How to access TableLayoutPanel through the element inside it?

Question

Namely what I mean. I created my MyTableLayoutPanel control, which almost completely coincides with the base one, with the exception of three redefined events. I redefined them so that it would be possible to move controls in form, here’s the code itself.

 class MyTableLayoutPanel:TableLayoutPanel { //точка перемещения Point DownPoint; //нажата ли кнопка мыши bool IsDragMode; protected override void OnMouseDown(MouseEventArgs mevent) { DownPoint = mevent.Location; IsDragMode = true; base.OnMouseDown(mevent); } protected override void OnMouseUp(MouseEventArgs mevent) { IsDragMode = false; base.OnMouseUp(mevent); } protected override void OnMouseMove(MouseEventArgs mevent) { //если кнопка мыши нажата if (IsDragMode) { Point p = mevent.Location; //вычисляем разницу в координатах между положением курсора и "нулевой" точкой кнопки Point dp = new Point(pX - DownPoint.X, pY - DownPoint.Y); Location = new Point(Location.X + dp.X, Location.Y + dp.Y); } base.OnMouseMove(mevent); } }

Everything works as it should, control moves, no errors. Further. In MyTableLayoutPanel I place pictures or buttons. Actually the question is how to press the pictures, move MyTableLayoutPanel , and not a picture or button?

Community spirit ♦ one · Accepted Answer · 2016-05-26T21:22:07

As such, the routing of events between the parent and child controls in WinForms is not provided, it is only in WPF. But you can partially simulate the routing of events from the child to the parent and use the following simple technique:

 public partial class MyTableLayoutPanel:TableLayoutPanel { public MyTableLayoutPanel() { InitializeComponent(); // Подписываемся на событие добавления дочернего контрола this.ControlAdded += MyTableLayoutPanel_ControlAdded; // Подписываемся на событие удаления дочернего контрола this.ControlRemoved += MyTableLayoutPanel_ControlRemoved; }

The Control.ControlAdded and Control.ControlRemoved events are triggered when child controls are added to the control. We will use this in order not to subscribe by hand to the events of the child controls to perform actions on the container.

  void MyTableLayoutPanel_ControlAdded(object sender, ControlEventArgs e) { // Добавляем свои обработчики к нужным событиям дочернего контрола // когда он добавляется в контейнер e.Control.MouseUp += MouseUpHandler; e.Control.MouseDown += MouseDownHandler; e.Control.MouseMove += MouseMoveHandler; } void MyTableLayoutPanel_ControlRemoved(object sender, ControlEventArgs e) { // Не забываем отписать дочерний контрол от наших обработчиков при его удалении, // чтобы не удерживать ссылку на объект дольше необходимого e.Control.MouseUp -= MouseUpHandler; e.Control.MouseDown -= MouseDownHandler; e.Control.MouseMove -= MouseMoveHandler; }

Events are based on delegates, and the delegate keeps a reference to the object whose method has been passed to it, so in order not to get a memory leak, do not forget to unsubscribe from the events when removing the control from the parent container. Also, in the handler of the ContolAdded event, you can make additional settings for the properties of the child controls.

And finally, we describe the handlers of the events we need to manage the parent container.

  private void MouseUpHandler(object sender, MouseEventArgs e) { MouseEventArgs newArgs = new MouseEventArgs( e.Button, e.Clicks, ((Control)sender).Location.X+eX, ((Control)sender).Location.Y+eY, e.Delta); OnMouseUp(newArgs); } // и так для каждого события, которое нужно передать в родительский контейнер }

If everything is done correctly, your child controls will also call the handlers of the parent container. One more nuance, the handler of the parent container must carefully check who caused it and transfer the coordinates from the coordinate system of the child control to its own, if of course it receives the coordinates in the event arguments and uses them. It may also concern other event arguments, so be careful when developing the logic of such forced event handlers.

Also read this question and answers , there is proposed a solution that may be suitable for your purposes.

Another solution is to switch to WPF and use event routing, which is available there without out-of-the-box shamanism.

I need to add 4 more event handlers to mine that already exist?
And what do you mean by UseControl for my example, child or parent?
In general, yes, you caught the idea, since the event cannot be transmitted, we call the handler after catching it in another control.
Just don’t enter OnSomthing calls OnSomthing(EventArgs e) into the plugin handler.
it triggers an event and this will result in a stack overflow.
If the child is a regular button, I should have this. this.MyButtonAdded += MyTableLayoutPanel_MyButtonAdded;
if yes, then the terms of error ... something I did not catch .. (
The only thing is to replace the subscription to the click event with the subscriptions you need.
Well, at least glance at MSDN in the description of the events ControlAdded and CotrolRemoved

How to access TableLayoutPanel through the element inside it?

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