OnEnter/OnDragOver API update (compiles, links, somewhat runs under wxGTK)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@4113 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/dnd.h

@@ -97,19 +97,28 @@ public:
         { if (m_dataObject) delete m_dataObject; 
 	  m_dataObject = dataObject; }
 
-    // called when mouse enters/leaves the window: might be used to give
+    // these functions are called when data is moved over position (x, y) and
-    // some visual feedback to the user
+    // may return either wxDragCopy, wxDragMove or wxDragNone depending on
-    virtual void OnLeave() { }
+    // what would happen if the data were dropped here.
-    
+    //
-    // this function is called when data enters over position (x, y) - if it
+    // the last parameter is what would happen by default and is determined by
-    // returns TRUE, the dragging icon can indicate that the window would
+    // the platform-specific logic (for example, under Windows it's wxDragCopy
-    // accept a drop here
+    // if Ctrl key is pressed and wxDragMove otherwise) except that it will
-    virtual bool OnEnter(wxCoord x, wxCoord y) = 0;
+    // always be wxDragNone if the carried data is in an unsupported format.
 
-    // this function is called when data is move over position (x, y) - if it
+    // called when the mouse enters the window (only once until OnLeave())
-    // returns TRUE, the dragging icon can indicate that the window would
+    virtual wxDragResult OnEnter(wxCoord x, wxCoord y, wxDragResult def)
-    // accept a drop here
+        { return OnDragOver(x, y, def); }
-    virtual bool OnMove(wxCoord x, wxCoord y) = 0;
+
+    // called when the mouse moves in the window - shouldn't take long to
+    // execute or otherwise mouse movement would be too slow
+    virtual wxDragResult OnDragOver(wxCoord WXUNUSED(x), wxCoord WXUNUSED(y),
+                                    wxDragResult def)
+        { return def; }
+    
+    // called when mouse leaves the window: might be used to remove the
+    // feedback which was given in OnEnter()
+    virtual void OnLeave() { }
     
     // this function is called when data is dropped at position (x, y) - if it
     // returns TRUE, OnData() will be called immediately afterwards which will

include/wx/gtk/dnd.h

@@ -45,8 +45,7 @@ class wxDropTarget: public wxDropTargetBase
 public:
     wxDropTarget(wxDataObject *dataObject = (wxDataObject*) NULL );
     
-    virtual bool OnEnter(wxCoord x, wxCoord y) ;
+    virtual wxDragResult OnDragOver(wxCoord x, wxCoord y, wxDragResult def);
-    virtual bool OnMove(wxCoord x, wxCoord y);
     virtual bool OnDrop(wxCoord x, wxCoord y);
     virtual bool OnData(wxCoord x, wxCoord y);
     virtual bool GetData();

include/wx/gtk1/dnd.h

@@ -45,8 +45,7 @@ class wxDropTarget: public wxDropTargetBase
 public:
     wxDropTarget(wxDataObject *dataObject = (wxDataObject*) NULL );
     
-    virtual bool OnEnter(wxCoord x, wxCoord y) ;
+    virtual wxDragResult OnDragOver(wxCoord x, wxCoord y, wxDragResult def);
-    virtual bool OnMove(wxCoord x, wxCoord y);
     virtual bool OnDrop(wxCoord x, wxCoord y);
     virtual bool OnData(wxCoord x, wxCoord y);
     virtual bool GetData();

src/gtk/dnd.cpp

@@ -188,22 +188,24 @@ static gboolean target_drag_motion( GtkWidget *WXUNUSED(widget),
        this is only valid for the duration of this call */
     drop_target->SetDragContext( context );
 
-    bool ret = FALSE;
+    /* TODO: what should be the default behaviour? Copy or move? */
+    wxDragResult result = wxDragMove;
 
     if (drop_target->m_firstMotion)
     {
         /* the first "drag_motion" event substitutes a "drag_enter" event */
-        ret = drop_target->OnEnter( x, y );
+        result = drop_target->OnEnter( x, y, result );
     }
     else
     {
         /* give program a chance to react (i.e. to say no by returning FALSE) */
-        ret = drop_target->OnMove( x, y );
+        result = drop_target->OnDragOver( x, y, result );
     }
 
     /* we don't yet handle which "actions" (i.e. copy or move)
        the target accepts. so far we simply accept the
        suggested action. TODO. */
+    bool ret = result != wxDragNone;
     if (ret)
         gdk_drag_status( context, context->suggested_action, time );
 
@@ -367,7 +369,17 @@ wxDropTarget::wxDropTarget( wxDataObject *data )
     m_dragTime = 0;
 }
 
-bool wxDropTarget::OnEnter( int WXUNUSED(x), int WXUNUSED(y) )
+wxDragResult wxDropTarget::OnDragOver( wxCoord WXUNUSED(x),
+                                       wxCoord WXUNUSED(y),
+                                       wxDragResult def )
+{
+    if (!m_dataObject)
+        return FALSE;
+	
+    return (GetMatchingPair() != (GdkAtom) 0) ? def : wxDragNone;
+}
+
+bool wxDropTarget::OnDrop( wxCoord WXUNUSED(x), wxCoord WXUNUSED(y) )
 {
     if (!m_dataObject)
         return FALSE;
@@ -375,23 +387,7 @@ bool wxDropTarget::OnEnter( int WXUNUSED(x), int WXUNUSED(y) )
     return (GetMatchingPair() != (GdkAtom) 0);
 }
 
-bool wxDropTarget::OnMove( int WXUNUSED(x), int WXUNUSED(y) )
+bool wxDropTarget::OnData( wxCoord WXUNUSED(x), wxCoord WXUNUSED(y) )
-{
-    if (!m_dataObject)
-        return FALSE;
-	
-    return (GetMatchingPair() != (GdkAtom) 0);
-}
-
-bool wxDropTarget::OnDrop( int WXUNUSED(x), int WXUNUSED(y) )
-{
-    if (!m_dataObject)
-        return FALSE;
-	
-    return (GetMatchingPair() != (GdkAtom) 0);
-}
-
-bool wxDropTarget::OnData( int WXUNUSED(x), int WXUNUSED(y) )
 {
     if (!m_dataObject)
         return FALSE;

src/gtk1/dnd.cpp

@@ -188,22 +188,24 @@ static gboolean target_drag_motion( GtkWidget *WXUNUSED(widget),
        this is only valid for the duration of this call */
     drop_target->SetDragContext( context );
 
-    bool ret = FALSE;
+    /* TODO: what should be the default behaviour? Copy or move? */
+    wxDragResult result = wxDragMove;
 
     if (drop_target->m_firstMotion)
     {
         /* the first "drag_motion" event substitutes a "drag_enter" event */
-        ret = drop_target->OnEnter( x, y );
+        result = drop_target->OnEnter( x, y, result );
     }
     else
     {
         /* give program a chance to react (i.e. to say no by returning FALSE) */
-        ret = drop_target->OnMove( x, y );
+        result = drop_target->OnDragOver( x, y, result );
     }
 
     /* we don't yet handle which "actions" (i.e. copy or move)
        the target accepts. so far we simply accept the
        suggested action. TODO. */
+    bool ret = result != wxDragNone;
     if (ret)
         gdk_drag_status( context, context->suggested_action, time );
 
@@ -367,7 +369,17 @@ wxDropTarget::wxDropTarget( wxDataObject *data )
     m_dragTime = 0;
 }
 
-bool wxDropTarget::OnEnter( int WXUNUSED(x), int WXUNUSED(y) )
+wxDragResult wxDropTarget::OnDragOver( wxCoord WXUNUSED(x),
+                                       wxCoord WXUNUSED(y),
+                                       wxDragResult def )
+{
+    if (!m_dataObject)
+        return FALSE;
+	
+    return (GetMatchingPair() != (GdkAtom) 0) ? def : wxDragNone;
+}
+
+bool wxDropTarget::OnDrop( wxCoord WXUNUSED(x), wxCoord WXUNUSED(y) )
 {
     if (!m_dataObject)
         return FALSE;
@@ -375,23 +387,7 @@ bool wxDropTarget::OnEnter( int WXUNUSED(x), int WXUNUSED(y) )
     return (GetMatchingPair() != (GdkAtom) 0);
 }
 
-bool wxDropTarget::OnMove( int WXUNUSED(x), int WXUNUSED(y) )
+bool wxDropTarget::OnData( wxCoord WXUNUSED(x), wxCoord WXUNUSED(y) )
-{
-    if (!m_dataObject)
-        return FALSE;
-	
-    return (GetMatchingPair() != (GdkAtom) 0);
-}
-
-bool wxDropTarget::OnDrop( int WXUNUSED(x), int WXUNUSED(y) )
-{
-    if (!m_dataObject)
-        return FALSE;
-	
-    return (GetMatchingPair() != (GdkAtom) 0);
-}
-
-bool wxDropTarget::OnData( int WXUNUSED(x), int WXUNUSED(y) )
 {
     if (!m_dataObject)
         return FALSE;

src/msw/ole/droptgt.cpp

@@ -79,6 +79,13 @@ private:
   static inline DWORD GetDropEffect(DWORD flags);
 };
 
+// ----------------------------------------------------------------------------
+// private functions
+// ----------------------------------------------------------------------------
+
+static wxDragResult ConvertDragEffectToResult(DWORD dwEffect);
+static DWORD ConvertDragResultToEffect(wxDragResult result);
+
 // ============================================================================
 // wxIDropTarget implementation
 // ============================================================================
@@ -138,16 +145,18 @@ STDMETHODIMP wxIDropTarget::DragEnter(IDataObject *pIDataSource,
     return S_OK;
   }
 
-  // TODO should check the point also?
-
-  *pdwEffect = GetDropEffect(grfKeyState);
-
   // get hold of the data object
   m_pIDataObject = pIDataSource;
   m_pIDataObject->AddRef();
 
   // give some visual feedback
-  m_pTarget->OnEnter();
+  *pdwEffect = ConvertDragResultToEffect(
+                 m_pTarget->OnEnter(pt.x, pt.y,
+                   ConvertDragEffectToResult(
+                     GetDropEffect(grfKeyState)
+                   )
+                 )
+               );
 
   return S_OK;
 }
@@ -167,8 +176,19 @@ STDMETHODIMP wxIDropTarget::DragOver(DWORD   grfKeyState,
 {
   // there are too many of them... wxLogDebug("IDropTarget::DragOver");
 
-  *pdwEffect = m_pIDataObject == NULL ? DROPEFFECT_NONE
+  wxDragResult result;
-                                      : GetDropEffect(grfKeyState);
+  if ( m_pIDataObject ) {
+      result = ConvertDragEffectToResult(GetDropEffect(grfKeyState));
+  }
+  else {
+      // can't accept data anyhow normally
+      result = wxDragNone;
+  }
+
+  *pdwEffect = ConvertDragResultToEffect(
+                 m_pTarget->OnDragOver(pt.x, pt.y, result)
+               );
+
   return S_OK;
 }
 
@@ -435,5 +455,45 @@ bool wxFileDropTarget::OnData(wxCoord x, wxCoord y)
                        ((wxFileDataObject *)m_dataObject)->GetFilenames());
 }
 
+// ----------------------------------------------------------------------------
+// private functions
+// ----------------------------------------------------------------------------
+
+static wxDragResult ConvertDragEffectToResult(DWORD dwEffect)
+{
+    switch ( dwEffect ) {
+        case DROPEFFECT_COPY:
+            return wxDragCopy;
+
+        case DROPEFFECT_MOVE:
+            return wxDragMove;
+
+        default:
+            wxFAIL_MSG(wxT("invalid value in ConvertDragEffectToResult"));
+            // fall through
+
+        case DROPEFFECT_NONE:
+            return wxDragNone;
+    }
+}
+
+static DWORD ConvertDragResultToEffect(wxDragResult result)
+{
+    switch ( result ) {
+        case wxDragCopy:
+            return DROPEFFECT_COPY;
+
+        case wxDragMove:
+            return DROPEFFECT_MOVE;
+
+        default:
+            wxFAIL_MSG(wxT("invalid value in ConvertDragResultToEffect"));
+            // fall through
+
+        case wxDragNone:
+            return DROPEFFECT_NONE;
+    }
+}
+
 #endif
  // wxUSE_DRAG_AND_DROP