C# forms rich text box cannot change selected text color

Question

C# forms rich text box cannot change selected text color

Matthew Jeschke 20

I'm designing a form that populates a rich text box from a text file. Certain lines in the text box have to be of a different style (different color and weight). I looked at numerous examples and think I have coded it correctly but whatever I do the style never updates / changes for the desired lines. It's always the default font from the form designer.

Any ideas why I cannot get the "SelectedText" method for Rich Text Box component to work?

Thanks!

Here's the code I am calling to populate the rich text box component:

        `this.rtbTraysTested.Text = "";`

foreach (string uid in ticket.TraysTested().Keys)

{

// Append Tray UID to the text box and select it

this.rtbTraysTested.SelectionStart = this.rtbTraysTested.Text.Length;

this.rtbTraysTested.Text += uid;

this.rtbTraysTested.SelectionLength = uid.Length;

// Text settings

if (ticket.TraysTested()[uid] > 1) // Highlight entry if tray has been tested more than once

{

this.rtbTraysTested.SelectionColor = Color.OrangeRed;

this.rtbTraysTested.SelectionFont = new Font(this.rtbTraysTested.Font, FontStyle.Regular);

}

else

{

this.rtbTraysTested.SelectionColor = Color.White;

this.rtbTraysTested.SelectionFont = new Font(this.rtbTraysTested.Font, FontStyle.Regular);

}

this.rtbTraysTested.Text += Environment.NewLine; // Add the endline to entry

this.rtbTraysTested.Select(0, 0); // Deselect the text

}

2 answers

Your answer

Answer 1

Viorel 123.6K

Try to use AppendText instead if “+=”:

// this.rtbTraysTested.Text += uid; -- REMOVED
int len = this.rtbTraysTested.Text.Length;
this.rtbTraysTested.AppendText( uid );
this.rtbTraysTested.SelectionStart = len;

In the second case, use this.rtbTraysTested.AppendText( Environment.NewLine ).

Answer 2

Hey thanks you have helped on a couple of my posts. I really appreciate it.

Got it working. I did as you suggested and also specified the length of the text in selection length.

this.rtbTraysTested.Text = "";
foreach (string uid in ticket.TraysTested().Keys)
{
	// Append Tray UID to the text box and select it     
    int len = this.rtbTraysTested.Text.Length;
	this.rtbTraysTested.AppendText(uid);    
	this.rtbTraysTested.SelectionStart = len;

	// ************************************************************************
	//  Adding this line in addition to your suggested usage worked! Thanks!
    this.rtbTraysTested.SelectionLength = uid.Length;
	// *************************************************************************

	// Text settings
	if (ticket.TraysTested()[uid] > 1)  // Highlight entry if tray has been tested more than once
	{
		this.rtbTraysTested.SelectionColor = Color.OrangeRed; 									
		this.rtbTraysTested.SelectionFont = new Font(this.rtbTraysTested.Font, FontStyle.Regular); 	
	}
    else
    {
		this.rtbTraysTested.SelectionColor = Color.Blue;
        this.rtbTraysTested.SelectionFont = new Font(this.rtbTraysTested.Font, FontStyle.Regular); 	
	} 

	this.rtbTraysTested.AppendText(Environment.NewLine);    // Add the endline to entry
	this.rtbTraysTested.Select(0, 0);                       // Deselect the text
}

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C# forms rich text box cannot change selected text color

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Your answer