Trait App 

pub trait App: 'static {
    // Required method
    fn build(
        &mut self,
        ui: &mut Ui,
        host: &mut Host<'_>,
    ) -> Result<(), Box<dyn Error>>;

    // Provided methods
    fn action(&mut self, ui: &mut Ui, host: &mut Host<'_>, action: Action) { ... }
    fn file_drop(&mut self, ui: &mut Ui, host: &mut Host<'_>, drop: FileDrop) { ... }
    fn frame(&mut self, ui: &mut Ui, host: &mut Host<'_>) -> bool { ... }
}

An application: it builds its interface once, then reacts to what widgets report and updates live content before each frame. Every call gets the Host: the window it runs in.

Required Methods

fn build( &mut self, ui: &mut Ui, host: &mut Host<'_>, ) -> Result<(), Box<dyn Error>>

Fills the interface: called once, when the window and its Ui exist.

Start threads that bring data here, giving each a Waker (host.waker()): they send what they read (over a channel, say) and call Waker::wake; frame takes it in. The densa crate’s front page and densa-widgets’ monitor example show the whole pattern.

Errors

Any error stops run, which returns it.

Provided Methods

fn action(&mut self, ui: &mut Ui, host: &mut Host<'_>, action: Action)

Handles an action a widget reported (a click, an edit), right after the input that caused it.

fn file_drop(&mut self, ui: &mut Ui, host: &mut Host<'_>, drop: FileDrop)

Handles a file dragged over the window or dropped on it (one call per file). Nothing happens unless the app does something with it.

fn frame(&mut self, ui: &mut Ui, host: &mut Host<'_>) -> bool

Updates live content before a frame is painted: take in what your threads sent, and change widgets through ui.update. Return true to keep painting frames continuously (animation), false to paint only when something changes or a Waker asks for a frame. Data that arrives from threads needs false: their wakes bring the frames.

Dyn Compatibility

This trait is dyn compatible.

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

Implementors