從WPF的串口接收數據時做點什麼

Question

我想創建一個程序，它會根據「實時」接收到的數據以任何方式對橢圓進行着色。數據是這樣的：x1-1,x2-1等

我有一個奇怪的問題，我可以在調試時看到，填充橢圓的顏色應該改變，但它不會發生。我與接收數據的代碼

部分：

private void ReceiveData() 
      { 
       SerialPort serialPort = new SerialPort("COM1", 9600); 
       serialPort.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler); 
       serialPort.Open(); 
      } 

private static void DataReceivedHandler(
       object sender, 
       SerialDataReceivedEventArgs e) 
      { 
       SerialPort sp = (SerialPort)sender; 
       string indata = sp.ReadExisting(); 
       if (indata.Contains(" ")) 
       { 
        testString = indata.Substring(0, 4); 

       } 
       Console.Write(indata); 
      } 

我可以看到在收到控制檯數據，甚至點擊按鈕後，啓動接收數據。 testString將從indata中提取單個x1-1，這在接收數據期間仍然在增長。我知道它不會像它應該那樣工作，但現在並不重要。行動按鈕

代碼：

private void button1_Click(object sender, RoutedEventArgs e) 
     { 
      ReceiveData(); 
      while (true) 
      { 
       if (testString == "x1-1") x1.Fill = Brushes.Blue; 
       else x1.Fill = Brushes.Red; 
      } 
     } 

x1是橢圓形，我想使紅色或藍色。我可以在這個函數中設置斷點，我可以看到它應該改變。我認爲問題在於，該程序正在等待關閉端口並完成傳輸，然後可能會改變，但我需要「實時」。任何人都知道如何做到這一點？

Answer 1

我相信你會這樣做是錯誤的。您不必經常檢查teststring的值，而只需啓動通信端口偵聽器並讓它在後臺運行 - 因爲這將在它自己的線程上運行。然後你需要創建一個數據綁定到顏色。每當通信端口偵聽器分析一個字符串時，它就會自動更新顏色。

首先，在CommPort的類：

class MyCommPort : INotifyPropertyChanged 
{ 
    SerialPort serialPort = null; 
    public MyCommPort() 
    { 
     serialPort = new SerialPort("COM3", 9600); 
     serialPort.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler); 
     serialPort.Open(); 
    } 
    ~MyCommPort() 
    { 
     serialPort.Close(); 
    } 

    private void DataReceivedHandler(object sender, SerialDataReceivedEventArgs e) 
    { 
     SerialPort sp = (SerialPort)sender; 
     string testString = null; 
     string indata = sp.ReadLine(); 
     if (indata.Length >= 4) 
     { 
      testString = indata.Substring(0, 4); 
      // Update the value 
      if (testString == "x1-1") EllipseBrush = Brushes.Blue; 
      else EllipseBrush = Brushes.Red; 
     } 
     Console.Write(testString); 
    } 

    // Create a property that will be bound 
    private SolidColorBrush ellipseBrush = Brushes.Red; 
    public SolidColorBrush EllipseBrush 
    { 
     get { return ellipseBrush; } 
     set 
     { 
      ellipseBrush = value; 
      OnPropertyChanged("EllipseBrush"); 
     } 
    } 

    // Extend the INotifyPropertyChanged interface 
    public event PropertyChangedEventHandler PropertyChanged; 
    private void OnPropertyChanged(string propertyName) 
    { 
     if (PropertyChanged != null) 
     { 
      // Alert anyone bound to this that the value has changed 
      PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); 
     } 
    } 
} 

然後，將橢圓的的DataContext到CommPort的類和綁定橢圓的Fill屬性EllipseBrush。 現在您只需啓動Commport監聽器（ReceiveData();），顏色更新應自動進行。

例如：MainWindow.xaml

<Window x:Class="delete_me.MainWindow" 
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
     Title="MainWindow" Height="350" Width="525"> 
    <Grid> 
     <Ellipse x:Name="ellipse" Fill="{Binding Path=EllipseBrush}" /> 
    </Grid> 
</Window> 

而後面的代碼：MainWindow.xaml.cs

public partial class MainWindow : Window 
{ 
    public MainWindow() 
    { 
     InitializeComponent(); 
     ellipse.DataContext = new MyCommPort(); 
    } 
} 

Answer 2

不要由具有while(true)點擊一個按鈕的內掛UI線程事件。改爲使用DispatchTimer每500秒執行一次工作。

System.Windows.Threading.DispatcherTimer MyTimer = null; 
private void ReceiveData() 
{ 
    MyTimer = new System.Windows.Threading.DispatcherTimer(); 
    MyTimer.Interval = new TimeSpan(0, 0, 0, 0, 500); 
    MyTimer.Tick += MyTimer_Tick; 
    MyTimer.Start(); 
    SerialPort serialPort = new SerialPort("COM1", 9600); 
    serialPort.DataReceived += new 
      SerialDataReceivedEventHandler(DataReceivedHandler); 
    serialPort.Open(); 
} 

private static void DataReceivedHandler(
       object sender, 
       SerialDataReceivedEventArgs e) 
{ 
    SerialPort sp = (SerialPort)sender; 
    string indata = sp.ReadExisting(); 
    if (indata.Contains(" ")) 
    { 
     testString = indata.Substring(0, 4); 

    } 
} 

private void button1_Click(object sender, RoutedEventArgs e) 
{ 
    ReceiveData(); 
} 

private void MyTimer_Tick(object sender, EventArgs e) 
{ 
    if (testString == "x1-1") 
    { 
     x1.Fill = Brushes.Blue; 
    } 
    else 
    { 
     x1.Fill = Brushes.Red; 
    } 
}