MFC Triangle Drawing in C++ Guide

1 year ago
Sophia Anderson
1 minute

When drawing a triangle using MFC, you can achieve this by overriding the OnPaint function of the CWnd class. The specific steps are as follows:

Firstly, create an MFC application and add a derived class from CWnd within it.

Add the following code to the header file of the CWnd class.

class CTriangleWnd : public CWnd
{
public:
    CTriangleWnd();
    virtual ~CTriangleWnd();

protected:
    DECLARE_MESSAGE_MAP()
    afx_msg void OnPaint();
};

3. Add the following code to the implementation file of the CWnd class:

BEGIN_MESSAGE_MAP(CTriangleWnd, CWnd)
    ON_WM_PAINT()
END_MESSAGE_MAP()

CTriangleWnd::CTriangleWnd()
{
}

CTriangleWnd::~CTriangleWnd()
{
}

void CTriangleWnd::OnPaint()
{
    CPaintDC dc(this);

    // 绘制三角形
    POINT points[3];
    points[0] = { 100, 100 };
    points[1] = { 150, 200 };
    points[2] = { 50, 200 };

    dc.Polygon(points, 3);
}

Create an instance of CTriangleWnd in the main window class and then display it.

BOOL CMyApp::InitInstance()
{
    // 创建主窗口
    CMainFrame* pFrame = new CMainFrame;
    m_pMainWnd = pFrame;

    // 创建三角形窗口
    CTriangleWnd* pTriangleWnd = new CTriangleWnd;
    pTriangleWnd->Create(NULL, _T("Triangle Window"), WS_VISIBLE | WS_OVERLAPPEDWINDOW, CRect(0, 0, 300, 300), pFrame);

    // 显示主窗口
    pFrame->ShowWindow(SW_SHOW);
    pFrame->UpdateWindow();

    return TRUE;
}

By following the above steps, you can use the CWnd class in MFC application to draw a simple triangle.

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