformMessage represents a binary message sent from or to the flutter application.

func (PlatformMessage) ExpectsResponse

func (p PlatformMessage) ExpectsResponse() bool

ExpectsResponse indicates whether the platform message should receive a response.

type PlatformMessageResponseHandle

type PlatformMessageResponseHandle uintptr

PlatformMessageResponseHandle is a pointer that is used to wire a platform message response to the original platform message.

type PointerEvent

type PointerEvent struct {
	Phase        PointerPhase
	Timestamp    int64
	X            float64
	Y            float64
	SignalKind   PointerSignalKind
	ScrollDeltaX float64
	ScrollDeltaY float64
}

PointerEvent represents the position and phase of the mouse at a given time.

type PointerPhase

type PointerPhase int32

PointerPhase corresponds to the C.enum describing phase of the mouse pointer.

const (
	PointerPhaseCancel PointerPhase = C.kCancel
	PointerPhaseUp     PointerPhase = C.kUp
	PointerPhaseDown   PointerPhase = C.kDown
	PointerPhaseMove   PointerPhase = C.kMove
	PointerPhaseAdd    PointerPhase = C.kAdd
	PointerPhaseRemove PointerPhase = C.kRemove
	PointerPhaseHover  PointerPhase = C.kHover
)

Values representing the mouse phase.

type PointerSignalKind

type PointerSignalKind int32

PointerSignalKind corresponds to the C.enum describing signal kind of the mouse pointer.

const (
	PointerSignalKindNone   PointerSignalKind = C.kFlutterPointerSignalKindNone
	PointerSignalKindScroll PointerSignalKind = C.kFlutterPointerSignalKindScroll
)

Values representing the pointer signal kind.

type Result

type Result int32

Result corresponds to the C.enum retuned by the shared flutter library whenever we call it.

const (
	ResultSuccess               Result = C.kSuccess
	ResultInvalidLibraryVersion Result = C.kInvalidLibraryVersion
	ResultInvalidArguments      Result = C.kInvalidArguments
)

Values representing the status of an Result.

type WindowMetricsEvent

type WindowMetricsEvent struct {
	Width      int
	Height     int
	PixelRatio float64
}

WindowMetricsEvent represents a window's resolution.