Win32GDI 学习

在Win32下面获取屏幕的高度和宽度：
  int  x=GetSystemMetrics(SM_CXSCREEN);//屏幕的宽度
  int  y=GetSystemMetrics(SM_CYSCREEN);//屏幕的高度

在Win32下绘制位图:

HBITMAP hbm=LoadBitmap(hInstance,MAKEINTRESOURCE(iResource));  //iResource为资源ID,hInstance可为NULL

BITMAP bm;

GetObject(hBm,sizeof(BITMAP),&bm);//获取位图信息

SelectObject(hdcsrc,hbm);

BitBlt(hdcdest,xpos,ypos,width,height,hdcsrc,0,0,SRCCOPY); 

将CBitmap 保存为bmp文件

bool SaveBitmapToFile(CBitmap* bitmap, LPSTR lpFileName)  
{              
	HBITMAP hBitmap;    // 为刚才的屏幕位图句柄  
	HDC hDC; //设备描述表    
	int iBits; //当前显示分辨率下每个像素所占字节数    
	WORD wBitCount; //位图中每个像素所占字节数    
	DWORD dwPaletteSize = 0, //定义调色板大小  
		dwBmBitsSize,  //位图中像素字节大小     
		dwDIBSize,   //位图文件大小  
		dwWritten;  //写入文件字节数  
	BITMAP Bitmap; //位图属性结构    
	BITMAPFILEHEADER bmfHdr; //位图文件头结构    
	BITMAPINFOHEADER bi; //位图信息头结构      
	LPBITMAPINFOHEADER lpbi; //指向位图信息头结构    
	HANDLE fh,   //定义文件  
		hDib,    //分配内存句柄  
		hPal,   //调色板句柄  
		hOldPal = NULL;  

	//计算位图文件每个像素所占字节数    
	hBitmap = (HBITMAP)*bitmap;    
	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 if (iBits <= 24)    
		wBitCount = 24;    
	else if (iBits <= 32)  
		wBitCount = 32;  

	//计算调色板大小    
	if (wBitCount <= 8)    
		dwPaletteSize = (1 << wBitCount) * sizeof (RGBQUAD);  

	//设置位图信息头结构    
	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;    

	//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,  
		(LPBITMAPINFO)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(lpFileName, 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;      
}