ltk/examples/dialog.rs

//! Example for the `dialog` widget.
//!
//! Demonstrates the three shapes the widget covers:
//!
//! * **Modal confirm** — title + subtitle + "Cancel" / "Delete"
//!   actions. Backed by `cancel( Msg::Cancel )` so pressing `Esc`
//!   matches tapping the Cancel button. Pointer events outside the
//!   card are silently absorbed.
//! * **Non-modal pick** — `modal( false ) + dismiss_on_scrim( … )`. A
//!   tap on the scrim outside the card emits the dismiss message; ESC
//!   still fires `cancel`.
//! * **Custom body** — a body element (here, a slider) injected
//!   between the subtitle and the action row.

use ltk::{
	App, ButtonVariant, Element, Keysym,
	button, column, dialog, slider, spacer, stack, text,
};

#[ derive( Clone, Copy, PartialEq, Eq ) ]
enum Open
{
	None,
	Modal,
	NonModal,
	CustomBody,
}

#[ derive( Clone ) ]
enum Msg
{
	Open( Open ),
	Close,
	Confirm,
	PickAlpha,
	PickBeta,
	PickGamma,
	BrightnessChanged( f32 ),
}

struct DialogApp
{
	open:       Open,
	last_event: String,
	brightness: f32,
}

impl DialogApp
{
	fn new() -> Self
	{
		Self
		{
			open:       Open::None,
			last_event: "(no dialog interactions yet)".to_string(),
			brightness: 0.5,
		}
	}
}

impl App for DialogApp
{
	type Message = Msg;

	fn view( &self ) -> Element<Msg>
	{
		let palette   = ltk::theme_palette();
		let primary   = palette.text_primary;
		let secondary = palette.text_secondary;

		let header = column::<Msg>()
			.spacing( 8.0 )
			.push( text( "ltk · dialog widget" ).size( 24.0 ).color( primary ) )
			.push( text( "Open one of the dialogs below. ESC always fires the dialog's `cancel` message." )
				.size( 14.0 )
				.color( secondary )
				.wrap( true ) );

		// Stacked, not a row: a centered row overflows both edges as
		// soon as the fluid button sizes outgrow the window, while a
		// column clamps each button to the available width.
		let openers = column::<Msg>()
			.padding( 0.0 )
			.spacing( 12.0 )
			.push(
				button::<Msg>( "Modal confirm" )
					.variant( ButtonVariant::Primary )
					.on_press( Msg::Open( Open::Modal ) ),
			)
			.push(
				button::<Msg>( "Non-modal pick" )
					.variant( ButtonVariant::Secondary )
					.on_press( Msg::Open( Open::NonModal ) ),
			)
			.push(
				button::<Msg>( "Custom body" )
					.variant( ButtonVariant::Tertiary )
					.on_press( Msg::Open( Open::CustomBody ) ),
			);

		let event_label = text( format!( "Last event: {}", self.last_event ) )
			.size( 13.0 )
			.color( secondary )
			.wrap( true );

		let main = column::<Msg>()
			.spacing( 24.0 )
			.padding( 32.0 )
			.push( header )
			.push( openers )
			.push( spacer() )
			.push( event_label );

		// Build the active dialog (if any) and stack it on top of the
		// main column. Stack draws children in order, so the dialog
		// always sits over the main UI.
		let overlay: Option<Element<Msg>> = match self.open
		{
			Open::None       => None,
			Open::Modal      => Some( modal_confirm() ),
			Open::NonModal   => Some( non_modal_pick() ),
			Open::CustomBody => Some( custom_body_dialog( self.brightness ) ),
		};

		match overlay
		{
			Some( o ) =>
			{
				stack::<Msg>()
					.push( main )
					.push( o )
					.into()
			}
			None => main.into(),
		}
	}

	fn update( &mut self, msg: Msg )
	{
		match msg
		{
			Msg::Open( o )                => { self.open = o;        self.last_event = "opened".into(); }
			Msg::Close                    => { self.open = Open::None; self.last_event = "cancelled (button or ESC or scrim)".into(); }
			Msg::Confirm                  => { self.open = Open::None; self.last_event = "confirmed".into(); }
			Msg::PickAlpha                => { self.open = Open::None; self.last_event = "picked Alpha".into(); }
			Msg::PickBeta                 => { self.open = Open::None; self.last_event = "picked Beta".into(); }
			Msg::PickGamma                => { self.open = Open::None; self.last_event = "picked Gamma".into(); }
			Msg::BrightnessChanged( v )   => { self.brightness = v; }
		}
	}

	// Only reached when no dialog is open: with one on screen, the ESC
	// dispatch chain fires the scrim's `on_escape` (the dialog's cancel)
	// before the app ever sees the key. First ESC closes, second quits.
	fn on_key( &mut self, keysym: Keysym ) -> Option<Msg>
	{
		if keysym == Keysym::Escape { std::process::exit( 0 ); }
		None
	}
}

fn modal_confirm() -> Element<Msg>
{
	dialog::<Msg>()
		.title( "Delete partition?" )
		.subtitle( "This will permanently erase every file in /dev/sda2 and cannot be undone. Make sure you have a backup before continuing." )
		.cancel( Msg::Close )
		.action(
			button::<Msg>( "Cancel" )
				.variant( ButtonVariant::Tertiary )
				.on_press( Msg::Close ),
		)
		.action(
			button::<Msg>( "Delete" )
				.variant( ButtonVariant::Primary )
				.on_press( Msg::Confirm ),
		)
		.into()
}

fn non_modal_pick() -> Element<Msg>
{
	dialog::<Msg>()
		.modal( false )
		.title( "Pick a flavour" )
		.subtitle( "Tap the dim background or press ESC to cancel." )
		.cancel( Msg::Close )
		.dismiss_on_scrim( Msg::Close )
		.action(
			button::<Msg>( "Alpha" )
				.variant( ButtonVariant::Tertiary )
				.on_press( Msg::PickAlpha ),
		)
		.action(
			button::<Msg>( "Beta" )
				.variant( ButtonVariant::Tertiary )
				.on_press( Msg::PickBeta ),
		)
		.action(
			button::<Msg>( "Gamma" )
				.variant( ButtonVariant::Primary )
				.on_press( Msg::PickGamma ),
		)
		.into()
}

fn custom_body_dialog( brightness: f32 ) -> Element<Msg>
{
	let palette   = ltk::theme_palette();
	let secondary = palette.text_secondary;

	let body = column::<Msg>()
		.spacing( 8.0 )
		.push( text( format!( "Brightness: {:>3.0} %", brightness * 100.0 ) )
			.size( 14.0 )
			.color( secondary ) )
		.push(
			slider::<Msg>( brightness )
				.on_change( |v| Msg::BrightnessChanged( v ) )
				.accent_thumb( true ),
		);

	dialog::<Msg>()
		.title( "Display brightness" )
		.subtitle( "Drag the slider, then accept or cancel." )
		.cancel( Msg::Close )
		.body( body )
		.action(
			button::<Msg>( "Cancel" )
				.variant( ButtonVariant::Tertiary )
				.on_press( Msg::Close ),
		)
		.action(
			button::<Msg>( "Accept" )
				.variant( ButtonVariant::Primary )
				.on_press( Msg::Confirm ),
		)
		.into()
}

fn main()
{
	ltk::run( DialogApp::new() );
}