Linked TextBox - CodeProject®

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Introduction

This is a short demo on how to make a textbox act as a hyperlink when the CTRL key is pressed and the control has the focus.

Background

I needed a LinkedTextBox control for a customer.

Using the code

The control has three additional properties:

CltrHyperLink
HyperLinkColor
HyperLinkVisitedColor

A new Event:

HyperLinkClicked

And a new Virtual method:

OnHyperLinkClicked

Setting the CtrlHyperLink property to true activates all the other properties and events.

HyperLinkColor is the color of the hyperlink when it is in the default state. HyperLinkVisitedColor is the color of the hyperlink in its visited state. Listening to the HyperLinkClicked event will result in the event being fired when the user holds down the Control key and clicks the left mouse button. OnHyperLinkClicked can be overridden if needed.

Overridding some of the features of the TextBox

protected override void OnKeyUp(KeyEventArgs e)
{
    base.OnKeyUp(e);
    FormatTextBox(false); //Set the decoration of the textbox to standard
}

protected override void OnKeyDown(KeyEventArgs e)
{
    base.OnKeyDown(e);
    FormatTextBox(e.Control);
    //if true Set the decoration of the textbox 
    //to an hyperlink else standard.
}

protected override void OnMouseClick(MouseEventArgs e)
{
    base.OnMouseClick(e);
    if (_IsHyperLink && e.Button == MouseButtons.Left)
    //If the the control is in hyperlink mode
    //and the left mouse button was clicked...
    {
        OnHyperLinkClicked(new EventArgs());
        FormatTextBox(false);
    }
}

private void FormatTextBox(bool ShowAsLink)
{
    if (!_CltrHyperLink)
    return;
    if (ShowAsLink)
    {
        Font = new Font(Font, FontStyle.Underline);
        ForeColor = (!_HyperLinkVisited ? _HyperLinkColor : 
                      _HyperLinkVisitedColor);
        Cursor = Cursors.Hand;
        _IsHyperLink = true;
    }
    else
    {
        Font = new Font(Font, FontStyle.Regular);
        ForeColor = SystemColors.WindowText;
        Cursor = Cursors.Default;
        _IsHyberLink = false;
    }
}

protected virtual void OnHyperLinkClicked(EventArgs e)
{
    _HyperLinkVisited = true;
    if (HyperLinkClicked != null)
        HyperLinkClicked(this, e);
}