VC++ mfc制作简易画图板要求可以画基本形状，并具有填充功能，可以画线段，圆，方，三角形，能改变颜色，线条粗细代码

以下是一个简单的VC++ MFC制作画图板的代码，包含基本形状和填充功能，可以画线段，圆，方，三角形，能改变颜色，线条粗细。

首先是头文件和全局变量的声明：

#pragma once

#include "afxwin.h"
#include "afxext.h"

class CMyPaintView : public CView
{
protected: 
    CMyPaintView();
    DECLARE_DYNCREATE(CMyPaintView)

public:
    virtual ~CMyPaintView();
    virtual void OnDraw(CDC* pDC);
    virtual BOOL PreCreateWindow(CREATESTRUCT& cs);
#ifdef _DEBUG
    virtual void AssertValid() const;
    virtual void Dump(CDumpContext& dc) const;
#endif

protected:
    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 void OnSize(UINT nType, int cx, int cy);
    afx_msg void OnColor();
    afx_msg void OnLineWidth();
    afx_msg void OnFill();
    DECLARE_MESSAGE_MAP()

private:
    CDC m_dcMem;
    CBitmap m_bmpMem;
    CPoint m_ptStart;
    CPoint m_ptEnd;
    BOOL m_bDrawing;
    BOOL m_bFill;
    COLORREF m_clr;
    int m_nLineWidth;
    int m_nShape;
};

接下来是实现代码：

#include "stdafx.h"
#include "MyPaint.h"
#include "MyPaintDoc.h"
#include "MyPaintView.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#endif


IMPLEMENT_DYNCREATE(CMyPaintView, CView)

BEGIN_MESSAGE_MAP(CMyPaintView, CView)
    ON_WM_LBUTTONDOWN()
    ON_WM_MOUSEMOVE()
    ON_WM_LBUTTONUP()
    ON_WM_SIZE()
    ON_COMMAND(ID_COLOR, &CMyPaintView::OnColor)
    ON_COMMAND(ID_LINEWIDTH, &CMyPaintView::OnLineWidth)
    ON_COMMAND(ID_FILL, &CMyPaintView::OnFill)
END_MESSAGE_MAP()

CMyPaintView::CMyPaintView()
{
    m_bDrawing = FALSE;
    m_bFill = FALSE;
    m_clr = RGB(0, 0, 0);
    m_nLineWidth = 1;
    m_nShape = 0;
}

CMyPaintView::~CMyPaintView()
{
}

BOOL CMyPaintView::PreCreateWindow(CREATESTRUCT& cs)
{
    return CView::PreCreateWindow(cs);
}

void CMyPaintView::OnDraw(CDC* pDC)
{
    CMyPaintDoc* pDoc = GetDocument();
    ASSERT_VALID(pDoc);
    if (!pDoc)
        return;

    pDC->BitBlt(0, 0, pDoc->m_nWidth, pDoc->m_nHeight, &m_dcMem, 0, 0, SRCCOPY);
}

void CMyPaintView::OnLButtonDown(UINT nFlags, CPoint point)
{
    if (!m_bDrawing)
    {
        m_ptStart = point;
        m_ptEnd = point;
        m_bDrawing = TRUE;
    }
}

void CMyPaintView::OnMouseMove(UINT nFlags, CPoint point)
{
    if (m_bDrawing)
    {
        CDC* pDC = GetDC();
        m_dcMem.SelectObject(&m_bmpMem);
        m_dcMem.BitBlt(0, 0, m_bmpMem.GetBitmapDimension().cx, m_bmpMem.GetBitmapDimension().cy, pDC, 0, 0, SRCCOPY);

        CPen pen;
        pen.CreatePen(PS_SOLID, m_nLineWidth, m_clr);
        CBrush brush;
        brush.CreateSolidBrush(m_clr);
        CPen* pOldPen = m_dcMem.SelectObject(&pen);
        CBrush* pOldBrush = m_dcMem.SelectObject(&brush);

        switch (m_nShape)
        {
        case 0: // 线段
            m_dcMem.MoveTo(m_ptStart);
            m_dcMem.LineTo(point);
            break;
        case 1: // 圆
            m_dcMem.Ellipse(m_ptStart.x, m_ptStart.y, point.x, point.y);
            break;
        case 2: // 方
            m_dcMem.Rectangle(m_ptStart.x, m_ptStart.y, point.x, point.y);
            break;
        case 3: // 三角形
            {
                POINT pts[3];
                pts[0] = m_ptStart;
                pts[1].x = m_ptStart.x;
                pts[1].y = point.y;
                pts[2] = point;
                m_dcMem.Polygon(pts, 3);
            }
            break;
        default:
            break;
        }

        if (m_bFill)
        {
            m_dcMem.SelectObject(&brush);
            m_dcMem.FillSolidRect(CRect(m_ptStart, point), m_clr);
        }

        m_dcMem.SelectObject(pOldPen);
        m_dcMem.SelectObject(pOldBrush);
        ReleaseDC(pDC);
        m_ptEnd = point;
        Invalidate(FALSE);
    }
}

void CMyPaintView::OnLButtonUp(UINT nFlags, CPoint point)
{
    if (m_bDrawing)
    {
        CDC* pDC = GetDC();
        m_dcMem.SelectObject(&m_bmpMem);
        m_dcMem.BitBlt(0, 0, m_bmpMem.GetBitmapDimension().cx, m_bmpMem.GetBitmapDimension().cy, pDC, 0, 0, SRCCOPY);

        CPen pen;
        pen.CreatePen(PS_SOLID, m_nLineWidth, m_clr);
        CBrush brush;
        brush.CreateSolidBrush(m_clr);
        CPen* pOldPen = m_dcMem.SelectObject(&pen);
        CBrush* pOldBrush = m_dcMem.SelectObject(&brush);

        switch (m_nShape)
        {
        case 0: // 线段
            m_dcMem.MoveTo(m_ptStart);
            m_dcMem.LineTo(point);
            break;
        case 1: // 圆
            m_dcMem.Ellipse(m_ptStart.x, m_ptStart.y, point.x, point.y);
            break;
        case 2: // 方
            m_dcMem.Rectangle(m_ptStart.x, m_ptStart.y, point.x, point.y);
            break;
        case 3: // 三角形
            {
                POINT pts[3];
                pts[0] = m_ptStart;
                pts[1].x = m_ptStart.x;
                pts[1].y = point.y;
                pts[2] = point;
                m_dcMem.Polygon(pts, 3);
            }
            break;
        default:
            break;
        }

        if (m_bFill)
        {
            m_dcMem.SelectObject(&brush);
            m_dcMem.FillSolidRect(CRect(m_ptStart, point), m_clr);
        }

        m_dcMem.SelectObject(pOldPen);
        m_dcMem.SelectObject(pOldBrush);
        ReleaseDC(pDC);
        m_ptEnd = point;
        m_bDrawing = FALSE;
    }
}

void CMyPaintView::OnSize(UINT nType, int cx, int cy)
{
    CView::OnSize(nType, cx, cy);

    if (cx > 0 && cy > 0)
    {
        m_dcMem.DeleteDC();
        m_bmpMem.DeleteObject();
        CDC* pDC = GetDC();
        m_dcMem.CreateCompatibleDC(pDC);
        m_bmpMem.CreateCompatibleBitmap(pDC, cx, cy);
        m_dcMem.SelectObject(&m_bmpMem);
        ReleaseDC(pDC);
    }
}

void CMyPaintView::OnColor()
{
    CColorDialog dlg(m_clr);
    if (dlg.DoModal() == IDOK)
    {
        m_clr = dlg.GetColor();
    }
}

void CMyPaintView::OnLineWidth()
{
    CInputDialog dlg(_T("请输入线条宽度："), m_nLineWidth);
    if (dlg.DoModal() == IDOK)
    {
        m_nLineWidth = dlg.GetValue();
    }
}

void CMyPaintView::OnFill()
{
    m_bFill = !m_bFill;
}

#ifdef _DEBUG
void CMyPaintView::AssertValid() const
{
    CView::AssertValid();
}

void CMyPaintView::Dump(CDumpContext& dc) const
{
    CView::Dump(dc);
}

CMyPaintDoc* CMyPaintView::GetDocument() const // 非调试版本是内联的
{
    ASSERT(m_pDocument->IsKindOf(RUNTIME_CLASS(CMyPaintDoc)));
    return (CMyPaintDoc*)m_pDocument;
}
#endif //_DEBUG

这里使用了一个自定义的输入框类CInputDialog，用于获取用户输入的线条宽度。

#pragma once

#include "afxwin.h"

// CInputDialog 对话框

class CInputDialog : public CDialogEx
{
	DECLARE_DYNAMIC(CInputDialog)

public:
	CInputDialog(CString strPrompt, int nDefaultVal, CWnd* pParent = NULL);   // 标准构造函数
	virtual ~CInputDialog();

// 对话框数据
#ifdef AFX_DESIGN_TIME
	enum { IDD = IDD_INPUT_DIALOG };
#endif

protected:
	virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV 支持

	DECLARE_MESSAGE_MAP()
public:
	int m_nValue;
	CString m_strPrompt;
	afx_msg void OnBnClickedOk();
	virtual BOOL OnInitDialog();
};

#include "stdafx.h"
#include "InputDialog.h"
#include "afxdialogex.h"


// CInputDialog 对话框

IMPLEMENT_DYNAMIC(CInputDialog, CDialogEx)

CInputDialog::CInputDialog(CString strPrompt, int nDefaultVal, CWnd* pParent /*=NULL*/)
	: CDialogEx(IDD_INPUT_DIALOG, pParent)
{
	m_strPrompt = strPrompt;
	m_nValue = nDefaultVal;
}

CInputDialog::~CInputDialog()
{
}

void CInputDialog::DoDataExchange(CDataExchange* pDX)
{
	CDialogEx::DoDataExchange(pDX);
	DDX_Text(pDX, IDC_EDIT_VALUE, m_nValue);
	DDX_Text(pDX, IDC_STATIC_PROMPT, m_strPrompt);
}


BEGIN_MESSAGE_MAP(CInputDialog, CDialogEx)
	ON_BN_CLICKED(IDOK, &CInputDialog::OnBnClickedOk)
END_MESSAGE_MAP()


// CInputDialog 消息处理程序


void CInputDialog::OnBnClickedOk()
{
	UpdateData(TRUE);
	CDialogEx::OnOK();
}


BOOL CInputDialog::OnInitDialog()
{
	CDialogEx::OnInitDialog();

	CEdit* pEditValue = (CEdit*)GetDlgItem(IDC_EDIT_VALUE);
	if (pEditValue)
	{
		pEditValue->SetLimitText(2);
	}

	return TRUE;  // return TRUE unless you set the focus to a control
				  // 异常: OCX 属性页应返回 FALSE
}

最后，在资源文件中添加菜单项和工具栏，具体操作可以参考MFC官方文档。