The Button Widget

A clickable button that wraps a child widget (typically text). Buttons trigger a callback when pressed and can be styled with custom width, height, and padding.

Interface

val button: fn(
  ?#on_press: fn(null) -> Any,
  ?#width: &Length,
  ?#height: &Length,
  ?#padding: &Padding,
  ?#disabled: &bool,
  &Widget
) -> Widget

Parameters

• #on_press – Callback invoked when the button is clicked. Receives null as its argument. Use the sample operator ~ inside the callback to capture current state at click time: |c| counter <- c ~ counter + 1. If omitted, the button renders but does nothing when clicked.
• #width – Width of the button. Accepts Length values: `Fill, `Shrink, or `Fixed(f64). Defaults to `Shrink.
• #height – Height of the button. Same Length values as width. Defaults to `Shrink.
• #padding – Interior padding around the child widget. Accepts Padding values: `All(f64), `Axis({x: f64, y: f64}), or `Each({top: f64, right: f64, bottom: f64, left: f64}).
• #disabled – When true, the button is grayed out and #on_press is not triggered. Defaults to false.
• positional &Widget – The child widget displayed inside the button. Usually a text widget.

Examples

Basic Buttons

use gui;
use gui::text;
use gui::column;
use gui::button;
mod icon;

let b0 = button(
    #on_press: |c| println(c ~ "normal button clicked"),
    #padding: &`All(10.0),
    &text(&"Click me!")
);

let b1 = button(
    #on_press: |c| println(c ~ "wide button clicked"),
    #padding: &`All(8.0),
    #width: &`Fixed(200.0),
    &text(#halign:&`Center, &"Wide button")
);

let col = column(
    #spacing: &20.0,
    #padding: &`All(30.0),
    #halign: &`Center,
    #width: &`Fill,
    &[
        text(#size: &24.0, &"Button Demo"),
        b0,
        b1
    ]
);

[&window(#icon: &icon::icon, #title: &"Button Widget", &col)]

See Also

• text – the most common child widget for buttons
• mouse_area – for click detection on arbitrary widgets