C＃GUI刷新和异步串口通信

Question

我试图创建一个应用程序，它通过串口与硬件进行通信并将结果报告给gui。

当前通过GUI进行的移动是由触发GUI的下一个“页面”绘制的KeyEvent完成的。然而，在一个步骤中（按下键后），我需要绘制新页面并通过串口发送少量命令。

命令发送通过完成：

port.Write(data, 0, data.Length); 

然后我通过等待DataReceivedHandler触发等待答案 - 它只是针从有数据等待和数据在另一个方法处理。

起初我只是把发送&接收命令放在绘制页面的函数之后的“绘制部分”，但是让它卡住了 - 数据被转移了，但是页面没有绘制 - 它被冻结了。

然后我做了一个异步方法：

private async void SendData() 
{ 
    await Task.Run(() => serialClass.SendAndReceive(command)); 
    // process reply etc. 
} 

这是用这样的：

public void LoadPage() 
{ 
    image = Image.FromFile(path); 
    //do some stuff on image using Graphics, adding texts etc. 
    picturebox1.Image = image; 
    SendData(); 
} 

它工作正常，但我需要“刷新”的页面（再次呼叫LoadPage） 。如果我这样做的异步方法里面是这样的：

private async void SendData() 
{ 
    await Task.Run(() => serialClass.SendAndReceive(command)); 
    // process reply etc. 
    LoadPage(); 
} 

那么很明显，图像不会被刷新，但该数据将通过串口发送。是否有可能以某种方式检查异步函数是否完成，并触发一个事件，我可以重新加载页面？

到目前为止，我尝试过使用BackGroundWorker工作完成和属性更改。数据再次发送，但图像未重新加载。任何想法我怎么能实现呢？

在此先感谢您的帮助， 最好的问候

Answer 1

你需要使用一个状态机和delegates达到什么你正在尝试做的。请参阅下面的代码，我建议在除Main之外的单独线程中完成所有这些操作。你跟踪你所处的状态，当你得到一个响应时，你用正确的回调函数解析它，如果它是你期望的，你将进入下一个发送命令状态。

private delegate void CallbackFunction(String Response); //our generic Delegate 
private CallbackFunction CallbackResponse;     //instantiate our delegate 
private StateMachine currentState = ATRHBPCalStateMachine.Waiting; 

SerialPort sp; //our serial port 

private enum StateMachine 
{ 
    Waiting, 
    SendCmd1, 
    Cmd1Response, 
    SendCmd2, 
    Cmd2Response, 
    Error 
} 

private void do_State_Machine() 
{ 
    switch (StateMachine) 
    { 
     case StateMachine.Waiting: 
      //do nothing 
      break; 
     case StateMachine.SendCmd1: 
      CallbackResponse = Cmd1Response; //set our delegate to the first response 
      sp.Write("Send first command1"); //send our command through the serial port 

      currentState = StateMachine.Cmd1Response; //change to cmd1 response state 
      break; 
     case StateMachine.Cmd1Response: 
      //waiting for a response....you can put a timeout here 
      break; 
     case StateMachine.SendCmd2: 
      CallbackResponse = Cmd2Response; //set our delegate to the second response 
      sp.Write("Send command2"); //send our command through the serial port 

      currentState = StateMachine.Cmd2Response; //change to cmd1 response state 
      break; 
     case StateMachine.Cmd2Response: 
      //waiting for a response....you can put a timeout here 
      break; 
     case StateMachine.Error: 
      //error occurred do something 
      break; 
    } 
} 

private void Cmd1Response(string s) 
{ 
    //Parse the string, make sure its what you expect 
    //if it is, then set the next state to run the next command 
    if(s.contains("expected")) 
    { 
     currentState = StateMachine.SendCmd2; 
    } 
    else 
    { 
     currentState = StateMachine.Error; 
    } 
} 

private void Cmd2Response(string s) 
{ 
    //Parse the string, make sure its what you expect 
    //if it is, then set the next state to run the next command 
    if(s.contains("expected")) 
    { 
     currentState = StateMachine.Waiting; 
     backgroundWorker1.CancelAsync(); 
    } 
    else 
    { 
     currentState = StateMachine.Error; 
    } 
} 

//In my case, I build a string builder until I get a carriage return or a colon character. This tells me 
//I got all the characters I want for the response. Now we call my delegate which calls the correct response 
//function. The datareceived event can fire mid response, so you need someway to know when you have the whole 
//message. 
private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e) 
{ 
    string CurrentLine = ""; 
    string Data = serialPortSensor.ReadExisting(); 

    Data.Replace("\n", ""); 

    foreach (char c in Data) 
    { 
     if (c == '\r' || c == ':') 
     { 
      sb.Append(c); 

      CurrentLine = sb.ToString(); 
      sb.Clear(); 

      CallbackResponse(CurrentLine); //calls our correct response function depending on the current delegate assigned 
     } 
     else 
     { 
      sb.Append(c); 
     } 
    } 
} 

我会把这个在后台工作，而当你按下按钮或东西，你可以设置当前状态SendCmd1。

按下按钮

private void buttonStart_Click(object sender, EventArgs e) 
{ 
    if(!backgroundWorker1.IsBusy) 
    { 
     currentState = StateMachine.SendCmd1; 

     backgroundWorker1.RunWorkerAsync(); 
    } 
} 

背景工人做的工作事件

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) 
{ 
    while (true) 
    { 
     if (backgroundWorker1.CancellationPending) 
      break; 

     do_State_Machine(); 
     Thread.Sleep(100); 
    } 
} 

编辑：您可以使用调用来更新您的后台工作线程的GUI。

this.Invoke((MethodInvoker)delegate 
{ 
    image = Image.FromFile(path); 
    //do some stuff on image using Graphics, adding texts etc. 
    picturebox1.Image = image; 
});