WPF启用/禁用DragMove委托 [英] WPF Enable / Disable DragMove delegate

问题描述

大家好！

我得到了需要拖动的自定义窗口，但是在某些情况下，我需要忽略拖动.

目前，我在窗口构造函数中订阅委托

Hi all!

I got custom window which need to be dragged around but some cases I need to ignore dragging.

At the moment I subcribe delegate in window constructor

MouseLeftButtonDown += delegate { DragMove(); };

效果很好，使我可以在自定义窗口中拖动

当我想禁用拖动事件时，我打电话

Which works fine and enables me to drag my custom window around

When I like to disable drag event I call

MouseLeftButtonDown -= delegate { DragMove(); };

这不起作用，我仍然可以拖动我的自定义窗口..

那么我如何正确取消订阅我的代表?

希望你有主意:)

干杯！

Which does not work, Im still able to drag my custom window..

So how I properly unsubcribe my delegate?

Hope you got idea :)

Cheers!

推荐答案

您应该通过创建一个布尔变量(称为canDrag)作为表单级变量并显式创建MouseLeftButtonDown事件(仅在canDrag时才拖动)来做到这一点. =正确.像这样的东西:-

You should do this by creating a bool varaiable (call it canDrag) as a form level variable and explicitly creating a MouseLeftButtonDown event which will only drag if canDrag = true. Something like this:-

bool canDrag = false;

       public MainWindow()
       {
           InitializeComponent();
           MouseLeftButtonDown +=new System.Windows.Input.MouseButtonEventHandler(MainWindow_MouseLeftButtonDown);
       }

       void MainWindow_MouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
       {
           if (canDrag)
           {
               this.DragMove();
           }
       }

然后，您可以在适当的位置将canDrag设置为true和false.我使用按钮进行了如下测试:-

You can then set canDrag to true and false in the appropriate places. I used buttons to test like this:-

private void btnDrag_Click(object sender, RoutedEventArgs e)
        {
            canDrag = true;
        }

        private void btnNoDrag_Click(object sender, RoutedEventArgs e)
        {
            canDrag = false ;
        }

希望对您有帮助

Hope this helps

不起作用的原因是因为

The reason it doesn''t work is because

delegate { DragMove(); }

和

and

delegate { DragMove(); }

并且不相等，因此不会删除该委托.
您必须存储委托才能再次将其删除，例如:

and not equal thus the delegate is not removed.
You have to store the delegate in order to be able to remove it again, like this:

MouseButtonEventHandler handler = delegate { GetMoreData(); };
MouseLeftButtonDown += handler;
MouseLeftButtonDown -= handler;

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