Question

我正在创建一个用于学习的应用程序。我有一个用于创建窗口的类。我正在创建一个单独的类，可以帮助在窗口上绘制不同的形状。但是，我无法在窗户上画画。当我们将所有代码保存在同一个类中时，它工作正常。但我想把课程分开。

这是代码： MainFrame.h

#include "afxwin.h"
class CMainFrame :  public CFrameWnd
{
public:
    CMainFrame(void);
    ~CMainFrame(void);
    static CRect GetClientRectangle();
protected:
    int OnCreate(LPCREATESTRUCT);
    void OnShowWindow(BOOL, UINT);
    void OnActivate(UINT, CWnd*, BOOL);
    void OnPaint();
    void OnSize(UINT, int, int);
    void OnSizing(UINT, LPRECT);
    void OnMove(int, int);
    void OnMoving(UINT, LPRECT);
    void OnClose();
    void OnDestroy();
    void OnLButtonUp(UINT, CPoint);    
    void DrawRectangle(CDC*);
    DECLARE_MESSAGE_MAP()
};

MainFrame.cpp

#include "MainFrame.h"
#include "Shapes.h"
#include <sstream>

CMainFrame::CMainFrame(void)
{
    Create(NULL, _T("Windows Application Tester"),WS_OVERLAPPEDWINDOW,CRect(120,100,700,480),NULL);
}
CMainFrame::~CMainFrame(void)
{
}


int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
    // Call the base class to create the window
    if (CFrameWnd::OnCreate(lpCreateStruct) == -1) {
        MessageBox(_T("The window was not created!!!"));
        return -1;
    }
    else {
        MessageBox(_T("The window has been created!!!"));
        return 0;
    }
}
void CMainFrame::OnShowWindow(BOOL bShow, UINT nStatus) 
{
    CFrameWnd::OnShowWindow(bShow, nStatus);
    // TODO: Add your message handler code here
    //ShowWindow(SW_MAXIMIZE);
}
void CMainFrame::OnActivate(UINT nState, CWnd* pWndOther, BOOL bMinimized) 
{
    CFrameWnd::OnActivate(nState, pWndOther, bMinimized);

    // TODO: Add your message handler code here
    switch( nState )
    {
    case WA_ACTIVE:
        SetWindowText(_T("This window has been activated, without the mouse!"));
        break;
    case WA_INACTIVE:
        SetWindowText(_T("This window has been deactivated and cannot be changed now!!"));
        break;
    case WA_CLICKACTIVE:
        SetWindowText(_T("This window has been activated using the mouse!!!"));
        break;
    }    
}
void CMainFrame::OnPaint() 
{
    CFrameWnd::OnPaint();

    CShapes shape;
    CPaintDC dc(this);
    CRect client;
    GetClientRect(&client);
    shape.DrawRectangle(&dc, client);
    SetWindowText(_T("The window has been painted<==>"));
}
void CMainFrame::OnSize(UINT nType, int cx, int cy) //nType-> window state; cx,cy->new width,height
{
    CFrameWnd::OnSize(nType, cx, cy);

    // TODO: Add your message handler code here
    char *MsgToShow = new char[20];
    char *MsgCoord  = new char[20];
    switch(nType) {
    case SIZE_MINIMIZED:
        strcpy(MsgToShow, "Minimized ");
        break;
    case SIZE_MAXIMIZED:
        strcpy(MsgToShow, "Maximized ");
        break;
    case SIZE_RESTORED:
        strcpy(MsgToShow, "Restored ");
        break;
    case SIZE_MAXHIDE:
        strcpy(MsgToShow, "Maximized Not Me ");
        break;
    case SIZE_MAXSHOW:
        strcpy(MsgToShow, "Restored Not Me ");
        break;
    }
    sprintf(MsgCoord, "Left = %d | Top = %d", cx, cy);
    strcat(MsgToShow, MsgCoord);
    SetWindowText(CString(MsgToShow));
}
void CMainFrame::OnSizing(UINT nType, LPRECT lpRect)
{
    CFrameWnd::OnSizing(nType,lpRect);
    // TODO: Add your message handler code here
    SetWindowText(_T("Resized"));
}
void CMainFrame::OnMove(int x, int y) 
{
    CFrameWnd::OnMove(x, y);
    // TODO: Add your message handler code here
    std::stringstream ss;
    ss<<"Window moved to " << x << ", " << y;
    std::string s = ss.str();
    SetWindowText(CString(s.c_str()));
}
void CMainFrame::OnMoving(UINT nSide, LPRECT lpRect)
{       
    CFrameWnd::OnMoving(nSide, lpRect);
    // TODO: Add your message handler code here
    std::stringstream ss;
    ss<<"Window moving to " << lpRect->top << ", " << lpRect->left;
    std::string s = ss.str();
    SetWindowText(CString(s.c_str()));;
}
void CMainFrame::OnClose() 
{
    CFrameWnd::OnClose();

}
void CMainFrame::OnDestroy()
{
    CFrameWnd::OnDestroy();
    MessageBox(_T("Window Destroyed"));
    // TODO: Add your message handler code here
}
void CMainFrame::OnLButtonUp(UINT nFlags, CPoint point) {
    CFrameWnd::OnLButtonUp(nFlags, point);
    MessageBox(_T("Hello"));
}


BEGIN_MESSAGE_MAP(CMainFrame,CFrameWnd)
    ON_WM_CREATE()
    ON_WM_SHOWWINDOW()
    ON_WM_ACTIVATE()
    ON_WM_PAINT()
    ON_WM_SIZE()
    ON_WM_SIZING()
    ON_WM_MOVE()
    ON_WM_MOVING()
    ON_WM_CLOSE()
    ON_WM_DESTROY()
    ON_WM_LBUTTONUP()
END_MESSAGE_MAP()

这是形状部分：

Shape.h

class CShapes
{
public:
    CShapes(void);
    ~CShapes(void);
    //void DrawArc(CDC*);
    void DrawRectangle(CDC*, CRect);
    /*void DrawRoundRectangle(CDC*);
    void DrawEllipse(CDC*);
    void DrawChord(CDC*);*/
};

Shape.cpp

#include "Shapes.h"

CShapes::CShapes(void)
{
}
CShapes::~CShapes(void)
{
}

void CShapes::DrawRectangle(CDC* dc, CRect client)
{
    dc->DrawText(_T("Rectangle with 1 call to CDC::Rectangle()"),-1,&client,
        DT_BOTTOM | DT_SINGLELINE | DT_CENTER );
    client.DeflateRect(100,100);
    dc->Rectangle(&client);
}

这是Main.cpp文件，它创建用于初始化窗口的对象。

#include "MainFrame.h"
class CIntroToMFCApp : public CWinApp {
    BOOL InitInstance()
    {
        CMainFrame *Frame = new CMainFrame();
        m_pMainWnd = Frame;
        Frame->ShowWindow(SW_NORMAL);
        Frame->UpdateWindow();      
        //AfxGetMainWnd()->PostMessageW(WM_CLOSE);
        return TRUE;
    }
};
CIntroToMFCApp MyApplication;

请告诉我需要进行更改的地方！

Answer 1

编辑：回答重写

好的，我在VS2010中使用全新的MFC项目进行了快速测试。

取消行

 CFrameWnd::OnPaint();

有了它，没有文字/矩形。没有它，text / recatngle。

当您使用“向导”生成项目时，您会注意到OnPaint处理程序包含：

// Do not call CWnd::OnPaint() for painting messages

Answer 2

在调用CDC :: Rectangle之前，用笔绘制矩形并填充您选择的画笔。但是你还没有提供这些。这里有一个例子：

http://msdn.microsoft.com/en-us/library/vstudio/8w4fzfxf.aspx

DrawText会遇到类似的问题，在绘图之前没有设置文本颜色或背景模式。

我不确定IInspectable提出的问题，但是注释掉对CFrameWnd :: OnPaint（）的调用不会造成任何伤害。它无论是无用的还是有害的。

MFC：在窗口中创建形状

2 个答案: