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

Question

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

Answer 1

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);
        foreach (char c in text)
        {
            if (token.IsCancellationRequested)
            {
                LblTextBottom.Text = text;
                break;
            }
            sb.Append(c);
            LblTextBottom.Text = sb.ToString();
            await Task.Delay(30);
        }
        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
    }
}