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C++針對bmp格局解析實例

編輯：關於C++

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本文實例講述了C++針對bmp格局解析的辦法，分享給年夜家供年夜家參考。詳細辦法以下：

寫這代碼時，輕易湧現以下毛病：
1. 忘了on_wm_paint() 一向在界面上畫不出來
2. 准確寫法

BYTE* pBits = (BYTE*)lpBase + pbitmapFileHeader->bfOffBits;

寫成了

BYTE* pBits = pbitmapFileHeader->bfOffBits;

這裡重要是用了後面一篇中的CWnd框架。

.cpp源文件以下：

#include "ReadBMP.h"
#include "resource.h"
#include <afxdlgs.h >

CMyApp theApp;
BOOL CMyApp::InitInstance()
{
    m_pMainWnd = new CMainWindow;
    m_pMainWnd->ShowWindow(m_nCmdShow);
    return TRUE; //必需前往TRUE,不然不會進入新聞輪回，界面會直接加入
}

//CMainWindow
BEGIN_MESSAGE_MAP(CMainWindow, CWnd)
ON_WM_CREATE()
ON_WM_PAINT()
ON_COMMAND(IDC_OPEN, OnOpen)
END_MESSAGE_MAP()
//結構函數
CMainWindow::CMainWindow()
{
    LPCTSTR lpszClassName = ::AfxRegisterWndClass(CS_HREDRAW|CS_VREDRAW, ::LoadCursorA(NULL, IDC_ARROW), (HBRUSH)(COLOR_3DFACE+1), theApp.LoadIcon(IDI_MAIN));
    CreateEx(WS_EX_CLIENTEDGE, lpszClassName, "xxx", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,NULL,NULL);
}
//析構函數
CMainWindow::~CMainWindow()
{

}
//新聞映照函數
int CMainWindow::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
    //OutputDebugString("oncreate");
    CClientDC dc(this);
    m_hMemDC = ::CreateCompatibleDC(dc);
    m_nWidth = 0;
    m_nHeight = 0;
    //設置菜單
    HMENU hMenu = ::LoadMenuA(theApp.m_hInstance, (LPCSTR)IDR_MENU);
    ::SetMenu(m_hWnd, hMenu);
    return 0;
}

void CMainWindow::OnNcDestroy( )
{
    delete this;
}
void CMainWindow::OnDestroy()
{

}
void CMainWindow::OnPaint()
{
    CPaintDC dc(this);
    ::BitBlt(dc, 0, 0, m_nWidth, m_nHeight, m_hMemDC, 0, 0, SRCCOPY);
}
void CMainWindow::OnOpen()
{
    CFileDialog dlg(TRUE);
    if (IDOK != dlg.DoModal())
    {
        return;
    }
    HANDLE hFile = ::CreateFile(dlg.GetPathName(), GENERIC_READ , FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
    if (INVALID_HANDLE_VALUE == hFile)
    {
        return;
    }
    HANDLE hFileMap = ::CreateFileMapping(hFile, NULL, PAGE_READONLY, 0, 0, NULL);
    if (NULL == hFileMap)
    {
        return;
    }
    LPVOID lpBase = ::MapViewOfFile(hFileMap, FILE_MAP_READ, 0, 0, 0);
    if (NULL == lpBase)
    {
        return;
    }
    //從頭構造中取三個信息：1.bfOffBits位圖數據在文件中的肇端地位，2.m_nWidth圖象的寬，3.m_nHeight圖象的高
    BITMAPFILEHEADER* pbitmapFileHeader;
    BITMAPINFO* pbitmapInfo;
    pbitmapFileHeader = (BITMAPFILEHEADER*)lpBase;
    if (pbitmapFileHeader->bfType != MAKEWORD('B','M'))
    {
        MessageBox("not bmp");
        ::UnmapViewOfFile(lpBase);
        ::CloseHandle(hFileMap);
        ::CloseHandle(hFile);
    }
    //DWORD bfOffBits = pbitmapFileHeader->bfOffBits;
    BYTE* pBits = (BYTE*)lpBase + pbitmapFileHeader->bfOffBits;
    pbitmapInfo = (BITMAPINFO*)((BYTE*)lpBase + sizeof(BITMAPFILEHEADER));
    m_nWidth = pbitmapInfo->bmiHeader.biWidth;
    m_nHeight = pbitmapInfo->bmiHeader.biHeight;
    //顯示BMP文件到內存裝備
    //得客戶區DC
    CClientDC dc(this);
    //創立與客戶區DC兼容的位圖
    HBITMAP hBitmap = ::CreateCompatibleBitmap(dc, m_nWidth, m_nHeight);
    if (hBitmap == 0)
    {
        return;
    }
    //位圖選入內存DC
    ::SelectObject(m_hMemDC, hBitmap);

    //圖象數據放到樹立的DC中
    ::SetDIBitsToDevice(m_hMemDC, 0, 0, m_nWidth, m_nHeight, 0, 0, 0, m_nHeight, pBits, pbitmapInfo, DIB_RGB_COLORS);

    ::InvalidateRect(m_hWnd, NULL, TRUE);
    ::DeleteObject(hBitmap);

    ::UnmapViewOfFile(lpBase);
    ::CloseHandle(hFileMap);
    ::CloseHandle(hFile);

}

.h頭文件以下：

#include <afxwin.h>

class CMyApp:public CWinApp
{
public:
    virtual BOOL InitInstance();
};

//CMainWindow
class CMainWindow:public CWnd
{
public:
    CMainWindow();
    ~CMainWindow();

protected:
    HDC m_hMemDC; //與客戶區兼容的內存DC句柄
    UINT m_nWidth; //BMP的寬度
    UINT m_nHeight; //BMP的高度

    //新聞映照
    afx_msg void OnNcDestroy( );
    afx_msg int OnCreate(LPCREATESTRUCT lpCreateStruct);
    afx_msg void OnDestroy( );
    afx_msg void OnOpen();
    afx_msg void OnPaint();
    DECLARE_MESSAGE_MAP()
};