[WPF] Fix drag&drop issue

Do an additional DragOver check before dropping, since the Drop event may
come without a DragOver. Also properly initialize the initial drag area.

1 files changed, 17 insertions, 7 deletions

diff --git a/Xwt.WPF/Xwt.WPFBackend/WidgetBackend.cs b/Xwt.WPF/Xwt.WPFBackend/WidgetBackend.cs
index 49e2c805..47874d7a 100644
--- a/Xwt.WPF/Xwt.WPFBackend/WidgetBackend.cs
+++ b/Xwt.WPF/Xwt.WPFBackend/WidgetBackend.cs
@@ -56,7 +56,7 @@ namespace Xwt.WPFBackend
 		{

 			// Source

 			public bool AutodetectDrag;

-			public Rect DragRect;

+			public Rect DragRect = Rect.Empty;

 			// Target

 			public TransferDataType [] TargetTypes = new TransferDataType [0];

 		}

@@ -821,12 +821,6 @@ namespace Xwt.WPFBackend
 

 		void WidgetDragOverHandler (object sender, System.Windows.DragEventArgs e)

 		{

-			var types = e.Data.GetFormats ().Select (t => t.ToXwtTransferType ()).ToArray ();

-			var pos = e.GetPosition (Widget).ToXwtPoint ();

-			var proposedAction = DetectDragAction (e.KeyStates);

-

-			e.Handled = true; // Prevent default handlers from being used.

-

 			if (Adorner != null) {

 				var w = GetParentWindow ();

 				var v = (UIElement)w.Content;

@@ -847,6 +841,16 @@ namespace Xwt.WPFBackend
 

 				Adorner.Offset = e.GetPosition (v);

 			}

+			CheckDrop (sender, e);

+		}

+

+		void CheckDrop (object sender, System.Windows.DragEventArgs e)

+		{

+			var types = e.Data.GetFormats ().Select (t => t.ToXwtTransferType ()).ToArray ();

+			var pos = e.GetPosition (Widget).ToXwtPoint ();

+			var proposedAction = DetectDragAction (e.KeyStates);

+

+			e.Handled = true; // Prevent default handlers from being used.

 

 			if ((enabledEvents & WidgetEvent.DragOverCheck) > 0) {

 				var checkArgs = new DragOverCheckEventArgs (pos, types, proposedAction);

@@ -884,6 +888,12 @@ namespace Xwt.WPFBackend
 

 		void WidgetDropHandler (object sender, System.Windows.DragEventArgs e)

 		{

+			// Do a DragOverCheck before proceeding to the drop. This is required since in some cases the DragOver

+			// handler may not be called.

+			CheckDrop (sender, e);

+			if (e.Effects == DragDropEffects.None)

+				return;

+

 			WidgetDragLeaveHandler (sender, e);

 

 			var types = e.Data.GetFormats ().Select (t => t.ToXwtTransferType ()).ToArray ();