I found a way which may not be the most elegant, but it's just a few lines of code and does the job. Namely, the idea is to simulate hyperlink appearance by means of font changes, and simulate hyperlink behavior by detecting what the mouse pointer is on.
The code:
public partial class Form1 : Form
{
private Cursor defaultRichTextBoxCursor = Cursors.Default;
private const string HOT_TEXT = "click here";
private bool mouseOnHotText = false;
// ... Lines skipped (constructor, etc.)
private void Form1_Load(object sender, EventArgs e)
{
// save the right cursor for later
this.defaultRichTextBoxCursor = richTextBox1.Cursor;
// Output some sample text, some of which contains
// the trigger string (HOT_TEXT)
richTextBox1.SelectionFont = new Font("Calibri", 11, FontStyle.Underline);
richTextBox1.SelectionColor = Color.Blue;
// output "click here" with blue underlined font
richTextBox1.SelectedText = HOT_TEXT + "\n";
richTextBox1.SelectionFont = new Font("Calibri", 11, FontStyle.Regular);
richTextBox1.SelectionColor = Color.Black;
richTextBox1.SelectedText = "Some regular text";
}
private void richTextBox1_MouseMove(object sender, MouseEventArgs e)
{
int mousePointerCharIndex = richTextBox1.GetCharIndexFromPosition(e.Location);
int mousePointerLine = richTextBox1.GetLineFromCharIndex(mousePointerCharIndex);
int firstCharIndexInMousePointerLine = richTextBox1.GetFirstCharIndexFromLine(mousePointerLine);
int firstCharIndexInNextLine = richTextBox1.GetFirstCharIndexFromLine(mousePointerLine + 1);
if (firstCharIndexInNextLine < 0)
{
firstCharIndexInNextLine = richTextBox1.Text.Length;
}
// See where the hyperlink starts, as long as it's on the same line
// over which the mouse is
int hotTextStartIndex = richTextBox1.Find(
HOT_TEXT, firstCharIndexInMousePointerLine, firstCharIndexInNextLine, RichTextBoxFinds.NoHighlight);
if (hotTextStartIndex >= 0 &&
mousePointerCharIndex >= hotTextStartIndex && mousePointerCharIndex < hotTextStartIndex + HOT_TEXT.Length)
{
// Simulate hyperlink behavior
richTextBox1.Cursor = Cursors.Hand;
mouseOnHotText = true;
}
else
{
richTextBox1.Cursor = defaultRichTextBoxCursor;
mouseOnHotText = false;
}
toolStripStatusLabel1.Text = mousePointerCharIndex.ToString();
}
private void richTextBox1_MouseClick(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left && mouseOnHotText)
{
// Insert your own URL here, to navigate to when "hot text" is clicked
Process.Start("http://www.google.com");
}
}
}
To improve on the code, one could create an elegant way to map multiple "hot text" strings to their own linked URLs (a Dictionary<K, V>
maybe). An additional improvement would be to subclass RichTextBox
to encapsulate the functionality that's in the code above.