MFC小程序

1.将菜单栏归零，工具栏放在窗口低部，加载自己新建的工具栏

CMainFrame::OnCreate（）函数中 this->SetMenu(0);

2.将窗口初始化为最大化

APP类中：m_pMainWnd->ShowWindow(SW_MAXIMIZE);

 3.去掉边框

CMainFrame::PreCreateWindow（）函数中 cs.style = WS_POPUP;
4.在FRAME类中添加工具栏命令消息，关闭    

通过ON_COMMAND(ToolBar下的图片ID,实现的函数)  this->PostMessage(WM_CLOSE);

5.在VIEW类中添加系统消息keydown

void CDRAWView::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)

{

　　if(nChar == VK_ESCAPE)

　　{

　　　　AfxGetMainWnd()->PostMessage(WM_CLOSE);

　　}　　

　　CView::OnKeyDown(nChar, nRepCnt, nFlags);

}

6.将桌面背景贴到窗口上
在Frame.h中添加成员变量和成员函数

class CMainFrame : public CFrameWnd
{
    public:
    int m_ScreenX;
    int m_ScreenY;
    stack<CBitmap*> stk;//保存图片，实现撤销操作
}

Frame.cpp的构造函数和析构函数

CMainFrame::CMainFrame()
{
    m_ScreenX = GetSystemMetrics(SM_CXSCREEN);//屏幕长（调用函数为获取屏幕分辨率）
    m_ScreenY = GetSystemMetrics(SM_CYSCREEN);//屏幕宽
    CWindowDC dc(GetDesktopWindow());//获取桌面屏幕
    CDC cdc;
    cdc.CreateCompatibleDC(&dc);//兼容性DC相当于没有画纸的DC
    CBitmap* bitmap = new CBitmap;
    bitmap->CreateCompatibleBitmap(&dc,m_ScreenX,m_ScreenY);//创建一个兼容性位图，第一个参数
    cdc.SelectObject(bitmap);//将画纸放在DC上（只有兼容性DC才可以放画纸）
    cdc.BitBlt(0,0,m_ScreenX,m_ScreenY,&dc,0,0,SRCCOPY);
    stk.push(bitmap);
}

CMainFrame::~CMainFrame()
{
    if(stk.empty() == false)
    {
        delete(stk.top());
        stk.pop();
    }
}

 VIEW.cpp

void CDRAWView::OnDraw(CDC* /*pDC*/)
{
    CDRAWDoc* pDoc = GetDocument();
    ASSERT_VALID(pDoc);
    if (!pDoc)
        return;

    CMainFrame* pFrame = (CMainFrame*)AfxGetMainWnd();//父类指针强转为子类，才可使用子类特有变量
    CClientDC dc(this);
    CDC cdc;
    cdc.CreateCompatibleDC(&dc);
    cdc.SelectObject(pFrame->stk.top());
    dc.BitBlt(0,0,pFrame->m_ScreenX,pFrame->m_ScreenY,&cdc,0,0,SRCCOPY);
    
}

7.添加工具栏

在资源视图中Toolbar下自行绘制，更改对应ID;

在resource.h中将宏改为连续数字

ON_COMMAND_RANGE(ID_PEN,ID_ELLIPSE,&CDRAWView::ONChangeDrawStyle)//连续宏可使用

声明枚举类型    enum{PEN,LINE,RECTANGLE,TRIANGLE,ELLIPSE};（铅笔，直线，长方形，三角形，椭圆形）与resource.h中的顺序对应

在View.h中

class CDRAWView : public CView
{
    public:
    int m_DrawStyle;
    void ONChangeDrawStyle(UINT uid);
    bool m_blsFlag;
    CPoint PointMouseDown;
};

在View.cpp中

void CDRAWView::ONChangeDrawStyle(UINT uid)
{
    m_DrawStyle = uid - ID_PEN;
}
CDRAWView::CDRAWView()
{
    m_DrawStyle = ID_PEN;
    m_blsFlag = false;
}
void CDRAWView::OnLButtonDown(UINT nFlags, CPoint point)
{
    m_blsFlag = true;
    PointMouseDown = point;
    CView::OnLButtonDown(nFlags, point);
}


void CDRAWView::OnLButtonUp(UINT nFlags, CPoint point)
{
    m_blsFlag = false;

    CView::OnLButtonUp(nFlags, point);
}


void CDRAWView::OnMouseMove(UINT nFlags, CPoint point)
{
    CClientDC dc(this);
    CMainFrame* pFrame = (CMainFrame*)AfxGetMainWnd();
    if(m_blsFlag)
    {
        if(m_DrawStyle == PEN)
        {
            dc.MoveTo(PointMouseDown.x,PointMouseDown.y);
            dc.LineTo(point.x,point.y);
            PointMouseDown = point;
            return ;
        }
        else
        {
            //======================================解决闪屏========================================
            CDC MemDC;
            MemDC.CreateCompatibleDC(&dc);
            CBitmap* bitmap = new CBitmap;
            bitmap->CreateCompatibleBitmap(&dc,pFrame->m_ScreenX,pFrame->m_ScreenY);
            MemDC.SelectObject(bitmap);
            //-------------------------------------栈顶图片贴图擦除痕迹------------------------------------------------
            CDC cdc;
            cdc.CreateCompatibleDC(&dc);
            cdc.SelectObject(pFrame->stk.top());
            MemDC.BitBlt(0,0,pFrame->m_ScreenX,pFrame->m_ScreenY,&cdc,0,0,SRCCOPY);
　　　　　　　//-------------------------------------------------------------------------------------------------------
            switch(m_DrawStyle)
            {
            case LINE:
                MemDC.MoveTo(PointMouseDown.x,PointMouseDown.y);
                MemDC.LineTo(point.x,point.y);
                break;
            case TRIANGLE:
                {
                    POINT points[3] = {{(PointMouseDown.x+point.x)/2,PointMouseDown.y},{PointMouseDown.x,point.y},{point.x,point.y}};
                    MemDC.Polygon(points,3);
                }
                break;
            case ELLIPSE:
                MemDC.Ellipse(PointMouseDown.x,PointMouseDown.y,point.x,point.y);
                break;
            case RECTANGLE:
                MemDC.Rectangle(PointMouseDown.x,PointMouseDown.y,point.x,point.y);
                break;
            }
            dc.BitBlt(0,0,pFrame->m_ScreenX,pFrame->m_ScreenY,&MemDC,0,0,SRCCOPY);
            //===================================================================================================
        }
    }

    CView::OnMouseMove(nFlags, point);
}