DragDelegate.cs

using System;
using System.Linq;
using ObjCRuntime;
using AppKit;
using ImageKit;
using Foundation;

namespace ImageKitDemo
{
	public class DragDelegate: NSDraggingDestination
	{
		public DragDelegate (IKImageBrowserView view)
		{
			browserView = view;
		}
		IKImageBrowserView browserView;

		public override NSDragOperation DraggingEntered (NSDraggingInfo sender)
		{
			Console.WriteLine ("Drag Delegate received 'DraggingEntered'");
			return DraggingUpdated (sender);
		}

		public override NSDragOperation DraggingUpdated (NSDraggingInfo sender)
		{
			//The ImageBrowserView uses this method to set the icon during dragging. Regardless
			//of what we return the view will send a moveitems message to the datasource.
			//so it is best to not display the copy icon.

			//Console.WriteLine ("Drag Delegate received 'DraggingUpdated'");
			NSObject obj = sender.DraggingSource;
			if (obj != null && obj.Equals (browserView))
			{
				return NSDragOperation.Move;
			}
			return NSDragOperation.Copy;
		}

		public override bool PerformDragOperation (NSDraggingInfo sender)
		{
			Console.WriteLine ("Drag Delegate received 'PerformDragOperation' sender: {0}", sender);

			//It seems that browserView does not send this message when it is an internal move.
			//It does all the work by sending a moveitems message to the datasource,
			// but I return false here just to be safe.

			NSObject obj = sender.DraggingSource;
			if (obj != null && obj.Equals (browserView)) {
				Console.WriteLine ("\tLet the image browser handle it.");
				return false;
			}

			NSPasteboard pb = sender.DraggingPasteboard ;
			NSArray data = null;
			//			if (pb.Types.Contains (NSPasteboard.NSUrlType))
			//				data = pb.GetPropertyListForType (NSPasteboard.NSUrlType) as NSArray;
			if (pb.Types.Contains (NSPasteboard.NSFilenamesType))
				data = pb.GetPropertyListForType (NSPasteboard.NSFilenamesType) as NSArray;
			if (data != null) {
				for (int i = 0; i < (int) data.Count; i++) {
					string path = (string)NSString.FromHandle (data.ValueAt ((uint)i));
					Console.WriteLine ("From pasteboard Item {0} = {1}", i, path);
					((BrowseData)browserView.DataSource).AddImages (
						NSUrl.FromFilename (path), (int)browserView.GetIndexAtLocationOfDroppedItem ());
					browserView.ReloadData ();
				}
			}
			return true;
		}

		#region implemented only for testing
		public override bool PrepareForDragOperation (NSDraggingInfo sender)
		{
			Console.WriteLine ("Drag Delegate received 'PrepareForDragOperation'");
			return true;
		}

		public override void ConcludeDragOperation (NSDraggingInfo sender)
		{
			Console.WriteLine ("Drag Delegate received 'ConcludeDragOperation'");
		}

		public override void DraggingExited (NSDraggingInfo sender)
		{
			Console.WriteLine ("Drag Delegate received 'DraggingExited'");
		}

		public override void DraggingEnded (NSDraggingInfo sender)
		{
			Console.WriteLine ("Drag Delegate received 'DraggingEnded'");
		}

		public override bool WantsPeriodicDraggingUpdates {
			get {
				Console.WriteLine ("Drag Delegate was queried for 'WantsPeriodicDraggingUpdates'");
				return true;
			}
		}
		#endregion
	}
}