Displaying tooltip on mouse hover of a text

Question

I want to display a tooltip when the mouse hovers over a link in my custom rich edit control. Consider the following text:

We all sleep at night .

In my case the word sleep is a link.

When the user moves the mouse under the link, in this case "sleep", I want to display a tooltip for the link.

The following came to my mind, but they are not working

1) Trapping OnMouseHover

if(this.Cursor == Cursors.Hand)
   tooltip.Show(textbox,"My tooltip");
else
   tooltip.Hide(textbox);

But this does not work out.

UPDATE

The links mentioned are not URLs, i.e these are custom links, so Regex won't be of much help here, it can be any text. The user can choose to create it a a link.

Though I have not tried GetPosition method, I dont think it would be that elegant in terms of design and maintenance.

Let me say I have the following line, in my richedit box

We sleep at night. But the bats stay awake. Cockroaches become active at night.

In the above sentence, I want three different tooltips, when the mouse hovers over them.

sleep -> Human beings
awake -> Nightwatchman here
active -> My day begins

I trapped OnMouseMove as follows:

Working- with Messagebox

OnMouseMove( )
{

   // check to see if the cursor is over a link
   // though this is not the correct approach, I am worried why does not a tooltip show up
   if(this.Cursor.current == Cursors.hand )
   {
     Messagebox.show("you are under a link");
   }
}

Not Working - with Tooltip - Tooltip does not show up

OnMouseMove( MouseventArgs e )
{

   if(cursor.current == cursors.hand )
   {
     tooltip.show(richeditbox,e.x,e.y,1000);
   }
}

Answer 1

Well, take a look, this works, If you have problems please tell me:

using System.Drawing;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1() { InitializeComponent(); }

        ToolTip tip = new ToolTip();
        void richTextBox1_MouseMove(object sender, MouseEventArgs e)
        {
            if (!timer1.Enabled)
            {
                string link = GetWord(richTextBox1.Text, richTextBox1.GetCharIndexFromPosition(e.Location));
                //Checks whether the current word i a URL, change the regex to whatever you want, I found it on www.regexlib.com.
//you could also check if current word is bold, underlined etc. but I didn't dig into it.
                if (System.Text.RegularExpressions.Regex.IsMatch(link, @"^(http|https|ftp)\://[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(:[a-zA-Z0-9]*)?/?([a-zA-Z0-9\-\._\?\,\'/\\\+&%\$#\=~])*$"))
                {
                    tip.ToolTipTitle = link;
                    Point p = richTextBox1.Location;
                    tip.Show(link, this, p.X + e.X,
                        p.Y + e.Y + 32, //You can change it (the 35) to the tooltip's height - controls the tooltips position.
                        1000);
                    timer1.Enabled = true;
                }
            }
        }

        private void timer1_Tick(object sender, EventArgs e) //The timer is to control the tooltip, it shouldn't redraw on each mouse move.
        {
            timer1.Enabled = false;
        }

        public static string GetWord(string input, int position) //Extracts the whole word the mouse is currently focused on.
        {
            char s = input[position];
            int sp1 = 0, sp2 = input.Length;
            for (int i = position; i > 0; i--)
            {
                char ch = input[i];
                if (ch == ' ' || ch == '\n')
                {
                    sp1 = i;
                    break;
                }
            }

            for (int i = position; i < input.Length; i++)
            {
                char ch = input[i];
                if (ch == ' ' || ch == '\n')
                {
                    sp2 = i;
                    break;
                }
            }

            return input.Substring(sp1, sp2 - sp1).Replace("\n", "");
        }
    }
}