有关CTreeCtrl拖拽的问题，请教！

Question

下面是有关拖拽的源代码，但是拖拽的时候拖拽的图标离鼠标有比较大的距离，不知道是怎么回事
各位大哥大姐能不能指点一下啊？？
void CXTreeCtrl::OnBegindrag(NMHDR* pNMHDR, LRESULT* pResult) 
{
NM_TREEVIEW* pNMTreeView = (NM_TREEVIEW*)pNMHDR;
// TODO: Add your control notification handler code here *pResult = 0; //Èç¹ûÊÇÎÞÒâÍÏÒ·£¬Ôò·ÅÆú²Ù×÷
if( (GetTickCount() - m_dwDragStart) < DRAG_DELAY )
return; m_hItemDragS = pNMTreeView->itemNew.hItem;
m_hItemDragD = NULL; //&micro;&Atilde;&micro;&frac12;&Oacute;&Atilde;&Oacute;&Uacute;&Iacute;&Iuml;&para;&macr;&Ecirc;±&Iuml;&Ocirc;&Ecirc;&frac34;&micro;&Auml;&Iacute;&frac14;&Iuml;ó&Aacute;&ETH;±í
m_pDragImage = CreateDragImage( m_hItemDragS );
if( !m_pDragImage )
return; m_bDragging = true;
m_pDragImage->BeginDrag ( 0, CPoint(8,8));
CPoint  pt = pNMTreeView->ptDrag;
ClientToScreen( &pt ); m_pDragImage->DragEnter ( NULL,pt);  //"this"&frac12;&laquo;&Iacute;&Iuml;&Ograve;·&para;&macr;×÷&Iuml;&THORN;&Ouml;&AElig;&Ocirc;&Uacute;&cedil;&Atilde;&acute;°&iquest;&Uacute;
SetCapture(); m_nScrollTimerID = SetTimer( 2,40,NULL );}

Answer 1

BeginDrag （）怎么实现的？

Answer 2

这是我以前写的相关代码你参考一下
         NM_TREEVIEW* pNMTreeView = (NM_TREEVIEW*)pNMHDR;
// TODO: Add your control notification handler code here
HTREEITEM hItem = pNMTreeView->itemNew.hItem;
int nData = m_cUserTree.GetItemData(hItem);
if (nData == -1)
{
*pResult = 0;
return;
}
m_hTreeItem = hItem;
m_pDragImageList = m_cUserTree.CreateDragImage(m_hTreeItem);
CRect rect;
if (m_pDragImageList)
{
SetCapture();
m_cUserTree.GetItemRect(m_hTreeItem, rect, TRUE);
CPoint pt;
pt.x = pNMTreeView->ptDrag.x - (rect.left-16);
pt.y = pNMTreeView->ptDrag.y - rect.top;
CImageList::DragShowNolock(TRUE);
m_pDragImageList->BeginDrag(0, pt);
CPoint      ptAction;

GetCursorPos(&ptAction);
m_cUserTree.ScreenToClient(&ptAction);
CImageList::DragMove(ptAction);
m_cUserTree.SelectDropTarget(m_hTreeItem);
CImageList::DragEnter(&m_cUserTree, ptAction);
m_pWndLocked = &m_cUserTree;
m_bDrag = TRUE;
}
*pResult = 0;