Develop Reference

Balancing calls inside of a EditorWindow OnGUI method causing problems

I'm making a system to balance calls inside of the OnGUI method of a EditorWindow.
I'm doing the following:
public void Update()
{
Repaint();
}
Inside of my OnGUI method I'm calling this Balancer. I have one list with the callbacks (List).
So the idea is simple, some callvaxc
I'm skipping some repaint frames for the callback that has the complete GUI, and calling on each repaint for other callbacks (for example, a marquee label or dispalying gifs).
By some reason, this error happens "Getting control 0's position in a group with only 0 controls when doing repaint"
private int m_repaintCounter;
public void Draw()
{
Event e = Event.current;
try
{
foreach (var action in m_actions)
{
try
{
// Test 1
// MainAction is a class that inherits from Action (class MainAction : Action)
if (action is MainAction)
{
bool isDesignedType = e.rawType == EventType.Repaint || e.rawType == EventType.Layout;
if (isDesignedType)
++m_repaintCounter;
if (!(m_repaintCounter == 20 && isDesignedType))
continue;
else
m_repaintCounter = 0;
}
// Test 2
action.Value();
}
catch (Exception ex)
{
Debug.LogException(ex);
}
}
}
catch
{
// Due to recompile the collection will modified, so we need to avoid the exception
}
}
But if I comment the "Test 1" everythings works fine.
On the ctor of the class we need to specify a callback to a GUI method, for example:
public Balancer(Action drawAction)
{
m_actions = new List<Action>();
m_actions.Add(drawAction);
}
So we could do easily (inside the EditorWindow):
private Balancer m_balancer;
public void OnEnable()
{
m_balancer = new Balancer(Draw);
}
public void Draw()
{
// This block will be called every 20 repaints as specified on the if statment
GUILayout.BeginHorizontal("box");
{
GUILayout.Button("I'm the first button");
GUILayout.Button("I'm to the right");
// This marquee will be called on each repaint
m_balancer.AddAction(() => CustomClass.DisplayMarquee("example"));
}
GUILayout.EndHorizontal();
}
// Inside of the Balancer class we have
// We use System.Linq.Expressions to identify actions that were added already
private HashSet<string> m_alreadyAddedActions = new HashSet<string>();
public void AddAction(Expression<Action> callback)
{
if(!m_alreadyAddedActions.Add(callback.ToString()))
return;
m_actions.Add(callback.Compile());
}
I can't figure this out. I couldn't find any information on the internet. Can anyone help me?

Ok, so, OnGui (IMGui) is awful to work with. If you aren't using it for an editor script, use the new 4.6 UI (UGui) instead.
Now then. The problem.
OnGui is called at least twice every frame. One of those is to calculate layouts and the other is to actually draw stuff ("repaint").
If the number of things, size of things, or anything else changes between these two calls then Unity will error with "Getting control 0's position in a group with only 0 controls when doing repaint."
That is: you cannot change UI state in the IMGui system at any point after Layout and before Repaint.
Only, only, only change state (and thereby which objects are being drawn) during Event.current == EventType.Repaint and only, only, only change state for the next frame (alternatively, do the changes during Event.current == EventType.Layout, provided that this same, new state will result in the same code path during Repaint). Do not, under any circumstances, make changes during Repaint that were not present during the previous Layout.

Find out which winforms controls are accessed from a background thread

We have built a huge winforms project, already in progress for multiple years.
Sometimes, our users get an exception which looks like this one.
The resolution of this problem seems to be:
don't acces UI components from a background thread
.
But since our project is a very big project with a lot of different threads, we don't succeed in finding all these.
Is there a way to check (with some tool or debugging option) which components are called from a background thread?
To clarify:
I created a sample winforms project with a single Form, containing two Button
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
button1.Text = "Clicked!";
}
private void button2_Click(object sender, EventArgs e)
{
Task.Run(() =>
{
button2.BackColor = Color.Red; //this does not throw an exception
//button2.Text = "Clicked"; //this throws an exception when uncommented
});
}
}
The background color of button2 is set to red when the button is clicked. This happens in a background thread (which is considered bad behavior). However, it doesn't (immediately) throw an exception. I would like a way to detect this as 'bad behavior'. Preferably by scanning my code, but if it's only possible by debugging, (so pausing as soon as a UI component is accessed from a background thread) it's also fine.

I've got 2 recommendations to use together, the first is a Visual Studio Plugin called DebugSingleThread.
You can freeze all the threads and work on one at a time (obviously the non-main-UI threads) and see each threads access to controls. Tedious I know but not so bad with the second method.
The second method is to get the steps in order to reproduce the problem. If you know the steps to reproduce it, it will be easier to see whats causing it. To do this I made this User Action Log project on Github.
It will record every action a user makes, you can read about it here on SO: User Activity Logging, Telemetry (and Variables in Global Exception Handlers).
I'd recommend you also log the Thread ID, then when you have been able to reproduce the problem, go to the end of the log and work out the exact steps. Its not as painful as it seems and its great for getting application telemetry.
You might be able to customise this project, eg trap a DataSource_Completed event or add a dummy DataSource property that sets the real Grids DataSource property and raises an INotifyPropertyChanged event - and if its a non-main thread ID then Debugger.Break();.
My gut feeling is you're changing a control's (eg a grid) data source in a background thread (for that non-freeze feel) and thats causing a problem with synchronisation. This is what happened to the other DevExpress customer who experienced this. Its discussed here in a different thread to the one you referenced.

Is your app set to ignore cross threading intentionally?
Cross-thread operations should be blowing up all the time in winforms. It checks for them like crazy in just about every method. for a starting point check out https://referencesource.microsoft.com/#System.Windows.Forms/winforms/Managed/System/WinForms/Control.cs.
Somewhere in your app, somebody might have put this line of code:
Control.CheckForIllegalCrossThreadCalls = False;
Comment that out and run the app, then follow the exceptions.
(Usually you can fix the problem by wrapping the update in an invoke, e.g., in a worker thread if you see textbox1.text=SomeString; change it to `textbox.invoke(()=>{textbox1.text=SomeString;});.
You may also have to add checking for InvokeRequired, use BeginInvoke to avoid deadlocks, and return values from invoke, those are all separate topics.
this is assuming even a moderate refactor is out of the question which for even a medium sized enterprise app is almost always the case.
Note: it's not possible to guarantee successful discovery of this case thru static analysis (that is, without running the app). unless you can solve the halting problem ... https://cs.stackexchange.com/questions/63403/is-the-halting-problem-decidable-for-pure-programs-on-an-ideal-computer etc...

I did this to search for that specific situation but of course, need to adjust it to your needs, but the purpose of this is to give you at least a possibility.
I called this method SearchForThreads but since it's just an example, you can call it whatever you want.
The main idea here is perhaps adding this Method call to a base class and call it on the constructor, makes it somewhat more flexible.
Then use reflection to invoke this method on all classes deriving from this base, and throw an exception or something if it finds this situation in any class.
There's one pre req, that is the usage of Framework 4.5.
This version of the framework added the CompilerServices attribute that gives us details about the Method's caller.
The documentation for this is here
With it we can open up the source file and dig into it.
What i did was just search for the situation you specified in your question, using rudimentary text search.
But it can give you an insight about how to do this on your solution, since i know very little about your solution, i can only work with the code you put on your post.
public static void SearchForThreads(
[System.Runtime.CompilerServices.CallerMemberName] string memberName = "",
[System.Runtime.CompilerServices.CallerFilePath] string sourceFilePath = "",
[System.Runtime.CompilerServices.CallerLineNumber] int sourceLineNumber = 0)
{
var startKey = "this.Controls.Add(";
var endKey = ")";
List<string> components = new List<string>();
var designerPath = sourceFilePath.Replace(".cs", ".Designer.cs");
if (File.Exists(designerPath))
{
var designerText = File.ReadAllText(designerPath);
var initSearchPos = designerText.IndexOf(startKey) + startKey.Length;
do
{
var endSearchPos = designerText.IndexOf(endKey, initSearchPos);
var componentName = designerText.Substring(initSearchPos, (endSearchPos - initSearchPos));
componentName = componentName.Replace("this.", "");
if (!components.Contains(componentName))
components.Add(componentName);
} while ((initSearchPos = designerText.IndexOf(startKey, initSearchPos) + startKey.Length) > startKey.Length);
}
if (components.Any())
{
var classText = File.ReadAllText(sourceFilePath);
var ThreadPos = classText.IndexOf("Task.Run");
if (ThreadPos > -1)
{
do
{
var endThreadPos = classText.IndexOf("}", ThreadPos);
if (endThreadPos > -1)
{
foreach (var component in components)
{
var search = classText.IndexOf(component, ThreadPos);
if (search > -1 && search < endThreadPos)
{
Console.WriteLine($"Found a call to UI thread component at pos: {search}");
}
}
}
}
while ((ThreadPos = classText.IndexOf("Task.Run", ++ThreadPos)) < classText.Length && ThreadPos > 0);
}
}
}
I hope it helps you out.
You can get the Line number if you split the text so you can output it, but i didn't want to go through the trouble, since i don't know what would work for you.
string[] lines = classText.Replace("\r","").Split('\n');

Try that:
public static void Main(string[] args)
{
// Add the event handler for handling UI thread exceptions to the event.
Application.ThreadException += new ThreadExceptionEventHandler(exception handler);
// Set the unhandled exception mode to force all Windows Forms errors to go through the handler.
Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException);
// Add the event handler for handling non-UI thread exceptions to the event.
AppDomain.CurrentDomain.UnhandledException += // add the handler here
// Runs the application.
Application.Run(new ......);
}
Then you can log the message and the call stack and that should give you enough information to fix the issue.

I recommend you update your GUI to handle this situation automatically for your convenience. You instead use a set of inherited controls.
The general principle here is to override the property Set methods in a way to make them Thread Safe. So, in each overridden property, instead of a straight update of the base control, there's a check to see if an invoke is required (meaning we're on a separate thread the the GUI). Then, the Invoke call updates the property on the GUI thread, instead of the secondary thread.
So, if the inherited controls are used, the form code that is trying to update GUI elements from a secondary thread can be left as is.
Here is the textbox and button ones. You would add more of them as needed and add other properties as needed. Rather than putting code on individual forms.
You don't need to go into the designer, you can instead do a find/replace on the designer files only. For example, in ALL designer.cs files, you would replace System.Windows.Forms.TextBox with ThreadSafeControls.TextBoxBackgroundThread and System.Windows.Forms.Button with ThreadSafeControls.ButtonBackgroundThread.
Other controls can be created with the same principle, based on which control types & properties are being updated from the background thread.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace ThreadSafeControls
{
class TextBoxBackgroundThread : System.Windows.Forms.TextBox
{
public override string Text
{
get
{
return base.Text;
}
set
{
if (this.InvokeRequired)
this.Invoke((MethodInvoker)delegate { base.Text = value; });
else
base.Text = value;
}
}
public override System.Drawing.Color ForeColor
{
get
{
return base.ForeColor;
}
set
{
if (this.InvokeRequired)
this.Invoke((MethodInvoker)delegate { base.ForeColor = value; });
else
base.ForeColor = value;
}
}
public override System.Drawing.Color BackColor
{
get
{
return base.BackColor;
}
set
{
if (this.InvokeRequired)
this.Invoke((MethodInvoker)delegate { base.BackColor = value; });
else
base.BackColor = value;
}
}
}
class ButtonBackgroundThread : System.Windows.Forms.Button
{
public override string Text
{
get
{
return base.Text;
}
set
{
if (this.InvokeRequired)
this.Invoke((MethodInvoker)delegate { base.Text = value; });
else
base.Text = value;
}
}
public override System.Drawing.Color ForeColor
{
get
{
return base.ForeColor;
}
set
{
if (this.InvokeRequired)
this.Invoke((MethodInvoker)delegate { base.ForeColor = value; });
else
base.ForeColor = value;
}
}
public override System.Drawing.Color BackColor
{
get
{
return base.BackColor;
}
set
{
if (this.InvokeRequired)
this.Invoke((MethodInvoker)delegate { base.BackColor = value; });
else
base.BackColor = value;
}
}
}
}

Checking for a condition in the calling scope or inside the function

i have the following 3 examples which does the same thing
//case1 do it if the condition is valid
private void SetMultiplePropertyValues()
{
if (Keyboard.GetKeyStates(Key.CapsLock) == KeyStates.Toggled)
{
//do somthing
}
}
//case 2 return if the condition is not valid
private void SetMultiplePropertyValues()
{
if (Keyboard.GetKeyStates(Key.CapsLock) != KeyStates.Toggled) return;
//do somthing
}
//case 3 checking the condition in the calling scope
if (Keyboard.GetKeyStates(Key.CapsLock)== KeyStates.Toggled)
SetMultiplePropertyValues())
private void SetMultiplePropertyValues()
{
//do somthing
}
which one would you go with and why

They do not do the same thing because in the first two cases the name of the method is a lie; the method name should be SetValuesIfTheKeyStateIsToggled or TryToSetValues or some such thing. Don't say you're going to do a thing and then not do it. More generally: separate your concerns. I would choose a fourth option:
public void TryToFrob()
{
if (CanFrob()) DoFrob();
}
private bool CanFrob()
{
return Keyboard.GetKeyStates(Key.CapsLock) == KeyStates.Toggled;
}
private void DoFrob()
{
// frob!
}
Notice what is public and what is private.
This is a silly looking example because each one is so simple, but one can easily imagine a situation in which these methods are complex. Keep your policies and your mechanisms logically separated. The mechanism is "is the keyboard in a particular state?" The policy is "I have some conditions under which I can frob; we must never frob unless those conditions are met".

First of all, as we can see at code comments, they don't do the same thing. So I think that you're talking about code architecture rather than functionality.
Second, here in SO isn't about giving opinions, but I'll try say to you concrete things about these differences.
1- Common if approach
if (true == false)
{
return true;
}
vs.
2 - Single line if approach
if (true == false) return true;
Most of code convetions says to use the option 1, because they're easier to read and understant code, and avoid some mistakes. We need to also understand that convetions are not rules! so they're just convetions, but really try to avoid option 2 in most of the cases.
One more thing, some code convetions also says that's ok using option 2 when you need something very simple, like this given example which is really easy to read and understand. But take this like an exception from the 'rules'.

How do I get these if statements to play nicely in c#

I've modified my code to the point where it will execute, but it's linked to a timer, and will attempt to execute over and over till the timed condition is lost. I tried putting a "lock" on the system with a variable I named "intLimiter", to force the sequence to stop after one execution, but the lock doesn't seem to be working.
if (DateTime.Now.Hour == intAlarmHour && DateTime.Now.Minute == intAlarmMinute)
{
if (intLimiter == 1)
{
intLimiter = 2;
if (radTG.Checked)
{
System.Media.SoundPlayer sound = new System.Media.SoundPlayer(Properties.Resources.Celldweller___Tough_Guy);
sound.Play();
}
...
}
}

As of what I understand from your question, you want to separate the if statements to work all at the same time...
What you can do is create new 'Threads' for each statement which would make you able to run all of then at once...
For thread, make sure you include the namespace System.Threading.
using System.Threading;
Now what you should do with your code:
...
if (DateTime.Now.Hour == intAlarmHour && DateTime.Now.Minute == intAlarmMinute)
{
if (radTG.Checked == true)
{
Thread radTG = new Thread(radTGChecked);
radTG.Start();
}
...
}
...
public void radTGChecked() {
SoundPlayer sound = new SoundPlayer(Properties.Resources.Celldweller);
sound.PlaySync();
}
Do this to all the if statements following, and they will all run together, each on a thread...
Forgive me if that was not the answer of your question, but the title corresponding to the content does seem a little blurry to me...
But if it did, here's an article that will help you understand Multi-Threading.

C# WinForms: Waiting for a button press inside an infinite loop

I'm making a simple Guess-The-Number game with a GUI. I need to wait on a loop waiting for the user to input a number in a text box and press "OK". How do I wait for an event inside a loop?
Note: I don't want message boxes. This is done in the main window, hence the need to wait for input.
EDIT: I should have explained myself better. I know that there's a loop inside the GUI. What I want is another loop inside a method. Maybe there's a better way to do this. I could code stuff inside the button's event handler, now that I think about it. Although I'd need global variables. Whataver, I'll think about it, but I hope my question is clearer now.
EDIT 2: Sorry that my question wasn't clear and the edit didn't do much help. First of all, the code is too big to be posted here. I'd probably have to post a screenshot of the GUI, so it wouldn't be of much use. Basically, I have two fields, "Max number" and "Number of allowed guesses". The user enters these two and clicks "Play". A new panel becomes available, with a text box and a "Guess" button. The user enters a guess, and the program checks to see if it's correct.
The purpose of the second infinite loop is to avoid global variables. See, each time the user clicks "Play", the game has to generate a new random number as the correct guess. If everything is done inside a method, no problem. But if the "Guess" button's event handler is called multiple times, the number has to be stored as an instance variable of the Form. Sure, it's not big deal, but I think the number should be a property of the method directing the current game, not of the Form.
I'd also have to keep track of the remaining number of guesses outside of the method. Again, it's no big deal. I just want to avoid globals if I can.
Again, I'm sorry that my question wasn't too clear. I'm kind of tired, and I didn't feel like writing too much. If this still isn't clear, then don't bother. I'll think of something.

C# automatically loops infinitely waiting for events until your form is closed. You just need to respond to the button click event.

Jason Down's suggestion is wise, create a new GuessingGame class and add it to your project. I know you're worried about "global variables" (which everyone is taught in school never to use unless you absolutely have to), but think about your design specifications for a minute.
But if the "Guess" button's event handler is called multiple times, the number has to be stored as an instance variable of the Form. Sure, it's not big deal, but I think the number should be a property of the method directing the current game, not of the Form.
As an alternative, store an instance of your GuessingGame class in the form. This is not a global variable! You said so yourself, the point of the game is keep track of the guesses and generate new numbers to guess every time "Play" is clicked. If you store an instance of the game in the form then open another form (e.g. a Help or About box), then the game's instance would not be available (thus, not global).
The GuessingGame object is going to look something like:
public class GuessingGame
{
private static Random _RNG = new Random();
private bool _GameRunning;
private bool _GameWon;
private int _Number;
private int _GuessesRemaining;
public int GuessesRemaining
{
get { return _GuessesRemaining; }
}
public bool GameEnded
{
get { return !_GameRunning; }
}
public bool GameWon
{
get { return _GameWon; }
}
public GuessingGame()
{
_GameRunning = false;
_GameWon = false;
}
public void StartNewGame(int numberOfGuesses, int max)
{
if (max <= 0)
throw new ArgumentOutOfRangeException("max", "Must be > 0");
if (max == int.MaxValue)
_Number = _RNG.Next();
else
_Number = _RNG.Next(0, max + 1);
_GuessesRemaining = numberOfGuesses;
_GameRunning = true;
}
public bool MakeGuess(int guess)
{
if (_GameRunning)
{
_GuessesRemaining--;
if (_GuessesRemaining <= 0)
{
_GameRunning = false;
_GameWon = false;
return false;
}
if (guess == _Number)
{
_GameWon = true;
return true;
}
else
{
return false;
}
}
else
{
throw new Exception("The game is not running. Call StartNewGame() before making a guess.");
}
}
}
This way, all the data related to the game is encapsulated within the class. Hooking up the events is easy in the codebehind of the form:
GuessingGame game = new GuessingGame();
private void btnPlay_Click(object sender, EventArgs e)
{
int numberOfGuesses = Convert.ToInt32(txtNumberOfGuesses.Text);
int max = Convert.ToInt32(txtMax.Text);
game.StartNewGame(numberOfGuesses, max);
}
private void btnGuess_Click(object sender, EventArgs e)
{
int guess = Convert.ToInt32(txtGuess.Text);
bool correct = game.MakeGuess(guess);
if (correct)
lblWin.Visible = true;
if (game.GameEnded)
{
// disable guess button, show loss label
}
}

You should probably look for a book to actually learn windows programming.
The very basics:
1) There is already an infinite loop deep down in the windows code somewhere. Any windows program is constantly looping and scanning for input.
2) Once input is found, this loop fires off an Event.
3) Your mission, should you choose to accept it, is to write event handlers to handle those events.

you are most likely doing it wrong as it has already been pointed out, but you can use this
Application.DoEvents();
to process events when you are on an actual loop
to do it the right way
- don't use a loop
- use an edit box for the input, then a button
- implement the button onclick event

Yes, and What if I am waiting for Speech events, it could happen anytime event when a function is running, I need to handle that without recursively call a function