Add index property to ItemState

examples/simple.rs

@@ -10,9 +10,13 @@ pub fn main() -> eframe::Result<()> {
  Default::default(),
  move |ctx, _frame| {
  CentralPanel::default().show(ctx, |ui| {
- dnd(ui, "dnd_example").show_vec(&mut items, |ui, item, handle, _state| {
+ dnd(ui, "dnd_example").show_vec(&mut items, |ui, item, handle, state| {
  handle.ui(ui, |ui| {
- ui.label("drag");
+ if state.dragged {
+ ui.label("dragging");
+ } else {
+ ui.label("drag");
+ }
  });
  ui.label(*item);
  });

src/lib.rs

@@ -146,8 +146,8 @@ impl<'a> Dnd<'a> {
  mut drag_drop_ui,
  } = self;
 
- let response = drag_drop_ui.ui(ui, items, |item, ui, handle, dragged| {
- item_ui(ui, item, handle, ItemState { dragged });
+ let response = drag_drop_ui.ui(ui, items, |item, ui, handle, item_state| {
+ item_ui(ui, item, handle, item_state);
  });
 
  ui.ctx().data_mut(|data| data.insert_temp(id, drag_drop_ui));
@@ -175,4 +175,9 @@ impl<'a> Dnd<'a> {
 pub struct ItemState {
  /// True if the item is currently being dragged.
  pub dragged: bool,
+ /// Index of the item in the list.
+ /// Note that when you sort the source list while the drag is still ongoing (default behaviour
+ /// of [Dnd::show_vec]), this index will updated while the item is being dragged.
+ /// If you sort once after the item is dropped, the index will be stable during the drag.
+ pub index: usize,
 }

src/state.rs

@@ -4,6 +4,7 @@ use std::time::{Duration, SystemTime};
 
 use egui::{CursorIcon, Id, InnerResponse, LayerId, Order, Pos2, Rect, Sense, Ui, Vec2};
 
+use crate::ItemState;
 #[cfg(target_arch = "wasm32")]
 use web_time::{Duration, SystemTime};
 
@@ -490,7 +491,7 @@ impl DragDropUi {
  &mut self,
  ui: &mut Ui,
  values: impl Iterator<Item = T>,
- mut item_ui: impl FnMut(T, &mut Ui, Handle, bool),
+ mut item_ui: impl FnMut(T, &mut Ui, Handle, ItemState),
  ) -> DragDropResponse {
  // During the first frame, we check if the pointer is actually over any of the item handles and cancel the drag if it isn't
  let mut first_frame = false;
@@ -626,7 +627,15 @@ impl DragDropUi {
  item_id,
  &mut hovering_over_any_handle,
  |ui, handle| {
- item_ui(item, ui, handle, is_dragged_item);
+ item_ui(
+ item,
+ ui,
+ handle,
+ ItemState {
+ dragged: is_dragged_item,
+ index: idx,
+ },
+ );
  },
  )
  })