Struct WidgetFetcher

pub struct WidgetFetcher<T: Send + 'static, W: Widget, F: Fn(Option<T>) -> W> { /* private fields */ }

Widget builder to fetch data from an asynchronous task. The TaskRunner needs to be initialized. This is similar to the FutureBuilder from Flutter.

Async + UI

Normally, a UI Application is not able to asynchronously spawn tasks and will block the UI thread instead of running tasks in the background. The WidgetFetcher is able to spawn asynchronous tasks on a global runner and construct a widget based on the result of the task. You can use it to fetch asynchronous data and either return something like a loading screen or the actual data.

Workflow of a WidgetFetcher.

1. Run the task in the background using the TaskRunner.
2. Construct the widget with None as the result (task is still loading).
3. Once the task is done, update the UI with the new result and trigger an Update.

Theming

The widget itself only draws the underlying widget, so theming is useless.

Implementations

impl<T: Send + 'static, W: Widget, F: Fn(Option<T>) -> W> WidgetFetcher<T, W, F>

pub fn new<Fut>(future: Fut, update: Update, render: F) -> Self

where Fut: Future<Output = T> + Send + 'static,

Creates a new WidgetFetcher with parameters:

• future: The future to execute.
• update: The update to trigger when the data is updated (from loading to done).
• render: The function to render the widget. The first parameter is the result of the future and the second parameter is the mutable app state.

Trait Implementations

impl<T: Send + 'static, W: Widget, F: Fn(Option<T>) -> W> Widget for WidgetFetcher<T, W, F>

fn render( &mut self, scene: &mut Scene, theme: &mut dyn Theme, layout_node: &LayoutNode, info: &AppInfo, context: AppContext, )

Render the widget to the canvas.

fn layout_style(&self) -> StyleNode

Return the layout style node for layout computation.

fn update( &mut self, layout: &LayoutNode, context: AppContext, info: &AppInfo, ) -> Update

Update the widget state with given info and layout. Returns if the app should be updated.

fn widget_id(&self) -> WidgetId

Return the widget id.