We Keep Coding

Access object in a different thread

Setup:
Win10 .NET 4.7.1/VS2017 .NET 4.5/ C#
Level:
Beginner/Intermediate/new to threading
Objective:
1: A selenium web automation class that is triggered by a timer class so that the web automation class can exchange data with a javascript site at specific times.
2: Should be possible to migrate solution from WebForms to .NET library (dll).
Problem:
Step 1. Timer class sends time event to method in Web class to login to internet site = working.
Step 2. Web automation class (WinForms/GUI) tries to retrieve data from the method that is triggered by timer class event = Exception: "Calling thread cannot access this object because a different thread owns it." (as translated from swe).
I admit I´m confused by the terminology in the area of threading that is new to me. Also, I understand some multithreading techniques are only valid for WinForms. Since my objective is to migrate the solution to a dll these are not an option for me. I´ve played around with Invoke(), but as I understand it´s limited to use in WinForms. Guidance is highly appreciated!
WEB AUTOMATION CLASS:
private EdgeDriver driver;
private SeleniumHelper helper;
private WebAutomationTimer timer;
private double account;
public double Account { get => this.account; set => this.account = value; }
public Form1()
{
InitializeComponent();
timer = new WebAutomationTimer(02, 36, 00, 02, 38, 00);
timer.OnLoginTime += Timer_OnLoginTime;
timer.OnLogoutTime += Timer_OnLogoutTime;
}
private void Timer_OnLoginTime()
{
Login();
}
private void Timer_OnLogoutTime()
{
Logout();
}
public bool Login()
{
try
{
// working login code
UpdateLabels();
}
catch (Exception e)
{
}
}
private void UpdateLabels()
{
// EXCEPTION !!!
lblAccount.Text = GetAccount();
// EXCEPTION !!!
}
TIMER CLASS:
class WebAutomationTimer
{
public event TimerEvent OnLoginTime;
public event TimerEvent OnLogoutTime;
//public event TimerEvent OnSecond;
private System.Timers.Timer timer;
private DateTime now;
private int loginHour;
private int loginMin;
private int loginSec;
private int logoutHour;
private int logoutMin;
private int logoutSec;
public WebAutomationTimer(int loginHour, int loginMin, int loginSec, int logoutHour, int logoutMin, int logoutSec)
{
timer = new System.Timers.Timer();
timer.Interval = 1000; // 1 sec
timer.Elapsed += Timer_Elapsed;
timer.Start();
this.loginHour = loginHour;
this.loginMin = loginMin;
this.loginSec = loginSec;
this.logoutHour = logoutHour;
this.logoutMin = logoutMin;
this.logoutSec = logoutSec;
}
// Each second event
private void Timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
now = DateTime.Now;
//OnSecond();
//login
if (now.Hour == loginHour && now.Minute == loginMin && now.Second == loginSec)
OnLoginTime();
//logout
if (now.Hour == logoutHour && now.Minute == logoutMin && now.Second == logoutSec)
OnLogoutTime();
}
}
}

When you want to update View's control from another Thread it must show you error. Because it is using by UI Thread. In this case you have to use SynchronizationContext class or you can send Delegate to the App.Current.Dispatcher.BeginInvoke(delegate must be here);
SynchronizationContext _context = SynchronizationContext.Current;
private void UpdateLabels()
{
_context.Post(x=>
{
lblAccount.Text = AccountBalance.ToString();
},null),
//...
}
Alternative of SynchronizationContext :
private void UpdateLabels()
{
var action = new Action(() =>
{
lblAccount.Text = AccountBalance.ToString();
});
App.Current.Dispatcher.BeginInvoke(action);
//...
}
Both of them are same.
UI thread adapted for keyboard event and mouse event.
When you App.Current.Dispatcher.BeginInvoke(delegate) you say to the UI Thread that
"execute this too".
In addition you can suppose UI Thread like this
while(!thisApplication.Ended)
{
wait for something to appear in message queue
Got something : what kind of this message?
Keyboard/Mouse message --> fire event handler
User BeginInvoke message --> execute delegate
User Invoke message --> execute delegate & post result
}

this error is beacuse of change lable text beacuse lable is in another thread you can use this code
lblAccount.Invoke(new EventHandler((s, ee) => { lblAccount.Text = AccountBalance.ToString(); }));

This solution is probably only valid in my case. OP can delete this question if it´s believed to be a duplicate.
The first objective with was an easy to develop/run/debug situation with a GUI. Setting properties causes no cross thread exception. Showing the properties in a MessageBox.Show() causes no exception either. Hence no cross thread issues to dodge in the development/GUI stage.
The second objective was to migrate to a dll, hence no need to interfere with a GUI thread.
/Thanks anyway

What is causing my UI Thread to be blocked?

I am completely lost in what is really causing the problem. So rather trying to explain the problem, I might as well as get straight to the code with the problem. Here is the layout of my program:
private void connection_OnMessage(object sender, agsXMPP.protocol.client.Message msg)
{
if (!string.IsNullOrEmpty(msg.Body) && ((msg.XDelay != null && msg.XDelay.Stamp.Date == DateTime.Today) || msg.XDelay == null))
{
agsXMPP.Jid JID = new Jid(msg.From.Bare);
int rowIndex = chatLog.Rows.Add();
chatLog.Rows[rowIndex].Cells["chatNameColumn"].Value = JID.User;
chatLog.Rows[rowIndex].Cells["chatMessageColumn"].Value = msg.Body;
//Begin line of the problem
if (IncomingMessage != null)
IncomingMessage(this, JID.User, msg.Body);
//End of the problem
}
}
The above code snippet is of class A. After starting up the program, this class makes the connection to the server. Right after being connected, this code snippet is rapidly fired about 20 times, once per line of message. (There are already about 20 lines of message in the chat log.) Since only one message makes it through the if condition, the lines commented with the problem is only run once. Those lines fire the code snippet below of class B.
(Around the time class A is firing, I have another class like A that fires the similar event to be handled by class B the same way, which will be handled by class C.)
private void newSource_IncomingMessage(IChatSource sender, string user, string message)
{
UpdatedMessageEventHandler temp = UpdatedMessage;
if (temp != null)
temp(sender, user, message);
}
The above code snippet of class B fires the code snippet below of class C.
private void chatManager_UpdatedMessage(IChatSource source, string user, string message)
{
if (!source.Muted)
{
updateMessage(source, user, message);
}
}
delegate void UpdateMessageCallback(IChatSource source, string user, string message);
private void updateMessage(IChatSource source, string user, string message)
{
if (allDataGridView.InvokeRequired)
{
UpdateMessageCallback d = new UpdateMessageCallback(updateMessage);
Invoke(d, new object[] { source, user, message });
}
else
{
int row = allDataGridView.Rows.Add();
allDataGridView.Rows[row].DefaultCellStyle.ForeColor = source.TextColor;
allDataGridView.Rows[row].Cells["NameColumn"].Value = user;
allDataGridView.Rows[row].Cells["MessageColumn"].Value = message;
if (!MenuItem.Checked)
{
MenuItem.Checked = true;
Show();
}
}
}
Here is what I tried to do to fix the problem, but the code is removed already:
I tried adding lock to certain codes.
I tried to put the certain codes on a separate thread and have them run.
Here is what happened:
When I run the program, the UI thread seems to be blocked. In other words, class C doesn't get painted. Sometimes, the form doesn't even appear.
A few times, it complaint about a strange error "An error occurred invoking the method. The destination thread no longer exists."
If I commented out the problem lines, everything work fine, but here is the strange part. If I create a timer object in class A and have it fired the event the same way, it works fine.
While line stepping in debug mode, I sometimes got it work fine, but majority of the time, it fails.
For a few times, I run into InvalidOperationException with the message, "Control accessed from a thread other than the thread it was created on." even though I did make it thread safe.
In conclusion, I don't know what is causing the UI thread to be blocked. Any pointer or what I might do wrong?

The problem is that you're calling methods crossthreading. This can lead to deadlocks.
You could solve this, adding the messages on a concurrent queue and on a timer (gui thread) checking the queue and adding the messages to controls.
This is not a complete solution, but a method to prevent crossthread method invoking
Like: (PSEUDO) (wrote online on the site)
// dataholder
public class ChatMsg
{
public string User {get;set;}
public string Message {get;set;}
}
// message store
private List<ChatMsg> _messages = new List<ChatMsg>();
// timer
private Timer _timer;
// callback for you chatapi?? (like you wrote)
private void newSource_IncomingMessage(IChatSource sender, string user, string message)
{
UpdatedMessageEventHandler temp = UpdatedMessage;
// lock the store
lock(_messages)
_messages.Add(new ChatMsg { User = user, Message = message });
}
// constructor
public Form1()
{
// create the check timer.
_timer = new Timer();
_timer.Interval = 100;
_timer.Tick += Timer_Tick;
_timer.Start();
}
// timer method
private void Timer_Tick(object sender, EventArgs e)
{
// copy of the queue
ChatMsg[] msgs;
// lock the store and 'move' the messages
lock(_messages)
{
msgs = _messages.ToArray();
_messages.Clear();
}
if(msgs.Length == 0)
return;
// add them to the controls
foreach(var msg in msgs)
{
// add the message to the gui controls... (copied from your question)
int row = allDataGridView.Rows.Add();
allDataGridView.Rows[row].DefaultCellStyle.ForeColor = source.TextColor;
allDataGridView.Rows[row].Cells["NameColumn"].Value = user;
allDataGridView.Rows[row].Cells["MessageColumn"].Value = message;
}
}
Something like that..

Indexer created to look at array doesn't see changes made to array

I am very new to c#, and I'm creating a serial port class for a board I have designed. In which this class contains methods to open/close a serial port connected to the board. It should also read messages from the board and write messages from the UI to the board (I am using a forms application to input and display values).
I read the internal input buffer and place the bytes into my own software buffer, when a message is complete, this will prompt the form to analyse the message...
For this I have created an indexer to point to the array (from the form) and take the bytes that it desires.
uint[] serialPortReceiveBuffer = new uint[3];
public delegate void Del();
Del promptFormAction = Form1.MsgReceived;
public void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
for (int i = 0; i <= 2; i++)
{
serialPortReceiveBuffer[i] = (uint)serialPort1.ReadByte();
}
promptFormAction();
}
public uint this[uint i]
{
get { return serialPortReceiveBuffer[i]; }
}
this is the code within my pcbSerialPort class, and the code related to it in the Form1 class is as follows:
public static void MsgReceived()
{
Form1 _frm = new Form1();
_frm.analyzeIncomingMessage();
}
public void analyzeIncomingMessage()
{
if (PCB[0] == 63)
{
setBoardDesignator(PCB[1], PCB[2]);
}
}
My problem is that the when I use the indexer to access the serialPortReceiveBuffer, it doesn't see the changes that I made to it when placing received bytes into the same array. For example, when I receive a string of my own protocol --> "?10" the buffer is filled with [63][49][48]
Though when I try to access this buffer using the indexer I get [0][0][0]
Please can anyone help? Also, I'm aware there is probably a few other things I could have done better so if you have any general tips that would be great. Also in a language I may understand. I am just getting my head around many of the c# aspects, I have been doing embedded software for the past year but I wouldn't consider my self to be a competent programmer.
Thank you

From your code I'm not quite sure that the PCB object you're working with in your form is actually the one that receives the data. Might well be that you're working with two different instances, especially as you're creating a new instance of Form1 whenever data comes in!
(EDIT: From your comment to the question it is clear that this is exactly the problem. Follow these instructions to get closed to what you want).
I suggest that you redesign your code to pass the received message as an event to the existing form instance instead of how you do it now. Another problem you might run into will be that data you think you get will be overridden by the next message coming in, das the DataReceived event is asynchronous.
I'd declare an event that the form instance can subscribe to, passing the data to be analyzed into the event:
public class MessageReceivedEventArgs: EventArgs
{
public MessageReceivedEventArgs(byte[] data) : base()
{
Data = data;
}
public byte[] Data
{
get;
private set;
}
}
public event EventHandler<MessageReceivedEventArgs> MessageReceived;
Then, I'd change your DataReceivedevent as follows:
public void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
for (int i = 0; i <= 2; i++)
{
serialPortReceiveBuffer[i] = (uint)serialPort1.ReadByte();
}
byte[] dataCopy = new byte[serialPortReceiveBuffer.Length];
Array.Copy(serialPortReceiveBuffer, dataCopy, dataCopy.Length);
promptFormAction(dataCopy);
}
private void promptForAction(byte[] data)
{
if (MessageReceived != null)
MessageReceived(this, new MessageReceivedEventArgs(data));
}
Also I'd keep the serialPortReceiveBuffer totally private to that class, as I said, you may run into synchronization issues if you don't. That'y why I copy the array before passing it to the event.
This change allows any subscriber to register for notifications whenever you realize that new data came in.
To use this, Form1 should look like this (roughly);
public class Form1
{
pcbSerialPort PCB; // The name of that class I don't know from your code
public Form1()
{
PCB = new pcbSerialPort();
PCB.MessageReceived += MessageReceived;
}
private void MessageReceived(object sender, pcbSerialPort.MessageReceivedEventArgs e)
{
analyzeIncomingMessage(e.Data);
}
private void analyzeIncomingMessage(byte[] data)
{
if (data[0] == 63)
{
setBoardDesignator(data[1], data[2]);
}
}
}
Another piece of advice on how you handle serial data: You need to decide whether you read from a serial port in a loop or whether you rely on the DataReceived event. Putting a loop into the event is not a good idea, as the event may be called upon arriving data again while you're waiting.
What you need to do is create a buffer that takes all the information from the serial port that's available. If you don't have enough data, don't wait for it. Instead add to the buffer whenever DataReceived is called and handle a message when enough data is present.

I think Thorsten's answer is good and it would make a lot of sense to redesign it along those lines, but as an absolute minimum, if you want to have it such that you create a new Form1 instance for every received message, then you will need to pass the instance of pcbSerialPort to MessageReceived and then to the constructor of your Form1 class. Something like:
Action<pcbSerialPort> promptFormAction = Form1.MsgReceived;
public void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
// as Thorsten noted, you need to rethink this loop anyway
// what if there aren't at least three bytes to read?
for (int i = 0; i <= 2; i++)
{
serialPortReceiveBuffer[i] = (uint)serialPort1.ReadByte();
}
promptFormAction(this);
}
And your static method:
public static void MsgReceived(pcbSerialPort pcb)
{
Form1 _frm = new Form1(pcb);
_frm.analyzeIncomingMessage();
}
And you constructor for Form1:
public Form1(pcbSerialPort pcb)
{
PCB = pcb;
}

Cross-thread operation not valid. Multiple solutions fail to work,

Before reading, I want everyone reading this to know that I have tried multiple delegate/Cross-Threading/Invoking Solutions from all over stack overflow.
With that said, this is what my program is supposed to do:
Worker Thread 1 is called to start Async Operation.
If it detects a line that has a typical PRIVMSG header along with the word subscribed!
Create a new MetroTaskWindow with a TaskWindowControl and Add it to the queue
Worker Thread 2 is called after worker thread 1
Worker Thread 2 checks every 5 seconds if queue contains something
If it does, show it and get rid of it
Here is the associated Code If you need more, let me know to the above requirements:
Worker Thread 1 Segment
string line = "";
while (!backgroundWorker1.CancellationPending)
{
try
{
line = reader.ReadLine();
}
catch { }
if (line != null && !line.Contains("JOIN"))
{
try
{
if (line.Contains("PING") && !line.Contains("PRIVMSG"))
{
writer.Write(line.Replace("PING", "PONG"));
Trace.WriteLine(line.Replace("PING", "PONG"));
}
else if (line.Split(new char[] { ' ' })[0].Equals(":twitchnotify!twitchnotify#twitchnotify.tmi.twitch.tv") ||
line.Split(new char[] { ' ' })[0].Equals(":stds_catchemall!stds_catchemall#stds_catchemall.tmi.twitch.tv") && line.Contains("subscribed!"))
{
total += 1;
checkNotifications();
}
}
catch
{
continue;
}
}
if (!String.IsNullOrEmpty(line))
Trace.WriteLine(line);
}
}
private void checkNotifications()
{
List<Achievement> tempQueue = new List<Achievement>();
foreach (Achievement a in achievements) {
//I know i could shorten this, but i need it left like this...
if (a.AfterSub)
tempQueue.Add(a);
if (total - a.Goal == start)
tempQueue.Add(a);
if (total == a.Goal)
tempQueue.Add(a);
}
foreach (Achievement a in Sort(tempQueue))
{
MetroTaskWindow m = new MetroTaskWindow(a, this, a.Type.ToString(), new TaskWindowControl(a.Name, a.Message, a), 4, r, ((ScreenRegion)r).getGS());
queue.Add(m);
}
}
Worker Thread 2
private void CheckAvailable_DoWork(object sender, DoWorkEventArgs e)
{
while (true)
{
Thread.Sleep(5250);
BeginInvoke((MethodInvoker)delegate
{
if (queue.Count > 0)
{
queue[0].Show(); // <---- Error Occurs Here
//Cross-thread operation not valid: Control 'TaskWindowControl' accessed from a thread other than the thread it was created on.
queue.RemoveAt(0);
}
});
}
}
Metro Task Window
public MetroTaskWindow(Achievement a, IWin32Window parent, string title, Control userControl, int secToClose, MetroForm r, Form gs)
{
controlContainer = new MetroPanel();
Controls.Add(controlContainer);
controlContainer.Controls.Add(userControl);
userControl.Dock = DockStyle.Fill;
closeTime = secToClose * 500;
this.a = a;
form = r;
chroma = gs;
p = (Form1)parent;
this.Text = title;
this.Resizable = false;
this.Movable = true;
this.StartPosition = FormStartPosition.Manual;
if (parent != null && parent is IMetroForm)
{
this.Theme = ((IMetroForm)parent).Theme;
this.Style = ((IMetroForm)parent).Style;
this.StyleManager = ((IMetroForm)parent).StyleManager.Clone(this) as MetroStyleManager;
this.ShadowType = MetroFormShadowType.None;
}
switch (a.Type)
{
case PopupType.Achievement:
Text = "Achievement!";
break;
case PopupType.Milestone:
Text = "Milestone!";
break;
case PopupType.Notification:
Text = "Notification";
break;
}
}
TaskWindowControl
public partial class TaskWindowControl : UserControl
{
public TaskWindowControl(string name, string info, Achievement a)
{
InitializeComponent();
metroLabel1.Text = name;
metroTextBox1.Text = info;
metroTextBox1.Select(0, 0);
try
{
Trace.WriteLine(Directory.GetCurrentDirectory() + "\\" + a.Picture);
pictureBox1.Image = Image.FromFile(Directory.GetCurrentDirectory() + "\\" + a.Picture);
}
catch
{
MessageBox.Show("There was an error loading the image for this achievement.");
}
}
}
And as I stated above, there are a LOT of duplicates, none of which have helped my answer. I also don't know much about the Delegate/Invoking process which is why I need some extra help.
Update #1
Anywhere I had queue.Add(m); is now replaced with queue.Enqueue(a);
And my update method (Without timer so far) is just:
public void DisplayDialog()
{
Achievement a = null;
queue.TryDequeue(out a);
MetroTaskWindow m = new MetroTaskWindow(a, this, a.Type.ToString(), new TaskWindowControl(a.Name, a.Message, a), 4, r, ((ScreenRegion)r).getGS());
m.Show();
}
Something that I found is that when I changed the code to this, the Thread that does the animations and things on my MetroTaskWindow doesn't get activated. The Windows Stays in with a windows loading circle and it never goes away. Any ideas? I'm using the OnActivated event, so it SHOULD fire when i .Show();
Edit #2
What I ended up doing to get my above error to work, was to switch all of my code to a new Windows Form Timer. This polls every 5 seconds, and keeps the MetroTaskWindow from hanging due to the while loop.
Form1.Designer.cs
private System.Windows.Forms.Timer timer2;
timer2 = new System.Windows.Forms.Timer(this.components);
timer2.Interval = 5250;
timer2.Tick += new System.EventHandler(this.timer2_Tick);
Form1.cs
private void timer2_Tick(object sender, EventArgs e)
{
if (queue.Count > 0)
{
DisplayDialog();
}
}

The error makes sense. The queue contains MetroTaskWindow instances created on a worker thread, not on the UI thread. You call checkNotifications in the background worker's entry point method, which runs on a separate thread.
What I recommend you do is:
Store in the queue only metadata about the windows. Create a new class with name, message and anything MetroTaskWindow needs to be created. Add instances of this class to the queue in checkNotifications. By the looks of it you might be able to use the Achievement class directly and push that to the queue.
Create the windows and show them in CheckAvailable_DoWork, where you now call queue[0].Show();.
After you solve this you should post a new question about how to refactor your code into async/await and get rid of that ugly background worker.
A quick refactoring idea
I would remove the second background worker altogether and use a timer instead that polls the queue every X seconds (or 5250ms, if you prefer).
To make this work you need to change the queue's type which is now actually a List<T> to a ConcurrentQueue<T>. This will allow you to push stuff from the worker, and pop from the UI thread (in the timer callback).
This way you can remove the second background worker and that while(true).

Waiting Dialog white wpf toolkit chart loads the graph

I want to display a large collection of points as a chart (at least 300 000 points), using wpf toolkit chart.
I have the following XAML
<chartingToolkit:Chart Name="chartHistory">
<chartingToolkit:Chart.Axes>
<chartingToolkit:LinearAxis x:Name="horizontalAxis" Orientation="X" Title="Time [s]" ShowGridLines="True"/>
<chartingToolkit:LinearAxis x:Name="verticalAxis" Orientation="Y" Title="Value [mm]" ShowGridLines="True"/>
</chartingToolkit:Chart.Axes>
<chartingToolkit:AreaSeries x:Name="chartSeries" DataPointStyle="{StaticResource chartDataPoint}"
IndependentValuePath="TimeInSeconds"
DependentValuePath="Value">
</chartingToolkit:AreaSeries>
</chartingToolkit:Chart>
And in code behind:
public class PointData
{
public double TimeInSeconds { get; set; }
public double Value { get; set; }
}
private List<PointData> points;
private void Screen_Loaded(object sender, RoutedEventArgs e)
{
// this is a large collection of points (minimum 300 000)
points = LoadPointsFromFile();
// and it takes a lot of time to read from the file and load in the UI
chartSeries.ItemsSource = points;
// additional chart display properties (setting min/max on the axes etc.)
}
So, I have 2 time consuming operations that block my UI. What I want is to display a "please load dialog" while the time consuming operations take place, so that the user knows the application is still doing something.
The time consuming operations are:
reading the points from the file (this operation could be done on a separate thread, but since the next operation (loading the points in the chart) depends on it and is a UI operation, I didn't put it in a separate thread)
loading the points as ItemsSource in the chart - this is a UI operation and should be done on the UI thread. But how can I still make the application responsive since I do not have any control on how the points are displayed - this is the chart's own logic?
So, any ideas? Did you have any similar problems?
Thank you,
Nadia

Actually, what I did was to create a separate thread that displays a different "loading dialog" that shows up while the data is loading. There still is about one second from the moment the dialog is closed until the UI gets fully responsive, but it's still better than looking at a unresponsive UI for 5-10 seconds.
public class PointData
{
public double TimeInSeconds { get; set; }
public double Value { get; set; }
}
#region Wait Dialog Thread
private class MainWindowSize
{
public double Left;
public double Top;
public double Width;
public double Height;
}
private Thread newWindowThread = null;
private void ThreadStartingPoint(object obj)
{
// WaitDialog is a new window from your project - you can place a animation or message inside it
WaitDialog tempWindow = new WaitDialog();
// since we don't have an owner for the window, we need
// to compute the location of the popup dialog, so that
// its centered inside the main window
MainWindowSize wndSize = obj as MainWindowSize;
if (wndSize != null)
{
tempWindow.Left = wndSize.Left + wndSize.Width / 2 - tempWindow.Width / 2;
tempWindow.Top = wndSize.Top + wndSize.Height / 2 - tempWindow.Height / 2;
}
// it's very important not to set the owner of this dialog
// otherwise it won't work in a separate thread
tempWindow.Owner = null;
// it shouldn't be a modal dialog
tempWindow.Show();
tempWindow.Closed += (sender1, e1) => tempWindow.Dispatcher.InvokeShutdown();
System.Windows.Threading.Dispatcher.Run();
}
private void CreateAndStartWaitWindowThread()
{
// create a thread only if you don't have an active one
if (newWindowThread == null)
{
// use ParameterizedThreadStart instead of ThreadStart
// in order to send a parameter to the thread start method
newWindowThread = new Thread(new ParameterizedThreadStart(ThreadStartingPoint));
newWindowThread.SetApartmentState(ApartmentState.STA);
newWindowThread.IsBackground = true;
// get the properties of the window, in order to compute the location of the new dialog
Window mainWnd = App.CurrentApp.MainWindow;
MainWindowSize threadParams = new MainWindowSize { Left = mainWnd.Left, Top = mainWnd.Top, Width = mainWnd.ActualWidth, Height = mainWnd.ActualHeight };
// start thread with parameters
newWindowThread.Start(threadParams);
}
}
private void AbortAndDeleteWaitWindowThread()
{
// abort a thread only if you have an active one
if (newWindowThread != null)
{
newWindowThread.Abort();
newWindowThread = null;
}
}
#endregion
private List<PointData> points;
private void Screen_Loaded(object sender, RoutedEventArgs e)
{
try
{
// call this before long operation
this.Cursor = Cursors.Wait;
CreateAndStartWaitWindowThread();
// this is a large collection of points (minimum 300 000)
points = LoadPointsFromFile();
// and it takes a lot of time to read from the file and load in the UI
chartSeries.ItemsSource = points;
// additional chart display properties (setting min/max on the axes etc.)
}
catch(Exception ex)
{
// do something with the exception
}
finally
{
// call this after long operation - and make sure it's getting called
// so put it in the finally block - to call it even if an exception is raised
this.Cursor = Cursors.Arrow;
AbortAndDeleteWaitWindowThread();
}
}
Source: http://www.c-sharpcorner.com/uploadfile/suchit_84/creating-wpf-windows-on-dedicated-threads/