位图文件的打开和保存
下面是两个函数， SaveBmp函数用于设备相关位图(DIB)保存为bmp格式的文件。DrawBitmapFile则用于将bmp格式的文件打开并显示在指定的设备环境上。
BOOL SaveBmp(HBITMAP hBitmap, const char *FileName)
{
HDC hDC; //当前分辨率下每象素所占字节数 int iBits; //位图中每象素所占字节数 WORD wBitCount; //定义调色板大小，位图中像素字节大小，位图文件大小，写入文件字节数 DWORD dwPaletteSize=0,dwBmBitsSize=0, dwDIBSize=0, dwWritten=0; //位图属性结构 BITMAP Bitmap; //位图文件头结构 BITMAPFILEHEADER bmfHdr; //位图信息头结构 BITMAPINFOHEADER bi; //指向位图信息头结构 LPBITMAPINFOHEADER lpbi; //定义文件，分配内存句柄，调色板句柄 HANDLE fh,hDib,hPal,hOldPal=NULL; //计算位图文件每个像素所占字节数 hDC=::CreateDC("DISPLAY",NULL, NULL, NULL); iBits=::GetDeviceCaps(hDC,BITSPIXEL)* ::GetDeviceCaps(hDC,PLANES); ::DeleteDC(hDC); if(iBits <= 1) wBitCount = 1; else if(iBits <= 4) wBitCount = 4; else if(iBits <= 8) wBitCount = 8; else wBitCount = 24; ::GetObject(hBitmap,sizeof(Bitmap),(LPSTR)&Bitmap); bi.biSize = sizeof(BITMAPINFOHEADER); bi.biWidth = Bitmap.bmWidth; bi.biHeight = Bitmap.bmHeight; bi.biPlanes = 1; bi.biBitCount = wBitCount; bi.biCompression = BI_RGB; bi.biSizeImage = 0; bi.biXPelsPerMeter = 0; bi.biYPelsPerMeter = 0; bi.biClrImportant = 0; bi.biClrUsed = 0; dwBmBitsSize = ((Bitmap.bmWidth * wBitCount + 31) / 32) * 4 * Bitmap.bmHeight; //为位图内容分配内存 hDib = ::GlobalAlloc(GHND,dwBmBitsSize + dwPaletteSize + sizeof(BITMAPINFOHEADER)); lpbi =(LPBITMAPINFOHEADER)::GlobalLock(hDib); *lpbi = bi; // 处理调色板 hPal = GetStockObject(DEFAULT_PALETTE); if(hPal) 
{ 
hDC = ::GetDC(NULL); hOldPal = ::SelectPalette(hDC,(HPALETTE)hPal,FALSE); RealizePalette(hDC); 
} // 获取该调色板下新的像素值 GetDIBits(hDC,hBitmap,0,(UINT)Bitmap.bmHeight,(LPSTR)lpbi + sizeof(BITMAPINFOHEADER) +dwPaletteSize, (BITMAPINFO*)lpbi,DIB_RGB_COLORS); //恢复调色板 if (hOldPal) { ::SelectPalette(hDC, (HPALETTE)hOldPal, TRUE); RealizePalette(hDC); ::ReleaseDC(NULL,hDC); } //创建位图文件 fh = CreateFile(FileName,GENERIC_WRITE,0,NULL,CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL|FILE_FLAG_SEQUENTIAL_SCAN,NULL); if(fh == INVALID_HANDLE_VALUE) return FALSE; // 设置位图文件头 bmfHdr.bfType = 0x4D42; // "BM" dwDIBSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + dwPaletteSize + dwBmBitsSize; bmfHdr.bfSize = dwDIBSize; bmfHdr.bfReserved1 = 0; bmfHdr.bfReserved2 = 0; bmfHdr.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) + (DWORD)sizeof(BITMAPINFOHEADER) + dwPaletteSize; // 写入位图文件头 WriteFile(fh,(LPSTR)&bmfHdr,sizeof(BITMAPFILEHEADER),&dwWritten,NULL); // 写入位图文件其余内容 WriteFile(fh,(LPSTR)lpbi,dwDIBSize,&dwWritten,NULL); //清除 GlobalUnlock(hDib); GlobalFree(hDib); CloseHandle(fh); return TRUE; 
}BOOL DrawBitmapFile(HDC hdc, int left, int top, char *szFilename){ // 打开要映射的位图文件 HANDLE hFile = CreateFile( szFilename, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL , NULL ) ; if( hFile == INVALID_HANDLE_VALUE ) return FALSE ; // 创建内存映象对象 HANDLE hMap = CreateFileMapping( hFile , NULL, PAGE_READONLY, NULL, NULL, NULL ) ; // 映射整个位图文件到内存，返回内存的首地址 LPVOID lpBase = MapViewOfFile( hMap , FILE_MAP_READ, 0, 0, 0 ) ; // 获取BMP文件信息 BITMAPFILEHEADER *pFileHeader ; BITMAPINFO *pInfoHeader ; // 获取位图象素 pFileHeader = (BITMAPFILEHEADER *) lpBase ; if( pFileHeader->bfType != MAKEWORD( 'B' , 'M' ) ) { UnmapViewOfFile( lpBase ) ; CloseHandle( hMap ) ; CloseHandle( hFile ) ; return FALSE ; } BYTE *pBits = (BYTE *)lpBase + pFileHeader->bfOffBits ; // 获取文件大小 pInfoHeader = (BITMAPINFO *)( (BYTE *)lpBase + sizeof(BITMAPFILEHEADER) ) ; LONG width = pInfoHeader->bmiHeader.biHeight ; LONG height = pInfoHeader->bmiHeader.biWidth ; // 显示位图文件至hdc指定的设备 HDC hMemDC = CreateCompatibleDC( hdc ) ; HBITMAP hBitmap = CreateCompatibleBitmap( hdc, width, height ) ; SelectObject( hMemDC, hBitmap ) ; // 把图象数据放到建立的内存设备中 int nRet = SetDIBitsToDevice( hMemDC, 0, 0, width, height, 0, 0, 0, height , pBits, pInfoHeader, DIB_RGB_COLORS ) ; // 绘制图象到hdc中 BitBlt( hdc, left, top, width, height, hMemDC , 0 , 0, SRCCOPY ) ; DeleteObject( hBitmap ) ; UnmapViewOfFile( lpBase ) ; DeleteDC ( hMemDC ) ; CloseHandle( hMap ) ; CloseHandle( hFile ) ;}
