WPF 拖拽从具有 SelectionMode Multiple 的 ListBox 中删除 [英] WPF Drag & drop from ListBox with SelectionMode Multiple
问题描述
除了一件烦人的小事之外，我几乎已经完成了这项工作......
I've almost got this working apart from one little annoying thing...
因为 ListBox 选择发生在鼠标按下时，如果您在选择要拖动的最后一个项目时用鼠标按下开始拖动它工作正常，但是如果您先选择所有要拖动的项目然后单击选择开始拖动它，您单击的那个会在拖动后被取消选中并留在后面.
Because the ListBox selection happens on mouse down, if you start the drag with the mouse down when selecting the last item to drag it works fine, but if you select all the items to drag first and then click on the selection to start dragging it, the one you click on gets unselected and left behind after the drag.
对解决此问题的最佳方法有什么想法吗?
Any thoughts on the best way to get around this?
<DockPanel LastChildFill="True">
<ListBox ItemsSource="{Binding SourceItems}"
SelectionMode="Multiple"
PreviewMouseLeftButtonDown="HandleLeftButtonDown"
PreviewMouseLeftButtonUp="HandleLeftButtonUp"
PreviewMouseMove="HandleMouseMove"
MultiSelectListboxDragDrop:ListBoxExtension.SelectedItemsSource="{Binding SelectedItems}"/>
<ListBox ItemsSource="{Binding DestinationItems}"
AllowDrop="True"
Drop="DropOnToDestination"/>
<DockPanel>
...
public partial class Window1
{
private bool clickedOnSourceItem;
public Window1()
{
InitializeComponent();
DataContext = new WindowViewModel();
}
private void DropOnToDestination(object sender, DragEventArgs e)
{
var viewModel = (WindowViewModel)
e.Data.GetData(typeof(WindowViewModel));
viewModel.CopySelectedItems();
}
private void HandleLeftButtonDown(object sender, MouseButtonEventArgs e)
{
var sourceElement = (FrameworkElement)sender;
var hitItem = sourceElement.InputHitTest(e.GetPosition(sourceElement))
as FrameworkElement;
if(hitItem != null)
{
clickedOnSourceItem = true;
}
}
private void HandleLeftButtonUp(object sender, MouseButtonEventArgs e)
{
clickedOnSourceItem = false;
}
private void HandleMouseMove(object sender, MouseEventArgs e)
{
if(clickedOnSourceItem)
{
var sourceItems = (FrameworkElement)sender;
var viewModel = (WindowViewModel)DataContext;
DragDrop.DoDragDrop(sourceItems, viewModel, DragDropEffects.Move);
clickedOnSourceItem = false;
}
}
}
推荐答案
所以......成为风滚草徽章的骄傲拥有者，我又回到了这个尝试 &想办法解决它.;-)
So...having become the proud owner of a tumbleweed badge, I've got back on to this to try & find a way around it. ;-)
我不确定我是否喜欢这个解决方案，所以我仍然非常愿意接受任何更好的方法.
I'm not sure I like the solution so I'm still very much open to any better approaches.
基本上，我最终要做的是记住最后一次单击 ListBoxItem 的内容 &然后确保在拖动之前将其添加到所选项目中.这也意味着在开始拖动之前查看鼠标移动了多远 - 因为单击所选项目以取消选择它有时可能会导致如果鼠标弹跳开始一点拖动操作，它会再次被选中.
Basically, what I ended up doing is remember what ListBoxItem was last clicked on & then make sure that gets added to the selected items before a drag. This also meant looking at how far the mouse moves before starting a drag - because clicking on a selected item to unselect it could sometimes result in it getting selected again if mouse bounce started a little drag operation.
最后，我为列表框项目添加了一些热跟踪，因此，如果您将鼠标放在选定的项目上，它将被取消选择，但您仍然会收到一些反馈，表明它将被包含在拖动操作中.
Finally, I added some hot tracking to the listbox items so, if you mouse down on a selected item it'll get unselected but you still get some feedback to indicate that it will get included in the drag operation.
private void HandleLeftButtonDown(object sender, MouseButtonEventArgs e)
{
var source = (FrameworkElement)sender;
var hitItem = source.InputHitTest(e.GetPosition(source)) as FrameworkElement;
hitListBoxItem = hitItem.FindVisualParent<ListBoxItem>();
origPos = e.GetPosition(null);
}
private void HandleLeftButtonUp(object sender, MouseButtonEventArgs e)
{
hitListBoxItem = null;
}
private void HandleMouseMove(object sender, MouseEventArgs e)
{
if (ShouldStartDrag(e))
{
hitListBoxItem.IsSelected = true;
var sourceItems = (FrameworkElement)sender;
var viewModel = (WindowViewModel)DataContext;
DragDrop.DoDragDrop(sourceItems, viewModel, DragDropEffects.Move);
hitListBoxItem = null;
}
}
private bool ShouldStartDrag(MouseEventArgs e)
{
if (hitListBoxItem == null)
return false;
var curPos = e.GetPosition(null);
return
Math.Abs(curPos.Y-origPos.Y) > SystemParameters.MinimumVerticalDragDistance ||
Math.Abs(curPos.X-origPos.X) > SystemParameters.MinimumHorizontalDragDistance;
}
XAML 更改以包括热跟踪...
XAML changes to include hot tracking...
<Style TargetType="ListBoxItem">
<Setter Property="Margin" Value="1"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ListBoxItem}">
<Grid>
<Border Background="{TemplateBinding Background}" />
<Border Background="#BEFFFFFF" Margin="1">
<Grid>
<Grid.RowDefinitions>
<RowDefinition /><RowDefinition />
</Grid.RowDefinitions>
<Border Margin="1" Grid.Row="0" Background="#57FFFFFF" />
</Grid>
</Border>
<ContentPresenter Margin="8,5" />
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter Property="Background" Value="PowderBlue" />
</Trigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsMouseOver" Value="True" />
<Condition Property="IsSelected" Value="False"/>
</MultiTrigger.Conditions>
<Setter Property="Background" Value="#5FB0E0E6" />
</MultiTrigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
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