[−][src]Trait druid::widget::Controller

pub trait Controller<T, W: Widget<T>> {
    fn event(
        &mut self, 
        child: &mut W, 
        ctx: &mut EventCtx, 
        event: &Event, 
        data: &mut T, 
        env: &Env
    ) { ... }

    fn lifecycle(
        &mut self, 
        child: &mut W, 
        ctx: &mut LifeCycleCtx, 
        event: &LifeCycle, 
        data: &T, 
        env: &Env
    ) { ... }

    fn update(
        &mut self, 
        child: &mut W, 
        ctx: &mut UpdateCtx, 
        old_data: &T, 
        data: &T, 
        env: &Env
    ) { ... }
}

A trait for types that modify behaviour of a child widget.

A Controller is a type that manages a child widget, overriding or customizing its event handling or update behaviour.

A controller can only handle events and update; it cannot effect layout or paint.

Controller is a convenience; anything it can do could also be done by creating a custom Widget that owned a child. This is somewhat cumbersome, however, especially when you only want to intercept or modify one or two events.

The methods on Controller are identical to the methods on Widget, except that they are also passed the controller's child. The controller is responsible for explicitly forwarding calls on to the child as needed.

A Controller is used with a ControllerHost, which manages the relationship between it and its child; although in general you would use the WidgetExt::controller method instead of instantiating a host directly.

Examples

A TextBox that takes focus on launch:

struct TakeFocus;

impl<T, W: Widget<T>> Controller<T, W> for TakeFocus {
    fn event(&mut self, child: &mut W, ctx: &mut EventCtx, event: &Event, data: &mut T, env: &Env) {
        if let Event::WindowConnected = event {
            ctx.request_focus();
        }
        child.event(ctx, event, data, env)
    }
}

Provided methods

fn event(
    &mut self,
    child: &mut W,
    ctx: &mut EventCtx,
    event: &Event,
    data: &mut T,
    env: &Env
)

fn lifecycle(
    &mut self,
    child: &mut W,
    ctx: &mut LifeCycleCtx,
    event: &LifeCycle,
    data: &T,
    env: &Env
)

fn update(
    &mut self,
    child: &mut W,
    ctx: &mut UpdateCtx,
    old_data: &T,
    data: &T,
    env: &Env
)

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Implementors

impl<T: Data, W: Widget<T>> Controller<T, W> for Click<T>[src]

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