VC技巧 - 常用控制之二
可以使用Drag&Drop的CTreeView


CTreeViewExt是MFC使用者可重用的类，该类由CTreeView派生，可以用在文档-
视结构的应用程序中，并且支持Drag&Drop。
使用者所需要做的仅仅是将文件加到AppWizard产生的工程中，(CTreeView为基
类)并且将CTreeView替换为CTreeViewExt。并重载三个Virtual Function。

(WenYY:这很简单吧，下面是源代码，我会在必要的地方加上注释，但由于原作
者并未加，所以如果有出入请原谅，作者定义了三处虚拟函数，其作用是让使
用者重载后，加入自己的判断条件和结果处理的功能，很巧妙的思想：
      CopyItemProperties
      IsItemCanBeDroppedOn(HTREEITEM hSource, HTREEITEM hTarget);
      BOOL ItemCanBeDragged(HTREEITEM hItem);//检查是否可以对该ITEM实施Drag&Drop
)
Header file
#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(); // protected constructor used by dynamic creation
    DECLARE_DYNCREATE(CTreeViewExt)
// Attributes
public:
// Operations
public:
// Overrides
    // ClassWizard generated virtual function overrides
    //{{AFX_VIRTUAL(CTreeViewExt)
    protected:
    virtual void OnDraw(CDC* pDC); // overridden to draw this view
    //}}AFX_VIRTUAL
// Implementation
protected:
    HTREEITEM m_hDraggedItem;
    BOOL m_bDraggingNow; //标记
    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);//检查是否可以对该ITEM实施Drag&Drop
    //{{AFX_MSG(CTreeViewExt)
    afx_msg void OnBegindrag(NMHDR* pNMHDR, LRESULT* pResult);//必须重载的函数
    afx_msg void OnMouseMove(UINT nFlags, CPoint point);
    afx_msg void OnLButtonUp(UINT nFlags, CPoint point);
    //}}AFX_MSG
    DECLARE_MESSAGE_MAP()
};
/////////////////////////////////////////
//{{AFX_INSERT_LOCATION}}
// Microsoft Developer Studio will insert additional declarations immediately before the previous line.
#endif // !defined(AFX_TREEVIEWEXT_H__99D8F6F8_79F0_11D1_8DC6_0000E8125FE5__INCLUDED_)
Implementation file
// 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)
    {//先检查是否正在过程中
        if (ItemCanBeDragged(pNMTreeView->itemNew.hItem))
        {//查询条件，是否允许Drag&Drop
            CTreeCtrl& tree = GetTreeCtrl();
            tree.SetCapture();
            m_bDraggingNow = TRUE;
            m_hDraggedItem = pNMTreeView->itemNew.hItem;//保存变量
            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);//得到目标
        if (hTargetItem != NULL && IsItemCanBeDroppedOn(m_hDraggedItem, hTargetItem))
        {//查询是否可以成功完成,条件是开始时选中的Item和结束使选中的ITEM是否满足你的条件
            HTREEITEM hNewItem = tree.InsertItem("Untitled", hTargetItem);
            CopyItemProperties(hNewItem, m_hDraggedItem);//进行处理
            if (nFlags != MK_CONTROL)
                tree.DeleteItem(m_hDraggedItem);
        }
        m_hDraggedItem = NULL;
    }
    CTreeView::OnLButtonUp(nFlags, point);
}
BOOL CTreeViewExt::ItemCanBeDragged(HTREEITEM hItem)
{//作用为决定现在是否能开始,可以作为一种运行时的选项
    return FALSE;
}
BOOL CTreeViewExt::IsItemCanBeDroppedOn(HTREEITEM hSource, HTREEITEM hTarget)
{//决定现在结束条件是否正常，如不正常则放弃这次操作
    return FALSE;
}
void CTreeViewExt::CopyItemProperties(HTREEITEM hNewItem, HTREEITEM hDraggedItem)
{//按照你的需要对两个ITEM进行处理。
}


有关属性对话框(property sheet )的几个提示
闻怡洋 
下面的所有例子，都假定你从CPropertySheet中派生了新类。
1、隐藏APPLY按钮
使用 PSH_NOAPPLYNOW 标志.
propsheet.m_psh.dwFlags |= PSH_NOAPPLYNOW;
2、增加新的子窗口
使用成员变量。CEdit m_edit.
BOOL CMyPropSheet::OnInitDialog()
{
    BOOL bResult = CPropertySheet::OnInitDialog();
    CRect rectWnd;
    GetWindowRect(rectWnd);
    SetWindowPos(NULL, 0, 0,
        rectWnd.Width() + 100,
        rectWnd.Height(),
        SWP_NOMOVE | SWP_NOZORDER | SWP_NOACTIVATE);
    m_edit.CreateEx( WS_EX_CLIENTEDGE, _T("EDIT"), NULL,
                WS_CHILD | WS_VISIBLE | WS_TABSTOP | WS_BORDER,
                rectWnd.Width(), 20, 80, 24, m_hWnd, 0, 0 );
    m_edit.SetFont( GetFont() );
    CenterWindow();
    return bResult;
}
3、改变页片上的字体
在 OnInitDialog() 中：
// m_fontEdit is a member variable
// Create a bold font
m_fontEdit.CreateFont( -8, 0, 0, 0, 700, 0, 0, 0, 1,
        0, 0, 0, 0, _T("MS Sans Serif") );
GetTabControl()->SetFont( &m_fontEdit );
4、使用Image
m_imageTab为成员变量。
BOOL CMyPropSheet::OnInitDialog()
{
BOOL bResult = CPropertySheet::OnInitDialog();
m_imageTab.Create( IDB_TABIMAGES, 13, 1, RGB(255,255,255) );
CTabCtrl *pTab = GetTabControl();
pTab->SetImageList( &m_imageTab );
TC_ITEM tcItem;
tcItem.mask = TCIF_IMAGE;
for( int i = 0; i <3; i++ )
{
tcItem.iImage = i;
pTab->SetItem( i, &tcItem );
}
return bResult;
}
　


为TreeCtrl中的项增加ToolTip
文洋译 
要点：通过OnToolHitTest来增加ToolTip，CTreeCtrl::HitTest(...)的使用，TTN_NEEDTEXT消息的处理。
定义一个新类，有CTreeCtrl派生
Step 1:打开ToolTip 功能
void CTreeCtrlX::PreSubclassWindow()
{
    CTreeCtrl::PreSubclassWindow();
    EnableToolTips(TRUE);
}
Step 2: OnToolHitTest() 的重载
首先通过HitTest决定是否增加ToolTip,如果需要则返回非零。
在本例中ToolTip使用了LPSTR_TEXTCALLBACK,而没有立即设定显示字符串。
在本例只在鼠标指向每项的图片时才显示ToolTip

int CTreeCtrlX::OnToolHitTest(CPoint point, TOOLINFO * pTI) const
{
    RECT rect;
    UINT nFlags;
    HTREEITEM hitem = HitTest( point, &nFlags );
    if( nFlags & TVHT_ONITEMICON )
    {
        CImageList *pImg = GetImageList( TVSIL_NORMAL );
        IMAGEINFO imageinfo;
        pImg->GetImageInfo( 0, &imageinfo );
        GetItemRect( hitem, &rect, TRUE );
        rect.right = rect.left - 2;
        rect.left -= (imageinfo.rcImage.right + 2);
        pTI->hwnd = m_hWnd;
        pTI->uId = (UINT)hitem;
        pTI->lpszText = LPSTR_TEXTCALLBACK;
        pTI->rect = rect;
        return pTI->uId;
    }
    else if( nFlags & TVHT_ONITEMSTATEICON )
    {
        CImageList *pImg = GetImageList( TVSIL_NORMAL );
        IMAGEINFO imageinfo;
        pImg->GetImageInfo( 0, &imageinfo );
        GetItemRect( hitem, &rect, TRUE );
        rect.right = rect.left - (imageinfo.rcImage.right + 2);
        pImg = GetImageList( TVSIL_STATE );
        rect.left = rect.right - imageinfo.rcImage.right ;
        pTI->hwnd = m_hWnd;
        pTI->uId = (UINT)hitem;
        pTI->lpszText = LPSTR_TEXTCALLBACK;
        pTI->rect = rect;
        // return value should be different from that used for item icon
        return pTI->uId*2;
    }
    return -1;
}
Step 3: ?? TTN_NEEDTEXT
由于在增加ToolTip是使用用了 LPSTR_TEXTCALLBACK，因此ToolTip在显示
时会发送该消息来得到显示字符串。
BEGIN_MESSAGE_MAP(CTreeCtrlX, CTreeCtrl)
    //{{AFX_MSG_MAP(CTreeCtrlX)
    :
    :
    //}}AFX_MSG_MAP
    ON_NOTIFY_EX_RANGE(TTN_NEEDTEXTW, 0, 0xFFFF, OnToolTipText)
    ON_NOTIFY_EX_RANGE(TTN_NEEDTEXTA, 0, 0xFFFF, OnToolTipText)
END_MESSAGE_MAP()
protected:
    //{{AFX_MSG(CTreeCtrlX)
    :
    :
    //}}AFX_MSG
    afx_msg BOOL OnToolTipText( UINT id, NMHDR * pNMHDR, LRESULT * pResult );
    DECLARE_MESSAGE_MAP()
BOOL CTreeCtrlX::OnToolTipText( UINT id, NMHDR * pNMHDR, LRESULT * pResult )
{
// need to handle both ANSI and UNICODE versions of the message
TOOLTIPTEXTA* pTTTA = (TOOLTIPTEXTA*)pNMHDR;
TOOLTIPTEXTW* pTTTW = (TOOLTIPTEXTW*)pNMHDR;
CString strTipText;
UINT nID = pNMHDR->idFrom;
// Do not process the message from built in tooltip
if( nID == (UINT)m_hWnd &&
(( pNMHDR->code == TTN_NEEDTEXTA && pTTTA->uFlags & TTF_IDISHWND ) ||
( pNMHDR->code == TTN_NEEDTEXTW && pTTTW->uFlags & TTF_IDISHWND ) ) )
return FALSE;
// Get the mouse position
const MSG* pMessage;
CPoint pt;
pMessage = GetCurrentMessage();
ASSERT ( pMessage );
pt = pMessage->pt;
ScreenToClient( &pt );
UINT nFlags;
HTREEITEM hitem = HitTest( pt, &nFlags );
if( nFlags & TVHT_ONITEMICON )
{
int nImage, nSelImage;
GetItemImage( (HTREEITEM ) nID, nImage, nSelImage );
strTipText.Format( "Image : %d", nImage );
}
else
{
strTipText.Format( "State : %d", GetItemState( (HTREEITEM ) nID,
     TVIS_STATEIMAGEMASK ) );
}
#ifndef _UNICODE
if (pNMHDR->code == TTN_NEEDTEXTA)
lstrcpyn(pTTTA->szText, strTipText, 80);
else
_mbstowcsz(pTTTW->szText, strTipText, 80);
#else
if (pNMHDR->code == TTN_NEEDTEXTA)
_wcstombsz(pTTTA->szText, strTipText, 80);
else
lstrcpyn(pTTTW->szText, strTipText, 80);
#endif
*pResult = 0;
return TRUE; // message was handled
}