请各位高手帮忙！！！

Question

小弟初学VC，最近在用bcg做一个程序，bcg里有一个workspacebar的树形菜单，我想实现对树的拖拽，拖拽到view栏中，并能够在视图栏中显示一个图标，请各位帮忙！！

Answer 1

WIN32拖拽扩展COleDropTarget，重写以下虚方法：
virtual DROPEFFECT OnDragEnter(CWnd* pWnd, COleDataObject* pDataObject,
DWORD dwKeyState, CPoint point);
virtual DROPEFFECT OnDragOver(CWnd* pWnd, COleDataObject* pDataObject,
DWORD dwKeyState, CPoint point);
virtual BOOL OnDrop(CWnd* pWnd, COleDataObject* pDataObject,
DROPEFFECT dropEffect, CPoint point);
virtual DROPEFFECT OnDropEx(CWnd* pWnd, COleDataObject* pDataObject,
DROPEFFECT dropEffect, DROPEFFECT dropEffectList, CPoint point);
virtual void OnDragLeave(CWnd* pWnd);

Answer 2

OleDropTargetEx.h// OleDropTargetEx.h: interface for the COleDropTargetEx class.#if !defined(AFX_OLEDROPTARGETEX_H__I_LOVE_MY_MOTHERLAND)
#define AFX_OLEDROPTARGETEX_H__I_LOVE_MY_MOTHERLAND#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
// OleDropTargetEx.h header file
//Drag & Drop User define Messages/////////////////////////////////////////////////////////////////////////////
//Drop info class
//ΪÍ϶¯ÏûÏ¢ÏìÓ¦º¯ÊýÌṩÍ϶¯ÐÅÏ¢
class COleDropInfo : public CObject
{
public:
COleDropInfo();
COleDropInfo(COleDataObject* pDataObject,DWORD dwKeyState,
DROPEFFECT dropEffect,DROPEFFECT dropEffectList,CPoint point );
virtual ~COleDropInfo();public:
//COleDropTargetEx member functions params
COleDataObject* m_pDataObject;
DWORD m_dwKeyState;
DROPEFFECT m_dropEffect;
DROPEFFECT m_dropEffectList;
CPoint m_point; DECLARE_DYNAMIC( COleDropInfo );
};/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
//COleDropTargetEx class 
class COleDropTargetEx : public COleDropTarget
{
public:
COleDropTargetEx();
virtual ~COleDropTargetEx();protected:
//´¦ÀíOnDropExÏûÏ¢ÊDZØÐëµÄ£¬·ñÔòOnDropº¯Êý²»»á±»Ö´ÐÐ
//µ±È»Ò²¿ÉÒÔÔÚOnDropExº¯ÊýÖд¦ÀíÊý¾Ý
virtual DROPEFFECT OnDragEnter(CWnd* pWnd, COleDataObject* pDataObject,
DWORD dwKeyState, CPoint point);
virtual DROPEFFECT OnDragOver(CWnd* pWnd, COleDataObject* pDataObject,
DWORD dwKeyState, CPoint point);
virtual BOOL OnDrop(CWnd* pWnd, COleDataObject* pDataObject,
DROPEFFECT dropEffect, CPoint point);
virtual DROPEFFECT OnDropEx(CWnd* pWnd, COleDataObject* pDataObject,
DROPEFFECT dropEffect, DROPEFFECT dropEffectList, CPoint point);
virtual void OnDragLeave(CWnd* pWnd);
};#endif // !defined(AFX_OLEDROPTARGETEX_H__I_LOVE_MY_MOTHERLAND)OleDropTargetEx.cpp// OleDropTargetEx.cpp: implementation of the COleDropTargetEx class.
//
//////////////////////////////////////////////////////////////////////#include "stdafx.h"
#include "LAD EDIT.h"
//#include "OleDropTargetEx.h"#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif//////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////
//COleDropInfo Construction/Destruction
IMPLEMENT_DYNAMIC( COleDropInfo, CObject );COleDropInfo::COleDropInfo()
{
m_pDataObject = NULL;
m_dwKeyState = 0;
m_dropEffect = (DROPEFFECT)-1;
m_dropEffectList = DROPEFFECT_NONE;
}COleDropInfo::COleDropInfo(COleDataObject* pDataObject,DWORD dwKeyState,
DROPEFFECT dropEffect,DROPEFFECT dropEffectList,CPoint point )
{
m_pDataObject = pDataObject;
m_dwKeyState = dwKeyState;
m_dropEffect = dropEffect;
m_dropEffectList = dropEffectList;
m_point = point;
}COleDropInfo::~COleDropInfo()
{
m_pDataObject = NULL;
}//////////////////////////////////////////////////////////////////////
//COleDropTargetEx Construction/Destruction
COleDropTargetEx::COleDropTargetEx()
{
}COleDropTargetEx::~COleDropTargetEx()
{
}//////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////
DROPEFFECT COleDropTargetEx::OnDragEnter(CWnd* pWnd, COleDataObject* pDataObject,
DWORD dwKeyState, CPoint point)
{
ASSERT_VALID(this);
ASSERT(::IsWindow(pWnd->m_hWnd)); if (pWnd->IsKindOf(RUNTIME_CLASS(CView)))//if CView,Call base class
return COleDropTarget::OnDragEnter(pWnd,pDataObject, dwKeyState, point); COleDropInfo DropInfo( pDataObject, dwKeyState, 0, 0, point );

return ::SendMessage( pWnd->GetSafeHwnd(), DROPM_DRAGENTER, (WPARAM)&DropInfo, 0 );
}DROPEFFECT COleDropTargetEx::OnDragOver(CWnd* pWnd, COleDataObject* pDataObject,
DWORD dwKeyState, CPoint point)
{
ASSERT_VALID(this);
ASSERT(::IsWindow(pWnd->m_hWnd)); if (pWnd->IsKindOf(RUNTIME_CLASS(CView)))//if CView,Call base class
return COleDropTarget::OnDragOver(pWnd,pDataObject, dwKeyState, point);

COleDropInfo DropInfo( pDataObject, dwKeyState, 0, 0, point ); return ::SendMessage( pWnd->GetSafeHwnd(), DROPM_DRAGOVER, (WPARAM)&DropInfo, 0 );
}BOOL COleDropTargetEx::OnDrop(CWnd* pWnd, COleDataObject* pDataObject,
DROPEFFECT dropEffect, CPoint point)
{
ASSERT_VALID(this);
ASSERT(::IsWindow(pWnd->m_hWnd)); if (pWnd->IsKindOf(RUNTIME_CLASS(CView)))//if CView,Call base class
return COleDropTarget::OnDrop(pWnd, pDataObject,dropEffect,point); COleDropInfo DropInfo( pDataObject, 0, dropEffect, 0, point ); return ::SendMessage( pWnd->GetSafeHwnd(), DROPM_DROP, (WPARAM)&DropInfo, 0 );
}DROPEFFECT COleDropTargetEx::OnDropEx(CWnd* pWnd, COleDataObject* pDataObject,
DROPEFFECT dropEffect, DROPEFFECT dropEffectList, CPoint point)
{
ASSERT_VALID(this);
ASSERT(::IsWindow(pWnd->m_hWnd)); if (pWnd->IsKindOf(RUNTIME_CLASS(CView)))//if CView,Call base class
return COleDropTarget::OnDropEx( pWnd, pDataObject, dropEffect, dropEffectList, point) ; COleDropInfo DropInfo( pDataObject, 0, dropEffect, dropEffectList, point ); return ::SendMessage( pWnd->GetSafeHwnd(), DROPM_DROPEX, (WPARAM)&DropInfo, 0 );
}void COleDropTargetEx::OnDragLeave(CWnd* pWnd)
{
ASSERT_VALID(this);
ASSERT(::IsWindow(pWnd->m_hWnd)); if (pWnd->IsKindOf(RUNTIME_CLASS(CView)))//if CView,Call base class
{
COleDropTarget::OnDragLeave( pWnd );
return;
} ::SendMessage( pWnd->GetSafeHwnd(), DROPM_DRAGLEAVE, 0, 0 ); return;
}

Answer 3

如何使用：
数据源注册：
COleDropTargetEx m_OleDropTarget;
   if(!m_OleDropTarget.Register(this))
   {
      MessageBox("Register error!", "Error" , MB_OK);
   }目标注册：
与数据来源者注册一样
COleDropTargetEx m_OleDropTarget;
   if(!m_OleDropTarget.Register(this))
   {
      MessageBox("Register error!", "Error" , MB_OK);
   }
注册是很重要的一步，只有两头都要注册才会有效

Answer 4

昨天连续发了3次，就不能发了，今天继续最后一步，模拟拖拽：
模拟拖拽动作数据源中响应鼠标消息， OnLButtonDown
[code=C/C++]
void CXX::OnLButtonDown(UINT nFlags, CPoint point) 
{
   // TODO: Add your message handler code here and/or call default
   SetFocus();
   
   HTREEITEM hItem = HitTest(point, NULL);
   if(NULL != hItem)
   {
      SelectItem(hItem);
      XX*pBlockLib = (XX*)GetItemData(hItem);
      if(NULL != pBlockLib)
      {
         HGLOBAL hData = GlobalAlloc(GHND|GMEM_SHARE, sizeof(XX));
         char *pS = (char *)GlobalLock(hData);
         memcpy(pS, (LPCTSTR)pBlockLib, sizeof(XX));
         GlobalUnlock(hData);
         
         COleDataSource source;
         UINT uBlockFormat = m_uBlockFormat;
         source.CacheGlobalData(uBlockFormat, hData);
         source.DoDragDrop(DROPEFFECT_COPY);
         GlobalFree(hData);
      }
   }
}
上边m_uBlockFormat要事先注册   UINT m_uBlockFormat = RegisterClipboardFormat("myblock");
   if(0 == m_uBlockFormat)
   {//register failed
      if(MessageBox(NULL, "Register the block format error!", "Error\n \
         close the instance(Y/N)", MB_YESNO) == IDYES)
      {
         return FALSE;
      }
   }
鼠标拖到目标上：
重写
virtual BOOL OnDrop(COleDataObject* pDataObject, DROPEFFECT dropEffect, CPoint point);
virtual DROPEFFECT OnDragOver(COleDataObject* pDataObject, DWORD dwKeyState, CPoint point);
DROPEFFECT CxxView::OnDragOver(COleDataObject* pDataObject, DWORD dwKeyState, CPoint point) 
{
// TODO: Add your specialized code here and/or call the base class

//return CScrollView::OnDragOver(pDataObject, dwKeyState, point);   UINT uBlockFormat = m_uBlockFormat;
   if(pDataObject->IsDataAvailable(uBlockFormat))
return DROPEFFECT_COPY;
else
return DROPEFFECT_NONE;
}BOOL CxxView::OnDrop(COleDataObject* pDataObject, DROPEFFECT dropEffect, CPoint point) 
{
   // TODO: Add your specialized code here and/or call the base class
   CPoint scrpt = GetScrollPosition();
   CPoint pt(point.x+scrpt.x, point.y+scrpt.y);   UINT uBlockFormat = m_uBlockFormat;
   if(pDataObject->IsDataAvailable(uBlockFormat))
   {
      HGLOBAL hMem = pDataObject->GetGlobalData(uBlockFormat);
      XX*pBlockLib = (XX*)GlobalLock((HGLOBAL)hMem);
      //自己处理的函数(pBlockLib, pt);
      GlobalUnlock(hMem);//unlock source
      Invalidate();
   }
   
return CScrollView::OnDrop(pDataObject, dropEffect, point);
}[/code]

Answer 5

楼主使用时，请去掉#include "LAD EDIT.h"