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Add scrollable Viewport
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tarkah committed Apr 17, 2023
1 parent b623f28 commit 6ad5e03
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Showing 4 changed files with 61 additions and 52 deletions.
6 changes: 3 additions & 3 deletions examples/scrollable/src/main.rs
Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,7 @@ enum Message {
ScrollerWidthChanged(u16),
ScrollToBeginning,
ScrollToEnd,
Scrolled(scrollable::CurrentOffset),
Scrolled(scrollable::Viewport),
}

impl Application for ScrollableDemo {
Expand Down Expand Up @@ -104,8 +104,8 @@ impl Application for ScrollableDemo {
self.current_scroll_offset,
)
}
Message::Scrolled(offset) => {
self.current_scroll_offset = offset.relative;
Message::Scrolled(viewport) => {
self.current_scroll_offset = viewport.relative_offset();

Command::none()
}
Expand Down
9 changes: 0 additions & 9 deletions native/src/widget/operation/scrollable.rs
Original file line number Diff line number Diff line change
Expand Up @@ -64,15 +64,6 @@ pub fn scroll_to<T>(target: Id, offset: AbsoluteOffset) -> impl Operation<T> {
ScrollTo { target, offset }
}

/// The current absolute & relative offset of a [`Scrollable`]
#[derive(Debug, Clone, Copy, PartialEq, Default)]
pub struct CurrentOffset {
/// The [`AbsoluteOffset`] of a [`Scrollable`]
pub absolute: AbsoluteOffset,
/// The [`RelativeOffset`] of a [`Scrollable`]
pub relative: RelativeOffset,
}

/// The amount of absolute offset in each direction of a [`Scrollable`].
#[derive(Debug, Clone, Copy, PartialEq, Default)]
pub struct AbsoluteOffset {
Expand Down
94 changes: 56 additions & 38 deletions native/src/widget/scrollable.rs
Original file line number Diff line number Diff line change
Expand Up @@ -15,9 +15,7 @@ use crate::{
};

pub use iced_style::scrollable::StyleSheet;
pub use operation::scrollable::{
AbsoluteOffset, CurrentOffset, RelativeOffset,
};
pub use operation::scrollable::{AbsoluteOffset, RelativeOffset};

pub mod style {
//! The styles of a [`Scrollable`].
Expand All @@ -40,7 +38,7 @@ where
vertical: Properties,
horizontal: Option<Properties>,
content: Element<'a, Message, Renderer>,
on_scroll: Option<Box<dyn Fn(CurrentOffset) -> Message + 'a>>,
on_scroll: Option<Box<dyn Fn(Viewport) -> Message + 'a>>,
style: <Renderer::Theme as StyleSheet>::Style,
}

Expand Down Expand Up @@ -95,11 +93,8 @@ where

/// Sets a function to call when the [`Scrollable`] is scrolled.
///
/// The function takes the [`CurrentOffset`] of the [`Scrollable`]
pub fn on_scroll(
mut self,
f: impl Fn(CurrentOffset) -> Message + 'a,
) -> Self {
/// The function takes the [`Viewport`] of the [`Scrollable`]
pub fn on_scroll(mut self, f: impl Fn(Viewport) -> Message + 'a) -> Self {
self.on_scroll = Some(Box::new(f));
self
}
Expand Down Expand Up @@ -437,7 +432,7 @@ pub fn update<Message>(
shell: &mut Shell<'_, Message>,
vertical: &Properties,
horizontal: Option<&Properties>,
on_scroll: &Option<Box<dyn Fn(CurrentOffset) -> Message + '_>>,
on_scroll: &Option<Box<dyn Fn(Viewport) -> Message + '_>>,
update_content: impl FnOnce(
Event,
Layout<'_>,
Expand Down Expand Up @@ -897,7 +892,7 @@ pub fn draw<Renderer>(

fn notify_on_scroll<Message>(
state: &mut State,
on_scroll: &Option<Box<dyn Fn(CurrentOffset) -> Message + '_>>,
on_scroll: &Option<Box<dyn Fn(Viewport) -> Message + '_>>,
bounds: Rectangle,
content_bounds: Rectangle,
shell: &mut Shell<'_, Message>,
Expand All @@ -909,39 +904,29 @@ fn notify_on_scroll<Message>(
return;
}

let absolute_x =
state.offset_x.absolute(bounds.width, content_bounds.width);
let relative_x = absolute_x / (content_bounds.width - bounds.width);

let absolute_y = state
.offset_y
.absolute(bounds.height, content_bounds.height);
let relative_y = absolute_y / (content_bounds.height - bounds.height);

let absolute = AbsoluteOffset {
x: absolute_x,
y: absolute_y,
};
let relative = RelativeOffset {
x: relative_x,
y: relative_y,
let viewport = Viewport {
offset_x: state.offset_x,
offset_y: state.offset_y,
bounds,
content_bounds,
};

// Don't publish redundant offsets to shell
if let Some(prev_relative) = state.last_notified {
// Don't publish redundant viewports to shell
if let Some(last_notified) = state.last_notified {
let prev = last_notified.relative_offset();
let curr = viewport.relative_offset();

let unchanged = |a: f32, b: f32| {
(a - b).abs() <= f32::EPSILON || (a.is_nan() && b.is_nan())
};

if unchanged(prev_relative.x, relative.x)
&& unchanged(prev_relative.y, relative.y)
{
if unchanged(prev.x, curr.x) && unchanged(prev.y, curr.y) {
return;
}
}

shell.publish(on_scroll(CurrentOffset { absolute, relative }));
state.last_notified = Some(relative);
shell.publish(on_scroll(viewport));
state.last_notified = Some(viewport);
}
}

Expand All @@ -954,7 +939,7 @@ pub struct State {
offset_x: Offset,
x_scroller_grabbed_at: Option<f32>,
keyboard_modifiers: keyboard::Modifiers,
last_notified: Option<RelativeOffset>,
last_notified: Option<Viewport>,
}

impl Default for State {
Expand Down Expand Up @@ -988,18 +973,51 @@ enum Offset {
}

impl Offset {
fn absolute(self, window: f32, content: f32) -> f32 {
fn absolute(self, viewport: f32, content: f32) -> f32 {
match self {
Offset::Absolute(absolute) => {
absolute.min((content - window).max(0.0))
absolute.min((content - viewport).max(0.0))
}
Offset::Relative(percentage) => {
((content - window) * percentage).max(0.0)
((content - viewport) * percentage).max(0.0)
}
}
}
}

/// The current [`Viewport`] of the [`Scrollable`].
#[derive(Debug, Clone, Copy)]
pub struct Viewport {
offset_x: Offset,
offset_y: Offset,
bounds: Rectangle,
content_bounds: Rectangle,
}

impl Viewport {
/// Returns the [`AbsoluteOffset`] of the current [`Viewport`].
pub fn absolute_offset(&self) -> AbsoluteOffset {
let x = self
.offset_x
.absolute(self.bounds.width, self.content_bounds.width);
let y = self
.offset_y
.absolute(self.bounds.height, self.content_bounds.height);

AbsoluteOffset { x, y }
}

/// Returns the [`RelativeOffset`] of the current [`Viewport`].
pub fn relative_offset(&self) -> RelativeOffset {
let AbsoluteOffset { x, y } = self.absolute_offset();

let x = x / (self.content_bounds.width - self.bounds.width);
let y = y / (self.content_bounds.height - self.bounds.height);

RelativeOffset { x, y }
}
}

impl State {
/// Creates a new [`State`] with the scrollbar(s) at the beginning.
pub fn new() -> Self {
Expand Down
4 changes: 2 additions & 2 deletions src/widget.rs
Original file line number Diff line number Diff line change
Expand Up @@ -109,8 +109,8 @@ pub mod radio {
pub mod scrollable {
//! Navigate an endless amount of content with a scrollbar.
pub use iced_native::widget::scrollable::{
snap_to, style::Scrollbar, style::Scroller, AbsoluteOffset,
CurrentOffset, Id, Properties, RelativeOffset, StyleSheet,
snap_to, style::Scrollbar, style::Scroller, AbsoluteOffset, Id,
Properties, RelativeOffset, StyleSheet, Viewport,
};

/// A widget that can vertically display an infinite amount of content
Expand Down

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