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Make scroll_to_* animations configurable (#4305)
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* Closes #4295

I based this on #4303, I'll rebase once that one gets merged.
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lucasmerlin authored Jul 31, 2024
1 parent ae7672e commit c5bea31
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Showing 5 changed files with 191 additions and 29 deletions.
34 changes: 20 additions & 14 deletions crates/egui/src/containers/scroll_area.rs
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ use crate::*;

#[derive(Clone, Copy, Debug)]
#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
struct ScrollTarget {
struct ScrollingToTarget {
animation_time_span: (f64, f64),
target_offset: f32,
}
Expand All @@ -17,7 +17,7 @@ pub struct State {
pub offset: Vec2,

/// If set, quickly but smoothly scroll to this target offset.
offset_target: [Option<ScrollTarget>; 2],
offset_target: [Option<ScrollingToTarget>; 2],

/// Were the scroll bars visible last frame?
show_scroll: Vec2b,
Expand Down Expand Up @@ -799,7 +799,8 @@ impl Prepared {

for d in 0..2 {
// FrameState::scroll_delta is inverted from the way we apply the delta, so we need to negate it.
let mut delta = -scroll_delta[d];
let mut delta = -scroll_delta.0[d];
let mut animation = scroll_delta.1;

// We always take both scroll targets regardless of which scroll axes are enabled. This
// is to avoid them leaking to other scroll areas.
Expand All @@ -808,20 +809,25 @@ impl Prepared {
.frame_state_mut(|state| state.scroll_target[d].take());

if scroll_enabled[d] {
delta += if let Some((target_range, align)) = scroll_target {
if let Some(target) = scroll_target {
let frame_state::ScrollTarget {
range,
align,
animation: animation_update,
} = target;
let min = content_ui.min_rect().min[d];
let clip_rect = content_ui.clip_rect();
let visible_range = min..=min + clip_rect.size()[d];
let (start, end) = (target_range.min, target_range.max);
let (start, end) = (range.min, range.max);
let clip_start = clip_rect.min[d];
let clip_end = clip_rect.max[d];
let mut spacing = ui.spacing().item_spacing[d];

if let Some(align) = align {
let delta_update = if let Some(align) = align {
let center_factor = align.to_factor();

let offset =
lerp(target_range, center_factor) - lerp(visible_range, center_factor);
lerp(range, center_factor) - lerp(visible_range, center_factor);

// Depending on the alignment we need to add or subtract the spacing
spacing *= remap(center_factor, 0.0..=1.0, -1.0..=1.0);
Expand All @@ -834,9 +840,10 @@ impl Prepared {
} else {
// Ui is already in view, no need to adjust scroll.
0.0
}
} else {
0.0
};

delta += delta_update;
animation = animation_update;
};

if delta != 0.0 {
Expand All @@ -850,11 +857,10 @@ impl Prepared {
animation.target_offset = target_offset;
} else {
// The further we scroll, the more time we take.
// TODO(emilk): let users configure this in `Style`.
let now = ui.input(|i| i.time);
let points_per_second = 1000.0;
let animation_duration = (delta.abs() / points_per_second).clamp(0.1, 0.3);
state.offset_target[d] = Some(ScrollTarget {
let animation_duration = (delta.abs() / animation.points_per_second)
.clamp(animation.duration.min, animation.duration.max);
state.offset_target[d] = Some(ScrollingToTarget {
animation_time_span: (now, now + animation_duration as f64),
target_offset,
});
Expand Down
32 changes: 28 additions & 4 deletions crates/egui/src/frame_state.rs
Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,30 @@ pub struct PerLayerState {
pub widget_with_tooltip: Option<Id>,
}

#[derive(Clone, Debug)]
pub struct ScrollTarget {
// The range that the scroll area should scroll to.
pub range: Rangef,

/// How should we align the rect within the visible area?
/// If `align` is [`Align::TOP`] it means "put the top of the rect at the top of the scroll area", etc.
/// If `align` is `None`, it'll scroll enough to bring the UI into view.
pub align: Option<Align>,

/// How should the scroll be animated?
pub animation: style::ScrollAnimation,
}

impl ScrollTarget {
pub fn new(range: Rangef, align: Option<Align>, animation: style::ScrollAnimation) -> Self {
Self {
range,
align,
animation,
}
}
}

#[cfg(feature = "accesskit")]
#[derive(Clone)]
pub struct AccessKitFrameState {
Expand Down Expand Up @@ -172,7 +196,7 @@ pub struct FrameState {
pub used_by_panels: Rect,

/// The current scroll area should scroll to this range (horizontal, vertical).
pub scroll_target: [Option<(Rangef, Option<Align>)>; 2],
pub scroll_target: [Option<ScrollTarget>; 2],

/// The current scroll area should scroll by this much.
///
Expand All @@ -183,7 +207,7 @@ pub struct FrameState {
///
/// A positive Y-value indicates the content is being moved down,
/// as when swiping down on a touch-screen or track-pad with natural scrolling.
pub scroll_delta: Vec2,
pub scroll_delta: (Vec2, style::ScrollAnimation),

#[cfg(feature = "accesskit")]
pub accesskit_state: Option<AccessKitFrameState>,
Expand All @@ -206,7 +230,7 @@ impl Default for FrameState {
unused_rect: Rect::NAN,
used_by_panels: Rect::NAN,
scroll_target: [None, None],
scroll_delta: Vec2::default(),
scroll_delta: (Vec2::default(), style::ScrollAnimation::none()),
#[cfg(feature = "accesskit")]
accesskit_state: None,
highlight_next_frame: Default::default(),
Expand Down Expand Up @@ -246,7 +270,7 @@ impl FrameState {
*unused_rect = screen_rect;
*used_by_panels = Rect::NOTHING;
*scroll_target = [None, None];
*scroll_delta = Vec2::default();
*scroll_delta = Default::default();

#[cfg(debug_assertions)]
{
Expand Down
26 changes: 21 additions & 5 deletions crates/egui/src/response.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2,10 +2,9 @@ use std::{any::Any, sync::Arc};

use crate::{
emath::{Align, Pos2, Rect, Vec2},
menu, AreaState, Context, CursorIcon, Id, LayerId, Order, PointerButton, Sense, Ui, WidgetRect,
WidgetText,
frame_state, menu, AreaState, Context, CursorIcon, Id, LayerId, Order, PointerButton, Sense,
Ui, WidgetRect, WidgetText,
};

// ----------------------------------------------------------------------------

/// The result of adding a widget to a [`Ui`].
Expand Down Expand Up @@ -888,9 +887,26 @@ impl Response {
/// # });
/// ```
pub fn scroll_to_me(&self, align: Option<Align>) {
self.scroll_to_me_animation(align, self.ctx.style().scroll_animation);
}

/// Like [`Self::scroll_to_me`], but allows you to specify the [`crate::style::ScrollAnimation`].
pub fn scroll_to_me_animation(
&self,
align: Option<Align>,
animation: crate::style::ScrollAnimation,
) {
self.ctx.frame_state_mut(|state| {
state.scroll_target[0] = Some((self.rect.x_range(), align));
state.scroll_target[1] = Some((self.rect.y_range(), align));
state.scroll_target[0] = Some(frame_state::ScrollTarget::new(
self.rect.x_range(),
align,
animation,
));
state.scroll_target[1] = Some(frame_state::ScrollTarget::new(
self.rect.y_range(),
align,
animation,
));
});
}

Expand Down
88 changes: 88 additions & 0 deletions crates/egui/src/style.rs
Original file line number Diff line number Diff line change
Expand Up @@ -280,6 +280,9 @@ pub struct Style {

/// If true and scrolling is enabled for only one direction, allow horizontal scrolling without pressing shift
pub always_scroll_the_only_direction: bool,

/// The animation that should be used when scrolling a [`crate::ScrollArea`] using e.g. [Ui::scroll_to_rect].
pub scroll_animation: ScrollAnimation,
}

#[test]
Expand Down Expand Up @@ -692,6 +695,88 @@ impl ScrollStyle {

// ----------------------------------------------------------------------------

/// Scroll animation configuration, used when programmatically scrolling somewhere (e.g. with `[crate::Ui::scroll_to_cursor]`)
/// The animation duration is calculated based on the distance to be scrolled via `[ScrollAnimation::points_per_second]`
/// and can be clamped to a min / max duration via `[ScrollAnimation::duration]`.
#[derive(Copy, Clone, Debug, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
#[cfg_attr(feature = "serde", serde(default))]
pub struct ScrollAnimation {
/// With what speed should we scroll? (Default: 1000.0)
pub points_per_second: f32,

/// The min / max scroll duration.
pub duration: Rangef,
}

impl Default for ScrollAnimation {
fn default() -> Self {
Self {
points_per_second: 1000.0,
duration: Rangef::new(0.1, 0.3),
}
}
}

impl ScrollAnimation {
/// New scroll animation
pub fn new(points_per_second: f32, duration: Rangef) -> Self {
Self {
points_per_second,
duration,
}
}

/// No animation, scroll instantly.
pub fn none() -> Self {
Self {
points_per_second: f32::INFINITY,
duration: Rangef::new(0.0, 0.0),
}
}

/// Scroll with a fixed duration, regardless of distance.
pub fn duration(t: f32) -> Self {
Self {
points_per_second: f32::INFINITY,
duration: Rangef::new(t, t),
}
}

pub fn ui(&mut self, ui: &mut crate::Ui) {
crate::Grid::new("scroll_animation").show(ui, |ui| {
ui.label("Scroll animation:");
ui.add(
DragValue::new(&mut self.points_per_second)
.speed(100.0)
.range(0.0..=5000.0),
);
ui.label("points/second");
ui.end_row();

ui.label("Min duration:");
ui.add(
DragValue::new(&mut self.duration.min)
.speed(0.01)
.range(0.0..=self.duration.max),
);
ui.label("seconds");
ui.end_row();

ui.label("Max duration:");
ui.add(
DragValue::new(&mut self.duration.max)
.speed(0.01)
.range(0.0..=1.0),
);
ui.label("seconds");
ui.end_row();
});
}
}

// ----------------------------------------------------------------------------

/// How and when interaction happens.
#[derive(Clone, Debug, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
Expand Down Expand Up @@ -1129,6 +1214,7 @@ impl Default for Style {
explanation_tooltips: false,
url_in_tooltip: false,
always_scroll_the_only_direction: false,
scroll_animation: ScrollAnimation::default(),
}
}
}
Expand Down Expand Up @@ -1425,6 +1511,7 @@ impl Style {
explanation_tooltips,
url_in_tooltip,
always_scroll_the_only_direction,
scroll_animation,
} = self;

visuals.light_dark_radio_buttons(ui);
Expand Down Expand Up @@ -1488,6 +1575,7 @@ impl Style {
ui.collapsing("📏 Spacing", |ui| spacing.ui(ui));
ui.collapsing("☝ Interaction", |ui| interaction.ui(ui));
ui.collapsing("🎨 Visuals", |ui| visuals.ui(ui));
ui.collapsing("🔄 Scroll Animation", |ui| scroll_animation.ui(ui));

#[cfg(debug_assertions)]
ui.collapsing("🐛 Debug", |ui| debug.ui(ui));
Expand Down
40 changes: 34 additions & 6 deletions crates/egui/src/ui.rs
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,6 @@ use crate::{
containers::*, ecolor::*, epaint::text::Fonts, layout::*, menu::MenuState, placer::Placer,
util::IdTypeMap, widgets::*, *,
};

// ----------------------------------------------------------------------------

/// This is what you use to place widgets.
Expand Down Expand Up @@ -1216,10 +1215,22 @@ impl Ui {
/// # });
/// ```
pub fn scroll_to_rect(&self, rect: Rect, align: Option<Align>) {
self.scroll_to_rect_animation(rect, align, self.style.scroll_animation);
}

/// Same as [`Self::scroll_to_rect`], but allows you to specify the [`style::ScrollAnimation`].
pub fn scroll_to_rect_animation(
&self,
rect: Rect,
align: Option<Align>,
animation: style::ScrollAnimation,
) {
for d in 0..2 {
let range = Rangef::new(rect.min[d], rect.max[d]);
self.ctx()
.frame_state_mut(|state| state.scroll_target[d] = Some((range, align)));
self.ctx().frame_state_mut(|state| {
state.scroll_target[d] =
Some(frame_state::ScrollTarget::new(range, align, animation));
});
}
}

Expand All @@ -1246,11 +1257,22 @@ impl Ui {
/// # });
/// ```
pub fn scroll_to_cursor(&self, align: Option<Align>) {
self.scroll_to_cursor_animation(align, self.style.scroll_animation);
}

/// Same as [`Self::scroll_to_cursor`], but allows you to specify the [`style::ScrollAnimation`].
pub fn scroll_to_cursor_animation(
&self,
align: Option<Align>,
animation: style::ScrollAnimation,
) {
let target = self.next_widget_position();
for d in 0..2 {
let target = Rangef::point(target[d]);
self.ctx()
.frame_state_mut(|state| state.scroll_target[d] = Some((target, align)));
self.ctx().frame_state_mut(|state| {
state.scroll_target[d] =
Some(frame_state::ScrollTarget::new(target, align, animation));
});
}
}

Expand Down Expand Up @@ -1284,8 +1306,14 @@ impl Ui {
/// # });
/// ```
pub fn scroll_with_delta(&self, delta: Vec2) {
self.scroll_with_delta_animation(delta, self.style.scroll_animation);
}

/// Same as [`Self::scroll_with_delta`], but allows you to specify the [`style::ScrollAnimation`].
pub fn scroll_with_delta_animation(&self, delta: Vec2, animation: style::ScrollAnimation) {
self.ctx().frame_state_mut(|state| {
state.scroll_delta += delta;
state.scroll_delta.0 += delta;
state.scroll_delta.1 = animation;
});
}
}
Expand Down

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