How to connect line with elements on cavas WPF diagram

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I have been following the series of wpf diagram posts to accomplish what i need to do at the project I´m working on at the moment.

Right now Im stuck with a little problem that you might have the answer straightway.
What I´m trying to do is create a line connection between two items on the canvas.
It works fine if i use the mouse, but I need to do that in the background.
Lets say I want to do that when i load the form.

I can load the elements and drawing the line but the problem is
the line and elements are not on connect on each other and thats is my problem.

Here is pice of code im using.

AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(canvas);

ConnectorAdorner cAdorner = new ConnectorAdorner(canvas, sourceConnector);

adornerLayer.Add(cAdorner);

cAdorner.HitConnector = sinkConnector;

cAdorner.pathGeometry = cAdorner.GetPathGeometry(new Point(211.0, 181.54));

cAdorner.HitDesignerItem = sinkConnector.parentDesignerItem;
cAdorner.hitDesignerItem.IsDragConnectionOver = true;

Connection connection = new Connection(sourceConnector, sinkConnector);

this.canvas.Children.Insert(0, connection);

if (adornerLayer != null)
{
adornerLayer.Remove(cAdorner);
}

I will really appreciate if someone can help me with that or just point in some direction.

thanks a lot

Posted 9-Oct-14 2:45am

Decarlos

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Sergey Alexandrovich Kryukov 9-Oct-14 11:35am

The problem is not clear. Why don't they connect?
—SA

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Sergey Alexandrovich Kryukov · Answer 1 · 2014-10-09T05:50:00

Your problem is unclear (probably you only need to calculate the line coordinates more accurately :-)), but I can suggest you the alternative idea. I am not sure what kind of diagramming you do, so I cannot be 100% sure my idea is useful, but for typical diagramming design it could be useful. Just try to analyze my considerations below.

I would suggest, instead of using an adorner layer (good idea itself; please see below), treating the connecting lines as first-class citizen, on par with the diagram elements they connect. For example, the user should be able to include the lines in group selection, select, remove (but not move; the lines will follow the other diagram element movement). In other words, make you lines using (System.Windows.Shapes.Line; curved lines would also be an option).

Why? Because this is the logic of diagramming. First of all due to the diagramming conception. Connecting lines are truly the part of the diagram, they are the firs-class diagram objects, they can have properties associated with them, and so on. Another reason is technical. It's really difficult to connect shapes, if they are not simple (say, not round or rectangular); it's hard to calculate the point of intersection between the shape and connecting line. But you could just connect the centers and mask the invisible part of line by the non-transparent shape. However, this won't work if you need to draw an arrow head. Anyway, there are other reasons for such design.

Now, a word on the adorner layers. It's important to isolate visual properties related to the document itself (your diagram objects) and visual aspects related to the user's manipulations in UI, which are secondary in relation to the document: zoom/pan, selection, etc. The adorner layers are great to show these secondary visual elements, such as selection marks, selected area during drag-style selection, etc.

—SA