removeItem method

void removeItem(
  1. int index,
  2. AnimatedRemovedItemBuilder builder, {
  3. Duration duration = _kDuration,
})
inherited

Remove the item at index and start an animation that will be passed to builder when the item is visible.

If using AnimatedList.separated, the animation will also be passed to the corresponding separator's AnimatedList.removedSeparatorBuilder.

Items are removed immediately. After an item has been removed, its index will no longer be passed to the builder. However, the item will still appear for duration and during that time builder must construct its widget as needed.

This method's semantics are the same as Dart's List.remove method: it decreases the length of items by one and shifts all items at or before index towards the beginning of the list of items.

See also:

Implementation

void removeItem(int index, AnimatedRemovedItemBuilder builder, { Duration duration = _kDuration }) {
  final AnimatedItemBuilder? removedSeparatorBuilder = widget.removedSeparatorBuilder;
  if (removedSeparatorBuilder == null) {
    // There are no separators. Remove only the item.
    _sliverAnimatedMultiBoxKey.currentState!.removeItem(index, builder, duration: duration);
  } else {
    final int itemIndex = _computeItemIndex(index);
    // Remove the item
    _sliverAnimatedMultiBoxKey.currentState!.removeItem(itemIndex, builder, duration: duration);
    if (_itemsCount > 1) {
      if (itemIndex == _itemsCount - 1) {
        // The item was removed from the end of the list, so the separator to remove is the one at `last index` - 1.
        _sliverAnimatedMultiBoxKey.currentState!.removeItem(itemIndex - 1, _toRemovedItemBuilder(removedSeparatorBuilder, index - 1), duration: duration);
      } else {
        // The item was removed from the middle or beginning of the list,
        // so the corresponding separator took its place and needs to be removed at `itemIndex`.
        _sliverAnimatedMultiBoxKey.currentState!.removeItem(itemIndex, _toRemovedItemBuilder(removedSeparatorBuilder, index), duration: duration);
      }
    }
  }
}