oak-gpui/crates/gpui/examples/learn/timeline.rs

//! Demo of the `gpui::timeline` video-editing timeline widget.
//!
//! This is the intended-usage sketch: a mock [`TimelineDataSource`] with two
//! video and two audio tracks carrying a handful of static clips, a
//! [`TimelineView`] placed in a window, and an event subscription that logs
//! the edit requests the widget emits.
//!
//! In a real host (Oak), the `match` arm in `TimelineExample::new` is where
//! each [`TimelineEvent`] becomes an undoable engine command, followed by a
//! `cx.notify()` on the model entity.
//!
//! NOTE: the timeline's rendering and interaction internals are still
//! `todo!()`; this example compiles and shows the wiring, not a usable UI.

// The modules under demo are skeletons whose bodies are `todo!()` by design.
#![allow(clippy::todo)]

use gpui::timeline::{
	ClipData, ClipId, Frame, FrameRange, FrameRate, TimelineDataSource, TimelineEvent,
	TimelineView, TrackData, TrackKind,
};
use gpui::{
	App, Bounds, Context, Entity, Pixels, Render, SharedString, Window, WindowBounds,
	WindowOptions, div, prelude::*, px, size,
};

#[path = "../shared/prelude.rs"]
mod example_prelude;

// --- mock model ------------------------------------------------------------

struct MockClip {
	id: ClipId,
	range: FrameRange,
	media_in: Frame,
	label: SharedString,
}

impl ClipData for MockClip {
	fn id(&self) -> ClipId {
		self.id
	}

	fn range(&self) -> FrameRange {
		self.range
	}

	fn media_in(&self) -> Frame {
		self.media_in
	}

	fn label(&self) -> SharedString {
		self.label.clone()
	}
}

struct MockTrack {
	kind: TrackKind,
	name: SharedString,
	height: Pixels,
	clips: Vec<MockClip>,
}

impl TrackData for MockTrack {
	type Clip = MockClip;

	fn kind(&self) -> TrackKind {
		self.kind
	}

	fn name(&self) -> SharedString {
		self.name.clone()
	}

	fn height(&self) -> Pixels {
		self.height
	}

	fn clips(&self) -> &[Self::Clip] {
		&self.clips
	}
}

struct MockSequence {
	tracks: Vec<MockTrack>,
}

impl MockSequence {
	fn demo() -> Self {
		let clip = |id: u64, start: i64, end: i64, label: &str| MockClip {
			id: ClipId(id),
			range: FrameRange::new(Frame(start), Frame(end)),
			media_in: Frame::ZERO,
			label: label.into(),
		};
		MockSequence {
			tracks: vec![
				MockTrack {
					kind: TrackKind::Video,
					name: "V1".into(),
					height: px(64.),
					clips: vec![
						clip(1, 0, 240, "opening.mov"),
						clip(2, 240, 600, "b-roll.mp4"),
					],
				},
				MockTrack {
					kind: TrackKind::Video,
					name: "V2".into(),
					height: px(64.),
					clips: vec![clip(3, 120, 300, "title.mov")],
				},
				MockTrack {
					kind: TrackKind::Audio,
					name: "A1".into(),
					height: px(48.),
					clips: vec![clip(4, 0, 600, "dialog.wav")],
				},
				MockTrack {
					kind: TrackKind::Audio,
					name: "A2".into(),
					height: px(48.),
					clips: vec![clip(5, 0, 480, "score.flac")],
				},
			],
		}
	}
}

impl TimelineDataSource for MockSequence {
	type Track = MockTrack;

	fn frame_rate(&self) -> FrameRate {
		FrameRate::NTSC_2997
	}

	fn sequence_length(&self) -> Frame {
		Frame(600)
	}

	fn track_count(&self) -> usize {
		self.tracks.len()
	}

	fn track(&self, index: usize) -> Option<Self::Track> {
		// A real host returns a lightweight snapshot; the mock simply
		// reports the track's existence. Returning an owned value here is
		// what the trait requires, so the mock clones its clips.
		self.tracks.get(index).map(|t| MockTrack {
			kind: t.kind,
			name: t.name.clone(),
			height: t.height,
			clips: t
				.clips
				.iter()
				.map(|c| MockClip {
					id: c.id,
					range: c.range,
					media_in: c.media_in,
					label: c.label.clone(),
				})
				.collect(),
		})
	}
}

// --- the example view ------------------------------------------------------

struct TimelineExample {
	timeline: Entity<TimelineView<MockSequence>>,
}

impl TimelineExample {
	fn new(model: Entity<MockSequence>, window: &mut Window, cx: &mut Context<Self>) -> Self {
		let timeline = cx.new(|cx| TimelineView::new(model, window, cx).zoom(2.0));
		cx.subscribe(&timeline, |_this, _timeline, event: &TimelineEvent, _cx| {
			// In Oak, each request becomes an undoable engine command
			// here, followed by `model.update(cx, |_, cx| cx.notify())`.
			println!("timeline edit request: {event:?}");
		})
		.detach();
		TimelineExample { timeline }
	}
}

impl Render for TimelineExample {
	fn render(&mut self, _window: &mut Window, _cx: &mut Context<Self>) -> impl IntoElement {
		div().size_full().child(self.timeline.clone())
	}
}

fn main() {
	gpui_platform::application().run(|cx: &mut App| {
		let bounds = Bounds::centered(None, size(px(1000.), px(480.)), cx);
		let model = cx.new(|_cx| MockSequence::demo());
		cx.open_window(
			WindowOptions {
				window_bounds: Some(WindowBounds::Windowed(bounds)),
				..Default::default()
			},
			|window, cx| cx.new(|cx| TimelineExample::new(model, window, cx)),
		)
		.expect("Failed to open window");

		example_prelude::init_example(cx, "Timeline");
	});
}