We Keep Coding

Not Responding - C# application crashes without any error message

I made a C# application which iterates through an image folder in order to classify the images, The problem is that during the execution. After it classified some images, the program crashes without any error, it just freezes with no error message.
private void ImageProcessing(string filename)
{
panel1.Controls.Clear();
pictureBox1.Image = new Bitmap(filename);
var predictions = _logic.Classify(filename);
foreach (var item in predictions)
{
if (this.InvokeRequired)
{
this.BeginInvoke((MethodInvoker)delegate ()
{
new Label() { Text = $"{item.Label} : {item.Confidence}", Parent = panel1, Dock = DockStyle.Top };
});
}
else
{
new Label() { Text = $"{item.Label} : {item.Confidence}", Parent = panel1, Dock = DockStyle.Top };
}
}
this.CompareScores(predictions);
var biggestCompare = this.CompareScores(predictions);
switch (biggestCompare.Label)
{
case "Has no Lighter":
TurnON_NOK_Lamp();
break;
case "Has Lighter":
TurnOn_OK_Lamp();
break;
}
}
private void Start()
{
Thread.Sleep(1000);
if (filenames.Length == 0)
{
NoFileLabel.Visible = false;
this.TurnOFF_LightTower();
}
else
{
foreach (string filename in filenames)
{
ImageProcessing(filename);
Thread.Sleep(1000);
this.TurnOFF_LightTower();
pictureBox1.Image = null;
pictureBox1.Invalidate();
}
foreach (string filename in filenames)
{
File.Delete(filename);
}
}
}

Apparently you are calling Start() and hence ImageProcessing() methods from UI thread. If there are any long-running calculations (and I believe there are some) then UI will become unresponsive, because you are blocking message processing loop for a long time and all UI is based on this message processing.
I recommend using switching to async methods for any long-running calculations.
Check https://learn.microsoft.com/en-us/dotnet/standard/parallel-programming/task-based-asynchronous-programming for detailed information.
In your case the ImageProcessing() and Classify() methods could look like:
private async Task ImageProcessingAsync(string filename)
{
pictureBox1.Image = new Bitmap(filename);
var predictions = await _logic.ClassifyAsync(filename);
foreach (var item in predictions)
{
label1.Text = $"{item.Label} : {item.Confidence}";
}
//await CompareScoresAsync(predictions);
var biggestCompare = this.CompareScoresAsync(predictions);
switch (biggestCompare.Label)
{
case "Has no Lighter":
TurnON_NOK_Lamp();
break;
case "Has Lighter":
TurnOn_OK_Lamp();
break;
}
}
public Task<List<Prediction>> ClassifyAsync(string filename)
{
return Task.Run(() =>
{
// TODO: prepare the result
return result;
});
}
Also you don't need to create a new label every time, so you could put a label once in the designer and then only change its Text.
Thread.Sleep() also is not desirable since it's blocking the executing thread and UI again becomes unresponsive. You could use await Task.Delay() instead.

C# Manually stopping an asynchronous for-statement (typewriter effect)

I'm making a retro-style game with C# .NET-Framework, and for dialogue I'm using a for-statement, that prints my text letter by letter (like a typewriter-effect):
I'm working with different scenes, and I have a skip button (bottom right) that skips the current dialogue and passes to the next scene. My typewriter-effect automatically stops when all the text is displayed, but when I click on the skip button, it automatically skips to the next scene.
I would like it, when the typewriter is still active, and if I click on the skip button, that it first shows all the text, instead of skipping to the next scene.
So that it only skips to the next scene when all the text is displayed (automatically or manually).
This is the (working code) that I'm using for my typewriter method (+ variables):
public string FullTextBottom;
public string CurrentTextBottom = "";
public bool IsActive;
public async void TypeWriterEffectBottom()
{
if(this.BackgroundImage != null) // only runs on backgrounds that arent black
{
for(i=0; i < FullTextBottom.Length + 1; i++)
{
CurrentTextBottom = FullTextBottom.Substring(0, i); // updating current string with one extra letter
LblTextBottom.Text = CurrentTextBottom; // "temporarily place string in text box"
await Task.Delay(30); // wait for next update
#region checks for IsActive // for debugging only!
if(i < FullTextBottom.Length + 1)
{
IsActive = true;
Debug1.Text = "IsActive = " + IsActive.ToString();
}
if(CurrentTextBottom.Length == FullTextBottom.Length)
{
IsActive = false;
Debug1.Text = "IsActive = " + IsActive.ToString();
}
#endregion
}
}
}
And this is the code that I want to get for my skip button (named Pb_FastForward):
private void PbFastForward_Click(object sender, EventArgs e)
{
if( //typewriter is active)
{
//print all text into the textbox
}
else if( //all text is printed)
{
// skip to the next scene
}
}
But I don't know how to formulate the 2nd part of code. I've tried many different approaches, like using counters that increase on a buttonclick (and using that to check in an if-statement), and many different types of if-statements to see if the typewriter is still active or not, but I haven't got anything to work yet.
Edit
This is the sequence in which different components need to be loaded (on button click), which is related to the way different variables are updated:
Gamestate_Cycle() --> called for loading new scene.
FullTextBottom = LblTextBottom.Text --> called to refresh variables for typewriter.
TypeWriterEffectBottom() --> called to perform typewriter effect.

Avoid async void. Otherwise you can get an Exception that will break your game and you will not able to catch it.
Then use as less global variables in async methods as possible.
I suggest CancellationTokenSource as thread-safe way to stop the Type Writer.
public async Task TypeWriterEffectBottom(string text, CancellationToken token)
{
if (this.BackgroundImage != null)
{
Debug1.Text = "TypeWriter is active";
StringBuilder sb = new StringBuilder(text.Length);
try
{
foreach (char c in text)
{
LblTextBottom.Text = sb.Append(c).ToString();
await Task.Delay(30, token);
}
}
catch (OperationCanceledException)
{
LblTextBottom.Text = text;
}
Debug1.Text = "TypeWriter is finished";
}
}
Define CTS. It's thread-safe, so it's ok to have it in global scope.
private CancellationTokenSource cts = null;
Call TypeWriter from async method to be able to await it.
// set button layout as "Skip text" here
using (cts = new CancellationTokenSource())
{
await TypeWriterEffectBottom(yourString, cts.Token);
}
cts = null;
// set button layout as "Go to the next scene" here
And finally
private void PbFastForward_Click(object sender, EventArgs e)
{
if (cts != null)
{
cts?.Cancel();
}
else
{
// go to the next scene
}
}

I pondered on your task a bit more and it occurred to me that it is a good job for the Rx.Net library.
An advantage of this approach is that you have less mutable state to care about and you almost don't need to think about threads, synchronization, etc.; you manipulate higher-level building blocks instead: observables, subscriptions.
I extended the task a bit to better illustrate Rx capabilities:
there are two pieces of animated text, each one can be fast-forwarded separately;
the user can fast-forward to the final state;
the user can reset the animation state.
Here is the form code (C# 8, System.Reactive.Linq v4.4.1):
private enum DialogState
{
NpcSpeaking,
PlayerSpeaking,
EverythingShown
}
private enum EventKind
{
AnimationFinished,
Skip,
SkipToEnd
}
DialogState _state;
private readonly Subject<DialogState> _stateChanges = new Subject<DialogState>();
Dictionary<DialogState, (string, Label)> _lines;
IDisposable _eventsSubscription;
IDisposable _animationSubscription;
public Form1()
{
InitializeComponent();
_lines = new Dictionary<DialogState, (string, Label)>
{
{ DialogState.NpcSpeaking, ("NPC speaking...", lblNpc) },
{ DialogState.PlayerSpeaking, ("Player speaking...", lblCharacter) },
};
// tick = 1,2...
IObservable<long> tick = Observable
.Interval(TimeSpan.FromSeconds(0.15))
.ObserveOn(this)
.StartWith(-1)
.Select(x => x + 2);
IObservable<EventPattern<object>> fastForwardClicks = Observable.FromEventPattern(
h => btnFastForward.Click += h,
h => btnFastForward.Click -= h);
IObservable<EventPattern<object>> skipToEndClicks = Observable.FromEventPattern(
h => btnSkipToEnd.Click += h,
h => btnSkipToEnd.Click -= h);
// On each state change animationFarames starts from scratch: 1,2...
IObservable<long> animationFarames = _stateChanges
.Select(
s => Observable.If(() => _lines.ContainsKey(s), tick.TakeUntil(_stateChanges)))
.Switch();
var animationFinished = new Subject<int>();
_animationSubscription = animationFarames.Subscribe(frame =>
{
(string line, Label lbl) = _lines[_state];
if (frame > line.Length)
{
animationFinished.OnNext(default);
return;
}
lbl.Text = line.Substring(0, (int)frame);
});
IObservable<EventKind> events = Observable.Merge(
skipToEndClicks.Select(_ => EventKind.SkipToEnd),
fastForwardClicks.Select(_ => EventKind.Skip),
animationFinished.Select(_ => EventKind.AnimationFinished));
_eventsSubscription = events.Subscribe(e =>
{
DialogState prev = _state;
_state = prev switch
{
DialogState.NpcSpeaking => WhenSpeaking(e, DialogState.PlayerSpeaking),
DialogState.PlayerSpeaking => WhenSpeaking(e, DialogState.EverythingShown),
DialogState.EverythingShown => WhenEverythingShown(e)
};
_stateChanges.OnNext(_state);
});
Reset();
}
private DialogState WhenEverythingShown(EventKind _)
{
Close();
return _state;
}
private DialogState WhenSpeaking(EventKind e, DialogState next)
{
switch (e)
{
case EventKind.AnimationFinished:
case EventKind.Skip:
{
(string l, Label lbl) = _lines[_state];
lbl.Text = l;
return next;
}
case EventKind.SkipToEnd:
{
ShowFinalState();
return DialogState.EverythingShown;
}
default:
throw new NotSupportedException($"Unknown event '{e}'.");
}
}
private void ShowFinalState()
{
foreach ((string l, Label lbl) in _lines.Values)
{
lbl.Text = l;
}
}
private void Reset()
{
foreach ((_, Label lbl) in _lines.Values)
{
lbl.Text = "";
}
_state = DialogState.NpcSpeaking;
_stateChanges.OnNext(_state);
}
protected override void OnClosed(EventArgs e)
{
_eventsSubscription?.Dispose();
_animationSubscription?.Dispose();
base.OnClosed(e);
}
private void btnReset_Click(object sender, EventArgs e)
{
Reset();
}

I adjusted your code a little bit to achieve your goal. I'm not sure it's the best way to do it, but it should work.
public async void TypeWriterEffectBottom()
{
if(this.BackgroundImage == null)
{
return;
}
IsActive = true;
for(i=0; i < FullTextBottom.Length && IsActive; i++)
{
CurrentTextBottom = FullTextBottom.Substring(0, i+1);
LblTextBottom.Text = CurrentTextBottom;
await Task.Delay(30);
Debug1.Text = "IsActive = " + IsActive.ToString();
}
IsActive = false;
}
private void PbFastForward_Click(object sender, EventArgs e)
{
if(IsActive)
{
LblTextBottom.Text = FullTextBottom;
IsActive = false;
return;
}
// IsActive == false means all text is printed
// skip to the next scene
}
UPD: Just noticed that Hans Kesting has suggested pretty much exactly this in his comment.

You write what skip / forward button does, so you control it. Just have a check if the length of written text is equal to text that supposed to be written and if yes move as usual if not just display the text in full have delay to be read and move on

Render to winforms picturebox over and over again

I have some bugs that need fixing, one of them involves an out of memory error.
Does anyone know how to do this properly? Thanks, I don't want it to be too messy, or too complicated. I just want to treat a new image as a buffer to render another image to (because of positional changes), and do it via a background thread. Not the UI thread (Too slow likely).
I get out of memory errors, and such. Also not able to access members of Form1 from within the thread function (images and the like throw access errors such as "Object already in use")
Here is my code:
System.Threading.Thread t;
public Image b;
public Bitmap c;
public Bitmap d;
public Bitmap e;
public Bitmap bg;
public Bitmap spr;
int spritex = 0;
int spritey = 0;
int spritedir = 1;
public Form1()
{
InitializeComponent();
Text = "Escape The Hypno Mansion!!".ToString();
t = new System.Threading.Thread(DoThisAllTheTime);
t.Start();
textBox1.Text = "Press Begin button to start!";
pictureBox1.Image = Image.FromFile(#"Images\introgirl.jpg");
b = new Bitmap(#"Images\introgirl.jpg");
c = new Bitmap(#"Images\sprite.png");
var graphics = Graphics.FromImage(b);
Pen blackpen = new Pen(Color.Black, 3);
graphics.DrawLine(blackpen, 0, 0, 100, 100);
graphics.DrawImage(c, new Point(500, 500));
pictureBox1.Image = b;
//pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
}
public void DoThisAllTheTime()
{
while (true)
{
Point p = new Point(spritex, spritey);
bg = new Bitmap(#"Images\test.bmp");
spr = new Bitmap(#"Images\sprite.png");
using (var graphics = Graphics.FromImage(bg))
{
graphics.DrawImage(spr, p);
}
if (pictureBox1.Image != null)
{
pictureBox1.Image.Dispose();
}
pictureBox1.Image = bg;
pictureBox1.Invalidate();
if (spritedir == 1) { spritex += 5; }
if (spritedir == 2) { spritex -= 5; }
if (spritex < 0) { spritex = 0; spritedir = 1; }
if (spritex > 700) { spritex = 700; spritedir = 2; }
}
}

The reason you can't change the image in your picturebox is because the thread that created the image is not the thread that created the picturebox.
In a debugger you can check this by asking the picturebox for InvokeRequired (function Control.IsInvokeRequired) just before changing the function.
So let's rewrite your function and show that modern classes Like Task are much easier to use the your thread.
I'll start your task when the form is loading, and try to stop it when the form is closing.
private Task myTask = null;
private CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
private void OnFormLoading(object sender, EventArgs e)
{
// Start the task
this.myTask = Task.Run( () => DoMyWork(this.cancellationTokenSource.Token));
}
private void OnFormClosing(object sender, FormClosingEventArgs e)
{
// if the Task is still running, ask it to stop itself:
if (myTask != null && !myTask.IsCompleted)
{ // ask the task to stop and wait until it is completed:
this.cancellationTokenSource.Cancel();
// all Tokens extractes from this source will get state CancellationRequested
// wait maximum 5 seconds until the task is completed:
this.UseWaitCursor = true;
this.myTask.Wait(TimeSpan.FromSeconds(5));
this.UseWaitCursor = false;
// cancel closing if the task is still not completed
e.Cancel = !this.myTask.Completed;
}
}
Now the function DoMyWork:
private void DoMyWork(CancellationToken cancellationToken)
{
// Do the same as in your DoThisAllTheTime
// except that you regularly check cancellationToken.IsCancelRequested:
while(!cancellationToken.IsCancelRequested)
{
// calculate the image to display
var imageToDisplay = ...
this.DisplayImage(imageToDisplay);
}
}
void DisplayImage(Image imageToDisplay)
{
if (this.pictureBox1.InvokeRequired)
{
this.Invoke(new MethodInvoker( () => this.DisplayImage(imageToDisplay)));
}
else
{
this.PictureBox1.Image = imageToDisplay;
}
}
See:
How to cancel a Task and its children
Use InvokeRequired with lambda expression

Dispose every disposable instances before the loop ends. Your memory leak is related with disposable items not being cleaned from memory, so you'll eventually run out of memory in your infinite loop.
At the very least, you'll want to dispose both bitmaps at the end of the loop:
bg = new Bitmap(#"Images\test.bmp");
spr = new Bitmap(#"Images\sprite.png");

Thread inside thread trying to invoke and update ui

I have on winform with a textbox and on textchanged executes a background thread:
private void txtFathersLast_TextChanged(object sender, EventArgs e)
{
ThreadPool.QueueUserWorkItem(_ => WaitWhileUserTyping());
}
private void WaitWhileUserTyping()
{
var keepWaiting = true;
while (keepWaiting)
{
_keyPressed = false;
Thread.Sleep(TypingDelay);
keepWaiting = _keyPressed;
}
Invoke((MethodInvoker)(ExecuteSearch));
_waiting = false;
}
private void ExecuteSearch()
{
Thread.Sleep(200);
Task.Factory.StartNew(() =>
{
using (DataReference.SearchWCF search = new DataReference.SearchWCF())
{
_similaritySearchResults = search.SearchPersonBySimilarity(txtFathersLast.Text, txtMothersLast.Text, txtName.Text, DateTime.Now, 10);
}
}).ContinueWith(t=>{
if (this.InvokeRequired)
{
this.BeginInvoke(new Action(() =>
{
if (_similaritySearchResults != null && _similaritySearchResults.Tables["data"].Rows.Count > 0)
{
DataTable dt = _similaritySearchResults.Tables["data"];
Infragistics.Win.Misc.UltraTile newTile = null;
for (int index = 0; index < dt.Rows.Count; index++)
{
newTile = new Infragistics.Win.Misc.UltraTile("Person X");
newTile.Control = new CustomControls.Controls.PersonResult("123", "123", index + 150);
newTile.Tag = new Guid("90D27721-7315-4B86-9CFD-4F7D02921E9A");
newTile.DoubleClick += TileDoubleClick;
tilePanel.Tiles.Add(newTile);
}
}
}));
}
else
{
if (_similaritySearchResults != null && _similaritySearchResults.Tables["data"].Rows.Count > 0)
{
DataTable dt = _similaritySearchResults.Tables["data"];
Infragistics.Win.Misc.UltraTile newTile = null;
for (int index = 0; index < dt.Rows.Count; index++)
{
newTile = new Infragistics.Win.Misc.UltraTile("Person X");
newTile.Control = new CustomControls.Controls.PersonResult("123", "123", index + 150);
newTile.Tag = new Guid("90D27721-7315-4B86-9CFD-4F7D02921E9A");
newTile.DoubleClick += TileDoubleClick;
tilePanel.Tiles.Add(newTile);
}
}
}
}, TaskScheduler.FromCurrentSynchronizationContext());
}
This is working fine, the application goes to a database then get results and update the UI, adding tiles to a control depending of the number of records returned by database.
Now, the problem comes when I try to add another background thread into my custom control:
new CustomControls.Controls.PersonResult("123", "123", index + 150);
The code for the control is:
protected override void InitLayout()
{
// if I comment this then everything works fine
// but if I leave this, then the UI freezes!!
GetPictureAsync();
base.InitLayout();
}
/// <summary>
///
/// </summary>
private void GetPictureAsync()
{
// This line needs to happen on the UI thread...
TaskScheduler uiScheduler = TaskScheduler.FromCurrentSynchronizationContext();
Task.Factory.StartNew(() =>
{
Random sleep = new Random();
System.Threading.Thread.Sleep(sleep.Next(1000,3000));
if (this.pbPhoto.InvokeRequired)
{
this.pbPhoto.Invoke(new Action(() =>
{
this.Load(#"E:\Photos\" + PhotoId.ToString() + ".jpg");
//this.pbPhoto.Image = Utility.Common.GetResourceImage("woman_sample.jpg");
}));
}
else
{
this.Load(#"E:\Photos\" + PhotoId.ToString() + ".jpg");
//this.pbPhoto.Image = Utility.Common.GetResourceImage("woman_sample.jpg");
}
}, CancellationToken.None, TaskCreationOptions.None, uiScheduler);
}
So the problem seems to be that I first execute a thread for looking when to start search, then inside that thread I run another thread in order to get data from database, and then each control updated in the UI will run another thread to get a picture and update a picturebox.
Anyone knows how to solve this? or a way to work around this?

When you call
new CustomControls.Controls.PersonResult("123", "123", index + 150)
Is "123" a literal string, or are they being read from UI controls. For example,
new CustomControls.Controls.PersonResult(txtFathersName.Text", txtMothersName.Text, index + 150)
i cant test it right now, but isnt accessing the Text property not allowed from a thread other than the one that created the control?

I think the problem lies in you forcing the Task in GetPictureAsync to execute on UI thread and then you are calling Thread.Sleep(). This update UI in Task using TaskScheduler.FromCurrentSynchronizationContext question tackles the same problem as you are having. I would rewrite your code as:
private void async GetPictureAsync()
{
Random sleep = new Random();
await TaskEx.Delay(sleep.Next(1000,3000));
this.Load(#"E:\Photos\" + PhotoId.ToString() + ".jpg");
}

How can I create a lock with Mutex?

I have defined a Mutex in my class (global):
static Mutex fooMutex;
And I want to lock something so that the user is not allowed to see the effect of tapping the image more then once per 3 seconds:
private void Image_Tap_1(...)
{
bool isRunnng = true;
try
{
Mutex.OpenExisting("foo");
}
catch
{
isRunnng = false;
fooMutex = new Mutex(true, "foo");
}
if (!isRunnng)
{
fooFadeIn.Begin();
fooFadeIn.Completed += fooFadeIn_Completed;
}
And dispose on Completed:
private void fooFadeIn_Completed(...)
{
fooMutex.Dispose()
But this does not work, anyone got an idea?

Rather than using a mutex or a timer, you can just store the time at which the image was last tapped:
private DateTime lastTap;
private void Image_Tap_1(...)
{
var now = DateTime.Now;
if ((now - lastTap).TotalSeconds < 3)
{
return;
}
lastTap = now;
// More than 3 seconds since last tap
...
}