随笔- 13 文章- 14 评论- 11 阅读- 92007

MFC初步教程（二）

绘制简单的图形几乎是所有的VC教程中的必须内容，这里面涉及到几个概念，设备（device context），画刷（Pen）等。CDC是所有设备的父类，其子类包括CClientDC（仅在客户区绘制）, CPaintDC, CWindowDC（可以在客户区和窗口非客户区绘制）等。所有继承于CWnd类的子类均可以构造设备类。

#include <afxwin.h>
 
class MFC_Tutorial_Window: public CFrameWnd
{
    CPoint m_startPoint;
    CPoint m_endPoint;
public:
    MFC_Tutorial_Window()
    {
        Create(NULL, "MFC Tutorial");
    }
 
    void OnLButtonDown(UINT nFlags, CPoint point);
/*  {
        CFrameWnd::OnLButtonDown(nFlags,point);
 
        m_startPoint = point;   
    }*/
     
    void OnLButtonUp(UINT nFlags, CPoint point);
/*  {
        CFrameWnd::OnLButtonUp(nFlags, point);
        m_endPoint = point;
 
        CClientDC dc(this);
        dc.MoveTo(m_startPoint);
        dc.LineTo(m_endPoint);
    }*/
 
    DECLARE_MESSAGE_MAP()
};
 
BEGIN_MESSAGE_MAP( MFC_Tutorial_Window, CFrameWnd)
ON_WM_LBUTTONDOWN() //Macro to map the left button click to the handler
ON_WM_LBUTTONUP() //Macro to map the left button click to the handler
END_MESSAGE_MAP()
 
void MFC_Tutorial_Window::OnLButtonDown(UINT nFlags, CPoint point)
{   
    m_startPoint = point;
     
    CFrameWnd::OnLButtonDown(nFlags,point);
}
 
void MFC_Tutorial_Window::OnLButtonUp(UINT nFlags, CPoint point)
{   
    m_endPoint = point;
 
    CPen pen(PS_SOLID, 1, RGB(255,0,0));
     
    CWindowDC dc(this);  　　　　// 构造dc时必须传入一个CWnd类或其子类对象
    CPen* pOldPen = dc.SelectObject(&pen);  
    dc.MoveTo(m_startPoint);
    dc.LineTo(m_endPoint);
    dc.SelectObject(pOldPen);
 
    CFrameWnd::OnLButtonUp(nFlags, point);
}
 
class MyApp: public CWinApp
{
    MFC_Tutorial_Window *wnd;
public:
    BOOL InitInstance()
    {
        wnd = new MFC_Tutorial_Window();
        m_pMainWnd = wnd;
        m_pMainWnd->ShowWindow(1);
        return 1;
    }
};
 
MyApp theApp;