对话框窗口中鼠标事件的问题

Question

想在对话框窗口中实现如下鼠标事件,不知道怎么弄,请教各位达人.
在对话框内任意位置按下鼠标左键开始出现虚线的矩形,大小随着鼠标拖拽而变化,放开左键后矩形消失.想达到鼠标在windows桌面上的的这种操作一样的效果.
不知道有没有表达清楚,唉,肯定各位指教

Answer 1

重载OnLButtonDown  OnLButtonUp   OnMouseMove,down的时候记下初始点,UP的时候记下终点,MOVE的时候有个过度点,在MOVE里写个函数,来擦画线,
如:int Oldmode,minx,miny;
minx=min(pDoc->Width*m_nZoom,rctClient.right)-16*m_nZoom;
miny=min(pDoc->Height*m_nZoom,rctClient.bottom);
point.x=min(point.x,minx-1);
point.y=min(point.y,miny-1);
m_pDC->SelectStockObject(BLACK_PEN);
Oldmode=m_pDC->SetROP2(R2_NOT);
//去除旧框
m_pDC->MoveTo(0,ptstart.y/m_nZoom*m_nZoom);
m_pDC->LineTo(minx,ptstart.y/m_nZoom*m_nZoom);
m_pDC->MoveTo(0,ptOld.y/m_nZoom*m_nZoom);
m_pDC->LineTo(minx,ptOld.y/m_nZoom*m_nZoom);
//画新框
m_pDC->MoveTo(0,ptstart.y/m_nZoom*m_nZoom);
m_pDC->LineTo(minx,ptstart.y/m_nZoom*m_nZoom);
m_pDC->MoveTo(0,point.y/m_nZoom*m_nZoom);
m_pDC->LineTo(minx,point.y/m_nZoom*m_nZoom);
ptOld=point;
m_pDC->SetROP2(Oldmode);

Answer 2

帮你写了一个
// DrawLineDlg.h : header file
//#if !defined(AFX_DRAWLINEDLG_H__52ED76FE_F760_4063_8C40_E4533813ED02__INCLUDED_)
#define AFX_DRAWLINEDLG_H__52ED76FE_F760_4063_8C40_E4533813ED02__INCLUDED_#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000/////////////////////////////////////////////////////////////////////////////
// CDrawLineDlg dialogclass CDrawLineDlg : public CDialog
{
// Construction
public:
CDrawLineDlg(CWnd* pParent = NULL); // standard constructor// Dialog Data
//{{AFX_DATA(CDrawLineDlg)
enum { IDD = IDD_DRAWLINE_DIALOG };
// NOTE: the ClassWizard will add data members here
//}}AFX_DATA // ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CDrawLineDlg)
protected:
virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
//}}AFX_VIRTUAL// Implementation
protected:
HICON m_hIcon;
CRect rcDrag;
BOOL m_bDrawing; // Generated message map functions
//{{AFX_MSG(CDrawLineDlg)
virtual BOOL OnInitDialog();
afx_msg void OnSysCommand(UINT nID, LPARAM lParam);
afx_msg void OnPaint();
afx_msg HCURSOR OnQueryDragIcon();
afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
afx_msg void OnMouseMove(UINT nFlags, CPoint point);
afx_msg void OnLButtonUp(UINT nFlags, CPoint point);
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
private:
void DrawLines();
};//{{AFX_INSERT_LOCATION}}
// Microsoft Visual C++ will insert additional declarations immediately before the previous line.#endif // !defined(AFX_DRAWLINEDLG_H__52ED76FE_F760_4063_8C40_E4533813ED02__INCLUDED_)
// DrawLineDlg.cpp : implementation file
//#include "stdafx.h"
#include "DrawLine.h"
#include "DrawLineDlg.h"#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif/////////////////////////////////////////////////////////////////////////////
// CAboutDlg dialog used for App Aboutclass CAboutDlg : public CDialog
{
public:
CAboutDlg();// Dialog Data
//{{AFX_DATA(CAboutDlg)
enum { IDD = IDD_ABOUTBOX };
//}}AFX_DATA // ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CAboutDlg)
protected:
virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support
//}}AFX_VIRTUAL// Implementation
protected:
//{{AFX_MSG(CAboutDlg)
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
};CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD)
{
//{{AFX_DATA_INIT(CAboutDlg)
//}}AFX_DATA_INIT
}void CAboutDlg::DoDataExchange(CDataExchange* pDX)
{
CDialog::DoDataExchange(pDX);
//{{AFX_DATA_MAP(CAboutDlg)
//}}AFX_DATA_MAP
}BEGIN_MESSAGE_MAP(CAboutDlg, CDialog)
//{{AFX_MSG_MAP(CAboutDlg)
// No message handlers
//}}AFX_MSG_MAP
END_MESSAGE_MAP()/////////////////////////////////////////////////////////////////////////////
// CDrawLineDlg dialogCDrawLineDlg::CDrawLineDlg(CWnd* pParent /*=NULL*/)
: CDialog(CDrawLineDlg::IDD, pParent)
{
//{{AFX_DATA_INIT(CDrawLineDlg)
// NOTE: the ClassWizard will add member initialization here
//}}AFX_DATA_INIT
// Note that LoadIcon does not require a subsequent DestroyIcon in Win32
m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);
m_bDrawing = FALSE;
}void CDrawLineDlg::DoDataExchange(CDataExchange* pDX)
{
CDialog::DoDataExchange(pDX);
//{{AFX_DATA_MAP(CDrawLineDlg)
// NOTE: the ClassWizard will add DDX and DDV calls here
//}}AFX_DATA_MAP
}BEGIN_MESSAGE_MAP(CDrawLineDlg, CDialog)
//{{AFX_MSG_MAP(CDrawLineDlg)
ON_WM_SYSCOMMAND()
ON_WM_PAINT()
ON_WM_QUERYDRAGICON()
ON_WM_LBUTTONDOWN()
ON_WM_MOUSEMOVE()
ON_WM_LBUTTONUP()
//}}AFX_MSG_MAP
END_MESSAGE_MAP()/////////////////////////////////////////////////////////////////////////////
// CDrawLineDlg message handlersBOOL CDrawLineDlg::OnInitDialog()
{
CDialog::OnInitDialog(); // Add "About..." menu item to system menu. // IDM_ABOUTBOX must be in the system command range.
ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);
ASSERT(IDM_ABOUTBOX < 0xF000); CMenu* pSysMenu = GetSystemMenu(FALSE);
if (pSysMenu != NULL)
{
CString strAboutMenu;
strAboutMenu.LoadString(IDS_ABOUTBOX);
if (!strAboutMenu.IsEmpty())
{
pSysMenu->AppendMenu(MF_SEPARATOR);
pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
}
} // Set the icon for this dialog.  The framework does this automatically
//  when the application's main window is not a dialog
SetIcon(m_hIcon, TRUE); // Set big icon
SetIcon(m_hIcon, FALSE); // Set small icon

// TODO: Add extra initialization here

return TRUE;  // return TRUE  unless you set the focus to a control
}void CDrawLineDlg::OnSysCommand(UINT nID, LPARAM lParam)
{
if ((nID & 0xFFF0) == IDM_ABOUTBOX)
{
CAboutDlg dlgAbout;
dlgAbout.DoModal();
}
else
{
CDialog::OnSysCommand(nID, lParam);
}
}// If you add a minimize button to your dialog, you will need the code below
//  to draw the icon.  For MFC applications using the document/view model,
//  this is automatically done for you by the framework.void CDrawLineDlg::OnPaint() 
{
if (IsIconic())
{
CPaintDC dc(this); // device context for painting SendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0); // Center icon in client rectangle
int cxIcon = GetSystemMetrics(SM_CXICON);
int cyIcon = GetSystemMetrics(SM_CYICON);
CRect rect;
GetClientRect(&rect);
int x = (rect.Width() - cxIcon + 1) / 2;
int y = (rect.Height() - cyIcon + 1) / 2; // Draw the icon
dc.DrawIcon(x, y, m_hIcon);
}
else
{
CDialog::OnPaint();
}
}// The system calls this to obtain the cursor to display while the user drags
//  the minimized window.
HCURSOR CDrawLineDlg::OnQueryDragIcon()
{
return (HCURSOR) m_hIcon;
}void CDrawLineDlg::OnLButtonDown(UINT nFlags, CPoint point) 
{
// TODO: Add your message handler code here and/or call default
m_bDrawing = TRUE;
rcDrag.left=rcDrag.right=point.x;
rcDrag.top=rcDrag.bottom=point.y;
DrawLines(); CDialog::OnLButtonDown(nFlags, point);
}void CDrawLineDlg::OnMouseMove(UINT nFlags, CPoint point) 
{
// TODO: Add your message handler code here and/or call default
if (m_bDrawing)
{

DrawLines();
rcDrag.bottom=point.y;
rcDrag.right=point.x;
DrawLines(); }
CDialog::OnMouseMove(nFlags, point);
}void CDrawLineDlg::OnLButtonUp(UINT nFlags, CPoint point) 
{
// TODO: Add your message handler code here and/or call default
m_bDrawing = FALSE;
DrawLines();
CDialog::OnLButtonUp(nFlags, point);
}void CDrawLineDlg::DrawLines()
{
CClientDC dc(this);
dc.SetROP2(R2_NOT);
dc.MoveTo(rcDrag.left,rcDrag.top);
dc.LineTo(rcDrag.left,rcDrag.bottom);
dc.LineTo(rcDrag.right,rcDrag.bottom);
dc.LineTo(rcDrag.right,rcDrag.top);
dc.LineTo(rcDrag.left,rcDrag.top);
}