Реализация drag'n'drop в CTreeView

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Файл объявления:

#if !defined(AFX_TREEVIEWEXT_H__99D8F6F8_79F0_11D1_8DC6_0000E8125FE5__INCLUDED_)
#define AFX_TREEVIEWEXT_H__99D8F6F8_79F0_11D1_8DC6_0000E8125FE5__INCLUDED_

#if _MSC_VER >= 1000
#pragma once
#endif // _MSC_VER >= 1000
// TreeViewExt.h : header file
//

//////////////////////////////////////////
// CTreeViewExt view

class CTreeViewExt : public CTreeView
{
protected:
CTreeViewExt(); 
DECLARE_DYNCREATE(CTreeViewExt)

// Attributes
public:

// Operations
public:

// Overrides
// ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CTreeViewExt)
protected:
virtual void OnDraw(CDC* pDC); // перегружено для рисования этого элемента
//}}AFX_VIRTUAL

// Implementation
protected:
HTREEITEM m_hDraggedItem;
BOOL m_bDraggingNow;
CImageList *m_pDragImageList;
virtual ~CTreeViewExt();
#ifdef _DEBUG
virtual void AssertValid() const;
virtual void Dump(CDumpContext& dc) const;
#endif

// Generated message map functions
protected:
virtual void CopyItemProperties(HTREEITEM hNewItem, HTREEITEM hDraggedItem);
virtual BOOL IsItemCanBeDroppedOn(HTREEITEM hSource, HTREEITEM hTarget);
virtual BOOL ItemCanBeDragged(HTREEITEM hItem);
//{{AFX_MSG(CTreeViewExt)
afx_msg void OnBegindrag(NMHDR* pNMHDR, LRESULT* pResult);
afx_msg void OnMouseMove(UINT nFlags, CPoint point);
afx_msg void OnLButtonUp(UINT nFlags, CPoint point);
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
};

//////////////////////////////////////////
//{{AFX_INSERT_LOCATION}}

#endif // !defined(AFX_TREEVIEWEXT_H__99D8F6F8_79F0_11D1_8DC6_0000E8125FE5__INCLUDED_)
 

Файл реализации:

// TreeViewExt.cpp : implementation file
//

#include "stdafx.h"
#include "TreeViewExt.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

//////////////////////////////////////
// CTreeViewExt

IMPLEMENT_DYNCREATE(CTreeViewExt, CTreeView)

CTreeViewExt::CTreeViewExt()
{
m_bDraggingNow= FALSE;
m_hDraggedItem= NULL;
m_pDragImageList= NULL;
}

CTreeViewExt::~CTreeViewExt()
{
}


BEGIN_MESSAGE_MAP(CTreeViewExt, CTreeView)
//{{AFX_MSG_MAP(CTreeViewExt)
ON_NOTIFY_REFLECT(TVN_BEGINDRAG, OnBegindrag)
ON_WM_MOUSEMOVE()
ON_WM_LBUTTONUP()
//}}AFX_MSG_MAP
END_MESSAGE_MAP()

///////////////////////////////////////////
// CTreeViewExt drawing

void CTreeViewExt::OnDraw(CDC* pDC)
{
CDocument* pDoc = GetDocument();
// TODO: add draw code here
}

////////////////////////////////////////////
// CTreeViewExt diagnostics

#ifdef _DEBUG
void CTreeViewExt::AssertValid() const
{
CTreeView::AssertValid();
}

void CTreeViewExt::Dump(CDumpContext& dc) const
{
CTreeView::Dump(dc);
}
#endif //_DEBUG

///////////////////////////////////////////////
// CTreeViewExt message handlers

void CTreeViewExt::OnBegindrag(NMHDR* pNMHDR, LRESULT* pResult) 
{
NM_TREEVIEW* pNMTreeView = (NM_TREEVIEW*)pNMHDR;

if (!m_bDraggingNow)
{
if (ItemCanBeDragged(pNMTreeView->itemNew.hItem))
{
CTreeCtrl& tree = GetTreeCtrl();
tree.SetCapture();
m_bDraggingNow = TRUE;
m_hDraggedItem = pNMTreeView->itemNew.hItem;
tree.Select(m_hDraggedItem, TVGN_CARET);
m_pDragImageList = tree.CreateDragImage(m_hDraggedItem);
m_pDragImageList->DragEnter(&tree, pNMTreeView->ptDrag);
m_pDragImageList->BeginDrag(0, CPoint(0, 0));
}
}

*pResult = 0;
}

void CTreeViewExt::OnMouseMove(UINT nFlags, CPoint point) 
{
if (m_bDraggingNow)
{
CTreeCtrl& tree = GetTreeCtrl();
m_pDragImageList->DragEnter(&tree, point);
m_pDragImageList->DragMove(point);
}

CTreeView::OnMouseMove(nFlags, point);
}

void CTreeViewExt::OnLButtonUp(UINT nFlags, CPoint point) 
{
if (m_bDraggingNow)
{
ReleaseCapture();

m_bDraggingNow = FALSE;
m_pDragImageList->EndDrag();
delete m_pDragImageList;
m_pDragImageList = NULL;

CTreeCtrl& tree = GetTreeCtrl();
UINT flags;
HTREEITEM hTargetItem = tree.HitTest(point, &flags);
if (hTargetItem != NULL && IsItemCanBeDroppedOn(m_hDraggedItem, hTargetItem))
{
HTREEITEM hNewItem = tree.InsertItem("Untitled", hTargetItem);
CopyItemProperties(hNewItem, m_hDraggedItem);
if (nFlags != MK_CONTROL)
tree.DeleteItem(m_hDraggedItem);
}

m_hDraggedItem = NULL;
}

CTreeView::OnLButtonUp(nFlags, point);
}

BOOL CTreeViewExt::ItemCanBeDragged(HTREEITEM hItem)
{
return FALSE;
}

BOOL CTreeViewExt::IsItemCanBeDroppedOn(HTREEITEM hSource, HTREEITEM hTarget)
{
return FALSE;
}

void CTreeViewExt::CopyItemProperties(HTREEITEM hNewItem, HTREEITEM hDraggedItem)
{

}