597 lines
18 KiB
Rust
597 lines
18 KiB
Rust
//! Navigate an endless amount of content with a scrollbar.
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use crate::{
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column, layout, mouse, overlay, Align, Clipboard, Column, Element, Event,
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Hasher, Layout, Length, Point, Rectangle, Size, Vector, Widget,
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};
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use std::{f32, hash::Hash, u32};
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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: self::Renderer> {
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state: &'a mut State,
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height: Length,
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max_height: u32,
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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: Column<'a, Message, Renderer>,
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style: Renderer::Style,
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}
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impl<'a, Message, Renderer: self::Renderer> Scrollable<'a, Message, Renderer> {
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/// Creates a new [`Scrollable`] with the given [`State`].
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///
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/// [`Scrollable`]: struct.Scrollable.html
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/// [`State`]: struct.State.html
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pub fn new(state: &'a mut State) -> Self {
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Scrollable {
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state,
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height: Length::Shrink,
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max_height: u32::MAX,
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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: Column::new(),
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style: Renderer::Style::default(),
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}
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}
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/// Sets the vertical spacing _between_ elements.
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///
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/// Custom margins per element do not exist in Iced. You should use this
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/// method instead! While less flexible, it helps you keep spacing between
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/// elements consistent.
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pub fn spacing(mut self, units: u16) -> Self {
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self.content = self.content.spacing(units);
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self
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}
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/// Sets the padding of the [`Scrollable`].
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///
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/// [`Scrollable`]: struct.Scrollable.html
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pub fn padding(mut self, units: u16) -> Self {
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self.content = self.content.padding(units);
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self
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}
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/// Sets the width of the [`Scrollable`].
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///
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/// [`Scrollable`]: struct.Scrollable.html
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pub fn width(mut self, width: Length) -> Self {
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self.content = self.content.width(width);
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self
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}
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/// Sets the height of the [`Scrollable`].
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///
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/// [`Scrollable`]: struct.Scrollable.html
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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 maximum width of the [`Scrollable`].
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///
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/// [`Scrollable`]: struct.Scrollable.html
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pub fn max_width(mut self, max_width: u32) -> Self {
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self.content = self.content.max_width(max_width);
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self
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}
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/// Sets the maximum height of the [`Scrollable`] in pixels.
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///
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/// [`Scrollable`]: struct.Scrollable.html
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pub fn max_height(mut self, max_height: u32) -> Self {
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self.max_height = max_height;
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self
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}
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/// Sets the horizontal alignment of the contents of the [`Scrollable`] .
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///
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/// [`Scrollable`]: struct.Scrollable.html
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pub fn align_items(mut self, align_items: Align) -> Self {
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self.content = self.content.align_items(align_items);
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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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///
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/// [`Scrollable`]: struct.Scrollable.html
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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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///
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/// [`Scrollable`]: struct.Scrollable.html
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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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/// Silently enforces a minimum value of 1.
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///
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/// [`Scrollable`]: struct.Scrollable.html
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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 the style of the [`Scrollable`] .
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///
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/// [`Scrollable`]: struct.Scrollable.html
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pub fn style(mut self, style: impl Into<Renderer::Style>) -> Self {
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self.style = style.into();
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self
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}
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/// Adds an element to the [`Scrollable`].
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///
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/// [`Scrollable`]: struct.Scrollable.html
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pub fn push<E>(mut self, child: E) -> Self
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where
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E: Into<Element<'a, Message, Renderer>>,
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{
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self.content = self.content.push(child);
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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: self::Renderer,
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{
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fn width(&self) -> Length {
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Widget::<Message, Renderer>::width(&self.content)
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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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let limits = limits
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.max_height(self.max_height)
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.width(Widget::<Message, Renderer>::width(&self.content))
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.height(self.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 = self.content.layout(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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fn on_event(
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&mut self,
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event: Event,
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layout: Layout<'_>,
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cursor_position: Point,
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messages: &mut Vec<Message>,
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renderer: &Renderer,
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clipboard: Option<&dyn Clipboard>,
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) {
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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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// TODO: Event capture. Nested scrollables should capture scroll events.
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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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self.state.scroll(y * 60.0, bounds, content_bounds);
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}
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mouse::ScrollDelta::Pixels { y, .. } => {
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self.state.scroll(y, bounds, content_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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}
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let offset = self.state.offset(bounds, content_bounds);
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let scrollbar = renderer.scrollbar(
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bounds,
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content_bounds,
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offset,
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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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);
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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 self.state.is_scroller_grabbed() {
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match event {
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Event::Mouse(mouse::Event::ButtonReleased(
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mouse::Button::Left,
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)) => {
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self.state.scroller_grabbed_at = None;
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}
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Event::Mouse(mouse::Event::CursorMoved { .. }) => {
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if let (Some(scrollbar), Some(scroller_grabbed_at)) =
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(scrollbar, self.state.scroller_grabbed_at)
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{
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self.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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}
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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(
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mouse::Button::Left,
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)) => {
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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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self.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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self.state.scroller_grabbed_at =
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Some(scroller_grabbed_at);
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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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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
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+ self.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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self.content.on_event(
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event,
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content,
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cursor_position,
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messages,
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renderer,
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clipboard,
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)
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}
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fn draw(
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&self,
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renderer: &mut Renderer,
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defaults: &Renderer::Defaults,
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layout: Layout<'_>,
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cursor_position: Point,
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_viewport: &Rectangle,
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) -> Renderer::Output {
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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 = self.state.offset(bounds, content_bounds);
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let scrollbar = renderer.scrollbar(
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bounds,
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content_bounds,
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offset,
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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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);
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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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let content = {
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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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self.content.draw(
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renderer,
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defaults,
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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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self::Renderer::draw(
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renderer,
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&self.state,
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bounds,
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content_layout.bounds(),
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is_mouse_over,
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is_mouse_over_scrollbar,
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scrollbar,
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offset,
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&self.style,
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content,
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)
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}
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fn hash_layout(&self, state: &mut Hasher) {
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struct Marker;
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std::any::TypeId::of::<Marker>().hash(state);
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self.height.hash(state);
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self.max_height.hash(state);
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self.content.hash_layout(state)
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}
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fn overlay(
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&mut self,
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layout: Layout<'_>,
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) -> Option<overlay::Element<'_, Message, Renderer>> {
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let Self { content, state, .. } = self;
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content
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.overlay(layout.children().next().unwrap())
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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 = state.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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/// The local state of a [`Scrollable`].
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///
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/// [`Scrollable`]: struct.Scrollable.html
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#[derive(Debug, Clone, Copy, Default)]
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pub struct State {
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scroller_grabbed_at: Option<f32>,
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offset: f32,
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}
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impl State {
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/// Creates a new [`State`] with the scrollbar located at the top.
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///
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/// [`State`]: struct.State.html
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pub fn new() -> Self {
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State::default()
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}
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/// Apply a scrolling offset to the current [`State`], given the bounds of
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/// the [`Scrollable`] and its contents.
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///
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/// [`Scrollable`]: struct.Scrollable.html
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/// [`State`]: struct.State.html
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pub fn scroll(
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&mut self,
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delta_y: f32,
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bounds: Rectangle,
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content_bounds: Rectangle,
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) {
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if bounds.height >= content_bounds.height {
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return;
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}
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self.offset = (self.offset - delta_y)
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.max(0.0)
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.min((content_bounds.height - bounds.height) as f32);
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}
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/// Moves the scroll position to a relative amount, given the bounds of
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/// the [`Scrollable`] and its contents.
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///
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/// `0` represents scrollbar at the top, while `1` represents scrollbar at
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/// the bottom.
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///
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/// [`Scrollable`]: struct.Scrollable.html
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/// [`State`]: struct.State.html
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pub fn scroll_to(
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&mut self,
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percentage: f32,
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bounds: Rectangle,
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content_bounds: Rectangle,
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) {
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self.offset =
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((content_bounds.height - bounds.height) * percentage).max(0.0);
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}
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/// Returns the current scrolling offset of the [`State`], given the bounds
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/// of the [`Scrollable`] and its contents.
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///
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/// [`Scrollable`]: struct.Scrollable.html
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/// [`State`]: struct.State.html
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pub fn offset(&self, bounds: Rectangle, content_bounds: Rectangle) -> u32 {
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let hidden_content =
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(content_bounds.height - bounds.height).max(0.0).round() as u32;
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self.offset.min(hidden_content as f32) as u32
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}
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/// Returns whether the scroller is currently grabbed or not.
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pub fn is_scroller_grabbed(&self) -> bool {
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self.scroller_grabbed_at.is_some()
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}
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}
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/// The scrollbar of a [`Scrollable`].
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///
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/// [`Scrollable`]: struct.Scrollable.html
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#[derive(Debug)]
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pub struct Scrollbar {
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/// The outer bounds of the scrollable, including the [`Scrollbar`] and
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/// [`Scroller`].
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///
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/// [`Scrollbar`]: struct.Scrollbar.html
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/// [`Scroller`]: struct.Scroller.html
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pub outer_bounds: Rectangle,
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/// The bounds of the [`Scrollbar`].
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///
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/// [`Scrollbar`]: struct.Scrollbar.html
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pub bounds: Rectangle,
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/// The margin within the [`Scrollbar`].
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///
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/// [`Scrollbar`]: struct.Scrollbar.html
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pub margin: u16,
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/// The bounds of the [`Scroller`].
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///
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/// [`Scroller`]: struct.Scroller.html
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pub scroller: Scroller,
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}
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impl Scrollbar {
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fn is_mouse_over(&self, cursor_position: Point) -> bool {
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self.outer_bounds.contains(cursor_position)
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}
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fn grab_scroller(&self, cursor_position: Point) -> Option<f32> {
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if self.outer_bounds.contains(cursor_position) {
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Some(if self.scroller.bounds.contains(cursor_position) {
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(cursor_position.y - self.scroller.bounds.y)
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/ self.scroller.bounds.height
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} else {
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0.5
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})
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} else {
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None
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}
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}
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fn scroll_percentage(
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&self,
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grabbed_at: f32,
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cursor_position: Point,
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) -> f32 {
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(cursor_position.y
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- self.bounds.y
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- self.scroller.bounds.height * grabbed_at)
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/ (self.bounds.height - self.scroller.bounds.height)
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}
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}
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/// The handle of a [`Scrollbar`].
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///
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/// [`Scrollbar`]: struct.Scrollbar.html
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#[derive(Debug, Clone, Copy)]
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pub struct Scroller {
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/// The bounds of the [`Scroller`].
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///
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/// [`Scroller`]: struct.Scrollbar.html
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pub bounds: Rectangle,
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}
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/// The renderer of a [`Scrollable`].
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///
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/// Your [renderer] will need to implement this trait before being
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/// able to use a [`Scrollable`] in your user interface.
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///
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/// [`Scrollable`]: struct.Scrollable.html
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/// [renderer]: ../../renderer/index.html
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pub trait Renderer: column::Renderer + Sized {
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/// The style supported by this renderer.
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type Style: Default;
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|
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/// Returns the [`Scrollbar`] given the bounds and content bounds of a
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/// [`Scrollable`].
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///
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/// [`Scrollbar`]: struct.Scrollbar.html
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/// [`Scrollable`]: struct.Scrollable.html
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fn scrollbar(
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&self,
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bounds: Rectangle,
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content_bounds: Rectangle,
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offset: u32,
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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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) -> Option<Scrollbar>;
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/// Draws the [`Scrollable`].
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///
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/// It receives:
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/// - the [`State`] of the [`Scrollable`]
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/// - the bounds of the [`Scrollable`] widget
|
|
/// - the bounds of the [`Scrollable`] content
|
|
/// - whether the mouse is over the [`Scrollable`] or not
|
|
/// - whether the mouse is over the [`Scrollbar`] or not
|
|
/// - a optional [`Scrollbar`] to be rendered
|
|
/// - the scrolling offset
|
|
/// - the drawn content
|
|
///
|
|
/// [`Scrollbar`]: struct.Scrollbar.html
|
|
/// [`Scrollable`]: struct.Scrollable.html
|
|
/// [`State`]: struct.State.html
|
|
fn draw(
|
|
&mut self,
|
|
scrollable: &State,
|
|
bounds: Rectangle,
|
|
content_bounds: Rectangle,
|
|
is_mouse_over: bool,
|
|
is_mouse_over_scrollbar: bool,
|
|
scrollbar: Option<Scrollbar>,
|
|
offset: u32,
|
|
style: &Self::Style,
|
|
content: Self::Output,
|
|
) -> Self::Output;
|
|
}
|
|
|
|
impl<'a, Message, Renderer> From<Scrollable<'a, Message, Renderer>>
|
|
for Element<'a, Message, Renderer>
|
|
where
|
|
Renderer: 'a + self::Renderer,
|
|
Message: 'a,
|
|
{
|
|
fn from(
|
|
scrollable: Scrollable<'a, Message, Renderer>,
|
|
) -> Element<'a, Message, Renderer> {
|
|
Element::new(scrollable)
|
|
}
|
|
}
|