Resolved Error Creating Window Handle

[Anonymous]

I am creating a winform app that accepts a name and position as input and upon clicking the submit button generates a barcode of that name and prints that on the entered position in a pdf file(generates this as well). The app is giving me error on Environment.Exit(1) - Error Creating Window Handle in the code below -

if(string.IsNullOrEmpty(textboxName.Text))
{
    MessageBox.Show("Name cannot be empty");
    Environment.Exit(1);
}

I googled about this error and it showed that this error is related to a memory leak. I checked in the task manager. When I ran this app, the memory usage field show 7.5 kb.
This is what I am doing in my app -

There are only two textbox (name and position) and a submit button.

try{
if(string.IsNullOrEmpty(textboxName.Text))
{
    MessageBox.Show("Name cannot be empty");
    Environment.Exit(1);
}

if(string.IsNullOrEmpty(textboxPosition.Text))
{
    MessageBox.Show("Name cannot be empty");
    Environment.Exit(1);
}
string name = textboxName.Text;
string position = Convert.ToInt32(textboxPosition.Text);

BarcodeWriter writer = new BarcodeWriter()
{
    Format = BarcodeFormat.CODE_128,
    Options = new EncodingOptions
    {
        Height = 100,
        Width = 180,
        PureBarcode = false,
        Margin = 10,
    },
};

string content = @"*" + name + "*";
var bitmap = writer.Write(content);

using (MemoryStream ms = new MemoryStream())
            {
                bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
                GeneratePDF(ms, position);
            }
}
catch
{
}

This is the generate PDF code

PdfDocument document = new PdfDocument();

try{
            // Create an empty page
            PdfPage page = document.AddPage();

            // Get an XGraphics object for drawing
            XGraphics gfx = XGraphics.FromPdfPage(page);

            XImage pic = XImage.FromStream(ms);
             
             string coordinates = GetCoordinates(position);

             string coordinate = coordinates.Split(',');

             int x = Convert.ToInt32(coordinate[0]);
             int y = Convert.ToInt32(coordinate[1]);

            gfx.DrawImage(pic,x , y , 110, 23);

            string filename = "Output.pdf";

            document.Save(@"E:\" + filename);

            MessageBox.Show("PDF saved successfully!");

}
catch
{
}

My PDF has 80 different static locations. These will never change. So, My GetCoordinates function has 80 different switch cases.

GetCoordinates(position)
{
    swtich(position)
    {
        case 1: x = 30;
               y = 40;
        break.
            case 2: x=60;
        y= 80;
        break;
        .
        .
        .
        .till case 80
    }
    return x +"," +y
}

For the time being, I have replaced the exit condition with the return statement and the app works now -

if(string.IsNullOrEmpty(textboxName.Text))

{

    MessageBox.Show("Name cannot be empty");

    return;

}

But I am not able to understand where my app is creating more than 10,000 handlers ( I have read that only 10,000 handlers per app is allowed).

 

[Skydiver]

First of all, Environment.Exit() should only be used as a last resort if you absolutely must abort a program. It terminates the application immediately. Invalid inputs that you can handle IS NOT something that should result in immediately exiting the program.

Furthermore, it looks like you are writing a GUI, you shouldn't be calling Exit() unless there is a fatal error that you must absolutely just stop everything and not clean up properly. In fact, for any C# program, you shouldn't be calling Exit() even if it is a console program. Calling Exit() is equivalent to the old C style of console program which would call exit(). You are writing in C# now, not C.

There also some other caveats about its use that you can read about in the documentation I linked to below. You might be hitting some of those corner cases.

CancellationTokenSource Constructor (System.Threading)

Initializes the CancellationTokenSource.

learn.microsoft.com

 

[Skydiver]

The app is giving me error on Environment.Exit(1) - Error Creating Window Handle in the code below

Where exactly is that code that you have above? If it is near a point where WinForms is handling form creation/initialization, then the exception is not actually about the Exit() call, but rather about the form's window not being created. Basically Windows doesn't like it when someone tries to abort a window creation, and Windows throws an error, but the WinForms framework ends up noticing the error and maps it to a exception.

 

[Skydiver]

Not related to your problem, but I'll comment about it here. You are doing returning multiple values from your GetCoordinates() the wrong way. It looks like you have something like:

string GetCoordinates(int position)
{
    int x, y;
   :
    return x + "," + y;
}

and then on return you are parsing the returned string:

string coordinates = GetCoordinates(position);

string coordinate = coordinates.Split(',');

int x = Convert.ToInt32(coordinate[0]);
int y = Convert.ToInt32(coordinate[1]);

gfx.DrawImage(pic,x , y , 110, 23);

You don't want to be stringly-typed. That's for JavaScript programmers. We are C# programmers and believe in strongly-typed programming.

If you using an old version of C# without support for Tuples, the correct way would be to do something like:

struct Coordinates
{
    public int X;
    public int Y;

    public Coordinates(int x, int y)
    {
        X = x;
        Y = y;
    }
}

:

Coordinates GetCoordinates(int position)
{
    int x, y;
   :
    return new Coordinates(x, y);
}

:

Coordinates coordinates = GetCoordinates(position);
gfx.DrawImage(pic, coordinates.X, coordinates.Y, 110, 23);

If you are using a newer version of C# with Tuple support:

(int x, int y) GetCoordinates(int position)
{
    int x, y;
   :
    return (x, y);
}

:

var (x, y) = GetCoordinates(position);
gfx.DrawImage(pic, x, y, 110, 23);

 

[Skydiver]

My PDF has 80 different static locations. These will never change. So, My GetCoordinates function has 80 different switch cases.

If the positions are well known intervals of position on a diagonal you could simply have:

(int x, int y) GetCoordinates(int position)
{
    return (position * 30, position * 40);
}

If on the other hand your coordinates are more of a grid pattern, something like this would work:

(int x, int y) GetCoordinates(int position)
{
    int column = (position - 1) % NumberOfColumns + 1;
    int row = (position - 1) / NumberOfColumns + 1;
    return (column * 30, row * 40);
}

And if the coordinates can't really be defined by set formula, then you could just use a dictionary of positions and coordinates:

Dictionary<int, (int x, int y)> MapOfCoordinates = new()
{
    [1] = (30, 40),
    [2] = (33, 94),
    [3] = (75, 63),
    :
   [80] = (128, 6332)
}

:

var (x, y) = MapOfCoordinates[position];

 

[Anonymous]

In fact, for any C# program, you shouldn't be calling Exit() even if it is a console program.

So, how should I exit an application with a specific error code?
For example, I have to a console application that I run using task scheduler, and I want the app to return a specific error code to task scheduler, I normally write

 Environment.Exit(1)

or

 If(this condition is true)
Environment.Exit(5); //to handle special case
else
Environment.Exit(0); //exit normally.

What are the alternatives of this?

 

[Anonymous]

Where exactly is that code that you have above?

The validation code is in the button click event. This is the first thing that I am checking.

 public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if(string.IsNullOrEmpty(textBox1.Text))
            {
                MessageBox.Show("Error");
                Environment.Exit(1);
            }
//rest of the code

 

[JohnH]

Set Environment.ExitCode and close the app normally with Close method. If there are multiple forms open they can all be closed normally with Application.Exit method.