C# 将用户控件从一个flowlayoutpanel拖动到另一个flowlayoutpanel
如何从2个flowlayoutpanels添加自定义usercontrol的拖放功能 Usercontrol在下面的代码行中保持为nullC# 将用户控件从一个flowlayoutpanel拖动到另一个flowlayoutpanel,c#,drag-and-drop,flowlayoutpanel,C#,Drag And Drop,Flowlayoutpanel,如何从2个flowlayoutpanels添加自定义usercontrol的拖放功能 Usercontrol在下面的代码行中保持为null private void flowLayoutPanel1_DragDrop(object sender, DragEventArgs e) { UserControl userControl = e.Data.GetData(typeof(UserControl)) as UserControl; 所做操作的问题在于,要提
private void flowLayoutPanel1_DragDrop(object sender, DragEventArgs e)
{
UserControl userControl = e.Data.GetData(typeof(UserControl)) as UserControl;
所做操作的问题在于,要提取存储在拖动中的数据,必须指定精确的类型
control.DoDragDrop(new Label(), DragDropEffects.Move);
e.Data.GetDataPresent(typeof(Control)) // = false
e.Data.GetDataPresent(typeof(Label)) // = true
您需要做的是创建一个包装器,并将其用于拖放代码
class ControlWrapper
{
public Control Control { get; private set; }
public ControlWrapper(Control control) { Control = control; }
}
control.DoDragDrop(new ControlWrapper(new Label()), DragDropEffects.Move);
e.Data.GetDataPresent(typeof(ControlWrapper)) // = true
你的代码现在变成了
ControlWrapper controlWrapper = e.Data.GetData(typeof(ControlWrapper)) as ControlWrapper;
UserControl userControl = controlWrapper.Control as UserControl;
尽量不要听起来太说教,但你应该先检查数据是否以你想要的形式存在e.Data.GetDataPresent(typeof(ControlWrapper))
将告诉您它是否是那种格式