怎樣實現動畫背景旗幟

作者：賈旭濱(譯)

//原著：Juan Carlos Urbina
//譯者：重慶大學光電工程學院  賈旭濱
//歡迎大家批評指教，謝謝！

    以下代碼是關于用類CmdiMainClient來顯示動畫背景旗幟的一個例子。原理是很簡單的，我們只需要一系列連續的位圖，并且讓它連續顯示。在這個例子中你可以用鼠標的右鍵來開始/停止這個動畫，如果點左鍵的話，就可以顯示一個子窗口，來保持動畫是繼續。為了你的方便，你可以把代碼直接從瀏覽器中拷貝下去，并且插到你的代碼中就行了。以下是代碼：


#include "stdafx.h"
#include "banner.h"
#include "mainfrm.h"

#include "resource.h"

#ifdef _DEBUG
#undef THIS_FILE
static char BASED_CODE THIS_FILE[] = __FILE__;
#endif

/////////////////////////////////////////////////////////////////////////////
// CMdiMainClient

CMdiMainClient::CMdiMainClient()
    :    m_sizeClient(0, 0)
        
{
    VERIFY (m_bmpBackGround.LoadBitmap(IDB_BCKGRD));
    ASSERT (m_bmpBackGround.GetSafeHandle());

    VERIFY (m_bmpBackGround2.LoadBitmap(IDB_BITMAP0));
    ASSERT (m_bmpBackGround2.GetSafeHandle());

    BmpLoaded = 1;
    StopRotation = FALSE;
}

CMdiMainClient::~CMdiMainClient()
{
    if(m_bmpBackGround.GetSafeHandle())
        m_bmpBackGround.DeleteObject();

    if(m_bmpBackGround2.GetSafeHandle())
        m_bmpBackGround2.DeleteObject();
}


BEGIN_MESSAGE_MAP(CMdiMainClient, CWnd)
    //{{AFX_MSG_MAP(CMdiMainClient)
        // NOTE - the ClassWizard will add and remove mapping macros here.
    ON_WM_TIMER()
    ON_WM_ERASEBKGND()
    ON_WM_RBUTTONDOWN()
    ON_WM_LBUTTONDOWN()
    ON_WM_SIZE()
    //}}AFX_MSG_MAP
END_MESSAGE_MAP()


/////////////////////////////////////////////////////////////////////////////
// CMdiMainClient message handlers
BOOL CMdiMainClient::OnEraseBkgnd(CDC* pDC)
{
    // Erase only the area needed
    CRect rect;
    GetClientRect(&rect) ;
   
    SetTimer(0,300,NULL);
                                       
    // Place the bitmap
    BITMAP bm ;
    CDC dcMem ;

    BITMAP bm2 ;
    CDC dcMem2;

     
    VERIFY(m_bmpBackGround.GetObject(sizeof(bm), (LPVOID)&bm));
    dcMem.CreateCompatibleDC(NULL);
    CBitmap* pbmpOld = (CBitmap*)dcMem.SelectObject(&m_bmpBackGround);
    ASSERT(pbmpOld) ;
    // Display red background
    pDC->StretchBlt(0, 0, rect.right, rect.bottom, &dcMem, 0,
                0, bm.bmWidth, bm.bmHeight,SRCCOPY);

    VERIFY(m_bmpBackGround2.GetObject(sizeof(bm2), (LPVOID)&bm2));
    dcMem2.CreateCompatibleDC(NULL);
    dcMem2.SelectObject(&m_bmpBackGround2);
    // Display picture background
    pDC->StretchBlt(200,100,400, 200, &dcMem2, 0,0, bm2.bmWidth, bm2.bmHeight,
                    SRCCOPY);

    // Display Instructions
    pDC->SetBkColor(RGB(255,0,0));
    pDC->SetTextColor(RGB(192,192,192));
    pDC->TextOut(480, 500, "Mouse Right Click to Stop/Start Special Effects");
    pDC->TextOut(480, 515, "Mouse Left-Click to Show Child Window");

    // CleanUp
    dcMem.SelectObject(pbmpOld) ;

    return TRUE;
}      

////////////////////////////////////////////////////////////////////
//
void CMdiMainClient::OnSize(UINT nType, int cx, int cy)
{
    Default() ;                
    // if the app is just starting up, save the window
    // dimensions and get out

    if ((m_sizeClient.cx == 0) && (m_sizeClient.cy==0))
        {
        m_sizeClient.cx = cx;
        m_sizeClient.cy = cy;

        return ;
        }

    // if the size hasn't changed, break and pass to default

    if ((m_sizeClient.cx == cx) && ( m_sizeClient.cy == cy))
    {
        return ;
    }

    // window size has changed so save new dimensions and force
    // entire background to redraw, including icon backgrounds

    m_sizeClient.cx = cx;
    m_sizeClient.cy = cy;
             
    RedrawWindow(NULL, NULL,
        RDW_INVALIDATE|RDW_ERASE|RDW_ERASENOW|RDW_ALLCHILDREN);    
            
    return ;                
}

void CMdiMainClient::OnTimer(UINT nIDEvent)
{
    DisplayNextLogoFrame();
    CWnd::OnTimer(nIDEvent);
}


void CMdiMainClient::DisplayNextLogoFrame()
{
        CRect rect;
        GetClientRect(&rect) ;
    
        BITMAP bm2 ;
        CDC dcMem2;

        CDC *pDC = GetDC();

        if (!StopRotation)
        {
            // Select next logo frame to be displayed
            switch (BmpLoaded)
            {
        case 1:    if(m_bmpBackGround2.GetSafeHandle())
                    m_bmpBackGround2.DeleteObject();
            VERIFY (m_bmpBackGround2.LoadBitmap(IDB_BITMAP1));
            ASSERT (m_bmpBackGround2.GetSafeHandle());
            break;
            case 2:    if(m_bmpBackGround2.GetSafeHandle())
                    m_bmpBackGround2.DeleteObject();
            VERIFY (m_bmpBackGround2.LoadBitmap(IDB_BITMAP2));
            ASSERT (m_bmpBackGround2.GetSafeHandle());
            break;
            case 3:    if(m_bmpBackGround2.GetSafeHandle())
                    m_bmpBackGround2.DeleteObject();
            VERIFY (m_bmpBackGround2.LoadBitmap(IDB_BITMAP3));
            ASSERT (m_bmpBackGround2.GetSafeHandle());
            break;
            case 4:    if(m_bmpBackGround2.GetSafeHandle())
                    m_bmpBackGround2.DeleteObject();
            VERIFY (m_bmpBackGround2.LoadBitmap(IDB_BITMAP4));
            ASSERT (m_bmpBackGround2.GetSafeHandle());
            break;
            case 5:    if(m_bmpBackGround2.GetSafeHandle())
                    m_bmpBackGround2.DeleteObject();
            VERIFY (m_bmpBackGround2.LoadBitmap(IDB_BITMAP5));
            ASSERT (m_bmpBackGround2.GetSafeHandle());
            break;
            case 6:    if(m_bmpBackGround2.GetSafeHandle())
                    m_bmpBackGround2.DeleteObject();
            VERIFY (m_bmpBackGround2.LoadBitmap(IDB_BITMAP6));
            ASSERT (m_bmpBackGround2.GetSafeHandle());
            break;
            case 7:    if(m_bmpBackGround2.GetSafeHandle())
                    m_bmpBackGround2.DeleteObject();
            VERIFY (m_bmpBackGround2.LoadBitmap(IDB_BITMAP7));
            ASSERT (m_bmpBackGround2.GetSafeHandle());
            break;
            case 8:    if(m_bmpBackGround2.GetSafeHandle())
                    m_bmpBackGround2.DeleteObject();
            VERIFY (m_bmpBackGround2.LoadBitmap(IDB_BITMAP8));
            ASSERT (m_bmpBackGround2.GetSafeHandle());
            break;
            case 9:    if(m_bmpBackGround2.GetSafeHandle())
                    m_bmpBackGround2.DeleteObject();
            VERIFY (m_bmpBackGround2.LoadBitmap(IDB_BITMAP9));
            ASSERT (m_bmpBackGround2.GetSafeHandle());
            break;
            }
            // Change Bitmap index
            if (BmpLoaded == 9)
                BmpLoaded = 0;
            else
                BmpLoaded++;
        }
          
    VERIFY(m_bmpBackGround2.GetObject(sizeof(bm2), (LPVOID)&bm2));
    dcMem2.CreateCompatibleDC(NULL);
    dcMem2.SelectObject(&m_bmpBackGround2);
    pDC->StretchBlt(200,100,400, 200, &dcMem2, 0,0, bm2.bmWidth, bm2.bmHeight,
        SRCCOPY);

    ReleaseDC(pDC);
}

void CMdiMainClient::OnRButtonDown(UINT nFlags, CPoint point)
{
    if (StopRotation)
        StopRotation = FALSE;
    else
        StopRotation = TRUE;

    CWnd::OnRButtonDown(nFlags, point);
}

void CMdiMainClient::OnLButtonDown(UINT nFlags, CPoint point)
{
    m_Hide_Logo = TRUE;
    KillTimer(0);

    // Display Application
    ((CBannerApp*)AfxGetApp())->pDocTemplate->OpenDocumentFile(NULL);

    CWnd::OnLButtonDown(nFlags, point);
}

// MdiMainClient.h : header file
//

/////////////////////////////////////////////////////////////////////////////
// CMdiMainClient window

extern BOOL m_Hide_Logo;

class CMdiMainClient : public CWnd
{
// Construction
public:
    CMdiMainClient();

// Attributes
protected:
    CBitmap m_bmpBackGround2;
    CBitmap m_bmpBackGround;

    int BmpLoaded;
public:
    BOOL StopRotation;
    CSize m_sizeClient;

// Overrides
    // ClassWizard generated virtual function overrides
    //{{AFX_VIRTUAL(CMdiMainClient)
    //}}AFX_VIRTUAL

// Implementation
public:
    void Display_Blank_Bitmap();
    void DisplayNextLogoFrame();
    virtual ~CMdiMainClient();
    // Generated message map functions
protected:
    //{{AFX_MSG(CMdiMainClient)
        // NOTE - the ClassWizard will add and remove member functions here.
        afx_msg BOOL OnEraseBkgnd(CDC* pDC);
        afx_msg void OnSize(UINT nType, int cx, int cy);
        afx_msg void OnTimer(UINT nIDEvent);
        afx_msg void OnRButtonDown(UINT nFlags, CPoint point);
        afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
    //}}AFX_MSG
    DECLARE_MESSAGE_MAP()
}; 

原文轉自：http://www.kjueaiud.com