Develop Reference

Live chart slowness

I am charting live data (ekg) from a vital sign monitor. The monitor outputs 500 data points per second which represent a single ekg waveform. I parse these in a backgroundWorker to display them in a chart without freezing the controls. The typical case lasts about an hour, which equals about 1.8 million data points that I have to display.
Here is the backgroundWorker code:
private void BackgroundWorker1_DoWork (object sender, DoWorkEventArgs e) {
backgroundWorker1.WorkerSupportsCancellation = true;
backgroundWorker1.WorkerReportsProgress = true;
if (backgroundWorker1.CancellationPending == true) {
e.Cancel = true;
}
for (int i = 0; i <= 100; i++) {
backgroundWorker1.ReportProgress(i);
if (i % 25 == 1) {
Thread.Sleep(500);
}
}
try {
Action action = () =>
FillChartEKG();
Invoke(action);
}
catch {
backgroundWorker1.CancelAsync();
MessageBox.Show("No EKG waveform data availaible to parse. Does your vital sign monitor support export of EKG wavedorm data?", "EKG waveform status", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}
}
And here is the long running method that charts the EKG data points:
public async void FillChartEKG() {
List<AnesthWaveformData> waveformData = AnesthWaveformDatas.CreateWaveformObjects(anestheticRecordNum);
var series1 = new Series {
Name = "EKG",
Color = Color.LawnGreen,
IsVisibleInLegend = false,
IsXValueIndexed = true,
ChartType = SeriesChartType.Line,
};
chartEKG.Series.Clear();
chartEKG.Series.Add(series1);
string timeStamp = DateTime.Now.ToString();
DateTime time = new DateTime();
int counter = 0;
int loopCount = 0;
int loopToStopAt = 0;
//await System.Threading.Tasks.Task.Run(() => {
for (int j = 0; j < waveformData.Count; j++) {
if (waveformData[j].EKGWaveform == String.Empty || waveformData[j].EKGWaveform.StartsWith("32767")) {
continue;
}
counter = counter + 1; //there are 500 data points in each EKG waveform HL7 message; counter is the number of valid EKG waveforms in waveFormData
try {
timeStamp = waveformData[j].VSTimeStamp + "000"; //get first VSTimeStamp in series
string format = "yyyyMMddHHmmssfff";
time = DateTime.ParseExact(timeStamp, format, CultureInfo.InvariantCulture);
}
catch { MessageBox.Show("No waveform data to display", "Waveform data status", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); }
string strEKG = String.Empty;
strEKG = strEKG + "^" + string.Join("^", waveformData[j].EKGWaveform.ToString());
strEKG = strEKG.Remove(0, 1); //remove leading ^
string[] count = strEKG.Split('^');
foreach (string point in count) {
try {
time = time.AddMilliseconds(2);
//await System.Threading.Tasks.Task.Run(() => {
chartEKG.Invoke(new Action(() => series1.Points.AddXY(time, Convert.ToDouble(point) * 0.61)));
//});
}
catch (ArgumentException) { }
loopCount = loopCount + 1;
string timeFormat = "yyyyMMddHHmmssfff";
string timeNow = DateTime.Now.ToString(timeFormat);
if (time == DateTime.ParseExact(DateTime.Now.ToString(timeNow), timeFormat, CultureInfo.InvariantCulture)) {
loopToStopAt = loopCount;
}
}
chartEKG.Invoke(new Action(() => chartEKG.ChartAreas[0].AxisX.Maximum = counter * 500));
}
//});
chartEKG.Invoke(new Action(() => chartEKG.ChartAreas[0].AxisX.ScaleView.Scroll(chartEKG.ChartAreas[0].AxisX.Maximum - Convert.ToDouble(loopToStopAt))));
}
The problem is the chart draws reaalllly slowly. If I remove the async from the method it draws really rapidly (what I want) but freezes the GUI while the drawing is completing. I've tried adjusting the Thread.Sleep in the _DoWork eventhandler but doesn't make an appreciable difference in speed. Any suggestions are appreciated.
Here is a YouTube video that shows the output:
https://youtu.be/CmlIScjowFc
Thanks,
-Will

C# winforms GUI will not accept data from other threads

Below is a function I have running in a while(true) loop in a thread running a Winforms GUI.
I have a button set to put text data into the inBuffer object. this always works, however when I place into the buffer object from a different thread, the data is detected, pulled, and printed out in the Console.out.WriteLine statement, however it never shows up in the Display (textBox) object
public void put()
{
string strDisplayMe = ModemKind.MainClass.inBuffer.MkRequest();
if (strDisplayMe != "")
{
Console.Out.WriteLine("FOUND SOMETHING IN BUFFER: " + strDisplayMe);
char[] DisplayMeArr = strDisplayMe.ToCharArray ();
for (int i = 0; i <= DisplayMeArr.Length -1; ++i)
{
this.display.Text += DisplayMeArr [i];
Thread.Sleep (100);
}
this.display.Text += '\n';
}
}
EDIT: this is a separate class from what is feeding it data through the static buffer objects

Only the main window thread can access/change controls... if you want update the UI from the thread that runs the loop, you need to sync the call with the main thread using the Control.Invoke method.
For instance...
public void put()
{
string strDisplayMe = ModemKind.MainClass.inBuffer.MkRequest();
if (strDisplayMe != string.Empty)
{
char[] DisplayMeArr = strDisplayMe.ToCharArray();
for (int i = 0; i <= DisplayMeArr.Length -1; ++i)
{
this.UpdateUI(() => { this.display.Text += DisplayMeArr[i]; });
Thread.Sleep(100);
}
this.UpdateUI(() => { this.display.Text += '\n'; });
}
}
private void UpdateUI(Action handler)
{
this.Invoke(handler);
}

You can use MethodInvoker to access TextBox from other thread then GUI thread. Make a method to access the TextBox using MethodInvoker. you are assigning text multiple times consider assigning it once for performance, and use StringBuilder for string concatenation.
public void put()
{
string strDisplayMe = ModemKind.MainClass.inBuffer.MkRequest();
if (strDisplayMe != "")
{
Console.Out.WriteLine("FOUND SOMETHING IN BUFFER: " + strDisplayMe);
char[] DisplayMeArr = strDisplayMe.ToCharArray ();
for (int i = 0; i <= DisplayMeArr.Length -1; ++i)
{
AssignToTextBox(this.display, this.display.Text + DisplayMeArr [i]);
Thread.Sleep (100);
}
AssignToTextBox(this.display, this.display.Text + '\n');
}
}
void AssignToTextBox(TextBox txtBox, string value)
{
if(txtBox.InvokeRequired)
{
txtBox.Invoke(new MethodInvoker(delegate { txtBox.text = value; }));
}
}
Edit You can use BeginInvoke instead of Invoke to call it asynchronously. Read more about the Invoke and BeginInvoke in this question.
void AssignToTextBox(TextBox txtBox, string value)
{
txtBox.BeginInvoke(new Action(()=>txtBox.Text = value ));
}

ThreadPool and displaying info without form freezing

I have one problem. In my project i need for more then 100 threads, that's why i prefer to use ThreadPool. here is a part of code, but in this case i have got a lot of memory usage and my form is very laggy, cuz of A lot of BeginInvoke calls(i suppose).
Is there any solutions for this problem?
public void launch()
{
while (data.Count > 0)
{
string[] part;
if (data.Count> 1000)
{
part = data.Take(1000).ToArray();
data = data.Skip(1000).ToList();
}
else
{
part = data.Take(data.Count).ToArray(); data = data.Skip(1000).ToList();
}
foreach (var input in part)
{
try
{
char splitter = ':';
if (input.Contains(';')) splitter = ';';
string login = input.Split(splitter)[0];
string pass = input.Split(splitter)[1];
EncryptCore ec = new EncryptCore(new byte[15]);
PacketSend ps = new PacketSend(ec, "");
ps._login = login;
ps._password = pass;
ps.Brutted+=ps_Parsed;
ps.Failed+=ps_Failed;
ThreadPool.QueueUserWorkItem(ps.Parse);
}
catch { Interlocked.Increment(ref curr); }
}
Thread.Sleep(1000);
}
data.Clear();
}
private void ps_Brutted(User Account)
{
toGet.Add(Account);
Interlocked.Increment(ref good);
goodLabl.BeginInvoke(new Action(delegate()
{
goodLabl.Text = "Good: " + good;
}));
Update();
}
private void Update()
{
try
{
Interlocked.Increment(ref curr);
progLabel.BeginInvoke(new Action(delegate()
{
progLabel.Text = (double.Parse(curr.ToString()) / double.Parse(max.ToString())).ToString("#%");
}));
progressBar.BeginInvoke(new Action(delegate()
{
progressBar.Text = (double.Parse(curr.ToString()) / double.Parse(max.ToString()) * 100).ToString("#");
}));
checkedLabl.BeginInvoke(new Action(delegate()
{
checkedLabl.Text = "Checked: " + curr + " / " + max;
}));
}
catch { }
}

So you have thousands of tasks, and each time one of them completes you update the UI by scheduling 4 updates on the UI thread. What you might consider doing is having the UI update on a timer-based schedule (try 100ms or 200ms) based on the integers that are updating.
Aside from that, you've got some strange numeric operations going on. You can just cast an int to a double, you don't have to round-trip through a String.

Display a string character by character on textbox

Is there any way i can display a String character by character? like in old RPGs
I've tried this:
string text1 ="this is a text";
for (int i = 0; i < text1.Length; i++)
{
textBox1.Text = "" + text1[i];
}
but it only replaces the last character on the text box.

Try This:
public partial class Form1 : Form
{
int count = 0;
string text1 = "this is a scrolling text";
System.Windows.Forms.Timer timer1 = new System.Windows.Forms.Timer();
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
button1.Enabled = false;
textBox1.ReadOnly = true;
SetTimer(500);
}
private void SetTimer(int milliseconds)
{
timer1.Tick+=new EventHandler(timer1_Tick);
timer1.Interval = milliseconds;
timer1.Start();
}
private void timer1_Tick(Object o, EventArgs e)
{
if (count < text1.Length)
{
textBox1.Text += text1[count];
count++;
}
else
{
timer1.Stop();
button1.Enabled = true;
textBox1.ReadOnly = false;
}
}
}
Output:

The following code should do it:
public Form1()
{
InitializeComponent();
TypeText("this is a text");
}
private void TypeText(string text)
{
textBox1.Clear(); // Make sure the textbox is empty
Thread thread = new Thread(delegate() // Create a new thread which fills the textbox periodically
{
button1.BeginInvoke((MethodInvoker)delegate { button1.Enabled = false; }); // Disables the button
for (int i = 0; i < text.Length; i++)
{
int temp = i; // Cache variable because without this, an 'ArgumentOutOfRange' Exception will be thrown
textBox1.BeginInvoke((MethodInvoker)delegate // Invoke to main thread
{
textBox1.Text += text[temp]; // Fill with next char
});
if (text[temp] != ' ') // This makes sure the user doesn't have to wait the double of the time when there is an empty space for the new character
Thread.Sleep(500); // This will stop the seperate thread for 500ms. Won't block the main thread
}
button1.BeginInvoke((MethodInvoker)delegate { button1.Enabled = true; }); // Reenables the button
});
thread.Start(); // Start the new thread and continue the main thread
}

I'm not sure exactly how that helps you. You might want to add why you are doing this. The issue you are having with your code is that your are not appending to the string. Try this line instead:
textBox1.Text += text1[i];
You need to clear textBox1.Text before you start (set it to "").
A better approach might be to print out the hex values so that non printing characters are easily seen. You can do something like this:
string text1 ="this is a text";
var sb = new StringBuilder();
for (int i = 0; i < text1.Length; i++) {
sb.AppendFormat("{0:X} ", text1[i]);
}
textBox1.Text = sb.ToString();
Reading Jeroen Vannevel makes me thing that you are trying to create a "typewriter" affect. In that case try something like:
string text1 ="this is a text";
textBox1.Text = "";
for (int i = 0; i < text1.Length; i++) {
textBox1.Text += text1[i];
Thread.Sleep(250); // 1/4 sec delay
}
This code was written modeled on the code given. There is an implied expectation that this is run from the main UI thread. This means that when you are sitting in a loop with a Sleep delay your UI will be unresponsive (since you are tying up the main thread). You can overcome this by using the Invoke method on the Dispatcher object (of your App) and running the code on a different thread. You should only Invoke the parts that are owned by the main UI (textBox1) in this case.

textBox1.Text = textBox1.Text + text1[i]

To me it seems that you want to break a string into its characters, there are several ways to do that:
1 - String.GetChar() Method:
http://msdn.microsoft.com/en-us/library/microsoft.visualbasic.strings.getchar%28v=vs.110%29.aspx
2 - String.Chars property:
http://msdn.microsoft.com/en-us/library/system.string.chars%28v=vs.110%29.aspx
TextBox1.Text += MyString.Chars[i];
Then if you want to show them one by one with a delay or something like that, you can use timers as others have suggested.

How to update button text after event

I'm trying to let a program post a bunch of text. The user enters text, the amount of messages and how fast these must be delivered. While the program is busy, the button text needs to be "Stop" instead of "Start". When you press the button to force it to stop after you've initially launched it, the text changes back to "Start", but this doesn't happen when the program stops after the given amount of messages are delivered, even though the code is in place and doesn't generate an error.
I have a feeling that this is because of the text not updating for some reason. I've tried to flush it with Invalidate() and Update(), but this isn't working. How to fix this?
Here is the code:
private void button1_Click(object sender, EventArgs e)
{
if (button1.Text == "Start")
{
isEvil = true;
button1.Text = "Stop";
Thread t = new Thread(StartTyping);
t.Start(textBox1.Text);
}
else
{
isEvil = false;
button1.Text = "Start";
}
}
private void StartTyping(object obj)
{
string message = obj.ToString();
int amount = (int)numericUpDown2.Value;
Thread.Sleep(3000);
for (int i = 0; i < amount; i++)
{
if (isEvil == false)
{
//////This does NOT work
//button1.Text = "Start";
//button1.Invalidate();
//button1.Update();
//button1.Refresh();
//Application.DoEvents();
break;
}
SendKeys.SendWait(message + "{ENTER}");
int j = (int)numericUpDown1.Value * 10;
Thread.Sleep(j);
}
}

You have four answers telling you to update UI stuff from the UI thread, but none of them address the logic flow problem with your code.
The reason why it doesn't happen is because it only happens in the for-loop when isEvil is false. When does isEvil get set to false? Only when you click "Stop", and nowhere else.
If you want the button to go back to "Start" after the thread finishes, without clicking "Stop", then you need to add code after the loop to do that, independent of the value of isEvil: (piggybacking off of VoidMain's answer)
private void StartTyping(object obj)
{
string message = obj.ToString();
int amount = (int)numericUpDown2.Value;
Thread.Sleep(3000);
for (int i = 0; i < amount; i++)
{
if (isEvil == false)
{
if (button1.InvokeRequired)
{
button1.BeginInvoke( new Action(() => { button1.Text = "Start"; }) );
}
else
{
button1.Text = "Start";
}
break;
}
SendKeys.SendWait(message + "{ENTER}");
int j = (int)numericUpDown1.Value * 10;
Thread.Sleep(j);
}
if (button1.InvokeRequired)
{
button1.BeginInvoke( new Action(() => { button1.Text = "Start"; }) );
}
else
{
button1.Text = "Start";
}
}
Now you have duplicated code, so you might want to split it off into a separate method.

You need to be on the UI thread to update the UI.
Try something called the SynchronizationContext. There are plenty of examples when you google it.
If you're in WPF or Silverlight, you could use the Dispatcher. Again, lots of examples if you search those keywords in google or StackOverflow.

You must update your controls from the UI thread. This is how you would do it for winforms.
for (int i = 0; i < amount; i++)
{
if (isEvil == false)
{
button1.Invoke(new Action(() => button1.Text = "Start"));
break;
}
SendKeys.SendWait(message + "{ENTER}");
int j = (int)numericUpDown1.Value * 10;
Thread.Sleep(j);
}
This will block till button1 get's its text updated. If you don't want it to block, replace Invoke with BeginInvoke

Your best bet is to use a BackgroundWorker. It's a bit too wieldy to add a concise example here but there's a decent tutorial from O'Reilly

Something like this (not tested) should work:
private void StartTyping(object obj)
{
string message = obj.ToString();
int amount = (int)numericUpDown2.Value;
Thread.Sleep(3000);
for (int i = 0; i < amount; i++)
{
if (isEvil == false)
{
if(button1.InvokeRequired)
{
button1.BeginInvoke( new Action(() => { button1.Text = "Start"; }) );
}
else
{
button1.Text = "Start";
}
break;
}
SendKeys.SendWait(message + "{ENTER}");
int j = (int)numericUpDown1.Value * 10;
Thread.Sleep(j);
}
}