public unsafe HRESULT GetDragDropEffect(BOOL fDrag, User32.MK grfKeyState, Ole32.DROPEFFECT *pdwEffect)
{
if (pdwEffect is null)
{
return(HRESULT.E_POINTER);
}
*pdwEffect = Ole32.DROPEFFECT.NONE;
return(HRESULT.S_OK);
}
public unsafe HRESULT GetDragDropEffect(BOOL fDrag, User32.MK grfKeyState, Ole32.DROPEFFECT *pdwEffect)
{
if (pdwEffect is null)
{
return(HRESULT.E_POINTER);
}
Debug.WriteLineIf(RichTextDbg.TraceVerbose, "IRichEditOleCallback::GetDragDropEffect");
if (owner.AllowDrop || owner.EnableAutoDragDrop)
{
if (fDrag.IsTrue() && grfKeyState == (User32.MK) 0)
{
// This is the very first call we receive in a Drag-Drop operation,
// so we will let the control know what we support.
// Note that we haven't gotten any data yet, so we will let QueryAcceptData
// do the OnDragEnter. Note too, that grfKeyState does not yet reflect the
// current keystate
if (owner.EnableAutoDragDrop)
{
lastEffect = (DragDropEffects.All | DragDropEffects.None);
}
else
{
lastEffect = DragDropEffects.None;
}
}
else
{
// We are either dragging over or dropping
// The below is the complete reverse of what the docs on MSDN suggest,
// but if we follow the docs, we would be firing OnDragDrop all the
// time instead of OnDragOver (see
// drag - fDrag = false, grfKeyState != 0
// drop - fDrag = false, grfKeyState = 0
// We only care about the drag.
//
// When we drop, lastEffect will have the right state
if (fDrag.IsFalse() && lastDataObject is not null && grfKeyState != (User32.MK) 0)
{
DragEventArgs e = new DragEventArgs(lastDataObject,
(int)grfKeyState,
Control.MousePosition.X,
Control.MousePosition.Y,
DragDropEffects.All,
lastEffect);
// Now tell which of the allowable effects we want to use, but only if we are not already none
if (lastEffect != DragDropEffects.None)
{
e.Effect = ((grfKeyState & User32.MK.CONTROL) == User32.MK.CONTROL) ? DragDropEffects.Copy : DragDropEffects.Move;
}
owner.OnDragOver(e);
lastEffect = e.Effect;
}
}
*pdwEffect = (Ole32.DROPEFFECT)lastEffect;
}
else
{
*pdwEffect = Ole32.DROPEFFECT.NONE;
}
return(HRESULT.S_OK);
}
