[QS] 同一个UI多个拥有右键菜单功能及数据拖动功能的Datagrid出现的假死问题

场景

多个DataGrid，每个Datagrid拥有右键菜单功能及数据拖动功能，会出现界面假死情况,如下图所示，第三步骤点击DataGrid one时将不会有任何反应，使用snoop查看事件发现，第二步操作后，DataGrid Two就没有释放鼠标捕捉

操作步骤

为了方便，直接上图，共三个步骤，如下所示：





相关后台代码：

public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();

var ls = new List<string> {"ss1", "ss2", "ss3"};
dg1.ItemsSource = ls;
var ls1 = new List<string> { "ss1", "ss2"};
dg2.ItemsSource = ls1;

dg1.ContextMenu=new ContextMenu();
dg1.ContextMenu.Items.Add("con1");
dg1.ContextMenu.Items.Add("con1");
dg1.ContextMenu.Items.Add("con1");

dg1.MouseMove += dg1_MouseMove;
dg2.MouseMove += dg2_MouseMove;
}

void dg2_MouseMove(object sender, MouseEventArgs e)
{
if (e.LeftButton == MouseButtonState.Pressed && dg2.IsKeyboardFocusWithin)
{
var item = dg2.GetMouseTargetItem(e.GetPosition) as DataGridRow;

if (null != item && item.IsSelected)
{
DragDrop.DoDragDrop(dg2, dg2.SelectedItem, DragDropEffects.Move);
//dg2.CaptureMouse();
//dg2.ReleaseMouseCapture();
e.Handled = true;
}
}
}

void dg1_MouseMove(object sender, MouseEventArgs e)
{
if (e.LeftButton == MouseButtonState.Pressed && dg1.IsKeyboardFocusWithin)
{
var item = dg1.GetMouseTargetItem(e.GetPosition) as DataGridRow;

if (null != item && item.IsSelected)
{
DragDrop.DoDragDrop(dg1, dg1.SelectedItem, DragDropEffects.Move);
e.Handled = true;
}
}
}

}

public static class SelectorExtend
{
public delegate Point GetPosition(IInputElement element);

private static DependencyObject GetItemByIndex(this Selector selector, int index)
{
if (null == selector)
return null;
if (selector.ItemContainerGenerator.Status
!= GeneratorStatus.ContainersGenerated)
return null;
return selector.ItemContainerGenerator.ContainerFromIndex(index);
}

private static bool IsMouseTargetItem(Visual theTarget, GetPosition pos)
{
if (null == theTarget)
return false;
Rect rect = VisualTreeHelper.GetDescendantBounds(theTarget);
Point point = pos((IInputElement)theTarget);
return rect.Contains(point);
}

public static object GetMouseTargetItem(this Selector selector, GetPosition pos)
{
if (null == selector)
return null;
for (int i = 0; i < selector.Items.Count; i++)
{
var itm = selector.GetItemByIndex(i);
if (IsMouseTargetItem(itm as Visual, pos))
{
return itm;
}
}
return null;
}
}

解决方案

即为代码中注释的两行代码，具体为什么，实话说，我也不是很清楚，该问题困扰了好几天，作过各种代码尝试，如，只有release的情况，是无效的，调试源码也未能发现问题所在，只有两行都加的情况下才能有效，若有大神能观察到其中的问题所在，求教，本人将不胜感激。