53175263a1
Follow up to: https://github.com/zed-industries/zed/pull/35670, simplifies the List state APIs so you no longer have to worry about strong vs. weak pointers when rendering list items. Release Notes: - N/A --------- Co-authored-by: Agus Zubiaga <agus@zed.dev>
1205 lines
43 KiB
Rust
1205 lines
43 KiB
Rust
//! A list element that can be used to render a large number of differently sized elements
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//! efficiently. Clients of this API need to ensure that elements outside of the scrolled
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//! area do not change their height for this element to function correctly. If your elements
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//! do change height, notify the list element via [`ListState::splice`] or [`ListState::reset`].
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//! In order to minimize re-renders, this element's state is stored intrusively
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//! on your own views, so that your code can coordinate directly with the list element's cached state.
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//!
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//! If all of your elements are the same height, see [`UniformList`] for a simpler API
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use crate::{
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AnyElement, App, AvailableSpace, Bounds, ContentMask, DispatchPhase, Edges, Element, EntityId,
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FocusHandle, GlobalElementId, Hitbox, HitboxBehavior, InspectorElementId, IntoElement,
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Overflow, Pixels, Point, ScrollDelta, ScrollWheelEvent, Size, Style, StyleRefinement, Styled,
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Window, point, px, size,
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};
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use collections::VecDeque;
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use refineable::Refineable as _;
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use std::{cell::RefCell, ops::Range, rc::Rc};
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use sum_tree::{Bias, Dimensions, SumTree};
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type RenderItemFn = dyn FnMut(usize, &mut Window, &mut App) -> AnyElement + 'static;
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/// Construct a new list element
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pub fn list(
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state: ListState,
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render_item: impl FnMut(usize, &mut Window, &mut App) -> AnyElement + 'static,
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) -> List {
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List {
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state,
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render_item: Box::new(render_item),
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style: StyleRefinement::default(),
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sizing_behavior: ListSizingBehavior::default(),
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}
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}
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/// A list element
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pub struct List {
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state: ListState,
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render_item: Box<RenderItemFn>,
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style: StyleRefinement,
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sizing_behavior: ListSizingBehavior,
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}
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impl List {
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/// Set the sizing behavior for the list.
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pub fn with_sizing_behavior(mut self, behavior: ListSizingBehavior) -> Self {
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self.sizing_behavior = behavior;
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self
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}
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}
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/// The list state that views must hold on behalf of the list element.
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#[derive(Clone)]
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pub struct ListState(Rc<RefCell<StateInner>>);
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impl std::fmt::Debug for ListState {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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f.write_str("ListState")
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}
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}
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struct StateInner {
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last_layout_bounds: Option<Bounds<Pixels>>,
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last_padding: Option<Edges<Pixels>>,
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items: SumTree<ListItem>,
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logical_scroll_top: Option<ListOffset>,
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alignment: ListAlignment,
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overdraw: Pixels,
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reset: bool,
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#[allow(clippy::type_complexity)]
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scroll_handler: Option<Box<dyn FnMut(&ListScrollEvent, &mut Window, &mut App)>>,
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scrollbar_drag_start_height: Option<Pixels>,
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}
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/// Whether the list is scrolling from top to bottom or bottom to top.
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#[derive(Clone, Copy, Debug, Eq, PartialEq)]
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pub enum ListAlignment {
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/// The list is scrolling from top to bottom, like most lists.
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Top,
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/// The list is scrolling from bottom to top, like a chat log.
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Bottom,
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}
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/// A scroll event that has been converted to be in terms of the list's items.
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pub struct ListScrollEvent {
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/// The range of items currently visible in the list, after applying the scroll event.
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pub visible_range: Range<usize>,
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/// The number of items that are currently visible in the list, after applying the scroll event.
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pub count: usize,
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/// Whether the list has been scrolled.
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pub is_scrolled: bool,
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}
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/// The sizing behavior to apply during layout.
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#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
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pub enum ListSizingBehavior {
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/// The list should calculate its size based on the size of its items.
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Infer,
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/// The list should not calculate a fixed size.
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#[default]
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Auto,
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}
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/// The horizontal sizing behavior to apply during layout.
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#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
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pub enum ListHorizontalSizingBehavior {
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/// List items' width can never exceed the width of the list.
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#[default]
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FitList,
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/// List items' width may go over the width of the list, if any item is wider.
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Unconstrained,
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}
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struct LayoutItemsResponse {
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max_item_width: Pixels,
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scroll_top: ListOffset,
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item_layouts: VecDeque<ItemLayout>,
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}
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struct ItemLayout {
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index: usize,
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element: AnyElement,
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size: Size<Pixels>,
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}
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/// Frame state used by the [List] element after layout.
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pub struct ListPrepaintState {
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hitbox: Hitbox,
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layout: LayoutItemsResponse,
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}
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#[derive(Clone)]
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enum ListItem {
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Unmeasured {
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focus_handle: Option<FocusHandle>,
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},
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Measured {
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size: Size<Pixels>,
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focus_handle: Option<FocusHandle>,
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},
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}
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impl ListItem {
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fn size(&self) -> Option<Size<Pixels>> {
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if let ListItem::Measured { size, .. } = self {
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Some(*size)
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} else {
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None
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}
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}
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fn focus_handle(&self) -> Option<FocusHandle> {
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match self {
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ListItem::Unmeasured { focus_handle } | ListItem::Measured { focus_handle, .. } => {
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focus_handle.clone()
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}
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}
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}
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fn contains_focused(&self, window: &Window, cx: &App) -> bool {
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match self {
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ListItem::Unmeasured { focus_handle } | ListItem::Measured { focus_handle, .. } => {
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focus_handle
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.as_ref()
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.is_some_and(|handle| handle.contains_focused(window, cx))
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}
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}
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}
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}
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#[derive(Clone, Debug, Default, PartialEq)]
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struct ListItemSummary {
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count: usize,
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rendered_count: usize,
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unrendered_count: usize,
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height: Pixels,
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has_focus_handles: bool,
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}
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#[derive(Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
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struct Count(usize);
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#[derive(Clone, Debug, Default)]
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struct Height(Pixels);
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impl ListState {
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/// Construct a new list state, for storage on a view.
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///
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/// The overdraw parameter controls how much extra space is rendered
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/// above and below the visible area. Elements within this area will
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/// be measured even though they are not visible. This can help ensure
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/// that the list doesn't flicker or pop in when scrolling.
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pub fn new(item_count: usize, alignment: ListAlignment, overdraw: Pixels) -> Self {
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let this = Self(Rc::new(RefCell::new(StateInner {
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last_layout_bounds: None,
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last_padding: None,
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items: SumTree::default(),
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logical_scroll_top: None,
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alignment,
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overdraw,
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scroll_handler: None,
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reset: false,
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scrollbar_drag_start_height: None,
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})));
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this.splice(0..0, item_count);
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this
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}
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/// Reset this instantiation of the list state.
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///
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/// Note that this will cause scroll events to be dropped until the next paint.
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pub fn reset(&self, element_count: usize) {
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let old_count = {
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let state = &mut *self.0.borrow_mut();
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state.reset = true;
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state.logical_scroll_top = None;
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state.scrollbar_drag_start_height = None;
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state.items.summary().count
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};
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self.splice(0..old_count, element_count);
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}
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/// The number of items in this list.
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pub fn item_count(&self) -> usize {
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self.0.borrow().items.summary().count
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}
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/// Inform the list state that the items in `old_range` have been replaced
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/// by `count` new items that must be recalculated.
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pub fn splice(&self, old_range: Range<usize>, count: usize) {
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self.splice_focusable(old_range, (0..count).map(|_| None))
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}
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/// Register with the list state that the items in `old_range` have been replaced
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/// by new items. As opposed to [`splice`], this method allows an iterator of optional focus handles
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/// to be supplied to properly integrate with items in the list that can be focused. If a focused item
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/// is scrolled out of view, the list will continue to render it to allow keyboard interaction.
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pub fn splice_focusable(
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&self,
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old_range: Range<usize>,
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focus_handles: impl IntoIterator<Item = Option<FocusHandle>>,
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) {
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let state = &mut *self.0.borrow_mut();
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let mut old_items = state.items.cursor::<Count>(&());
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let mut new_items = old_items.slice(&Count(old_range.start), Bias::Right);
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old_items.seek_forward(&Count(old_range.end), Bias::Right);
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let mut spliced_count = 0;
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new_items.extend(
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focus_handles.into_iter().map(|focus_handle| {
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spliced_count += 1;
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ListItem::Unmeasured { focus_handle }
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}),
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&(),
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);
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new_items.append(old_items.suffix(), &());
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drop(old_items);
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state.items = new_items;
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if let Some(ListOffset {
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item_ix,
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offset_in_item,
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}) = state.logical_scroll_top.as_mut()
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{
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if old_range.contains(item_ix) {
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*item_ix = old_range.start;
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*offset_in_item = px(0.);
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} else if old_range.end <= *item_ix {
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*item_ix = *item_ix - (old_range.end - old_range.start) + spliced_count;
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}
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}
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}
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/// Set a handler that will be called when the list is scrolled.
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pub fn set_scroll_handler(
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&self,
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handler: impl FnMut(&ListScrollEvent, &mut Window, &mut App) + 'static,
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) {
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self.0.borrow_mut().scroll_handler = Some(Box::new(handler))
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}
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/// Get the current scroll offset, in terms of the list's items.
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pub fn logical_scroll_top(&self) -> ListOffset {
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self.0.borrow().logical_scroll_top()
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}
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/// Scroll the list by the given offset
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pub fn scroll_by(&self, distance: Pixels) {
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if distance == px(0.) {
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return;
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}
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let current_offset = self.logical_scroll_top();
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let state = &mut *self.0.borrow_mut();
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let mut cursor = state.items.cursor::<ListItemSummary>(&());
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cursor.seek(&Count(current_offset.item_ix), Bias::Right);
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let start_pixel_offset = cursor.start().height + current_offset.offset_in_item;
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let new_pixel_offset = (start_pixel_offset + distance).max(px(0.));
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if new_pixel_offset > start_pixel_offset {
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cursor.seek_forward(&Height(new_pixel_offset), Bias::Right);
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} else {
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cursor.seek(&Height(new_pixel_offset), Bias::Right);
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}
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state.logical_scroll_top = Some(ListOffset {
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item_ix: cursor.start().count,
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offset_in_item: new_pixel_offset - cursor.start().height,
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});
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}
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/// Scroll the list to the given offset
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pub fn scroll_to(&self, mut scroll_top: ListOffset) {
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let state = &mut *self.0.borrow_mut();
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let item_count = state.items.summary().count;
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if scroll_top.item_ix >= item_count {
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scroll_top.item_ix = item_count;
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scroll_top.offset_in_item = px(0.);
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}
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state.logical_scroll_top = Some(scroll_top);
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}
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/// Scroll the list to the given item, such that the item is fully visible.
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pub fn scroll_to_reveal_item(&self, ix: usize) {
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let state = &mut *self.0.borrow_mut();
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let mut scroll_top = state.logical_scroll_top();
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let height = state
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.last_layout_bounds
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.map_or(px(0.), |bounds| bounds.size.height);
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let padding = state.last_padding.unwrap_or_default();
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if ix <= scroll_top.item_ix {
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scroll_top.item_ix = ix;
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scroll_top.offset_in_item = px(0.);
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} else {
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let mut cursor = state.items.cursor::<ListItemSummary>(&());
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cursor.seek(&Count(ix + 1), Bias::Right);
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let bottom = cursor.start().height + padding.top;
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let goal_top = px(0.).max(bottom - height + padding.bottom);
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cursor.seek(&Height(goal_top), Bias::Left);
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let start_ix = cursor.start().count;
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let start_item_top = cursor.start().height;
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if start_ix >= scroll_top.item_ix {
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scroll_top.item_ix = start_ix;
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scroll_top.offset_in_item = goal_top - start_item_top;
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}
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}
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state.logical_scroll_top = Some(scroll_top);
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}
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/// Get the bounds for the given item in window coordinates, if it's
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/// been rendered.
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pub fn bounds_for_item(&self, ix: usize) -> Option<Bounds<Pixels>> {
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let state = &*self.0.borrow();
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let bounds = state.last_layout_bounds.unwrap_or_default();
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let scroll_top = state.logical_scroll_top();
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if ix < scroll_top.item_ix {
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return None;
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}
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let mut cursor = state.items.cursor::<Dimensions<Count, Height>>(&());
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cursor.seek(&Count(scroll_top.item_ix), Bias::Right);
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let scroll_top = cursor.start().1.0 + scroll_top.offset_in_item;
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cursor.seek_forward(&Count(ix), Bias::Right);
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if let Some(&ListItem::Measured { size, .. }) = cursor.item() {
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let &Dimensions(Count(count), Height(top), _) = cursor.start();
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if count == ix {
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let top = bounds.top() + top - scroll_top;
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return Some(Bounds::from_corners(
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point(bounds.left(), top),
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point(bounds.right(), top + size.height),
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));
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}
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}
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None
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}
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/// Call this method when the user starts dragging the scrollbar.
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///
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/// This will prevent the height reported to the scrollbar from changing during the drag
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/// as items in the overdraw get measured, and help offset scroll position changes accordingly.
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pub fn scrollbar_drag_started(&self) {
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let mut state = self.0.borrow_mut();
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state.scrollbar_drag_start_height = Some(state.items.summary().height);
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}
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/// Called when the user stops dragging the scrollbar.
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///
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/// See `scrollbar_drag_started`.
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pub fn scrollbar_drag_ended(&self) {
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self.0.borrow_mut().scrollbar_drag_start_height.take();
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}
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/// Set the offset from the scrollbar
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pub fn set_offset_from_scrollbar(&self, point: Point<Pixels>) {
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self.0.borrow_mut().set_offset_from_scrollbar(point);
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}
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/// Returns the maximum scroll offset according to the items we have measured.
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/// This value remains constant while dragging to prevent the scrollbar from moving away unexpectedly.
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pub fn max_offset_for_scrollbar(&self) -> Size<Pixels> {
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let state = self.0.borrow();
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let bounds = state.last_layout_bounds.unwrap_or_default();
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let height = state
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.scrollbar_drag_start_height
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.unwrap_or_else(|| state.items.summary().height);
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Size::new(Pixels::ZERO, Pixels::ZERO.max(height - bounds.size.height))
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}
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/// Returns the current scroll offset adjusted for the scrollbar
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pub fn scroll_px_offset_for_scrollbar(&self) -> Point<Pixels> {
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let state = &self.0.borrow();
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let logical_scroll_top = state.logical_scroll_top();
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let mut cursor = state.items.cursor::<ListItemSummary>(&());
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let summary: ListItemSummary =
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cursor.summary(&Count(logical_scroll_top.item_ix), Bias::Right);
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let content_height = state.items.summary().height;
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let drag_offset =
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// if dragging the scrollbar, we want to offset the point if the height changed
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content_height - state.scrollbar_drag_start_height.unwrap_or(content_height);
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let offset = summary.height + logical_scroll_top.offset_in_item - drag_offset;
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Point::new(px(0.), -offset)
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}
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|
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/// Return the bounds of the viewport in pixels.
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pub fn viewport_bounds(&self) -> Bounds<Pixels> {
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self.0.borrow().last_layout_bounds.unwrap_or_default()
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}
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}
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|
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impl StateInner {
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fn visible_range(&self, height: Pixels, scroll_top: &ListOffset) -> Range<usize> {
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let mut cursor = self.items.cursor::<ListItemSummary>(&());
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cursor.seek(&Count(scroll_top.item_ix), Bias::Right);
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let start_y = cursor.start().height + scroll_top.offset_in_item;
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cursor.seek_forward(&Height(start_y + height), Bias::Left);
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scroll_top.item_ix..cursor.start().count + 1
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}
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|
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fn scroll(
|
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&mut self,
|
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scroll_top: &ListOffset,
|
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height: Pixels,
|
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delta: Point<Pixels>,
|
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current_view: EntityId,
|
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window: &mut Window,
|
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cx: &mut App,
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) {
|
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// Drop scroll events after a reset, since we can't calculate
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// the new logical scroll top without the item heights
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if self.reset {
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return;
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}
|
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|
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let padding = self.last_padding.unwrap_or_default();
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let scroll_max =
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(self.items.summary().height + padding.top + padding.bottom - height).max(px(0.));
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let new_scroll_top = (self.scroll_top(scroll_top) - delta.y)
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.max(px(0.))
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.min(scroll_max);
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|
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if self.alignment == ListAlignment::Bottom && new_scroll_top == scroll_max {
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self.logical_scroll_top = None;
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} else {
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let mut cursor = self.items.cursor::<ListItemSummary>(&());
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cursor.seek(&Height(new_scroll_top), Bias::Right);
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let item_ix = cursor.start().count;
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let offset_in_item = new_scroll_top - cursor.start().height;
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self.logical_scroll_top = Some(ListOffset {
|
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item_ix,
|
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offset_in_item,
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});
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|
}
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|
|
if self.scroll_handler.is_some() {
|
|
let visible_range = self.visible_range(height, scroll_top);
|
|
self.scroll_handler.as_mut().unwrap()(
|
|
&ListScrollEvent {
|
|
visible_range,
|
|
count: self.items.summary().count,
|
|
is_scrolled: self.logical_scroll_top.is_some(),
|
|
},
|
|
window,
|
|
cx,
|
|
);
|
|
}
|
|
|
|
cx.notify(current_view);
|
|
}
|
|
|
|
fn logical_scroll_top(&self) -> ListOffset {
|
|
self.logical_scroll_top
|
|
.unwrap_or_else(|| match self.alignment {
|
|
ListAlignment::Top => ListOffset {
|
|
item_ix: 0,
|
|
offset_in_item: px(0.),
|
|
},
|
|
ListAlignment::Bottom => ListOffset {
|
|
item_ix: self.items.summary().count,
|
|
offset_in_item: px(0.),
|
|
},
|
|
})
|
|
}
|
|
|
|
fn scroll_top(&self, logical_scroll_top: &ListOffset) -> Pixels {
|
|
let mut cursor = self.items.cursor::<ListItemSummary>(&());
|
|
cursor.seek(&Count(logical_scroll_top.item_ix), Bias::Right);
|
|
cursor.start().height + logical_scroll_top.offset_in_item
|
|
}
|
|
|
|
fn layout_items(
|
|
&mut self,
|
|
available_width: Option<Pixels>,
|
|
available_height: Pixels,
|
|
padding: &Edges<Pixels>,
|
|
render_item: &mut RenderItemFn,
|
|
window: &mut Window,
|
|
cx: &mut App,
|
|
) -> LayoutItemsResponse {
|
|
let old_items = self.items.clone();
|
|
let mut measured_items = VecDeque::new();
|
|
let mut item_layouts = VecDeque::new();
|
|
let mut rendered_height = padding.top;
|
|
let mut max_item_width = px(0.);
|
|
let mut scroll_top = self.logical_scroll_top();
|
|
let mut rendered_focused_item = false;
|
|
|
|
let available_item_space = size(
|
|
available_width.map_or(AvailableSpace::MinContent, |width| {
|
|
AvailableSpace::Definite(width)
|
|
}),
|
|
AvailableSpace::MinContent,
|
|
);
|
|
|
|
let mut cursor = old_items.cursor::<Count>(&());
|
|
|
|
// Render items after the scroll top, including those in the trailing overdraw
|
|
cursor.seek(&Count(scroll_top.item_ix), Bias::Right);
|
|
for (ix, item) in cursor.by_ref().enumerate() {
|
|
let visible_height = rendered_height - scroll_top.offset_in_item;
|
|
if visible_height >= available_height + self.overdraw {
|
|
break;
|
|
}
|
|
|
|
// Use the previously cached height and focus handle if available
|
|
let mut size = item.size();
|
|
|
|
// If we're within the visible area or the height wasn't cached, render and measure the item's element
|
|
if visible_height < available_height || size.is_none() {
|
|
let item_index = scroll_top.item_ix + ix;
|
|
let mut element = render_item(item_index, window, cx);
|
|
let element_size = element.layout_as_root(available_item_space, window, cx);
|
|
size = Some(element_size);
|
|
if visible_height < available_height {
|
|
item_layouts.push_back(ItemLayout {
|
|
index: item_index,
|
|
element,
|
|
size: element_size,
|
|
});
|
|
if item.contains_focused(window, cx) {
|
|
rendered_focused_item = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
let size = size.unwrap();
|
|
rendered_height += size.height;
|
|
max_item_width = max_item_width.max(size.width);
|
|
measured_items.push_back(ListItem::Measured {
|
|
size,
|
|
focus_handle: item.focus_handle(),
|
|
});
|
|
}
|
|
rendered_height += padding.bottom;
|
|
|
|
// Prepare to start walking upward from the item at the scroll top.
|
|
cursor.seek(&Count(scroll_top.item_ix), Bias::Right);
|
|
|
|
// If the rendered items do not fill the visible region, then adjust
|
|
// the scroll top upward.
|
|
if rendered_height - scroll_top.offset_in_item < available_height {
|
|
while rendered_height < available_height {
|
|
cursor.prev();
|
|
if let Some(item) = cursor.item() {
|
|
let item_index = cursor.start().0;
|
|
let mut element = render_item(item_index, window, cx);
|
|
let element_size = element.layout_as_root(available_item_space, window, cx);
|
|
let focus_handle = item.focus_handle();
|
|
rendered_height += element_size.height;
|
|
measured_items.push_front(ListItem::Measured {
|
|
size: element_size,
|
|
focus_handle,
|
|
});
|
|
item_layouts.push_front(ItemLayout {
|
|
index: item_index,
|
|
element,
|
|
size: element_size,
|
|
});
|
|
if item.contains_focused(window, cx) {
|
|
rendered_focused_item = true;
|
|
}
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
|
|
scroll_top = ListOffset {
|
|
item_ix: cursor.start().0,
|
|
offset_in_item: rendered_height - available_height,
|
|
};
|
|
|
|
match self.alignment {
|
|
ListAlignment::Top => {
|
|
scroll_top.offset_in_item = scroll_top.offset_in_item.max(px(0.));
|
|
self.logical_scroll_top = Some(scroll_top);
|
|
}
|
|
ListAlignment::Bottom => {
|
|
scroll_top = ListOffset {
|
|
item_ix: cursor.start().0,
|
|
offset_in_item: rendered_height - available_height,
|
|
};
|
|
self.logical_scroll_top = None;
|
|
}
|
|
};
|
|
}
|
|
|
|
// Measure items in the leading overdraw
|
|
let mut leading_overdraw = scroll_top.offset_in_item;
|
|
while leading_overdraw < self.overdraw {
|
|
cursor.prev();
|
|
if let Some(item) = cursor.item() {
|
|
let size = if let ListItem::Measured { size, .. } = item {
|
|
*size
|
|
} else {
|
|
let mut element = render_item(cursor.start().0, window, cx);
|
|
element.layout_as_root(available_item_space, window, cx)
|
|
};
|
|
|
|
leading_overdraw += size.height;
|
|
measured_items.push_front(ListItem::Measured {
|
|
size,
|
|
focus_handle: item.focus_handle(),
|
|
});
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
|
|
let measured_range = cursor.start().0..(cursor.start().0 + measured_items.len());
|
|
let mut cursor = old_items.cursor::<Count>(&());
|
|
let mut new_items = cursor.slice(&Count(measured_range.start), Bias::Right);
|
|
new_items.extend(measured_items, &());
|
|
cursor.seek(&Count(measured_range.end), Bias::Right);
|
|
new_items.append(cursor.suffix(), &());
|
|
self.items = new_items;
|
|
|
|
// If none of the visible items are focused, check if an off-screen item is focused
|
|
// and include it to be rendered after the visible items so keyboard interaction continues
|
|
// to work for it.
|
|
if !rendered_focused_item {
|
|
let mut cursor = self
|
|
.items
|
|
.filter::<_, Count>(&(), |summary| summary.has_focus_handles);
|
|
cursor.next();
|
|
while let Some(item) = cursor.item() {
|
|
if item.contains_focused(window, cx) {
|
|
let item_index = cursor.start().0;
|
|
let mut element = render_item(cursor.start().0, window, cx);
|
|
let size = element.layout_as_root(available_item_space, window, cx);
|
|
item_layouts.push_back(ItemLayout {
|
|
index: item_index,
|
|
element,
|
|
size,
|
|
});
|
|
break;
|
|
}
|
|
cursor.next();
|
|
}
|
|
}
|
|
|
|
LayoutItemsResponse {
|
|
max_item_width,
|
|
scroll_top,
|
|
item_layouts,
|
|
}
|
|
}
|
|
|
|
fn prepaint_items(
|
|
&mut self,
|
|
bounds: Bounds<Pixels>,
|
|
padding: Edges<Pixels>,
|
|
autoscroll: bool,
|
|
render_item: &mut RenderItemFn,
|
|
window: &mut Window,
|
|
cx: &mut App,
|
|
) -> Result<LayoutItemsResponse, ListOffset> {
|
|
window.transact(|window| {
|
|
let mut layout_response = self.layout_items(
|
|
Some(bounds.size.width),
|
|
bounds.size.height,
|
|
&padding,
|
|
render_item,
|
|
window,
|
|
cx,
|
|
);
|
|
|
|
// Avoid honoring autoscroll requests from elements other than our children.
|
|
window.take_autoscroll();
|
|
|
|
// Only paint the visible items, if there is actually any space for them (taking padding into account)
|
|
if bounds.size.height > padding.top + padding.bottom {
|
|
let mut item_origin = bounds.origin + Point::new(px(0.), padding.top);
|
|
item_origin.y -= layout_response.scroll_top.offset_in_item;
|
|
for item in &mut layout_response.item_layouts {
|
|
window.with_content_mask(Some(ContentMask { bounds }), |window| {
|
|
item.element.prepaint_at(item_origin, window, cx);
|
|
});
|
|
|
|
if let Some(autoscroll_bounds) = window.take_autoscroll() {
|
|
if autoscroll {
|
|
if autoscroll_bounds.top() < bounds.top() {
|
|
return Err(ListOffset {
|
|
item_ix: item.index,
|
|
offset_in_item: autoscroll_bounds.top() - item_origin.y,
|
|
});
|
|
} else if autoscroll_bounds.bottom() > bounds.bottom() {
|
|
let mut cursor = self.items.cursor::<Count>(&());
|
|
cursor.seek(&Count(item.index), Bias::Right);
|
|
let mut height = bounds.size.height - padding.top - padding.bottom;
|
|
|
|
// Account for the height of the element down until the autoscroll bottom.
|
|
height -= autoscroll_bounds.bottom() - item_origin.y;
|
|
|
|
// Keep decreasing the scroll top until we fill all the available space.
|
|
while height > Pixels::ZERO {
|
|
cursor.prev();
|
|
let Some(item) = cursor.item() else { break };
|
|
|
|
let size = item.size().unwrap_or_else(|| {
|
|
let mut item = render_item(cursor.start().0, window, cx);
|
|
let item_available_size = size(
|
|
bounds.size.width.into(),
|
|
AvailableSpace::MinContent,
|
|
);
|
|
item.layout_as_root(item_available_size, window, cx)
|
|
});
|
|
height -= size.height;
|
|
}
|
|
|
|
return Err(ListOffset {
|
|
item_ix: cursor.start().0,
|
|
offset_in_item: if height < Pixels::ZERO {
|
|
-height
|
|
} else {
|
|
Pixels::ZERO
|
|
},
|
|
});
|
|
}
|
|
}
|
|
}
|
|
|
|
item_origin.y += item.size.height;
|
|
}
|
|
} else {
|
|
layout_response.item_layouts.clear();
|
|
}
|
|
|
|
Ok(layout_response)
|
|
})
|
|
}
|
|
|
|
// Scrollbar support
|
|
|
|
fn set_offset_from_scrollbar(&mut self, point: Point<Pixels>) {
|
|
let Some(bounds) = self.last_layout_bounds else {
|
|
return;
|
|
};
|
|
let height = bounds.size.height;
|
|
|
|
let padding = self.last_padding.unwrap_or_default();
|
|
let content_height = self.items.summary().height;
|
|
let scroll_max = (content_height + padding.top + padding.bottom - height).max(px(0.));
|
|
let drag_offset =
|
|
// if dragging the scrollbar, we want to offset the point if the height changed
|
|
content_height - self.scrollbar_drag_start_height.unwrap_or(content_height);
|
|
let new_scroll_top = (point.y - drag_offset).abs().max(px(0.)).min(scroll_max);
|
|
|
|
if self.alignment == ListAlignment::Bottom && new_scroll_top == scroll_max {
|
|
self.logical_scroll_top = None;
|
|
} else {
|
|
let mut cursor = self.items.cursor::<ListItemSummary>(&());
|
|
cursor.seek(&Height(new_scroll_top), Bias::Right);
|
|
|
|
let item_ix = cursor.start().count;
|
|
let offset_in_item = new_scroll_top - cursor.start().height;
|
|
self.logical_scroll_top = Some(ListOffset {
|
|
item_ix,
|
|
offset_in_item,
|
|
});
|
|
}
|
|
}
|
|
}
|
|
|
|
impl std::fmt::Debug for ListItem {
|
|
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
|
|
match self {
|
|
Self::Unmeasured { .. } => write!(f, "Unrendered"),
|
|
Self::Measured { size, .. } => f.debug_struct("Rendered").field("size", size).finish(),
|
|
}
|
|
}
|
|
}
|
|
|
|
/// An offset into the list's items, in terms of the item index and the number
|
|
/// of pixels off the top left of the item.
|
|
#[derive(Debug, Clone, Copy, Default)]
|
|
pub struct ListOffset {
|
|
/// The index of an item in the list
|
|
pub item_ix: usize,
|
|
/// The number of pixels to offset from the item index.
|
|
pub offset_in_item: Pixels,
|
|
}
|
|
|
|
impl Element for List {
|
|
type RequestLayoutState = ();
|
|
type PrepaintState = ListPrepaintState;
|
|
|
|
fn id(&self) -> Option<crate::ElementId> {
|
|
None
|
|
}
|
|
|
|
fn source_location(&self) -> Option<&'static core::panic::Location<'static>> {
|
|
None
|
|
}
|
|
|
|
fn request_layout(
|
|
&mut self,
|
|
_id: Option<&GlobalElementId>,
|
|
_inspector_id: Option<&InspectorElementId>,
|
|
window: &mut Window,
|
|
cx: &mut App,
|
|
) -> (crate::LayoutId, Self::RequestLayoutState) {
|
|
let layout_id = match self.sizing_behavior {
|
|
ListSizingBehavior::Infer => {
|
|
let mut style = Style::default();
|
|
style.overflow.y = Overflow::Scroll;
|
|
style.refine(&self.style);
|
|
window.with_text_style(style.text_style().cloned(), |window| {
|
|
let state = &mut *self.state.0.borrow_mut();
|
|
|
|
let available_height = if let Some(last_bounds) = state.last_layout_bounds {
|
|
last_bounds.size.height
|
|
} else {
|
|
// If we don't have the last layout bounds (first render),
|
|
// we might just use the overdraw value as the available height to layout enough items.
|
|
state.overdraw
|
|
};
|
|
let padding = style.padding.to_pixels(
|
|
state.last_layout_bounds.unwrap_or_default().size.into(),
|
|
window.rem_size(),
|
|
);
|
|
|
|
let layout_response = state.layout_items(
|
|
None,
|
|
available_height,
|
|
&padding,
|
|
&mut self.render_item,
|
|
window,
|
|
cx,
|
|
);
|
|
let max_element_width = layout_response.max_item_width;
|
|
|
|
let summary = state.items.summary();
|
|
let total_height = summary.height;
|
|
|
|
window.request_measured_layout(
|
|
style,
|
|
move |known_dimensions, available_space, _window, _cx| {
|
|
let width =
|
|
known_dimensions
|
|
.width
|
|
.unwrap_or(match available_space.width {
|
|
AvailableSpace::Definite(x) => x,
|
|
AvailableSpace::MinContent | AvailableSpace::MaxContent => {
|
|
max_element_width
|
|
}
|
|
});
|
|
let height = match available_space.height {
|
|
AvailableSpace::Definite(height) => total_height.min(height),
|
|
AvailableSpace::MinContent | AvailableSpace::MaxContent => {
|
|
total_height
|
|
}
|
|
};
|
|
size(width, height)
|
|
},
|
|
)
|
|
})
|
|
}
|
|
ListSizingBehavior::Auto => {
|
|
let mut style = Style::default();
|
|
style.refine(&self.style);
|
|
window.with_text_style(style.text_style().cloned(), |window| {
|
|
window.request_layout(style, None, cx)
|
|
})
|
|
}
|
|
};
|
|
(layout_id, ())
|
|
}
|
|
|
|
fn prepaint(
|
|
&mut self,
|
|
_id: Option<&GlobalElementId>,
|
|
_inspector_id: Option<&InspectorElementId>,
|
|
bounds: Bounds<Pixels>,
|
|
_: &mut Self::RequestLayoutState,
|
|
window: &mut Window,
|
|
cx: &mut App,
|
|
) -> ListPrepaintState {
|
|
let state = &mut *self.state.0.borrow_mut();
|
|
state.reset = false;
|
|
|
|
let mut style = Style::default();
|
|
style.refine(&self.style);
|
|
|
|
let hitbox = window.insert_hitbox(bounds, HitboxBehavior::Normal);
|
|
|
|
// If the width of the list has changed, invalidate all cached item heights
|
|
if state.last_layout_bounds.map_or(true, |last_bounds| {
|
|
last_bounds.size.width != bounds.size.width
|
|
}) {
|
|
let new_items = SumTree::from_iter(
|
|
state.items.iter().map(|item| ListItem::Unmeasured {
|
|
focus_handle: item.focus_handle(),
|
|
}),
|
|
&(),
|
|
);
|
|
|
|
state.items = new_items;
|
|
}
|
|
|
|
let padding = style
|
|
.padding
|
|
.to_pixels(bounds.size.into(), window.rem_size());
|
|
let layout =
|
|
match state.prepaint_items(bounds, padding, true, &mut self.render_item, window, cx) {
|
|
Ok(layout) => layout,
|
|
Err(autoscroll_request) => {
|
|
state.logical_scroll_top = Some(autoscroll_request);
|
|
state
|
|
.prepaint_items(bounds, padding, false, &mut self.render_item, window, cx)
|
|
.unwrap()
|
|
}
|
|
};
|
|
|
|
state.last_layout_bounds = Some(bounds);
|
|
state.last_padding = Some(padding);
|
|
ListPrepaintState { hitbox, layout }
|
|
}
|
|
|
|
fn paint(
|
|
&mut self,
|
|
_id: Option<&GlobalElementId>,
|
|
_inspector_id: Option<&InspectorElementId>,
|
|
bounds: Bounds<crate::Pixels>,
|
|
_: &mut Self::RequestLayoutState,
|
|
prepaint: &mut Self::PrepaintState,
|
|
window: &mut Window,
|
|
cx: &mut App,
|
|
) {
|
|
let current_view = window.current_view();
|
|
window.with_content_mask(Some(ContentMask { bounds }), |window| {
|
|
for item in &mut prepaint.layout.item_layouts {
|
|
item.element.paint(window, cx);
|
|
}
|
|
});
|
|
|
|
let list_state = self.state.clone();
|
|
let height = bounds.size.height;
|
|
let scroll_top = prepaint.layout.scroll_top;
|
|
let hitbox_id = prepaint.hitbox.id;
|
|
let mut accumulated_scroll_delta = ScrollDelta::default();
|
|
window.on_mouse_event(move |event: &ScrollWheelEvent, phase, window, cx| {
|
|
if phase == DispatchPhase::Bubble && hitbox_id.should_handle_scroll(window) {
|
|
accumulated_scroll_delta = accumulated_scroll_delta.coalesce(event.delta);
|
|
let pixel_delta = accumulated_scroll_delta.pixel_delta(px(20.));
|
|
list_state.0.borrow_mut().scroll(
|
|
&scroll_top,
|
|
height,
|
|
pixel_delta,
|
|
current_view,
|
|
window,
|
|
cx,
|
|
)
|
|
}
|
|
});
|
|
}
|
|
}
|
|
|
|
impl IntoElement for List {
|
|
type Element = Self;
|
|
|
|
fn into_element(self) -> Self::Element {
|
|
self
|
|
}
|
|
}
|
|
|
|
impl Styled for List {
|
|
fn style(&mut self) -> &mut StyleRefinement {
|
|
&mut self.style
|
|
}
|
|
}
|
|
|
|
impl sum_tree::Item for ListItem {
|
|
type Summary = ListItemSummary;
|
|
|
|
fn summary(&self, _: &()) -> Self::Summary {
|
|
match self {
|
|
ListItem::Unmeasured { focus_handle } => ListItemSummary {
|
|
count: 1,
|
|
rendered_count: 0,
|
|
unrendered_count: 1,
|
|
height: px(0.),
|
|
has_focus_handles: focus_handle.is_some(),
|
|
},
|
|
ListItem::Measured {
|
|
size, focus_handle, ..
|
|
} => ListItemSummary {
|
|
count: 1,
|
|
rendered_count: 1,
|
|
unrendered_count: 0,
|
|
height: size.height,
|
|
has_focus_handles: focus_handle.is_some(),
|
|
},
|
|
}
|
|
}
|
|
}
|
|
|
|
impl sum_tree::Summary for ListItemSummary {
|
|
type Context = ();
|
|
|
|
fn zero(_cx: &()) -> Self {
|
|
Default::default()
|
|
}
|
|
|
|
fn add_summary(&mut self, summary: &Self, _: &()) {
|
|
self.count += summary.count;
|
|
self.rendered_count += summary.rendered_count;
|
|
self.unrendered_count += summary.unrendered_count;
|
|
self.height += summary.height;
|
|
self.has_focus_handles |= summary.has_focus_handles;
|
|
}
|
|
}
|
|
|
|
impl<'a> sum_tree::Dimension<'a, ListItemSummary> for Count {
|
|
fn zero(_cx: &()) -> Self {
|
|
Default::default()
|
|
}
|
|
|
|
fn add_summary(&mut self, summary: &'a ListItemSummary, _: &()) {
|
|
self.0 += summary.count;
|
|
}
|
|
}
|
|
|
|
impl<'a> sum_tree::Dimension<'a, ListItemSummary> for Height {
|
|
fn zero(_cx: &()) -> Self {
|
|
Default::default()
|
|
}
|
|
|
|
fn add_summary(&mut self, summary: &'a ListItemSummary, _: &()) {
|
|
self.0 += summary.height;
|
|
}
|
|
}
|
|
|
|
impl sum_tree::SeekTarget<'_, ListItemSummary, ListItemSummary> for Count {
|
|
fn cmp(&self, other: &ListItemSummary, _: &()) -> std::cmp::Ordering {
|
|
self.0.partial_cmp(&other.count).unwrap()
|
|
}
|
|
}
|
|
|
|
impl sum_tree::SeekTarget<'_, ListItemSummary, ListItemSummary> for Height {
|
|
fn cmp(&self, other: &ListItemSummary, _: &()) -> std::cmp::Ordering {
|
|
self.0.partial_cmp(&other.height).unwrap()
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod test {
|
|
|
|
use gpui::{ScrollDelta, ScrollWheelEvent};
|
|
|
|
use crate::{self as gpui, TestAppContext};
|
|
|
|
#[gpui::test]
|
|
fn test_reset_after_paint_before_scroll(cx: &mut TestAppContext) {
|
|
use crate::{
|
|
AppContext, Context, Element, IntoElement, ListState, Render, Styled, Window, div,
|
|
list, point, px, size,
|
|
};
|
|
|
|
let cx = cx.add_empty_window();
|
|
|
|
let state = ListState::new(5, crate::ListAlignment::Top, px(10.));
|
|
|
|
// Ensure that the list is scrolled to the top
|
|
state.scroll_to(gpui::ListOffset {
|
|
item_ix: 0,
|
|
offset_in_item: px(0.0),
|
|
});
|
|
|
|
struct TestView(ListState);
|
|
impl Render for TestView {
|
|
fn render(&mut self, _: &mut Window, _: &mut Context<Self>) -> impl IntoElement {
|
|
list(self.0.clone(), |_, _, _| {
|
|
div().h(px(10.)).w_full().into_any()
|
|
})
|
|
.w_full()
|
|
.h_full()
|
|
}
|
|
}
|
|
|
|
// Paint
|
|
cx.draw(point(px(0.), px(0.)), size(px(100.), px(20.)), |_, cx| {
|
|
cx.new(|_| TestView(state.clone()))
|
|
});
|
|
|
|
// Reset
|
|
state.reset(5);
|
|
|
|
// And then receive a scroll event _before_ the next paint
|
|
cx.simulate_event(ScrollWheelEvent {
|
|
position: point(px(1.), px(1.)),
|
|
delta: ScrollDelta::Pixels(point(px(0.), px(-500.))),
|
|
..Default::default()
|
|
});
|
|
|
|
// Scroll position should stay at the top of the list
|
|
assert_eq!(state.logical_scroll_top().item_ix, 0);
|
|
assert_eq!(state.logical_scroll_top().offset_in_item, px(0.));
|
|
}
|
|
|
|
#[gpui::test]
|
|
fn test_scroll_by_positive_and_negative_distance(cx: &mut TestAppContext) {
|
|
use crate::{
|
|
AppContext, Context, Element, IntoElement, ListState, Render, Styled, Window, div,
|
|
list, point, px, size,
|
|
};
|
|
|
|
let cx = cx.add_empty_window();
|
|
|
|
let state = ListState::new(5, crate::ListAlignment::Top, px(10.));
|
|
|
|
struct TestView(ListState);
|
|
impl Render for TestView {
|
|
fn render(&mut self, _: &mut Window, _: &mut Context<Self>) -> impl IntoElement {
|
|
list(self.0.clone(), |_, _, _| {
|
|
div().h(px(20.)).w_full().into_any()
|
|
})
|
|
.w_full()
|
|
.h_full()
|
|
}
|
|
}
|
|
|
|
// Paint
|
|
cx.draw(point(px(0.), px(0.)), size(px(100.), px(100.)), |_, cx| {
|
|
cx.new(|_| TestView(state.clone()))
|
|
});
|
|
|
|
// Test positive distance: start at item 1, move down 30px
|
|
state.scroll_by(px(30.));
|
|
|
|
// Should move to item 2
|
|
let offset = state.logical_scroll_top();
|
|
assert_eq!(offset.item_ix, 1);
|
|
assert_eq!(offset.offset_in_item, px(10.));
|
|
|
|
// Test negative distance: start at item 2, move up 30px
|
|
state.scroll_by(px(-30.));
|
|
|
|
// Should move back to item 1
|
|
let offset = state.logical_scroll_top();
|
|
assert_eq!(offset.item_ix, 0);
|
|
assert_eq!(offset.offset_in_item, px(0.));
|
|
|
|
// Test zero distance
|
|
state.scroll_by(px(0.));
|
|
let offset = state.logical_scroll_top();
|
|
assert_eq!(offset.item_ix, 0);
|
|
assert_eq!(offset.offset_in_item, px(0.));
|
|
}
|
|
}
|