Dropping into Viewbox

[Tom]

I have my drop and drag working to drop object into Canvas wrapped in a ViewBox.    The viewbox is scaling the canvas so that it displays the fill object on the screen.

My problem is that the coordinates within the canvas are no longer the same as the screen coordinates.  I'm currently using below code from examples -

Camera1Canvas.Children.Add(userControl);
// Determine the drop point for the new UserControl.
Point canvasPosition = Camera1Canvas.TransformToVisual(null).Transform(new Point(0, 0));
var userControlDesiredPosition = new Point
           {
              X = e.Options.CurrentDragPoint.X - canvasPosition.X,
              Y = e.Options.CurrentDragPoint.Y - canvasPosition.Y
            };
// e.Options.CurrentDragPoint returns the absolute mouse position,
// that is why we have to transform the host canvas and subtract its position from the absolute mouse position.
userControl.SetValue(Canvas.LeftProperty, canvasPosition1.X);
userControl.SetValue(Canvas.TopProperty, canvasPosition1.Y);
userControl.SetValue(Canvas.ZIndexProperty, Camera1Canvas.Children.Count);
userControl.TabIndex = Camera1Canvas.Children.Count;

And this code works just fine if I'm positioning object to the screen coordinates.  I need to understand how to map those coordinates so that object is placed in the correct location inside the canvas inside of the viewbox.

Tom

[Tsvyatko]

Hi Tom,

Please, have a look at this thread - http://www.telerik.com/community/forums/silverlight/drag-and-drop/drag-and-drop-from-listbox-to-canvas-that-has-a-transform.aspx. Let me know if this solves the problem or if you have any futher questions.

Regards,
Tsvyatko
the Telerik team

[Tom]

I could not get the code to work as written.  In GetPropPoint() routine, scaleTransform was NULL.  I added the following line

if (scaleTransform == null)
   scaleTransform = new ScaleTransform {ScaleX = transform.Matrix.M11, ScaleY =
                        transform.Matrix.M22};

It is now dropping correctly, except that it is putting the upper right corner of the object as the mouse position.  Pardon my lack of xaml knowledge, but how do I determine where the upper left corner of my object is realitive to the e.Options.CurrentDragPoint?

[Tsvyatko]

Hi Tom,

I guess that what you are trying to achieve is when the item is dropped in the canvas its position corresponds to the mouse position relative to the dragged element. I have modified the sample project to illustrate my idea. Please, have a look and let me know if this works in our scenario.

Best wishes,
Tsvyatko
the Telerik team