HowTo : Implementation of CFormView::OnDragEnter od OnDragDrop in VC++
| Article | 41023925 |
| Type | HowTo |
| Product | Engine |
| Version | 5.0.1.1036 |
| Date Added | 4/13/2005 |
| Submitted by | A. Zuzel |
| Keywords | |
Subject
Implementation of CFormView::OnDragEnter od OnDragDrop in VC++
Summary
To provide drag&drop functionality to our customers we used in former versions of vectordraw the standard implementation of CFormView::OnDragEnter od OnDragDrop. Since version 5 this events are overridden by vectordraw events OnVdDragEnterEx and OnVdDragDropEx which use the vdDataObject.
How can the standard events still be fired. We need the Ole information from COleDataObject* pDataObject
Solution
Use the VectorCAD Sample to test the following code:
1.In CVdView class add a member variable : COleDropTarget m_dragObject;(it can be also a class derived fromCOleDropTarget )
2.in void CVdView::OnInitialUpdate() function add the following code:
void CVdView::OnInitialUpdate()
{
CFormView::OnInitialUpdate();
m_tab.SetVdraw(&m_Vdraw);
SetFocus();
//Revokes the registration of default VectorDraw DragDrop Implementation
//The dragdrop events of VectorDraw will not be fired
HRESULT res = RevokeDragDrop(this->m_Vdraw.GetSafeHwnd());
//Register the default MFC DragDrop Implementation.
BOOL success = m_dragObject.Register(this);
/*
//ReRegister the default VectorDraw DragDrop Implementation
//The dragdrop events of VectorDraw will be fired.
//By default the events are fired.
//call this code if you have previous call the RevokeDragDrop in order to re-enable VectorDraw DragDrop events
CvdDataObject dobj = m_Vdraw.GetDraggingObject();
LPDROPTARGET targ = NULL;
dobj.m_lpDispatch->QueryInterface(IID_IDropTarget, (LPVOID*)&targ);
HRESULT hres = RegisterDragDrop(this->m_Vdraw.GetSafeHwnd(),targ);
*/
}
3.Overwrite the Default CFormView DragDrop functions:
//Default MFC DragDrop Events
DROPEFFECT CVdView::OnDragEnter(COleDataObject* pDataObject, DWORD dwKeyState, CPoint point)
{
// TODO: Add your specialized code here and/or call the base class
DROPEFFECT efect = DROPEFFECT_NONE;
if (dwKeyState & MK_CONTROL )
efect = DROPEFFECT_COPY;
else
efect = DROPEFFECT_MOVE;
return efect;
//return CFormView::OnDragEnter(pDataObject, dwKeyState, point);
}
void CVdView::OnDragLeave()
{
// TODO: Add your specialized code here and/or call the base class
CFormView::OnDragLeave();
}
DROPEFFECT CVdView::OnDragOver(COleDataObject* pDataObject, DWORD dwKeyState, CPoint point)
{
// TODO: Add your specialized code here and/or call the base class
DROPEFFECT efect = DROPEFFECT_NONE;
if ( dwKeyState & MK_CONTROL )
efect = DROPEFFECT_COPY;
else
efect = DROPEFFECT_MOVE;
return efect;
//return CFormView::OnDragOver(pDataObject, dwKeyState, point);
}
BOOL CVdView::OnDrop(COleDataObject* pDataObject, DROPEFFECT dropEffect, CPoint point)
{
// TODO: Add your specialized code here and/or call the base class
//return CFormView::OnDrop(pDataObject, dropEffect, point);
return TRUE;
}
4.Add the Implemetation of DragDrop Events to test if they will be fired,
//VectorDraw DragDrop Events
void CVdView::OnVDDragDropExvdrawCTRL2(LPDISPATCH DataObject, double Xpos, double Ypos, double ZPos, long DropEffect, short FAR* Cancel)
{
// TODO: Add your control notification handler code here
}
void CVdView::OnVDDragEnterExvdrawCTRL2(LPDISPATCH DataObject, double Xpos, double Ypos, double ZPos, long FAR* DropEffect, short FAR* Cancel)
{
// TODO: Add your control notification handler code here
}
void CVdView::OnVDDragLeaveExvdrawCTRL2(LPDISPATCH DataObject)
{
// TODO: Add your control notification handler code here
}
void CVdView::OnVDDragOverExvdrawCTRL2(LPDISPATCH DataObject, double Xpos, double Ypos, double ZPos, long FAR* DropEffect, short FAR* Cancel)
{
// TODO: Add your control notification handler code here
}