agui_core 0.3.0

The core library of agui
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28

use downcast_rs::{impl_downcast, Downcast};

use crate::{context::WidgetContext, event::WidgetEvent};

/// A plugin for the widget system.
pub trait WidgetPlugin: Downcast + Send + Sync {
    /// Fired in the same context as a widget `build()` context.
    /// 
    /// Plugins utilizing this are essentially widgets that don't exist in the widget tree. They
    /// may have state, listen to state, etc, but do not contain children.
    fn on_update(&self, ctx: &WidgetContext);

    /// Fired after widget tree layout is resolved.
    /// 
    /// This may listen to changes, however it's fired following the layout being resolved, meaning
    /// it has up-to-date information on real widget size. This may listen and react to state, but if
    /// possible it should only modify state if absolutely necessary because any update notifications
    /// will cause the layout to be recalculated.
    fn on_layout(&self, ctx: &WidgetContext);

    /// Allows the plugin to listen to widget tree events.
    /// 
    /// This may only react to changes. If it updates state, it will not actually cause changes until
    /// the next frame or update call, possibly causing flickering if used incorrectly.
    fn on_events(&self, ctx: &WidgetContext, events: &[WidgetEvent]);
}

impl_downcast!(WidgetPlugin);