WinForms TextBox Get as Double or Integer

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I always end up returning to Windows Forms when I want to code some tool or prototype an idea. This time I just want to share two extension methods for retrieving the contents of a TextBox as an Integer or a Double.

public static double AsDouble(this TextBox textBox)
{
 var s = textBox.Text.Replace(",", ".").Trim();
 return double.TryParse(s, out var d) ? d : double.NaN;
}
public static int AsInt(this TextBox textBox)
{
 var s = textBox.Text.Trim();
 return int.TryParse(s, out var i) ? i : 0;
}

The colon to period replacement is to ensure that Swedish formatting works with the default parser. No guarantee that it will work with all cultures.


All code provided as-is. This is copied from my own code-base, May need some additional programming to work. Use for whatever you want, how you want! If you find this helpful, please leave a comment, not required but appreciated! :)

Hope this helps someone out there!

Extension PictureBox ResizeImageToFit

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Another useful extension, this time for the standard Windows Forms PictureBox. The issue for me, is that I usually just want to throw a picture at it and it should just show it, not crop it, not kill the aspect ratio etc. So I tend to use this extension method after assigning a new picture to the PictureBox.Image property to correctly show the picture in center mode if it is smaller then the box, or zoom it to fit inside the box if it is larger, still keeping the aspect ratio.

Some source-code (C#)

public static void ResizeImageToFit(this PictureBox pbox)
{
 if (pbox.Size.Height > pbox.Image.Size.Height && pbox.Size.Width > pbox.Image.Size.Width)
  pbox.SizeMode = PictureBoxSizeMode.CenterImage;
 else
  pbox.SizeMode = PictureBoxSizeMode.Zoom;
}

Hope this helps someone out there :)

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WinForms RichTextBox Append Log and UIThread extensions

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Turn any RichTextBox in winforms to a log view. Just call rtxt.AppendLog("someString"); and it will append that to a new line in the richtextbox. And scroll it to view.

public static void AppendLog(this RichTextBox rtxt, string s)
{
 rtxt.UIThread(() =>
 {
  rtxt.AppendText($"{s}{Environment.NewLine}");
  rtxt.SelectionLength = 0;
  if (rtxt.Lines.Length > 10000)
  {
   rtxt.Lines = rtxt.Lines.Skip(5000).ToArray();
  }
  rtxt.SelectionStart = rtxt.TextLength;
  rtxt.ScrollToCaret();
 });
}

The above snippet of code requires the following to function correctly.

static public void UIThread(this Control control, Action code)
{
 if (control.InvokeRequired)
 {
  control.BeginInvoke(code);
  return;
 }
 code.Invoke();
}

I can't take credit, found it years ago on some forum somewhere. But here it is anyway. It makes a call to a winforms control synschronize with the GUI thread so that no cross-threading exceptions is thrown. GUI items can only be modified from the GUI thread and this ensures just that.

The exception thrown if correct thread synchronization is not used is: 

System.InvalidOperationException was unhandled
  HResult=-2146233079
  Message=Cross-thread operation not valid: Control 'rtxtOutput' accessed from a thread other than the thread it was created on.
  Source=System.Windows.Forms
  StackTrace:
       at System.Windows.Forms.Control.get_Handle()
       at System.Windows.Forms.TextBoxBase.GetSelectionStartAndLength(Int32& start, Int32& length)
       at System.Windows.Forms.TextBoxBase.set_SelectionLength(Int32 value)
       at System.Windows.Forms.RichTextBox.set_SelectionLength(Int32 value)
       at ave.dev.winform.Form1.ticker_Tick(Object sender, EventArgs e) in C:\tfs\YYY\Form1.cs:line 54
       at ave.dev.winform.Form1._loggerHook_NewLogLine(String s) in C:\tfs\YYY\Form1.cs:line 38

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