X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/57bd4c6031d438f11af0ec540136f49a928b923c..99d21c0e1f8d87570702c52dccd3ad698f0a0931:/src/msw/ole/droptgt.cpp

diff --git a/src/msw/ole/droptgt.cpp b/src/msw/ole/droptgt.cpp
index 84d718ff17..4601d19be4 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 inline DWORD GetDropEffect(DWORD flags, wxDragResult defaultAction);
+    static DWORD GetDropEffect(DWORD flags, wxDragResult defaultAction, DWORD pdwEffect);
 
     DECLARE_NO_COPY_CLASS(wxIDropTarget)
 };
@@ -99,16 +99,39 @@ static DWORD ConvertDragResultToEffect(wxDragResult result);
 // Name    : static wxIDropTarget::GetDropEffect
 // Purpose : determine the drop operation from keyboard/mouse state.
 // Returns : DWORD combined from DROPEFFECT_xxx constants
-// Params  : [in] DWORD flags       kbd & mouse flags as passed to
-//                                  IDropTarget methods
+// Params  : [in] DWORD flags                 kbd & mouse flags as passed to
+//                                            IDropTarget methods
+//           [in] wxDragResult defaultAction  the default action of the drop target
+//           [in] DWORD pdwEffect             the supported actions of the drop 
+//                                            source passed to IDropTarget methods
 // 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)
@@ -131,10 +154,12 @@ IMPLEMENT_IUNKNOWN_METHODS(wxIDropTarget)
 // Name    : wxIDropTarget::DragEnter
 // Purpose : Called when the mouse enters the window (dragging something)
 // Returns : S_OK
-// Params  : [in] IDataObject *pIDataSource : source data
-//           [in] DWORD        grfKeyState  : kbd & mouse state
-//           [in] POINTL       pt           : mouse coordinates
-//           [out]DWORD       *pdwEffect    : effect flag
+// Params  : [in]    IDataObject *pIDataSource : source data
+//           [in]    DWORD        grfKeyState  : kbd & mouse state
+//           [in]    POINTL       pt           : mouse coordinates
+//           [in/out]DWORD       *pdwEffect    : effect flag
+//                                               In:  Supported effects
+//                                               Out: Resulting effect
 // Notes   :
 STDMETHODIMP wxIDropTarget::DragEnter(IDataObject *pIDataSource,
                                       DWORD        grfKeyState,
@@ -187,7 +212,7 @@ 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))
                     )
                  );
 
@@ -198,9 +223,9 @@ STDMETHODIMP wxIDropTarget::DragEnter(IDataObject *pIDataSource,
 // Purpose : Indicates that the mouse was moved inside the window represented
 //           by this drop target.
 // Returns : S_OK
-// Params  : [in] DWORD   grfKeyState     kbd & mouse state
-//           [in] POINTL  pt              mouse coordinates
-//           [out]LPDWORD pdwEffect       effect flag
+// Params  : [in]    DWORD   grfKeyState     kbd & mouse state
+//           [in]    POINTL  pt              mouse coordinates
+//           [in/out]LPDWORD pdwEffect       current effect flag
 // Notes   : We're called on every WM_MOUSEMOVE, so this function should be
 //           very efficient.
 STDMETHODIMP wxIDropTarget::DragOver(DWORD   grfKeyState,
@@ -212,7 +237,7 @@ 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
@@ -253,10 +278,10 @@ STDMETHODIMP wxIDropTarget::DragLeave()
 // Purpose : Instructs the drop target to paste data that was just now
 //           dropped on it.
 // Returns : S_OK
-// Params  : [in] IDataObject *pIDataSource     the data to paste
-//           [in] DWORD        grfKeyState      kbd & mouse state
-//           [in] POINTL       pt               where the drop occurred?
-//           [ouy]DWORD       *pdwEffect        operation effect
+// Params  : [in]    IDataObject *pIDataSource     the data to paste
+//           [in]    DWORD        grfKeyState      kbd & mouse state
+//           [in]    POINTL       pt               where the drop occurred?
+//           [in/out]DWORD       *pdwEffect        operation effect
 // Notes   :
 STDMETHODIMP wxIDropTarget::Drop(IDataObject *pIDataSource,
                                  DWORD        grfKeyState,
@@ -269,9 +294,6 @@ 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 +307,20 @@ 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);