《Windows程序设计》之位块传输

LRESULT CALLBACK WndProc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam)
{
	static HBITMAP hBitmap;
	static int cxClient,cyClient,cxSource,cySource;
	BITMAP bitmap;
	HDC hdc,hdcMem;
	HINSTANCE hInstance;
	int x,y;
	PAINTSTRUCT ps;

	switch(message)
	{
	case WM_CREATE:
		//实例句柄
		hInstance=((LPCREATESTRUCT)lParam)->hInstance;
		//载入图片
		hBitmap=LoadBitmap(hInstance,TEXT("Bricks"));
		//该函数得到指定图形对象的信息
		GetObject(hBitmap,sizeof(BITMAP),&bitmap);
		cxSource=bitmap.bmWidth;
		cySource=bitmap.bmHeight;
		return 0;
	case WM_SIZE:
		cxClient=LOWORD(lParam);
		cyClient=HIWORD(lParam);
		return 0;
	case WM_PAINT:
		hdc=BeginPaint(hwnd,&ps);
		//创建设备上下文
		hdcMem=CreateCompatibleDC(hdc);
		//把hBitmap选入设备
		SelectObject(hdcMem,hBitmap);
		for(y=0;y<cyClient;y+=cySource)
			for(x=0;x<cxClient;x+=cxSource)
				//把设备环境中的图像进行块转换，放入目标设备中
				BitBlt(hdc,x,y,cxSource,cySource,hdcMem,0,0,SRCCOPY);
		//删除设备环境
		DeleteDC(hdcMem);
		EndPaint(hwnd,&ps);
		return 0;
	case WM_DESTROY:
		//删除hBitmap
		DeleteObject(hBitmap);
		PostQuitMessage(0);
		return 0;
	}
	return DefWindowProc(hwnd,message,wParam,lParam);
}