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Notify scrollable::Viewport changes #2438

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Merged
hecrj merged 1 commit into from
Sep 10, 2024
Merged

Notify scrollable::Viewport changes #2438

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58 changes: 44 additions & 14 deletions widget/src/scrollable.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ use crate::core::touch;
use crate::core::widget;
use crate::core::widget::operation::{self, Operation};
use crate::core::widget::tree::{self, Tree};
use crate::core::window;
use crate::core::{
self, Background, Clipboard, Color, Element, Layout, Length, Padding,
Pixels, Point, Rectangle, Shell, Size, Theme, Vector, Widget,
Expand Down Expand Up @@ -526,7 +527,7 @@ where
content_bounds,
);

let _ = notify_on_scroll(
let _ = notify_scroll(
state,
&self.on_scroll,
bounds,
Expand Down Expand Up @@ -564,7 +565,7 @@ where

state.y_scroller_grabbed_at = Some(scroller_grabbed_at);

let _ = notify_on_scroll(
let _ = notify_scroll(
state,
&self.on_scroll,
bounds,
Expand Down Expand Up @@ -597,7 +598,7 @@ where
content_bounds,
);

let _ = notify_on_scroll(
let _ = notify_scroll(
state,
&self.on_scroll,
bounds,
Expand Down Expand Up @@ -635,7 +636,7 @@ where

state.x_scroller_grabbed_at = Some(scroller_grabbed_at);

let _ = notify_on_scroll(
let _ = notify_scroll(
state,
&self.on_scroll,
bounds,
Expand Down Expand Up @@ -759,7 +760,7 @@ where
content_bounds,
);

if notify_on_scroll(
if notify_scroll(
state,
&self.on_scroll,
bounds,
Expand Down Expand Up @@ -807,7 +808,7 @@ where
Some(cursor_position);

// TODO: bubble up touch movements if not consumed.
let _ = notify_on_scroll(
let _ = notify_scroll(
state,
&self.on_scroll,
bounds,
Expand All @@ -821,6 +822,17 @@ where

event::Status::Captured
}
Event::Window(window::Event::RedrawRequested(_)) => {
let _ = notify_viewport(
state,
&self.on_scroll,
bounds,
content_bounds,
shell,
);

event::Status::Ignored
}
_ => event::Status::Ignored,
}
}
Expand Down Expand Up @@ -1153,8 +1165,23 @@ pub fn scroll_by<T>(id: Id, offset: AbsoluteOffset) -> Task<T> {
)))
}

/// Returns [`true`] if the viewport actually changed.
fn notify_on_scroll<Message>(
fn notify_scroll<Message>(
state: &mut State,
on_scroll: &Option<Box<dyn Fn(Viewport) -> Message + '_>>,
bounds: Rectangle,
content_bounds: Rectangle,
shell: &mut Shell<'_, Message>,
) -> bool {
if notify_viewport(state, on_scroll, bounds, content_bounds, shell) {
state.last_scrolled = Some(Instant::now());

true
} else {
false
}
}

fn notify_viewport<Message>(
state: &mut State,
on_scroll: &Option<Box<dyn Fn(Viewport) -> Message + '_>>,
bounds: Rectangle,
Expand All @@ -1167,6 +1194,11 @@ fn notify_on_scroll<Message>(
return false;
}

let Some(on_scroll) = on_scroll else {
state.last_notified = None;
return false;
};

let viewport = Viewport {
offset_x: state.offset_x,
offset_y: state.offset_y,
Expand All @@ -1186,7 +1218,9 @@ fn notify_on_scroll<Message>(
(a - b).abs() <= f32::EPSILON || (a.is_nan() && b.is_nan())
};

if unchanged(last_relative_offset.x, current_relative_offset.x)
if last_notified.bounds == bounds
&& last_notified.content_bounds == content_bounds
&& unchanged(last_relative_offset.x, current_relative_offset.x)
&& unchanged(last_relative_offset.y, current_relative_offset.y)
&& unchanged(last_absolute_offset.x, current_absolute_offset.x)
&& unchanged(last_absolute_offset.y, current_absolute_offset.y)
Expand All @@ -1195,12 +1229,8 @@ fn notify_on_scroll<Message>(
}
}

if let Some(on_scroll) = on_scroll {
shell.publish(on_scroll(viewport));
}

shell.publish(on_scroll(viewport));
state.last_notified = Some(viewport);
state.last_scrolled = Some(Instant::now());

true
}
Expand Down