yew_virtual/core/
virtual_item.rs

1use crate::core::virtual_key::VirtualKey;
2
3/// Metadata for a single virtualized item.
4///
5/// Represents the computed layout information that the virtualizer
6/// produces for each item within the visible range. Components use
7/// this metadata to position and render items in the scroll container.
8#[derive(Debug, Clone, PartialEq)]
9pub struct VirtualItem {
10    /// The index of this item in the full dataset.
11    pub index: usize,
12
13    /// The measured or estimated size of this item in pixels.
14    ///
15    /// Represents height for vertical lists or width for horizontal lists.
16    pub size: f64,
17
18    /// The offset in pixels from the start of the virtualized region.
19    ///
20    /// Represents the top offset for vertical lists or the left offset
21    /// for horizontal lists.
22    pub start: f64,
23
24    /// The end position in pixels (start + size).
25    pub end: f64,
26
27    /// A stable identity key for this item.
28    ///
29    /// When a custom `get_item_key` is provided, this key follows the
30    /// item across reorders. Otherwise it equals the index.
31    pub key: VirtualKey,
32
33    /// The lane index for grid layouts (0 for single-column lists).
34    pub lane: usize,
35}
36
37impl VirtualItem {
38    /// Creates a new virtual item with the given layout parameters.
39    ///
40    /// # Parameters
41    ///
42    /// - `index`: The item's position in the full dataset.
43    /// - `size`: The item's size in pixels along the scroll axis.
44    /// - `start`: The item's offset from the start of the virtual region.
45    pub fn new(index: usize, size: f64, start: f64) -> Self {
46        // Compute the end position from start and size.
47        let end = start + size;
48
49        // Construct the virtual item with the computed layout.
50        Self {
51            index,
52            size,
53            start,
54            end,
55            key: VirtualKey::Index(index),
56            lane: 0,
57        }
58    }
59
60    /// Creates a new virtual item with a specific key and lane.
61    ///
62    /// # Parameters
63    ///
64    /// - `index`: The item's position in the full dataset.
65    /// - `size`: The item's size in pixels along the scroll axis.
66    /// - `start`: The item's offset from the start of the virtual region.
67    /// - `key`: The stable identity key for this item.
68    /// - `lane`: The lane (column/row) index for grid layouts.
69    pub fn with_key_and_lane(
70        index: usize,
71        size: f64,
72        start: f64,
73        key: VirtualKey,
74        lane: usize,
75    ) -> Self {
76        // Compute the end position from start and size.
77        let end = start + size;
78
79        // Construct the virtual item with key and lane information.
80        Self {
81            index,
82            size,
83            start,
84            end,
85            key,
86            lane,
87        }
88    }
89}
yew_virtual/core/virtual_item.rs

yew_virtual/core/
virtual_item.rs
