在MFC++6.0中用鼠标选择圆心和半径实现椭圆的扫描转换的代码

以下是一个简单的MFC++ 6.0示例程序，可以使用鼠标选择椭圆的中心和半径，并使用扫描转换算法绘制椭圆：

// EllipseScanConversionDlg.h

#if !defined(AFX_ELLIPSESCANCONVERSIONDLG_H__E7BD3A2A_6A5E_4D8F_AE82_8F1B44C55D98__INCLUDED_)
#define AFX_ELLIPSESCANCONVERSIONDLG_H__E7BD3A2A_6A5E_4D8F_AE82_8F1B44C55D98__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

/////////////////////////////////////////////////////////////////////////////
// CEllipseScanConversionDlg dialog

class CEllipseScanConversionDlg : public CDialog
{
// Construction
public:
    CEllipseScanConversionDlg(CWnd* pParent = NULL);   // standard constructor

// Dialog Data
    //{{AFX_DATA(CEllipseScanConversionDlg)
    enum { IDD = IDD_ELLIPSESCANCONVERSION_DIALOG };
    //}}AFX_DATA

    // ClassWizard generated virtual function overrides
    //{{AFX_VIRTUAL(CEllipseScanConversionDlg)
    protected:
    virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support
    //}}AFX_VIRTUAL

// Implementation
protected:
    HICON m_hIcon;
    int m_nXCenter, m_nYCenter, m_nXRadius, m_nYRadius;

    // Generated message map functions
    //{{AFX_MSG(CEllipseScanConversionDlg)
    virtual BOOL OnInitDialog();
    afx_msg void OnPaint();
    afx_msg HCURSOR OnQueryDragIcon();
    afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
    //}}AFX_MSG
    DECLARE_MESSAGE_MAP()
};

//{{AFX_INSERT_LOCATION}}
// Microsoft Visual C++ will insert additional declarations immediately before the previous line.

#endif // !defined(AFX_ELLIPSESCANCONVERSIONDLG_H__E7BD3A2A_6A5E_4D8F_AE82_8F1B44C55D98__INCLUDED_)

// EllipseScanConversionDlg.cpp

#include "stdafx.h"
#include "EllipseScanConversion.h"
#include "EllipseScanConversionDlg.h"

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

/////////////////////////////////////////////////////////////////////////////
// CEllipseScanConversionDlg dialog

CEllipseScanConversionDlg::CEllipseScanConversionDlg(CWnd* pParent /*=NULL*/)
    : CDialog(CEllipseScanConversionDlg::IDD, pParent)
{
    //{{AFX_DATA_INIT(CEllipseScanConversionDlg)
    //}}AFX_DATA_INIT
    m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);
    m_nXCenter = m_nYCenter = m_nXRadius = m_nYRadius = 0;
}

void CEllipseScanConversionDlg::DoDataExchange(CDataExchange* pDX)
{
    CDialog::DoDataExchange(pDX);
    //{{AFX_DATA_MAP(CEllipseScanConversionDlg)
    //}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CEllipseScanConversionDlg, CDialog)
    //{{AFX_MSG_MAP(CEllipseScanConversionDlg)
    ON_WM_PAINT()
    ON_WM_QUERYDRAGICON()
    ON_WM_LBUTTONDOWN()
    //}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CEllipseScanConversionDlg message handlers

BOOL CEllipseScanConversionDlg::OnInitDialog()
{
    CDialog::OnInitDialog();

    // 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 CEllipseScanConversionDlg::OnPaint()
{
    CPaintDC dc(this); // device context for painting

    // TODO: Add your message handler code here
    if (m_nXRadius > 0 && m_nYRadius > 0)
    {
        int x, y;
        double dAngle;
        const double PI = 3.1415926536;
        const double dStep = PI / 180.0;
        CPoint ptCenter(m_nXCenter, m_nYCenter);

        for (int i = 0; i < 360; i++)
        {
            dAngle = i * dStep;
            x = m_nXRadius * cos(dAngle) + 0.5;
            y = m_nYRadius * sin(dAngle) + 0.5;
            dc.SetPixel(ptCenter.x + x, ptCenter.y + y, RGB(255, 0, 0));
        }
    }
}

HCURSOR CEllipseScanConversionDlg::OnQueryDragIcon()
{
    return (HCURSOR) m_hIcon;
}

void CEllipseScanConversionDlg::OnLButtonDown(UINT nFlags, CPoint point)
{
    // TODO: Add your message handler code here and/or call default
    m_nXCenter = point.x;
    m_nYCenter = point.y;
    m_nXRadius = m_nYRadius = 0;
    Invalidate();

    CDialog::OnLButtonDown(nFlags, point);
}

在这个示例程序中，我们使用`OnLButtonDown`处理程序来记录鼠标单击事件的位置，并使用`OnPaint`处理程序来绘制椭圆。 在`OnPaint`处理程序中，我们使用扫描转换算法来绘制椭圆的每个像素。 您可以更改此示例程序以适应您的需求。