怎样保存画在对话框上的波形图

HBITMAP CopyDCToBitmap(HDC hScrDC, LPRECT lpRect)

{

	HDC hMemDC; 

	// 屏幕和内存设备描述表 

	HBITMAP hBitmap,hOldBitmap; 

	// 位图句柄 

	int nX, nY, nX2, nY2; 

	// 选定区域坐标 

	int nWidth, nHeight; 

	// 位图宽度和高度 

	

	// 确保选定区域不为空矩形 

	if ( IsRectEmpty( lpRect ) ) return NULL; 

	

	// 获得选定区域坐标 

	nX=   lpRect->left; 

	nY=   lpRect->top; 

	nX2 = lpRect->right; 

	nY2 = lpRect->bottom; 

	nWidth  = nX2 - nX; 

	nHeight = nY2 - nY; 

	//为屏幕设备描述表创建兼容的内存设备描述表 

	hMemDC= CreateCompatibleDC( hScrDC ); 

	// 创建一个与屏幕设备描述表兼容的位图 

	hBitmap = CreateCompatibleBitmap( hScrDC, nWidth, nHeight ); 

	// 把新位图选到内存设备描述表中 

	hOldBitmap = ( HBITMAP )SelectObject( hMemDC, hBitmap ); 

	// 把屏幕设备描述表拷贝到内存设备描述表中 

	StretchBlt( hMemDC, 0, 0, nWidth, nHeight, hScrDC, nX, nY, nWidth, nHeight, SRCCOPY );

	//得到屏幕位图的句柄 

	hBitmap = ( HBITMAP )SelectObject( hMemDC, hOldBitmap ); 

	//清除

	DeleteDC( hMemDC ); 

	DeleteObject( hOldBitmap ); 

	//返回位图句柄 

	return hBitmap;

}

BOOL SaveBmp(HBITMAP hBitmap, CString 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); 

		//hDC = m_pDc->GetSafeHdc(); 

		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; 

}

	CDC *pdc=GetDC();

	CDC MenDC; 

	CBitmap bm;	

	MenDC.CreateCompatibleDC( pdc ); 

	bm.CreateCompatibleBitmap( pdc, int( txWD+2 ), int( txHT+2 ) ); 

	//txWD和TxHT为客户区大小，根据你的窗口来设定

	MenDC.SelectObject( &bm );

	

	//MenDC.TextOut( 1, 1, “写一行文字”);

        //此处用MenDC绘制你所要的波形	

	//----------------------------------------------------

	// 设定你要从CBitmap bm;上截取哪一部分。

	//----------------------------------------------------

	RECT rt;

	rt.left = 0; rt.right  = int( 512 );

	rt.top  = 0; rt.bottom = int( 512 );

	

	//----------------------------------------------------

	

	HBITMAP hBmp = Kp.CopyDCToBitmap( MenDC.GetSafeHdc(), &rt ); 

	Kp.SaveBmp( hBmp, "MyDC.bmp" );

	

	//----------------------------------------------------

	

	bm.DeleteObject();

	MenDC.DeleteDC();

	ReleaseDC(pdc);