Trait Platform 

pub trait Platform: Any {
    // Required methods
    fn target_platform(&self) -> TargetPlatform;
    fn request_frame(&self, view: ViewId);
    fn now(&self) -> Instant;
    fn dispatcher(&self) -> Arc<dyn Dispatcher> ;
    fn views(&self) -> Vec<ViewRef> ;
    fn view(&self, id: ViewId) -> Option<ViewRef>;

    // Provided methods
    fn request_view(
        &self,
        config: WindowConfig,
        initial_data: Option<String>,
    ) -> Result<RequestId, ViewError> { ... }
    fn locales(&self) -> Vec<Locale> { ... }
    fn set_application_locale(&self, locale: &Locale) { ... }
    fn platform_brightness(&self) -> Brightness { ... }
    fn default_route_name(&self) -> String { ... }
    fn initial_lifecycle_state(&self) -> Option<AppLifecycleState> { ... }
    fn font_source(&self) -> Option<Box<dyn FontSource>> { ... }
    fn default_font_families(&self) -> Vec<String> { ... }
    fn open_image_codec(&self, bytes: Arc<[u8]>) -> ImageCodecFuture { ... }
    fn import_pixels(&self, pixels: PixelBuffer) -> Option<Image> { ... }
    fn compositor(&self) -> Option<Arc<dyn Compositor>> { ... }
    fn vsync_waiter(&self) -> Option<Arc<dyn VsyncWaiter>> { ... }
    fn screens(&self) -> Option<&dyn Screens> { ... }
    fn clipboard(&self) -> Option<&dyn Clipboard> { ... }
    fn system_chrome(&self) -> Option<&dyn SystemChrome> { ... }
    fn haptics(&self) -> Option<&dyn Haptics> { ... }
    fn system_context_menu(&self) -> Option<&dyn SystemContextMenu> { ... }
    fn menu_bar(&self) -> Option<&dyn MenuBar> { ... }
    fn popup_menus(&self) -> Option<&dyn PopupMenus> { ... }
    fn tray_icons(&self) -> Option<&dyn TrayIcons> { ... }
    fn file_dialogs(&self) -> Option<&dyn FileDialogs> { ... }
    fn players(&self) -> Option<&dyn Players> { ... }
    fn cameras(&self) -> Option<&dyn Cameras> { ... }
    fn video_frame_readers(&self) -> Option<&dyn VideoFrameReaders> { ... }
    fn caption_settings(&self) -> Option<&dyn CaptionSettings> { ... }
    fn view_embedder(&self) -> Option<&dyn ViewEmbedder> { ... }
    fn dock_menu(&self) -> Option<&dyn DockMenu> { ... }
    fn text_services(&self) -> Option<&dyn TextServices> { ... }
    fn restoration(&self) -> Option<&dyn Restoration> { ... }
    fn app_exit(&self) -> Option<&dyn AppExit> { ... }
    fn opener(&self) -> Option<&dyn Opener> { ... }
    fn notifications(&self) -> Option<&dyn Notifications> { ... }
}

The long-lived host object held by the application.

Implementations must queue requests and return. They must not synchronously re-enter the EmbedderClient while App is active.

A host may offer more than this interface — a picture from a buffer only its system has, a handle to its renderer. An app that knows its host reaches that through [downcast_ref](dyn Platform::downcast_ref); the interface itself names nothing of any one system.

Required Methods

fn target_platform(&self) -> TargetPlatform

Which host this is, for behaviour that follows platform convention (Flutter defaultTargetPlatform).

Required rather than defaulted: an embedder must say what it is, and a default would let one silently claim the wrong conventions.

fn request_frame(&self, view: ViewId)

Asks for a frame of view: Flutter’s PlatformDispatcher.scheduleFrame, for one view.

view is in the next EmbedderClient::frame of the screen it is on once its window is in sight; the host holds the request while the window is minimized or occluded. Asked again before then, it is in that refresh once.

fn now(&self) -> Instant

The host clock used for frame and timer timestamps.

fn dispatcher(&self) -> Arc<dyn Dispatcher>

The host’s threads, for waking the application or running work off the main thread: see Dispatcher.

fn views(&self) -> Vec<ViewRef>

Every view the app has now: those the platform gave it, such as a phone’s screen or an embedder’s views, and those it asked for. An app may run with none, as one on a desktop does until it asks.

fn view(&self, id: ViewId) -> Option<ViewRef>

Looks up one of the app’s views.

Provided Methods

fn request_view( &self, config: WindowConfig, initial_data: Option<String>, ) -> Result<RequestId, ViewError>

Asks for a view in a window configured as config, carrying initial_data (View::initial_data), such as which screen to show. A desktop makes the window; a platform that gives the app its views and makes none, a phone or an embedder, answers ViewError::Unsupported. The view arrives later, through EmbedderClient::view_added, carrying the id answered here; a request that fails on the way is reported through EmbedderClient::view_request_failed.

fn locales(&self) -> Vec<Locale>

The full system-reported supported locales of the device (Flutter PlatformDispatcher.locales), in order of preference; empty until the host reports them.

fn set_application_locale(&self, locale: &Locale)

Tells the host which locale the application resolved to (Flutter PlatformDispatcher.setApplicationLocale); the default drops it.

fn platform_brightness(&self) -> Brightness

The platform’s light/dark preference (Flutter PlatformDispatcher.platformBrightness).

Defaults to Brightness::Light, matching Flutter’s view configuration default. A live host that can see the OS theme overrides this.

fn default_route_name(&self) -> String

The route the application was started with (Flutter PlatformDispatcher.defaultRouteName).

Defaults to "/", Flutter’s value for a host that was not asked to open a particular route; a host that receives a deep link answers it here.

fn initial_lifecycle_state(&self) -> Option<AppLifecycleState>

The lifecycle state immediately after the application started (Flutter PlatformDispatcher.initialLifecycleState).

This property will not be updated as the lifecycle changes: a host reports each change through EmbedderClient::app_lifecycle_state_changed.

It is used to initialize SchedulerBinding::lifecycle_state at startup. Defaults to None, Flutter’s empty string: a host that has no state to report yet.

fn font_source(&self) -> Option<Box<dyn FontSource>>

The platform’s own font lookup: faces by family name and by codepoint, the way Flutter’s engine asks the OS. None for a host without one; text then shapes only against fonts the application registers.

fn default_font_families(&self) -> Vec<String>

Flutter’s txt::GetDefaultFontFamilies(): the families text uses when its style names none, first match first.

Defaults to the engine’s answer on the OS this build targets (default_font_families). A host that learns its OS at run time answers for that OS, and one whose fonts are not the OS’s, as a web page’s are not, answers its own.

fn open_image_codec(&self, bytes: Arc<[u8]>) -> ImageCodecFuture

Open an encoded image, answering with a codec for its frames.

Flutter dart:ui instantiateImageCodec. The host decodes with whatever its platform provides and uploads each frame, so the framework never sees pixels and the set of readable formats is the platform’s rather than the framework’s.

The default answers a failure at once, so a host with no decoder leaves nobody waiting.

fn import_pixels(&self, pixels: PixelBuffer) -> Option<Image>

An image from pixels the app already holds, with no codec in between: Flutter’s decodeImageFromPixels. None when the host has no renderer to put it on yet.

fn compositor(&self) -> Option<Arc<dyn Compositor>>

The host’s compositor, where it has one: composition layers shown beside the framework’s picture. None on the web, on X11, on the inert host, and on an embedder that chose not to have one.

fn vsync_waiter(&self) -> Option<Arc<dyn VsyncWaiter>>

Flutter’s VsyncWaiter, for any screen: the refreshes the host draws the framework’s frames at, for a producer that paces by them, as a composition layer’s does. None for a host without screen ticks.

fn screens(&self) -> Option<&dyn Screens>

The screens the app’s views are on, and where the pointer is on them (Flutter PlatformDispatcher.displays), or None where the host has none to report. Every host with screens answers, a phone with its one included; a view’s metrics name the screen it is on, and a host that hears the screens change says so through EmbedderClient::screens_changed.

fn clipboard(&self) -> Option<&dyn Clipboard>

The system clipboard, or None where the host has none.

fn system_chrome(&self) -> Option<&dyn SystemChrome>

The system UI drawn around the app, or None where the host has none.

fn haptics(&self) -> Option<&dyn Haptics>

Haptic feedback on the device, or None where the host has none.

fn system_context_menu(&self) -> Option<&dyn SystemContextMenu>

The system’s own menu over a text selection, or None where the host has none.

fn menu_bar(&self) -> Option<&dyn MenuBar>

The app’s menu bar, or None where the system has none and the app draws its own, as on Windows, Linux and phones (menus).

fn popup_menus(&self) -> Option<&dyn PopupMenus>

Menus the system opens at a point in a view, or None where the system has none and the framework draws them.

fn tray_icons(&self) -> Option<&dyn TrayIcons>

The app’s icons in the system’s tray, or None where the system has no tray.

fn file_dialogs(&self) -> Option<&dyn FileDialogs>

The system’s file dialogs, or None where the system has none.

fn players(&self) -> Option<&dyn Players>

The system’s media players, or None where the host has none.

fn cameras(&self) -> Option<&dyn Cameras>

The system’s cameras, or None where the host has none. A host with cameras answers one with none attached as an empty list.

fn video_frame_readers(&self) -> Option<&dyn VideoFrameReaders>

The system’s frame readers, which a player or a camera hands its frames to, or None where the system hands out no frames.

fn caption_settings(&self) -> Option<&dyn CaptionSettings>

The user’s caption settings, or None where the system keeps none, as Linux and the web keep none.

fn view_embedder(&self) -> Option<&dyn ViewEmbedder>

What the app embeds views of its own with, on layers it makes and places, or None where the host cannot draw a view into such a layer: everywhere but macOS today.

fn dock_menu(&self) -> Option<&dyn DockMenu>

The menu of the app’s Dock icon, or None where the system has no Dock.

fn text_services(&self) -> Option<&dyn TextServices>

The system services a selection toolbar offers, or None where the host has none.

fn restoration(&self) -> Option<&dyn Restoration>

Application state kept across relaunches, or None where the host has none.

fn app_exit(&self) -> Option<&dyn AppExit>

Quitting at the application’s own request, or None where the host cannot quit itself: a phone, a browser tab.

fn opener(&self) -> Option<&dyn Opener>

The system’s way to open links and files in other apps, or None where it has none.

fn notifications(&self) -> Option<&dyn Notifications>

The system’s notifications, or None where it has none for the app.

Implementations

impl dyn Platform

pub fn downcast_ref<T: Platform>(&self) -> Option<&T>

The host as its own type, for what it offers beyond the interface.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl Platform for InertPlatform