可能用到的庫：

#include <afxwin.h>
#include <windows.h>

void CScreenShotDlg::OnBnClickedOk()
{
	// TODO: 在此新增控制元件通知處理程式程式碼
	//CClientDC dc(this);//只截對話方塊，用這句
	HWND hwnd = ::GetDesktopWindow();//截整個螢幕，用從這往下4句
	HDC hdc = ::GetDC(hwnd);
	CDC dc;
	dc.Attach(hdc);
	CRect rc;
	//GetClientRect(&rc);//只截對話方塊，用這句
	rc.SetRect(0,0, GetSystemMetrics(   SM_CXSCREEN   ), GetSystemMetrics(   SM_CYSCREEN   ));//截整個螢幕，用這句
	int iBitPerPixel = dc.GetDeviceCaps(BITSPIXEL);
	int iWidth = rc.Width();
	int iHeight = rc.Height();
	CDC memDC;
	memDC.CreateCompatibleDC(&dc);

	CBitmap memBitmap, *oldBitmap;

	memBitmap.CreateCompatibleBitmap(&dc, iWidth, iHeight);
	oldBitmap = memDC.SelectObject(&memBitmap);

	memDC.BitBlt(0,0,iWidth, iHeight, &dc, 0,0,SRCCOPY);

	BITMAP bmp;
	memBitmap.GetBitmap(&bmp);

	FILE *fp = fopen("test2.bmp", "wb");
	BITMAPINFOHEADER bih;
	memset(&bih, 0, sizeof(bih));
	bih.biBitCount = bmp.bmBitsPixel;
	bih.biCompression = BI_RGB;//表示不壓縮
	bih.biHeight = bmp.bmHeight;
	bih.biPlanes = 1;//位平面數，必須為1
	bih.biSize = sizeof(BITMAPINFOHEADER);
	bih.biSizeImage = bmp.bmWidthBytes * bmp.bmHeight;
	bih.biWidth = bmp.bmWidth;
	BITMAPFILEHEADER bfh;
	memset(&bfh, 0, sizeof(bfh));
	bfh.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);

	bfh.bfSize = bfh.bfOffBits + bmp.bmWidthBytes * bmp.bmHeight;
	bfh.bfType = (WORD)0x4d42;//必須表示"BM"

	fwrite(&bfh, 1, sizeof(BITMAPFILEHEADER), fp);
	fwrite(&bih, 1, sizeof(bih), fp);

	byte * p = new byte[bmp.bmWidthBytes * bmp.bmHeight];
	GetDIBits(memDC.m_hDC, (HBITMAP)memBitmap.m_hObject, 0, iHeight, p, (LPBITMAPINFO)&bih, DIB_RGB_COLORS);
	fwrite(p, 1, bmp.bmWidthBytes * bmp.bmHeight, fp);
	delete [] p;

	fclose(fp);

	memDC.SelectObject(oldBitmap);
}
 

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