Visio VSTO Drag and Drop - drag-and-drop

Question

I am trying to create a custom VSTO AddIn for Visio 2013 and 2015 where I have a list of items in an anchor view. I would like to allow the user to drag an item from the list and drop it on the Visio page. Once dropped I would like to use the x and y coordinates of the drop so that I can create specific shapes and connectors. I have not been able to find any articles or samples that shows how to get this done. The only reference I found was on how to achieve this for Word 2010 and I could not get the technique they used for Word to work for Visio.
Any assistance and guide would be greatly appreciated.

Answer 1

That's actually not that complicated. This (my) pretty old post explains how to drop shape from a memory stream:
http://unmanagedvisio.blogspot.co.at/2010/05/persisting-visio-shapes.html
If you want to drop from existing masters on a stencil (the code below assumes "Basic shapes", then it might be easier. You just need to handle "Item drag" in your form and then set the drag object to the desired master. DoDragDrop is a built-in function (the code below assumes winforms, for different framework you may need a different approach). Anyways, the basic idea is that "Master" visio object implements IDataObject interface, and that's enough to make drag-drop work.
Assuming your list view has two items, named "Triangle" and "Circle", if you drag "triangle" item, you should get "triangle" shape and for the "circle", the circle, respectively.
private void listView1_ItemDrag(object sender, ItemDragEventArgs e)
{
var item = (ListViewItem) e.Item;
var app = Globals.ThisAddIn.Application;
var myStencil = app.Documents.OpenEx("BASIC_M.VSS",
(short)VisOpenSaveArgs.visOpenDocked | (short)VisOpenSaveArgs.visOpenRO);
var masterToDrag = myStencil.Masters[item.Text];
var data = new DataObject(masterToDrag);
DoDragDrop(data, DragDropEffects.Copy);
}