Hot Label Component

Key features of the component are:

• All properties of TLabel are supported, although the usage and default values of some of the inherited properties have been changed.
• The URL property is used for storing the URL to be accessed when the label is clicked. The Caption property can either store descriptive text or can reflect the URL, depending on the value of the CaptionIsURL property. The ability to link the Caption and URL makes it easy to display the URL without having to keep two properties synchronised.
• The URL can be validated to check for supported protocols. This validation is switched on and off using the ValidateURL property. Supported protocols are:
  • http://
  • https://
  • mailto:
  • file:
  • ftp://
• The label's Font property defaults to navy blue to indicate a link.
• The label can be highlighted when the mouse passes over it. Highlighting is used if the HighlightURL property is True, and the font used for highlighting is set using the HighlightFont property.
• The label can also display differently when its "link" has been clicked successfully. The font to be used is specified via the VistedFont property. The user can switch the visited state on and off via the Visited property or the component can be enabled to track visits automatically using the TrackVisits property.
• The label displays the "hand point" cursor by default.
• The component's pop-up hints can be customised as follows, using the HintStyle property:
  • the hint text can come from the Hint property as normal,
      or
  • the hint text can come from the URL property with the Hint property being ignored,
      or
  • the hint text can be modified just before the hint is shown by handling the OnCustomHint event, which is useful for displaying dynamic information in the hint.

A demo program is included in the download. See the Demo sub-directory.

The component functions mainly as a standard TLabel except that:

1. It handles the Delphi-specific CM_MOUSEENTER and CM_MOUSELEAVE messages to highlight the label when the mouse is over it.
2. It handles Delphi's CM_HINTSHOW message to provide customised hints.
3. The Caption property may automatically change when the optionally linked URL property changes.

TPJHotLabel uses the Windows ShellAPI ShellExecute function to start the default browser or email client when a URL is clicked.