Add Drag and Drop Capablilities to the objects derived from VObject

Hello,

VObjects are drawn directly to control's surface, they don't exist as separate entities in WinForms hierarchy. Therefore separate VObject cannot handle drag-n-drop events.

Instead, you should handle drag-n-drop events of the MultiLayerViewer control and map screen coordinates to canvas points. After that you can iterate through VObjects and determine which one, for example, received "drop" event using HitTest() method.

Hello, Alex,

Well, it seems that it can achieve what we want by simply iterating through VObjects to test HitTest within dragover and dragdrop event method of multiviewer without evoking dragover and dragdrop event for VObject.

But it would be nice if you can further elaborate the discussion of item 1 in our previous reply.

Also, it would be nicer if you can talk about some approaches to implement dragover and dragdrop event for VObject without having VObject derived from Window.Form.Control

Thank you.

Hello, Alex,

Appreciate that you spent some time on this discussion.

Following are what we see how to approach this:

1. Agree with you that VObject should not be derived from Window.Form.Control.
2. To have dragdrop capablility be added to VObject, VObject should implement : a. IDragTarget Interface, b. Events associated each method of IDragTarget Interface.
3. There are two possible ways to fire those events
a. in the same events of MultiLayerViewer using VObject.HitTest to identify the right VObject instance to fire the related event:
something like this:

MultiLayerViewer1_DragDrop (object sender, DragEventArg e)
{

Point newPoint = MultiLayerViewer1.PointToClient(new Point((int)e.X, (int)E.Y));
PointF PosicaoNoCanvas = MultiLayerViewer1.ControlToWorkspace(newPoint, Aurigma.GraphicsMill.Unit.Point);


foreach (VObject vo in MultiLayerViewer1.CurrentLayer.VObjects)
{
if(vo.HitTest (PosicaoNoCanvas, 0.0F))
{
vo.OnDragDrop(e);
}
}

}


b. If we want to implement IDragTarget Interface of VObject completely within VObject, is this possible? Then, we need to talk about how to receive the dragdrop data, how create DragEventArg, when and where and how to evoke the event

We are very interested in your input to this second possible way: item b in above.

thank you.