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我有一个网格，上面有两列。左列是 TreeView，右列是 TextBox。现在我希望能够将一个项目从 TreeView 拖到 TextBox 并且所选 TreeViewItem 的标题应该附加到文本中。我在网上搜索了很多“控件之间的拖放”，但所有这些都对我不起作用。

我的实际代码是：

private Point startPoint;

    private void tvPreviewLeftMouseDown(object sender, MouseButtonEventArgs e)
    {
        startPoint = e.GetPosition(null);
    }

    private void tvPreviewMouseMove(object sender, MouseEventArgs e)
    {
        if(e.LeftButton == MouseButtonState.Released)
            return;

        Point mousePos = e.GetPosition(null);
        Vector diff = startPoint - mousePos;
        if (e.LeftButton == MouseButtonState.Pressed &&
            Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance ||
            Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance)
        {
            TreeView treeView = sender as TreeView;
            TreeViewItem treeViewItem = FindAnchestor<TreeViewItem>((DependencyObject)e.OriginalSource);
            object val = treeView.ItemContainerGenerator.ItemFromContainer(treeViewItem);
            DataObject dragData = new DataObject("myFormat", treeViewItem.Header);
            DragDrop.DoDragDrop(treeViewItem, dragData, DragDropEffects.Move);
        }
    }

    private static T FindAnchestor<T>(DependencyObject current)
        where T : DependencyObject
    {
        do
        {
            if (current is T)
                return (T) current;
            current = VisualTreeHelper.GetParent(current);
        } while (current != null);
        return null;
    }

    private void frtbDrop(object sender, DragEventArgs e)
    {
        if (e.Data.GetDataPresent("myFormat"))
        {
            var val = (string) e.Data.GetData("myFormat");
        }
    }

    private void frtbDragEnter(object sender, DragEventArgs e)
    {
        if(!e.Data.GetDataPresent("myFormat") || sender == e.Source)
            e.Effects = DragDropEffects.None;
    }

相应的 XAML 是：

<Grid >
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="200"/>
        <ColumnDefinition Width="*"/>
    </Grid.ColumnDefinitions>
    <TreeView Grid.Column="0" x:Name="treeview" PreviewMouseLeftButtonDown="tvPreviewLeftMouseDown" PreviewMouseMove="tvPreviewMouseMove"/>
    <TextBox Grid.Column="1" AllowDrop="True" Drop="frtbDrop" DragEnter="frtbDragEnter"/>
</Grid>

如果我调试它，方法tvPreviewMouseMove工作正常。DataObject 已创建并获得正确的值。但是 drop- 和 dragenter- 事件永远不会被触发。这里有什么问题？

4

2 回答 2

1

解决了。问题是我订阅了 DragEnter 和 Drop-Event。我将它们更改为 PreviewDragEnter 和 PreviewDrop，现在它可以工作了

于 2013-09-05T11:37:29.393 回答
0 
private void frtbDragEnter(object sender, DragEventArgs e)
{
    if(!e.Data.GetDataPresent("myFormat") || sender == e.Source)
        e.Effects = DragDropEffects.None;
    else
        e.Effects = DragDropEffects.Move;
}
于 2013-09-05T11:21:46.373 回答