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mikayla-maki merged 1 commit into from
Aug 17, 2026
Merged

gpui: Add spring animations; examples #62778

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245 changes: 239 additions & 6 deletions crates/gpui/examples/animation.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,9 +4,10 @@ use std::time::Duration;

use anyhow::Result;
use gpui::{
Animation, AnimationExt as _, App, AssetSource, Bounds, Context, SharedString, Transformation,
Window, WindowBounds, WindowOptions, bounce, div, ease_in_out, percentage, prelude::*, px,
size, svg,
Animation, AnimationExt as _, AnimationPhase, App, AssetSource, Bounds, Context, MouseButton,
MouseDownEvent, MouseMoveEvent, Pixels, SharedString, SpringAnimation, SpringConfig,
Transformation, Window, WindowBounds, WindowOptions, bounce, div, ease_in_out, percentage,
prelude::*, px, relative, rgba, size, svg,
};
use gpui_platform::application;

Expand Down Expand Up @@ -36,10 +37,26 @@ const ARROW_CIRCLE_SVG: &str = concat!(
"/examples/image/arrow_circle.svg"
);

struct AnimationExample {}
struct AnimationExample {
spring_phase: u8,
spring_damping: f32,
spring_damping_drag: Option<(Pixels, f32)>,
}

impl Render for AnimationExample {
fn render(&mut self, _window: &mut Window, _cx: &mut Context<Self>) -> impl IntoElement {
fn render(&mut self, _window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
const MINIMUM_DAMPING: f32 = 2.0;
const MAXIMUM_DAMPING: f32 = 32.0;
const DAMPING_SLIDER_WIDTH: Pixels = px(224.0);

let spring_phase = self.spring_phase;
let spring_position = px(98.0 * f32::from(spring_phase));
let spring_damping = self.spring_damping;
let spring = SpringConfig::new(170.0, spring_damping, 1.0);
let (_, damping_ratio) = spring.canonical();
let damping_fraction =
(spring_damping - MINIMUM_DAMPING) / (MAXIMUM_DAMPING - MINIMUM_DAMPING);

div()
.flex()
.flex_col()
Expand Down Expand Up @@ -67,6 +84,190 @@ impl Render for AnimationExample {
.text_xl()
.gap_4()
.child("Hello Animation")
.child(
div()
.id("spring-demo")
.flex()
.flex_col()
.gap_2()
.p_2()
.w(px(240.0))
.rounded_md()
.bg(rgba(0x00000010))
.cursor_pointer()
.on_mouse_down(
MouseButton::Left,
cx.listener(|this, _, _, cx| {
this.spring_phase = (this.spring_phase + 1) % 3;
cx.notify();
}),
)
.child(format!(
"Target phase {spring_phase}: click rapidly to redirect momentum"
))
.child(
div()
.id("spring-damping-controls")
.flex()
.flex_col()
.gap_1()
.text_sm()
.on_click(|_, _, cx| cx.stop_propagation())
.child(format!(
"Drag damping: {spring_damping:.1} (ζ {damping_ratio:.2})"
))
.child(
div()
.id("spring-damping")
.relative()
.h(px(20.0))
.w(DAMPING_SLIDER_WIDTH)
.cursor_pointer()
.on_mouse_down(
MouseButton::Left,
cx.listener(
|this,
event: &MouseDownEvent,
_,
cx| {
this.spring_damping_drag = Some((
event.position.x,
this.spring_damping,
));
cx.stop_propagation();
},
),
)
.on_mouse_move(cx.listener(
|this,
event: &MouseMoveEvent,
_,
cx| {
let Some((
start_position,
start_damping,
)) = this.spring_damping_drag
else {
return;
};

let delta = (event.position.x
- start_position)
/ DAMPING_SLIDER_WIDTH;
this.spring_damping = (start_damping
+ delta
* (MAXIMUM_DAMPING
- MINIMUM_DAMPING))
.clamp(
MINIMUM_DAMPING,
MAXIMUM_DAMPING,
);
cx.stop_propagation();
cx.notify();
},
))
.on_mouse_up(
MouseButton::Left,
cx.listener(|this, _, _, cx| {
this.spring_damping_drag = None;
cx.stop_propagation();
}),
)
.on_mouse_up_out(
MouseButton::Left,
cx.listener(|this, _, _, cx| {
this.spring_damping_drag = None;
cx.stop_propagation();
}),
)
.child(
div()
.absolute()
.top(px(8.0))
.h(px(4.0))
.w_full()
.rounded_full()
.bg(rgba(0x00000030)),
)
.child(
div()
.absolute()
.top(px(8.0))
.h(px(4.0))
.w(relative(damping_fraction))
.rounded_full()
.bg(rgba(0x3b82f6ff)),
)
.child(
div()
.absolute()
.top(px(3.0))
.left(relative(damping_fraction))
.ml(px(-7.0))
.size(px(14.0))
.rounded_full()
.bg(rgba(0x2563ebff)),
),
),
)
.child(
div().relative().h(px(32.0)).w_full().child(
div()
.absolute()
.top_1()
.size(px(24.0))
.rounded_full()
.bg(rgba(0x3b82f6ff))
.cursor_pointer()
.debug_selector(|| "spring-position".into())
.with_spring(
"spring-position",
SpringAnimation::new(spring)
.to(spring_position)
.with_epsilon(0.25),
|this, left| this.left(left),
),
),
)
.child(
div().h(px(24.0)).rounded_sm().with_spring(
"spring-phase",
SpringAnimation::new(spring)
.to(AnimationPhase(f32::from(spring_phase)))
.with_epsilon(0.001),
|this, phase| {
let (width, color) = if phase.0 <= 1.0 {
(
phase.interpolate_between(
0.0..=1.0,
px(48.0),
px(224.0),
),
phase.interpolate_between_clamped(
0.0..=1.0,
rgba(0xf97316ff),
rgba(0x22c55eff),
),
)
} else {
(
phase.interpolate_between(
1.0..=2.0,
px(224.0),
px(96.0),
),
phase.interpolate_between_clamped(
1.0..=2.0,
rgba(0x22c55eff),
rgba(0xa855f7ff),
),
)
};
this.w(width).bg(color)
},
),
),
)
.child(
svg()
.size_20()
Expand Down Expand Up @@ -115,7 +316,11 @@ fn run_example() {
};
cx.open_window(options, |_, cx| {
cx.activate(false);
cx.new(|_| AnimationExample {})
cx.new(|_| AnimationExample {
spring_phase: 0,
spring_damping: 14.0,
spring_damping_drag: None,
})
})
.unwrap();
});
Expand All @@ -132,3 +337,31 @@ pub fn start() {
gpui_platform::web_init();
run_example();
}

#[cfg(all(test, feature = "test-support"))]
mod tests {
use gpui::{Modifiers, TestAppContext};

use super::*;

#[gpui::test]
fn clicking_spring_position_changes_the_target(cx: &mut TestAppContext) {
let (view, cx) = cx.add_window_view(|_, _| AnimationExample {
spring_phase: 0,
spring_damping: 14.0,
spring_damping_drag: None,
});
cx.simulate_resize(size(px(300.0), px(300.0)));
cx.run_until_parked();

let position_bounds = cx
.debug_bounds("spring-position")
.expect("spring position should be rendered");
let position = position_bounds.center();
cx.simulate_mouse_move(position, None, Modifiers::default());
cx.simulate_click(position, Modifiers::default());
cx.run_until_parked();

assert_eq!(cx.update(|_, cx| view.read(cx).spring_phase), 1);
}
}
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