如何在毛伊岛实现两个CollectionView之间的拖放

Question

我正在尝试在 Maui 项目中的两个 CollectionView 之间实现拖放。

在我的示例中，我在第一个 CollectionView 中有一个歌曲集合，在第二个集合中有一个播放列表组。歌曲 CollectionView 看起来像这样：

        <CollectionView
            Grid.Row="2"
            Margin="0,4"
            EmptyView="You have no songs in your library!"
            ItemsSource="{Binding Songs}">
            <CollectionView.ItemTemplate>
                <DataTemplate x:DataType="m:Song">
                    <SwipeView android:SwipeView.SwipeTransitionMode="Reveal">
                        <SwipeView.RightItems>
                            <SwipeItems SwipeBehaviorOnInvoked="Close">
                                <SwipeItem
                                    BackgroundColor="Pink"
                                    Command="{Binding Source={RelativeSource AncestorType={x:Type vm:PlayListViewModel}}, Path=FavoriteCommand}"
                                    CommandParameter="{Binding .}"
                                    Text="Favorite" />
                            </SwipeItems>
                        </SwipeView.RightItems>
                        <Frame Margin="4" Padding="4">
                            <cell:SongArtist />
                            <Frame.GestureRecognizers>
                                <DragGestureRecognizer
                                    CanDrag="True"
                                    DragStartingCommand="{Binding Source={RelativeSource AncestorType={x:Type vm:PlayListViewModel}}, Path=DragStartedCommand}"
                                    DragStartingCommandParameter="{Binding .}" />
                            </Frame.GestureRecognizers>
                        </Frame>
                    </SwipeView>


                </DataTemplate>
            </CollectionView.ItemTemplate>
        </CollectionView>

播放列表集合视图如下所示：

        <CollectionView
            Grid.Row="5"
            Margin="0,4"
            EmptyView="You have no songs in your playlist!" 
            ItemsSource="{Binding PlayList}">
            <CollectionView.ItemTemplate>
                <DataTemplate x:DataType="m:Song">
                    <SwipeView android:SwipeView.SwipeTransitionMode="Reveal">
                        <SwipeView.RightItems>
                            <SwipeItems SwipeBehaviorOnInvoked="Close">
                                <SwipeItem
                                    BackgroundColor="Red"
                                    Command="{Binding Source={RelativeSource AncestorType={x:Type vm:PlayListViewModel}}, Path=DeleteCommand}"
                                    CommandParameter="{Binding .}"
                                    Text="Delete" />
                            </SwipeItems>
                        </SwipeView.RightItems>
                        <Frame Margin="4" Padding="4">
                            <cell:SongArtist />
                            <Frame.GestureRecognizers>
                                <DropGestureRecognizer AllowDrop="True" DropCommand="{Binding Source={RelativeSource AncestorType={x:Type vm:PlayListViewModel}}, Path=SongDropped}" />
                            </Frame.GestureRecognizers>
                        </Frame>
                    </SwipeView>
                </DataTemplate>
            </CollectionView.ItemTemplate>
        </CollectionView>

DragStartedCommand 确实会触发。 SongDroppedCommand 则不然。这是我的 ViewModel 中的代码：

        [RelayCommand]
        void DragStarted(Song song)
        {
            dragged_song = song;
            Songs.Remove(song);
            Debug.WriteLine($"DragStarted {song.Name}");
        }

        [RelayCommand]
        void SongDropped(Song song)
        {
            PlayList.Add(song);
            Debug.WriteLine($"SongDropped");
        }

不确定为什么 SongDroppedCommand 没有触发。

提前致谢！

Answer 1

查看评论。在@Jason 的帮助下，这就是答案。