[英]Streamming high-speed data to WPF UI using threading and MVVM
使用新的WPF應用程序時出現問題,該應用程序試圖向文本框顯示高速字節流。 字節來自串行端口,我制作了一個較舊的WinForms應用程序,該應用程序可以很好地處理該流,並具有從串行端口讀取並通過調用委托發布到UI的后台線程。
現在,此WPF應用程序存在的問題是我正在使用基本的MVVM方法。 我將UI上的文本框綁定到VM上的一個屬性,該屬性觸發基於INotifyPropertyChanged的PropertyChanged事件。 當數據准備通過讀取串行端口的服務上的已訂閱事件發布到ui時,我將使用以下命令:
Action dispatchAction = () => { FormattedStream += s; };
_currentDispatcher.Invoke(dispatchAction);
FormattedStream是UI綁定到的VM字符串屬性。
WPF應用程序發生的情況與WinForms版本中未發生的情況一樣,是WPF應用程序在運行過程中變得緩慢且無響應,並且與WinForms應用程序和wpf應用程序一樣無法跟上潮流根據我的任務管理器使用/需要更多處理器。
我想知道的是,是否有某種解決方案來處理流到WPF UI的流(高速)數據。
預計到達時間:我還嘗試使用BeginInvoke代替Invoke,當使用BeginInvoke時,流持續幾秒鍾然后凍結。 調用是獲得連續流到UI的唯一方法。
ETA:這是代碼:
//窗口/視圖
public partial class MainWindow : Window, IView
{
public MainWindow()
{
InitializeComponent();
}
public IViewModel ViewModel
{
get { return DataContext as IViewModel; }
set { DataContext = value; }
}
public void ScrollToCaret()
{
txtBoxOutPut.ScrollToEnd();
if (txtBoxOutPut.Text.Length > 10000)
txtBoxOutPut.Text = txtBoxOutPut.Text.Remove(0, 9000);
}
public event Action ComPortSelected;
public event Action StartPortReader;
public event Action StopPortReader;
private void Start_Click(object sender, RoutedEventArgs e)
{
StartPortReader.Invoke();
}
private void Stop_Click(object sender, RoutedEventArgs e)
{
StopPortReader.Invoke();
}
}
// ViewModel
public class ViewModel : IViewModel, INotifyPropertyChanged
{私人唯讀ISerialPortReaderService _portReaderService; 私有只讀Dispatcher _currentDispatcher;
public ViewModel(IView view, ISerialPortReaderService portReaderService)
{
View = view;
View.ViewModel = this;
View.StartPortReader += View_StartPortReader;
View.StopPortReader += View_StopPortReader;
_portReaderService = portReaderService;
_currentDispatcher = Dispatcher.CurrentDispatcher;
_portReaderService.ByteArrived += _portReaderService_ByteArrived;
}
private void _portReaderService_ByteArrived(string s)
{
Action dispatchAction = () => { FormattedStream = s; };
_currentDispatcher.Invoke(dispatchAction);
}
private void View_StopPortReader()
{
_portReaderService.Stop();
}
private void View_StartPortReader()
{
_portReaderService.Start(SelectedPort);
}
public IView View { get; private set; }
public void ShowView()
{
View.Show();
}
private StringBuilder _FormattedStream = new StringBuilder();
public string FormattedStream
{
get
{
return _FormattedStream.ToString();
}
set
{
_FormattedStream.Append(value);
PropertyChanged(this, new PropertyChangedEventArgs("FormattedStream"));
View.ScrollToCaret();
}
}
private string _SelectedPort;
public string SelectedPort
{
get
{
return _SelectedPort;
}
set
{
_SelectedPort = value;
PropertyChanged(this, new PropertyChangedEventArgs("SelectedPort"));
}
}
public ReadOnlyCollection<string> AvailablePorts
{
get { return GetAvailablePorts(); }
}
private ReadOnlyCollection<string> GetAvailablePorts()
{
var ports = System.IO.Ports.SerialPort.GetPortNames();
return new ReadOnlyCollection<string>(ports.ToList());
}
public event PropertyChangedEventHandler PropertyChanged = delegate { };
}
//串口讀卡器服務
public class SerialPortReaderService : ISerialPortReaderService
{private SerialPort _port = new SerialPort(); 私有只讀IThreadRunner _threadRunner;
public SerialPortReaderService(IThreadRunner threadRunner)
{
_threadRunner = threadRunner;
}
public void Start(string comPort)
{
if (_port != null && !_port.IsOpen)
{
_port.PortName = comPort;
_port.BaudRate = 4800;
_port.Open();
_threadRunner.Start(() =>
{
var b = new byte[20];
var bArray = _port.Read(b, 0, 20);
foreach (var b1 in b)
{
next10Bytes.Append(b1 + ", ");
}
BytesArrived(next10Bytes.ToString());
next10Bytes.Clear();
Thread.Sleep(10);
});
}
}
private StringBuilder next10Bytes = new StringBuilder();
public void Stop()
{
if (_port.IsOpen)
{
_threadRunner.Stop();
_port.Close();
}
}
public event Action<string> BytesArrived;
}
//我使用的線程運行器
public class ThreadRunner : IThreadRunner
{私有線程_thread; 私人布爾值_isRunning;
/// <summary>
/// Will continuously run in a while loop the action submitted in a separate thread
/// </summary>
/// <param name="toDoAction"></param>
public void Start(Action toDoAction)
{
if (_thread != null && _thread.IsAlive)
Stop();
_isRunning = true;
_thread = new Thread(() =>
{
while (_isRunning)
{
toDoAction.Invoke();
}
});
_thread.Start();
}
public void Stop()
{
_isRunning = false;
if (_thread != null && _thread.IsAlive)
{
_thread.Abort();
_thread.Join(new TimeSpan(0, 0, 1));
}
}
public bool ThreadIsRunning
{
get { return _isRunning; }
}
}
根據Petoj所說的,我創建了一個新窗口,仍在使用流服務,但僅窗口本身訂閱了bytesarrived事件並通過Dispatcher手動附加到txtbox上。沒有大量的CPU使用率。
這個故事的寓意是,每次添加新的字符串時,不斷綁定或至少綁定到字符串會導致速度變慢。
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