Flutter Engine
The Flutter Engine
No Matches
Functions | Variables
fl_event_channel.h File Reference
#include <gio/gio.h>
#include <glib-object.h>
#include <gmodule.h>
#include "fl_binary_messenger.h"
#include "fl_method_channel.h"
#include "fl_method_response.h"

Go to the source code of this file.


G_BEGIN_DECLS G_MODULE_EXPORT G_DECLARE_FINAL_TYPE (FlEventChannel, fl_event_channel, FL, EVENT_CHANNEL, GObject) typedef FlMethodErrorResponse *(*FlEventChannelHandler)(FlEventChannel *channel
: a channel name.

fl_event_channel_new: @messenger: an #FlBinaryMessenger.

@codec: the message codec.

Creates an event channel. @codec must match the codec used on the Dart end of the channel.

Returns: a new #FlEventChannel.

FlEventChannel * fl_event_channel_new (FlBinaryMessenger *messenger, const gchar *name, FlMethodCodec *codec)
void fl_event_channel_set_stream_handlers (FlEventChannel *channel, FlEventChannelHandler listen_handler, FlEventChannelHandler cancel_handler, gpointer user_data, GDestroyNotify destroy_notify)
gboolean fl_event_channel_send (FlEventChannel *channel, FlValue *event, GCancellable *cancellable, GError **error)


G_BEGIN_DECLS G_MODULE_EXPORT FlValue gpointer user_data

Function Documentation

◆ fl_event_channel_new()

FlEventChannel * fl_event_channel_new ( FlBinaryMessenger *  messenger,
const gchar *  name,
FlMethodCodec *  codec 

Definition at line 159 of file fl_event_channel.cc.

162 {
163 g_return_val_if_fail(FL_IS_BINARY_MESSENGER(messenger), nullptr);
164 g_return_val_if_fail(name != nullptr, nullptr);
165 g_return_val_if_fail(FL_IS_METHOD_CODEC(codec), nullptr);
167 FlEventChannel* self =
168 FL_EVENT_CHANNEL(g_object_new(fl_event_channel_get_type(), nullptr));
170 self->messenger = FL_BINARY_MESSENGER(g_object_ref(messenger));
171 self->name = g_strdup(name);
172 self->codec = FL_METHOD_CODEC(g_object_ref(codec));
175 self->messenger, self->name, message_cb, g_object_ref(self),
178 return self;
G_MODULE_EXPORT void fl_binary_messenger_set_message_handler_on_channel(FlBinaryMessenger *self, const gchar *channel, FlBinaryMessengerMessageHandler handler, gpointer user_data, GDestroyNotify destroy_notify)
static void message_cb(FlBinaryMessenger *messenger, const gchar *channel, GBytes *message, FlBinaryMessengerResponseHandle *response_handle, gpointer user_data)
static void channel_closed_cb(gpointer user_data)
const char * name
Definition fuchsia.cc:50

◆ fl_event_channel_send()

gboolean fl_event_channel_send ( FlEventChannel *  channel,
FlValue event,
GCancellable *  cancellable,
GError **  error 

fl_event_channel_send: @channel: an #FlEventChannel. @event: event to send, must match what the #FlMethodCodec supports. @cancellable: (allow-none): a #GCancellable or NULL. @error: (allow-none): #GError location to store the error occurring, or NULL to ignore.

Sends an event on the channel. Events should only be sent once the channel is being listened to.

Returns: TRUE if successful.

Definition at line 196 of file fl_event_channel.cc.

199 {
200 g_return_val_if_fail(FL_IS_EVENT_CHANNEL(self), FALSE);
201 g_return_val_if_fail(event != nullptr, FALSE);
203 g_autoptr(GBytes) data =
205 if (data == nullptr) {
206 return FALSE;
207 }
209 fl_binary_messenger_send_on_channel(self->messenger, self->name, data,
210 cancellable, nullptr, nullptr);
212 return TRUE;
G_MODULE_EXPORT void fl_binary_messenger_send_on_channel(FlBinaryMessenger *self, const gchar *channel, GBytes *message, GCancellable *cancellable, GAsyncReadyCallback callback, gpointer user_data)
FlKeyEvent * event
GBytes * fl_method_codec_encode_success_envelope(FlMethodCodec *self, FlValue *result, GError **error)
const uint8_t uint32_t uint32_t GError ** error
return FALSE
DEF_SWITCHES_START aot vmservice shared library Name of the *so containing AOT compiled Dart assets for launching the service isolate vm snapshot data
Definition switches.h:41

◆ fl_event_channel_set_stream_handlers()

void fl_event_channel_set_stream_handlers ( FlEventChannel *  channel,
FlEventChannelHandler  listen_handler,
FlEventChannelHandler  cancel_handler,
gpointer  user_data,
GDestroyNotify  destroy_notify 

fl_event_channel_set_stream_handlers: @channel: an #FlEventChannel. @listen_handler: (allow-none): function to call when the Dart side of the channel starts listening to the stream. @cancel_handler: (allow-none): function to call when the Dart side of the channel cancels their subscription to the stream. @user_data: (closure): user data to pass to @listen_handler and @cancel_handler. @destroy_notify: (allow-none): a function which gets called to free @user_data, or NULL.

Sets the functions called when the Dart side requests the stream to start and finish.

The handlers are removed if the channel is closed or is replaced by another handler, set @destroy_notify if you want to detect this.

Definition at line 181 of file fl_event_channel.cc.

186 {
187 g_return_if_fail(FL_IS_EVENT_CHANNEL(self));
190 self->listen_handler = listen_handler;
191 self->cancel_handler = cancel_handler;
192 self->handler_data = user_data;
193 self->handler_data_destroy_notify = destroy_notify;
static void remove_handlers(FlEventChannel *self)


fl_event_channel  ,
FL  ,


#FlEventChannel is an object that allows sending an events stream to Dart code over platform channels.

The following example shows how to send events on a channel:

|[ static FlEventChannel *channel = NULL; static gboolean send_events = FALSE;

static void event_occurs_cb (FooEvent *event) { if (send_events) { g_autoptr(FlValue) message = foo_event_to_value (event); g_autoptr(GError) error = NULL; if (!fl_event_channel_send (channel, message, NULL, &error)) { g_warning ("Failed to send event: %s", error->message); } } }

static FlMethodErrorResponse* listen_cb (FlEventChannel* channel, FlValue *args, gpointer user_data) { send_events = TRUE; return NULL; }

static FlMethodErrorResponse* cancel_cb (GObject *object, FlValue *args, gpointer user_data) { send_events = FALSE; return NULL; }

static void setup_channel () { g_autoptr(FlStandardMethodCodec) codec = fl_standard_method_codec_new (); channel = fl_event_channel_new (messenger, "flutter/foo", FL_METHOD_CODEC (codec)); fl_event_channel_set_stream_handlers (channel, listen_cb, cancel_cb, NULL, NULL); } ]|

#FlEventChannel matches the EventChannel class in the Flutter services library. FlEventChannelHandler: @channel: an #FlEventChannel. @args: arguments passed from the Dart end of the channel. @user_data: (closure): data provided when registering this handler.

Function called when the stream is listened to or cancelled.

Returns: (transfer full): an #FlMethodErrorResponse or NULL if no error.

Variable Documentation

◆ args


Definition at line 89 of file fl_event_channel.h.

◆ user_data

G_BEGIN_DECLS G_MODULE_EXPORT FlValue gpointer user_data

Definition at line 90 of file fl_event_channel.h.