WebMessagePort class

The representation of the HTML5 message ports.

A Message port represents one endpoint of a Message Channel. In Android webview, there is no separate Message Channel object. When a message channel is created, both ports are tangled to each other and started. See InAppWebViewController.createWebMessageChannel for creating a message channel.

When a message port is first created or received via transfer, it does not have a WebMessageCallback to receive web messages. On Android, the messages are queued until a WebMessageCallback is set.

A message port should be closed when it is not used by the embedder application anymore. A closed port cannot be transferred or cannot be reopened to send messages. Close can be called multiple times.

When a port is transferred to JavaScript, it cannot be used to send or receive messages at the Dart side anymore. Different from HTML5 Spec, a port cannot be transferred if one of these has ever happened: i. a message callback was set, ii. a message was posted on it. A transferred port cannot be closed by the application, since the ownership is also transferred.

It is possible to transfer both ports of a channel to JavaScript, for example for communication between subframes.

Implemented types

• IWebMessagePort

Constructors

WebMessagePort({required int index})

The representation of the HTML5 message ports.

WebMessagePort.fromPlatform({required PlatformWebMessagePort platform})

Constructs a WebMessagePort from a specific platform implementation.

WebMessagePort.fromPlatformCreationParams({required PlatformWebMessagePortCreationParams params})

Constructs a WebMessagePort.

Properties

hashCode → int

The hash code for this object.

no setter, inherited

platform → PlatformWebMessagePort

Implementation of PlatformWebMessagePort for the current platform.

final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

close() → Future<void>

Close the message port and free any resources associated with it.

override

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

postMessage(WebMessage message) → Future<void>

Post a WebMessage to the entangled port.

override

setWebMessageCallback(WebMessageCallback? onMessage) → Future<void>

Sets a callback to receive message events on the main thread.

override

toJson() → Map<String, dynamic>

override

toMap() → Map<String, dynamic>

override

toString() → String

A string representation of this object.

override

Operators

operator ==(Object other) → bool

The equality operator.

inherited