如何实现画位图并保存？多谢~~

Question

一个小程序，一个“画图“按钮，按下后出现一个实心圆的位图，再按“保存“按钮保存该位图（.bmp）
请问分别在哪里写这两段代码，怎么写？
谢谢~~

Answer 1

http://www.vckbase.com/code/listcode.asp?mclsid=7&sclsid=701

Answer 2

BOOL SaveBitmapToFile(HBITMAP hBitmap, LPCTSTR lpszFileName, int nBitCount)
{
HDC hDC;
    int iBits;
WORD            wBitCount;
DWORD           dwPaletteSize=0,
dwBmBitsSize,
dwDIBSize, 
dwWritten;
BITMAP          Bitmap;        
BITMAPFILEHEADER   bmfHdr;
    BITMAPINFOHEADER   bi;
LPBITMAPINFOHEADER lpbi;
    HANDLE          fh, hDib, hPal,hOldPal=NULL; if(nBitCount == -1)
{
hDC = CreateDC(NULL, NULL, NULL, NULL);
iBits = GetDeviceCaps(hDC, BITSPIXEL) * GetDeviceCaps(hDC, PLANES);
DeleteDC(hDC);
}
else
{
iBits = nBitCount;
} if (iBits <= 1)
wBitCount = 1;
else if (iBits <= 4)
wBitCount = 4;
else if (iBits <= 8)
wBitCount = 8;
else if (iBits <= 24)
wBitCount = 24; if (wBitCount <= 8)
dwPaletteSize = (1 << wBitCount) * sizeof(RGBQUAD); 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.biClrUsed = 0;
bi.biClrImportant = 0; dwBmBitsSize = ((Bitmap.bmWidth * wBitCount+31)/32)* 4 * Bitmap.bmHeight ; hDib  = GlobalAlloc(GHND,dwBmBitsSize + dwPaletteSize+sizeof(BITMAPINFOHEADER));
lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDib);
*lpbi = bi; hPal = GetStockObject(DEFAULT_PALETTE);
if (hPal)
{
hDC  = ::GetDC(NULL);
hOldPal = SelectPalette(hDC, (HPALETTE)hPal, FALSE);
RealizePalette(hDC);
}

GetDIBits(hDC, hBitmap, 0, (UINT) Bitmap.bmHeight,
(LPSTR)lpbi + sizeof(BITMAPINFOHEADER)+dwPaletteSize,
(LPBITMAPINFO)lpbi, DIB_RGB_COLORS);

if (hOldPal)
{
SelectPalette(hDC, (HPALETTE)hOldPal, TRUE);
RealizePalette(hDC);
::ReleaseDC(NULL, hDC);
}

fh = CreateFile(lpszFileName, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL);

if (fh == INVALID_HANDLE_VALUE)
return FALSE;

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;

WriteFile(fh, (LPSTR)&bmfHdr, sizeof(BITMAPFILEHEADER), &dwWritten, NULL);
WriteFile(fh, (LPSTR)lpbi, dwDIBSize, &dwWritten, NULL);
GlobalUnlock(hDib);
GlobalFree(hDib);
CloseHandle(fh);

return TRUE;
}
BOOL SaveRectBmpToFile(CDC *pDC, CRect rect, char *filename)
{
CDC MemDC;
CBitmap NewBmp,*pOldBmp;
BOOL bflag;
MemDC.CreateCompatibleDC(pDC);
NewBmp.CreateCompatibleBitmap(pDC,rect.Width(),rect.Height());
pOldBmp=MemDC.SelectObject(&NewBmp);
MemDC.BitBlt(0,0,rect.Width(),rect.Height(),pDC,rect.left,rect.top,SRCCOPY);
bflag=SaveBitmapToFile(NewBmp,filename,4);
MemDC.SelectObject(pOldBmp);
NewBmp.DeleteObject();
MemDC.DeleteDC();
return bflag;
}在按钮事件中调用函数SaveRectBmpToFile就可以了，参数分别为CDC指针，保存区域，文件名