920 lines
27 KiB
Rust
920 lines
27 KiB
Rust
//! Navigate an endless amount of content with a scrollbar.
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use crate::event::{self, Event};
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use crate::layout;
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use crate::mouse;
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use crate::overlay;
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use crate::renderer;
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use crate::touch;
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use crate::widget::tree::{self, Tree};
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use crate::{
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Background, Clipboard, Color, Element, Layout, Length, Point, Rectangle,
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Shell, Size, Vector, Widget,
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};
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use std::{f32, u32};
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pub use iced_style::scrollable::StyleSheet;
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pub mod style {
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//! The styles of a [`Scrollable`].
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//!
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//! [`Scrollable`]: crate::widget::Scrollable
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pub use iced_style::scrollable::{Scrollbar, Scroller};
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}
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/// A widget that can vertically display an infinite amount of content with a
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/// scrollbar.
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#[allow(missing_debug_implementations)]
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pub struct Scrollable<'a, Message, Renderer>
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where
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Renderer: crate::Renderer,
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Renderer::Theme: StyleSheet,
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{
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height: Length,
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scrollbar_width: u16,
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scrollbar_margin: u16,
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scroller_width: u16,
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content: Element<'a, Message, Renderer>,
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on_scroll: Option<Box<dyn Fn(f32) -> Message + 'a>>,
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style: <Renderer::Theme as StyleSheet>::Style,
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}
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impl<'a, Message, Renderer> Scrollable<'a, Message, Renderer>
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where
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Renderer: crate::Renderer,
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Renderer::Theme: StyleSheet,
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{
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/// Creates a new [`Scrollable`].
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pub fn new(content: impl Into<Element<'a, Message, Renderer>>) -> Self {
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Scrollable {
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height: Length::Shrink,
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scrollbar_width: 10,
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scrollbar_margin: 0,
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scroller_width: 10,
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content: content.into(),
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on_scroll: None,
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style: Default::default(),
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}
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}
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/// Sets the height of the [`Scrollable`].
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pub fn height(mut self, height: Length) -> Self {
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self.height = height;
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self
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}
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/// Sets the scrollbar width of the [`Scrollable`] .
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/// Silently enforces a minimum value of 1.
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pub fn scrollbar_width(mut self, scrollbar_width: u16) -> Self {
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self.scrollbar_width = scrollbar_width.max(1);
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self
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}
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/// Sets the scrollbar margin of the [`Scrollable`] .
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pub fn scrollbar_margin(mut self, scrollbar_margin: u16) -> Self {
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self.scrollbar_margin = scrollbar_margin;
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self
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}
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/// Sets the scroller width of the [`Scrollable`] .
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///
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/// It silently enforces a minimum value of 1.
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pub fn scroller_width(mut self, scroller_width: u16) -> Self {
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self.scroller_width = scroller_width.max(1);
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self
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}
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/// Sets a function to call when the [`Scrollable`] is scrolled.
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///
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/// The function takes the new relative offset of the [`Scrollable`]
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/// (e.g. `0` means top, while `1` means bottom).
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pub fn on_scroll(mut self, f: impl Fn(f32) -> Message + 'a) -> Self {
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self.on_scroll = Some(Box::new(f));
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self
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}
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/// Sets the style of the [`Scrollable`] .
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pub fn style(
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mut self,
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style: impl Into<<Renderer::Theme as StyleSheet>::Style>,
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) -> Self {
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self.style = style.into();
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self
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}
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}
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impl<'a, Message, Renderer> Widget<Message, Renderer>
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for Scrollable<'a, Message, Renderer>
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where
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Renderer: crate::Renderer,
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Renderer::Theme: StyleSheet,
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{
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fn tag(&self) -> tree::Tag {
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tree::Tag::of::<State>()
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}
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fn state(&self) -> tree::State {
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tree::State::new(State::new())
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}
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fn children(&self) -> Vec<Tree> {
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vec![Tree::new(&self.content)]
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}
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fn diff(&self, tree: &mut Tree) {
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tree.diff_children(std::slice::from_ref(&self.content))
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}
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fn width(&self) -> Length {
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self.content.as_widget().width()
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}
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fn height(&self) -> Length {
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self.height
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}
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fn layout(
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&self,
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renderer: &Renderer,
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limits: &layout::Limits,
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) -> layout::Node {
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layout(
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renderer,
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limits,
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Widget::<Message, Renderer>::width(self),
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self.height,
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u32::MAX,
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|renderer, limits| {
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self.content.as_widget().layout(renderer, limits)
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},
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)
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}
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fn on_event(
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&mut self,
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tree: &mut Tree,
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event: Event,
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layout: Layout<'_>,
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cursor_position: Point,
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renderer: &Renderer,
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clipboard: &mut dyn Clipboard,
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shell: &mut Shell<'_, Message>,
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) -> event::Status {
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update(
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tree.state.downcast_mut::<State>(),
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event,
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layout,
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cursor_position,
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clipboard,
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shell,
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self.scrollbar_width,
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self.scrollbar_margin,
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self.scroller_width,
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&self.on_scroll,
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|event, layout, cursor_position, clipboard, shell| {
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self.content.as_widget_mut().on_event(
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&mut tree.children[0],
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event,
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layout,
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cursor_position,
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renderer,
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clipboard,
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shell,
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)
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},
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)
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}
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fn draw(
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&self,
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tree: &Tree,
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renderer: &mut Renderer,
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theme: &Renderer::Theme,
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style: &renderer::Style,
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layout: Layout<'_>,
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cursor_position: Point,
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_viewport: &Rectangle,
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) {
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draw(
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tree.state.downcast_ref::<State>(),
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renderer,
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theme,
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layout,
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cursor_position,
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self.scrollbar_width,
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self.scrollbar_margin,
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self.scroller_width,
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self.style,
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|renderer, layout, cursor_position, viewport| {
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self.content.as_widget().draw(
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&tree.children[0],
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renderer,
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theme,
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style,
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layout,
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cursor_position,
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viewport,
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)
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},
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)
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}
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fn mouse_interaction(
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&self,
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tree: &Tree,
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layout: Layout<'_>,
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cursor_position: Point,
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_viewport: &Rectangle,
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renderer: &Renderer,
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) -> mouse::Interaction {
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mouse_interaction(
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tree.state.downcast_ref::<State>(),
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layout,
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cursor_position,
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self.scrollbar_width,
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self.scrollbar_margin,
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self.scroller_width,
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|layout, cursor_position, viewport| {
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self.content.as_widget().mouse_interaction(
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&tree.children[0],
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layout,
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cursor_position,
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viewport,
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renderer,
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)
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},
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)
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}
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fn overlay<'b>(
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&'b self,
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tree: &'b mut Tree,
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layout: Layout<'_>,
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renderer: &Renderer,
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) -> Option<overlay::Element<'b, Message, Renderer>> {
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self.content
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.as_widget()
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.overlay(
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&mut tree.children[0],
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layout.children().next().unwrap(),
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renderer,
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)
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.map(|overlay| {
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let bounds = layout.bounds();
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let content_layout = layout.children().next().unwrap();
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let content_bounds = content_layout.bounds();
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let offset = tree
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.state
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.downcast_ref::<State>()
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.offset(bounds, content_bounds);
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overlay.translate(Vector::new(0.0, -(offset as f32)))
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})
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}
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}
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impl<'a, Message, Renderer> From<Scrollable<'a, Message, Renderer>>
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for Element<'a, Message, Renderer>
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where
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Message: 'a,
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Renderer: 'a + crate::Renderer,
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Renderer::Theme: StyleSheet,
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{
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fn from(
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text_input: Scrollable<'a, Message, Renderer>,
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) -> Element<'a, Message, Renderer> {
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Element::new(text_input)
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}
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}
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/// Computes the layout of a [`Scrollable`].
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pub fn layout<Renderer>(
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renderer: &Renderer,
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limits: &layout::Limits,
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width: Length,
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height: Length,
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max_height: u32,
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layout_content: impl FnOnce(&Renderer, &layout::Limits) -> layout::Node,
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) -> layout::Node {
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let limits = limits.max_height(max_height).width(width).height(height);
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let child_limits = layout::Limits::new(
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Size::new(limits.min().width, 0.0),
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Size::new(limits.max().width, f32::INFINITY),
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);
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let content = layout_content(renderer, &child_limits);
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let size = limits.resolve(content.size());
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layout::Node::with_children(size, vec![content])
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}
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/// Processes an [`Event`] and updates the [`State`] of a [`Scrollable`]
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/// accordingly.
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pub fn update<Message>(
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state: &mut State,
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event: Event,
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layout: Layout<'_>,
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cursor_position: Point,
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clipboard: &mut dyn Clipboard,
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shell: &mut Shell<'_, Message>,
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scrollbar_width: u16,
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scrollbar_margin: u16,
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scroller_width: u16,
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on_scroll: &Option<Box<dyn Fn(f32) -> Message + '_>>,
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update_content: impl FnOnce(
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Event,
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Layout<'_>,
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Point,
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&mut dyn Clipboard,
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&mut Shell<'_, Message>,
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) -> event::Status,
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) -> event::Status {
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let bounds = layout.bounds();
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let is_mouse_over = bounds.contains(cursor_position);
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let content = layout.children().next().unwrap();
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let content_bounds = content.bounds();
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let scrollbar = scrollbar(
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state,
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scrollbar_width,
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scrollbar_margin,
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scroller_width,
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bounds,
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content_bounds,
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);
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let is_mouse_over_scrollbar = scrollbar
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.as_ref()
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.map(|scrollbar| scrollbar.is_mouse_over(cursor_position))
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.unwrap_or(false);
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let event_status = {
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let cursor_position = if is_mouse_over && !is_mouse_over_scrollbar {
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Point::new(
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cursor_position.x,
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cursor_position.y + state.offset(bounds, content_bounds) as f32,
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)
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} else {
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// TODO: Make `cursor_position` an `Option<Point>` so we can encode
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// cursor availability.
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// This will probably happen naturally once we add multi-window
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// support.
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Point::new(cursor_position.x, -1.0)
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};
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update_content(
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event.clone(),
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content,
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cursor_position,
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clipboard,
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shell,
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)
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};
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if let event::Status::Captured = event_status {
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return event::Status::Captured;
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}
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if is_mouse_over {
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match event {
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Event::Mouse(mouse::Event::WheelScrolled { delta }) => {
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match delta {
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mouse::ScrollDelta::Lines { y, .. } => {
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// TODO: Configurable speed (?)
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state.scroll(y * 60.0, bounds, content_bounds);
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}
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mouse::ScrollDelta::Pixels { y, .. } => {
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state.scroll(y, bounds, content_bounds);
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}
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}
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notify_on_scroll(
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state,
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on_scroll,
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bounds,
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content_bounds,
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shell,
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);
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return event::Status::Captured;
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}
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Event::Touch(event) => {
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match event {
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touch::Event::FingerPressed { .. } => {
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state.scroll_box_touched_at = Some(cursor_position);
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}
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touch::Event::FingerMoved { .. } => {
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if let Some(scroll_box_touched_at) =
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state.scroll_box_touched_at
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{
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let delta =
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cursor_position.y - scroll_box_touched_at.y;
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state.scroll(delta, bounds, content_bounds);
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state.scroll_box_touched_at = Some(cursor_position);
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notify_on_scroll(
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state,
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on_scroll,
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bounds,
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content_bounds,
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shell,
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);
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}
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}
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touch::Event::FingerLifted { .. }
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| touch::Event::FingerLost { .. } => {
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state.scroll_box_touched_at = None;
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}
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}
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return event::Status::Captured;
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}
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_ => {}
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}
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}
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if state.is_scroller_grabbed() {
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match event {
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Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left))
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| Event::Touch(touch::Event::FingerLifted { .. })
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| Event::Touch(touch::Event::FingerLost { .. }) => {
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state.scroller_grabbed_at = None;
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return event::Status::Captured;
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}
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Event::Mouse(mouse::Event::CursorMoved { .. })
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| Event::Touch(touch::Event::FingerMoved { .. }) => {
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if let (Some(scrollbar), Some(scroller_grabbed_at)) =
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(scrollbar, state.scroller_grabbed_at)
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{
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state.scroll_to(
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scrollbar.scroll_percentage(
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scroller_grabbed_at,
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cursor_position,
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),
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bounds,
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content_bounds,
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);
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notify_on_scroll(
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state,
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on_scroll,
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bounds,
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content_bounds,
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shell,
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);
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return event::Status::Captured;
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}
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}
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_ => {}
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}
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} else if is_mouse_over_scrollbar {
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match event {
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Event::Mouse(mouse::Event::ButtonPressed(mouse::Button::Left))
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| Event::Touch(touch::Event::FingerPressed { .. }) => {
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if let Some(scrollbar) = scrollbar {
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if let Some(scroller_grabbed_at) =
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scrollbar.grab_scroller(cursor_position)
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{
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state.scroll_to(
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scrollbar.scroll_percentage(
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scroller_grabbed_at,
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cursor_position,
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),
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bounds,
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content_bounds,
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);
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state.scroller_grabbed_at = Some(scroller_grabbed_at);
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notify_on_scroll(
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state,
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on_scroll,
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bounds,
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content_bounds,
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shell,
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);
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return event::Status::Captured;
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}
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}
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}
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_ => {}
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}
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}
|
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event::Status::Ignored
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}
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/// Computes the current [`mouse::Interaction`] of a [`Scrollable`].
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pub fn mouse_interaction(
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state: &State,
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layout: Layout<'_>,
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cursor_position: Point,
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scrollbar_width: u16,
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scrollbar_margin: u16,
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scroller_width: u16,
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content_interaction: impl FnOnce(
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Layout<'_>,
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Point,
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&Rectangle,
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) -> mouse::Interaction,
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) -> mouse::Interaction {
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let bounds = layout.bounds();
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let content_layout = layout.children().next().unwrap();
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let content_bounds = content_layout.bounds();
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let scrollbar = scrollbar(
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state,
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scrollbar_width,
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scrollbar_margin,
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scroller_width,
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bounds,
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content_bounds,
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);
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let is_mouse_over = bounds.contains(cursor_position);
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let is_mouse_over_scrollbar = scrollbar
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.as_ref()
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.map(|scrollbar| scrollbar.is_mouse_over(cursor_position))
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.unwrap_or(false);
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if is_mouse_over_scrollbar || state.is_scroller_grabbed() {
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mouse::Interaction::Idle
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} else {
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let offset = state.offset(bounds, content_bounds);
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let cursor_position = if is_mouse_over && !is_mouse_over_scrollbar {
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Point::new(cursor_position.x, cursor_position.y + offset as f32)
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} else {
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Point::new(cursor_position.x, -1.0)
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};
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content_interaction(
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content_layout,
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cursor_position,
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&Rectangle {
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y: bounds.y + offset as f32,
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..bounds
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},
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)
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}
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}
|
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|
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/// Draws a [`Scrollable`].
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pub fn draw<Renderer>(
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state: &State,
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renderer: &mut Renderer,
|
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theme: &Renderer::Theme,
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layout: Layout<'_>,
|
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cursor_position: Point,
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scrollbar_width: u16,
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scrollbar_margin: u16,
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scroller_width: u16,
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style: <Renderer::Theme as StyleSheet>::Style,
|
|
draw_content: impl FnOnce(&mut Renderer, Layout<'_>, Point, &Rectangle),
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) where
|
|
Renderer: crate::Renderer,
|
|
Renderer::Theme: StyleSheet,
|
|
{
|
|
let bounds = layout.bounds();
|
|
let content_layout = layout.children().next().unwrap();
|
|
let content_bounds = content_layout.bounds();
|
|
let offset = state.offset(bounds, content_bounds);
|
|
let scrollbar = scrollbar(
|
|
state,
|
|
scrollbar_width,
|
|
scrollbar_margin,
|
|
scroller_width,
|
|
bounds,
|
|
content_bounds,
|
|
);
|
|
|
|
let is_mouse_over = bounds.contains(cursor_position);
|
|
let is_mouse_over_scrollbar = scrollbar
|
|
.as_ref()
|
|
.map(|scrollbar| scrollbar.is_mouse_over(cursor_position))
|
|
.unwrap_or(false);
|
|
|
|
let cursor_position = if is_mouse_over && !is_mouse_over_scrollbar {
|
|
Point::new(cursor_position.x, cursor_position.y + offset as f32)
|
|
} else {
|
|
Point::new(cursor_position.x, -1.0)
|
|
};
|
|
|
|
if let Some(scrollbar) = scrollbar {
|
|
renderer.with_layer(bounds, |renderer| {
|
|
renderer.with_translation(
|
|
Vector::new(0.0, -(offset as f32)),
|
|
|renderer| {
|
|
draw_content(
|
|
renderer,
|
|
content_layout,
|
|
cursor_position,
|
|
&Rectangle {
|
|
y: bounds.y + offset as f32,
|
|
..bounds
|
|
},
|
|
);
|
|
},
|
|
);
|
|
});
|
|
|
|
let style = if state.is_scroller_grabbed() {
|
|
theme.dragging(style)
|
|
} else if is_mouse_over_scrollbar {
|
|
theme.hovered(style)
|
|
} else {
|
|
theme.active(style)
|
|
};
|
|
|
|
let is_scrollbar_visible =
|
|
style.background.is_some() || style.border_width > 0.0;
|
|
|
|
renderer.with_layer(
|
|
Rectangle {
|
|
width: bounds.width + 2.0,
|
|
height: bounds.height + 2.0,
|
|
..bounds
|
|
},
|
|
|renderer| {
|
|
if is_scrollbar_visible {
|
|
renderer.fill_quad(
|
|
renderer::Quad {
|
|
bounds: scrollbar.bounds,
|
|
border_radius: style.border_radius,
|
|
border_width: style.border_width,
|
|
border_color: style.border_color,
|
|
},
|
|
style
|
|
.background
|
|
.unwrap_or(Background::Color(Color::TRANSPARENT)),
|
|
);
|
|
}
|
|
|
|
if is_mouse_over
|
|
|| state.is_scroller_grabbed()
|
|
|| is_scrollbar_visible
|
|
{
|
|
renderer.fill_quad(
|
|
renderer::Quad {
|
|
bounds: scrollbar.scroller.bounds,
|
|
border_radius: style.scroller.border_radius,
|
|
border_width: style.scroller.border_width,
|
|
border_color: style.scroller.border_color,
|
|
},
|
|
style.scroller.color,
|
|
);
|
|
}
|
|
},
|
|
);
|
|
} else {
|
|
draw_content(
|
|
renderer,
|
|
content_layout,
|
|
cursor_position,
|
|
&Rectangle {
|
|
y: bounds.y + offset as f32,
|
|
..bounds
|
|
},
|
|
);
|
|
}
|
|
}
|
|
|
|
fn scrollbar(
|
|
state: &State,
|
|
scrollbar_width: u16,
|
|
scrollbar_margin: u16,
|
|
scroller_width: u16,
|
|
bounds: Rectangle,
|
|
content_bounds: Rectangle,
|
|
) -> Option<Scrollbar> {
|
|
let offset = state.offset(bounds, content_bounds);
|
|
|
|
if content_bounds.height > bounds.height {
|
|
let outer_width =
|
|
scrollbar_width.max(scroller_width) + 2 * scrollbar_margin;
|
|
|
|
let outer_bounds = Rectangle {
|
|
x: bounds.x + bounds.width - outer_width as f32,
|
|
y: bounds.y,
|
|
width: outer_width as f32,
|
|
height: bounds.height,
|
|
};
|
|
|
|
let scrollbar_bounds = Rectangle {
|
|
x: bounds.x + bounds.width
|
|
- f32::from(outer_width / 2 + scrollbar_width / 2),
|
|
y: bounds.y,
|
|
width: scrollbar_width as f32,
|
|
height: bounds.height,
|
|
};
|
|
|
|
let ratio = bounds.height / content_bounds.height;
|
|
let scroller_height = bounds.height * ratio;
|
|
let y_offset = offset as f32 * ratio;
|
|
|
|
let scroller_bounds = Rectangle {
|
|
x: bounds.x + bounds.width
|
|
- f32::from(outer_width / 2 + scroller_width / 2),
|
|
y: scrollbar_bounds.y + y_offset,
|
|
width: scroller_width as f32,
|
|
height: scroller_height,
|
|
};
|
|
|
|
Some(Scrollbar {
|
|
outer_bounds,
|
|
bounds: scrollbar_bounds,
|
|
scroller: Scroller {
|
|
bounds: scroller_bounds,
|
|
},
|
|
})
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
fn notify_on_scroll<Message>(
|
|
state: &State,
|
|
on_scroll: &Option<Box<dyn Fn(f32) -> Message + '_>>,
|
|
bounds: Rectangle,
|
|
content_bounds: Rectangle,
|
|
shell: &mut Shell<'_, Message>,
|
|
) {
|
|
if content_bounds.height <= bounds.height {
|
|
return;
|
|
}
|
|
|
|
if let Some(on_scroll) = on_scroll {
|
|
shell.publish(on_scroll(
|
|
state.offset.absolute(bounds, content_bounds)
|
|
/ (content_bounds.height - bounds.height),
|
|
));
|
|
}
|
|
}
|
|
|
|
/// The local state of a [`Scrollable`].
|
|
#[derive(Debug, Clone, Copy)]
|
|
pub struct State {
|
|
scroller_grabbed_at: Option<f32>,
|
|
scroll_box_touched_at: Option<Point>,
|
|
offset: Offset,
|
|
}
|
|
|
|
impl Default for State {
|
|
fn default() -> Self {
|
|
Self {
|
|
scroller_grabbed_at: None,
|
|
scroll_box_touched_at: None,
|
|
offset: Offset::Absolute(0.0),
|
|
}
|
|
}
|
|
}
|
|
|
|
/// The local state of a [`Scrollable`].
|
|
#[derive(Debug, Clone, Copy)]
|
|
enum Offset {
|
|
Absolute(f32),
|
|
Relative(f32),
|
|
}
|
|
|
|
impl Offset {
|
|
fn absolute(self, bounds: Rectangle, content_bounds: Rectangle) -> f32 {
|
|
match self {
|
|
Self::Absolute(absolute) => {
|
|
let hidden_content =
|
|
(content_bounds.height - bounds.height).max(0.0);
|
|
|
|
absolute.min(hidden_content)
|
|
}
|
|
Self::Relative(percentage) => {
|
|
((content_bounds.height - bounds.height) * percentage).max(0.0)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
impl State {
|
|
/// Creates a new [`State`] with the scrollbar located at the top.
|
|
pub fn new() -> Self {
|
|
State::default()
|
|
}
|
|
|
|
/// Apply a scrolling offset to the current [`State`], given the bounds of
|
|
/// the [`Scrollable`] and its contents.
|
|
pub fn scroll(
|
|
&mut self,
|
|
delta_y: f32,
|
|
bounds: Rectangle,
|
|
content_bounds: Rectangle,
|
|
) {
|
|
if bounds.height >= content_bounds.height {
|
|
return;
|
|
}
|
|
|
|
self.offset = Offset::Absolute(
|
|
(self.offset.absolute(bounds, content_bounds) - delta_y)
|
|
.max(0.0)
|
|
.min((content_bounds.height - bounds.height) as f32),
|
|
);
|
|
}
|
|
|
|
/// Scrolls the [`Scrollable`] to a relative amount.
|
|
///
|
|
/// `0` represents scrollbar at the top, while `1` represents scrollbar at
|
|
/// the bottom.
|
|
pub fn scroll_to(
|
|
&mut self,
|
|
percentage: f32,
|
|
bounds: Rectangle,
|
|
content_bounds: Rectangle,
|
|
) {
|
|
self.snap_to(percentage);
|
|
self.unsnap(bounds, content_bounds);
|
|
}
|
|
|
|
/// Snaps the scroll position to a relative amount.
|
|
///
|
|
/// `0` represents scrollbar at the top, while `1` represents scrollbar at
|
|
/// the bottom.
|
|
pub fn snap_to(&mut self, percentage: f32) {
|
|
self.offset = Offset::Relative(percentage.max(0.0).min(1.0));
|
|
}
|
|
|
|
/// Unsnaps the current scroll position, if snapped, given the bounds of the
|
|
/// [`Scrollable`] and its contents.
|
|
pub fn unsnap(&mut self, bounds: Rectangle, content_bounds: Rectangle) {
|
|
self.offset =
|
|
Offset::Absolute(self.offset.absolute(bounds, content_bounds));
|
|
}
|
|
|
|
/// Returns the current scrolling offset of the [`State`], given the bounds
|
|
/// of the [`Scrollable`] and its contents.
|
|
pub fn offset(&self, bounds: Rectangle, content_bounds: Rectangle) -> u32 {
|
|
self.offset.absolute(bounds, content_bounds) as u32
|
|
}
|
|
|
|
/// Returns whether the scroller is currently grabbed or not.
|
|
pub fn is_scroller_grabbed(&self) -> bool {
|
|
self.scroller_grabbed_at.is_some()
|
|
}
|
|
|
|
/// Returns whether the scroll box is currently touched or not.
|
|
pub fn is_scroll_box_touched(&self) -> bool {
|
|
self.scroll_box_touched_at.is_some()
|
|
}
|
|
}
|
|
|
|
/// The scrollbar of a [`Scrollable`].
|
|
#[derive(Debug)]
|
|
struct Scrollbar {
|
|
/// The outer bounds of the scrollable, including the [`Scrollbar`] and
|
|
/// [`Scroller`].
|
|
outer_bounds: Rectangle,
|
|
|
|
/// The bounds of the [`Scrollbar`].
|
|
bounds: Rectangle,
|
|
|
|
/// The bounds of the [`Scroller`].
|
|
scroller: Scroller,
|
|
}
|
|
|
|
impl Scrollbar {
|
|
fn is_mouse_over(&self, cursor_position: Point) -> bool {
|
|
self.outer_bounds.contains(cursor_position)
|
|
}
|
|
|
|
fn grab_scroller(&self, cursor_position: Point) -> Option<f32> {
|
|
if self.outer_bounds.contains(cursor_position) {
|
|
Some(if self.scroller.bounds.contains(cursor_position) {
|
|
(cursor_position.y - self.scroller.bounds.y)
|
|
/ self.scroller.bounds.height
|
|
} else {
|
|
0.5
|
|
})
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
fn scroll_percentage(
|
|
&self,
|
|
grabbed_at: f32,
|
|
cursor_position: Point,
|
|
) -> f32 {
|
|
(cursor_position.y
|
|
- self.bounds.y
|
|
- self.scroller.bounds.height * grabbed_at)
|
|
/ (self.bounds.height - self.scroller.bounds.height)
|
|
}
|
|
}
|
|
|
|
/// The handle of a [`Scrollbar`].
|
|
#[derive(Debug, Clone, Copy)]
|
|
struct Scroller {
|
|
/// The bounds of the [`Scroller`].
|
|
bounds: Rectangle,
|
|
}
|