From c25db584321f33376b4b7b2124e85fc8374f8418 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Mon, 15 Jan 2007 19:02:29 +0000
Subject: [PATCH] honour the drag effect supported by the drag source in
 wxIDropTarget (Tim Kosse)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@44229 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 src/msw/ole/droptgt.cpp | 48 ++++++++++++++++++++++++++++++-----------
 1 file changed, 35 insertions(+), 13 deletions(-)

diff --git a/src/msw/ole/droptgt.cpp b/src/msw/ole/droptgt.cpp
index be6d4fcdfb..6be0765f45 100644
--- a/src/msw/ole/droptgt.cpp
+++ b/src/msw/ole/droptgt.cpp
@@ -80,7 +80,7 @@ protected:
     HWND          m_hwnd;         // window we're associated with
 
     // get default drop effect for given keyboard flags
-    static DWORD GetDropEffect(DWORD flags, wxDragResult defaultAction);
+    static DWORD GetDropEffect(DWORD flags, wxDragResult defaultAction, DWORD pdwEffect);
 
     DECLARE_NO_COPY_CLASS(wxIDropTarget)
 };
@@ -104,11 +104,31 @@ static DWORD ConvertDragResultToEffect(wxDragResult result);
 // Notes   : We do "move" normally and "copy" if <Ctrl> is pressed,
 //           which is the standard behaviour (currently there is no
 //           way to redefine it)
-DWORD wxIDropTarget::GetDropEffect(DWORD flags, wxDragResult defaultAction)
+DWORD wxIDropTarget::GetDropEffect(DWORD flags,
+                                   wxDragResult defaultAction,
+                                   DWORD pdwEffect)
 {
-  if (defaultAction == wxDragCopy)
-    return flags & MK_SHIFT ? DROPEFFECT_MOVE : DROPEFFECT_COPY;
-  return flags & MK_CONTROL ? DROPEFFECT_COPY : DROPEFFECT_MOVE;
+    DWORD effectiveAction;
+    if ( defaultAction == wxDragCopy )
+        effectiveAction = flags & MK_SHIFT ? DROPEFFECT_MOVE : DROPEFFECT_COPY;
+    else
+        effectiveAction = flags & MK_CONTROL ? DROPEFFECT_COPY : DROPEFFECT_MOVE;
+
+    if ( !(effectiveAction & pdwEffect) )
+    {
+        // the action is not supported by drag source, fall back to something
+        // that it does support
+        if ( pdwEffect & DROPEFFECT_MOVE )
+            effectiveAction = DROPEFFECT_MOVE;
+        else if ( pdwEffect & DROPEFFECT_COPY )
+            effectiveAction = DROPEFFECT_COPY;
+        else if ( pdwEffect & DROPEFFECT_LINK )
+            effectiveAction = DROPEFFECT_LINK;
+        else
+            effectiveAction = DROPEFFECT_NONE;
+    }
+
+    return effectiveAction;
 }
 
 wxIDropTarget::wxIDropTarget(wxDropTarget *pTarget)
@@ -187,7 +207,7 @@ STDMETHODIMP wxIDropTarget::DragEnter(IDataObject *pIDataSource,
     // give some visual feedback
     *pdwEffect = ConvertDragResultToEffect(
         m_pTarget->OnEnter(pt.x, pt.y, ConvertDragEffectToResult(
-            GetDropEffect(grfKeyState, m_pTarget->GetDefaultAction()))
+            GetDropEffect(grfKeyState, m_pTarget->GetDefaultAction(), *pdwEffect))
                     )
                  );
 
@@ -212,7 +232,7 @@ STDMETHODIMP wxIDropTarget::DragOver(DWORD   grfKeyState,
     wxDragResult result;
     if ( m_pIDataObject ) {
         result = ConvertDragEffectToResult(
-            GetDropEffect(grfKeyState, m_pTarget->GetDefaultAction()));
+            GetDropEffect(grfKeyState, m_pTarget->GetDefaultAction(), *pdwEffect));
     }
     else {
         // can't accept data anyhow normally
@@ -269,9 +289,6 @@ STDMETHODIMP wxIDropTarget::Drop(IDataObject *pIDataSource,
     //      that it's the same we've already got in DragEnter
     wxASSERT( m_pIDataObject == pIDataSource );
 
-    // by default, nothing happens
-    *pdwEffect = DROPEFFECT_NONE;
-
     // we need client coordinates to pass to wxWin functions
     if ( !ScreenToClient(m_hwnd, (POINT *)&pt) )
     {
@@ -285,15 +302,20 @@ STDMETHODIMP wxIDropTarget::Drop(IDataObject *pIDataSource,
 
         // and now it has the data
         wxDragResult rc = ConvertDragEffectToResult(
-            GetDropEffect(grfKeyState, m_pTarget->GetDefaultAction()));
+            GetDropEffect(grfKeyState, m_pTarget->GetDefaultAction(), *pdwEffect));
         rc = m_pTarget->OnData(pt.x, pt.y, rc);
         if ( wxIsDragResultOk(rc) ) {
             // operation succeeded
             *pdwEffect = ConvertDragResultToEffect(rc);
         }
-        //else: *pdwEffect is already DROPEFFECT_NONE
+        else {
+            *pdwEffect = DROPEFFECT_NONE;
+        }
+    }
+    else {
+        // OnDrop() returned false, no need to copy data
+        *pdwEffect = DROPEFFECT_NONE;
     }
-    //else: OnDrop() returned false, no need to copy data
 
     // release the held object
     RELEASE_AND_NULL(m_pIDataObject);
-- 
2.45.2