# aardio 范例: 鼠标画渐开线

```aardio
//鼠标画渐开线
import win.ui;
/*DSG{{*/
var winform = ..win.form(text="鼠标画线";right=349;bottom=249;)
winform.add(
button={cls="button";text="运行范例";left=33;top=55;right=312;bottom=108;z=1}
)
/*}}*/

winform.wndproc = function(hwnd,message,wParam,lParam){
	select(message) {//判断消息类型
		case 0x201/*_WM_LBUTTONDOWN*/{
			if(winform.button.disabled = true)
				win.quitMessage()
		}
	} 
}

winform.button.oncommand = function(id,event){
	winform.capture = true;
	winform.button.disabled = true;
	winform.button.text = "按下鼠标左键停止演示并退出程序"
	winform.capture = true;
	//鼠标画渐开线
	import mouse.draw; 
 	
	//自定义此函数,每移动到一个点,画线函数会自动调用此函数
	//mouse.draw库所有函数遵守约定：返回值为true表示继续,返回false表示停止画线
	mouse.draw.move = function(x,y){ 
		hdc = ::GetDC(0)
    	SetPixel(hdc ,x,y,255 )
    	::ReleaseDC(0,hdc);
    	
		mouse.move(x,y,true)
		return win.delay(1)  
	}
	  
	// 画正弦曲线
	mouse.draw.sin() 
 	
	// 画渐开线
	mouse.draw.involute(); 
 	
	// 画方形仿渐开线,步进为5,中间忽略的正方形边长为50
	mouse.draw.rectInvolute(5,50); 
 	
	//这是真正的渐开线,第三个参数指定基圆的半径
	mouse.draw.involute2(1024/2,768/2,0.1,10); 
} 

winform.show() 
win.loopMessage();

```