Change style of selected Text in RichTextBox

Question

How can I change styles (such as Font, FontSize, Brush) of selected Text in RichTextBox ?

Update : Let's say I've a RichTextBox and a Toolbar. User comes and select text inside the RichTextBox box and change the font size from toolbar. I want to change style of selected text.

Answer 1

WPF

if (this.TextEditor.Selection.IsEmpty)
    this.TextEditor.CurrentFontFamily = SelectedFont;
else
    this.TextEditor.Selection.ApplyPropertyValue(TextElement.FontFamilyProperty, SelectedFont);

or another WPF Example

 private void ChangeTextProperty(DependencyProperty dp, string value)
    {
        if (mainRTB == null) return;

        TextSelection ts = richTextBox.Selection;
        if (ts!=null)
            ts.ApplyPropertyValue(dp, value);
        richTextBox.Focus();
    }

here are some examples Windows Changing the Font & Font Color (not wpf)

richTextBox1.SelectionFont = new Font("Tahoma", 12, FontStyle.Bold);
richTextBox1.SelectionColor = System.Drawing.Color.Red;

another example below (not wpf)

private void WriteTextToRichTextBox()
{
   // Clear all text from the RichTextBox;
   richTextBox1.Clear();
   // Set the font for the opening text to a larger Arial font;
   richTextBox1.SelectionFont = new Font("Arial", 16);
   // Assign the introduction text to the RichTextBox control.
   richTextBox1.SelectedText = "The following is a list of bulleted items:" + "\n";
   // Set the Font for the first item to a smaller size Arial font.
   richTextBox1.SelectionFont = new Font("Arial", 12);
   // Specify that the following items are to be added to a bulleted list.
   richTextBox1.SelectionBullet = true;
   // Set the color of the item text.
   richTextBox1.SelectionColor = Color.Red;
   // Assign the text to the bulleted item.
   richTextBox1.SelectedText = "Apples" + "\n";
   // Apply same font since font settings do not carry to next line.
   richTextBox1.SelectionFont = new Font("Arial", 12);
   richTextBox1.SelectionColor = Color.Orange;
   richTextBox1.SelectedText = "Oranges" + "\n";
   richTextBox1.SelectionFont = new Font("Arial", 12);
   richTextBox1.SelectionColor = Color.Purple;
   richTextBox1.SelectedText = "Grapes" + "\n";
   // End the bulleted list.
   richTextBox1.SelectionBullet = false;
   // Specify the font size and string for text displayed below bulleted list.
   richTextBox1.SelectionFont = new Font("Arial", 16);
   richTextBox1.SelectedText = "Bulleted Text Complete!";
}

Answer 2

For a WPF RichTextBox, you have to use the ApplyPropertyValue method to a TextRange. You can get the selected TextRange using the Selected property of the RichTextBox instance.

var selection = myRichTextBox.Selection;
if (!selection.IsEmpty)
    selection.ApplyPropertyValue(TextElement.FontSizeProperty, 10.0);