TPJHotLabel Component

Contents

• Description
• Compatibility
• Installation
• Known Issues
• Update History
• License and Disclaimer
• About the Author

Description

Overview

TPJHotLabel is a simple Delphi component that descends from TLabel. It provides a clickable label that can start the default browser or email client to access a specific URL. 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 and 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 a navy blue to indicate a hot link.
• The label can be highlighted when the mouse passes over it. Highligting is used if the HighlightURL property is True, and the font used for highlighting is set using the HighlightFont property.
• The label displays the "hand point" cursor by default. For versions of Delphi that do not support provide the crHandPoint cursor, a custom cursor is linked in to the program by the component.
• 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 help file is provided that can inegrate with the IDE of Delphi 3 to 7.

Backwards compatibility with v1

This v2 release is backwards compatible with v1 of the component. All new properties that are not available in v1 are either switched off by default or emulate the properties available in v1.

File manifest

This release contains the following files:

• PJHotLabel.pas -- the component source code unit.
• PJHotLabel.dcr -- the Delphi component palette glyph.
• PJHotLabel.res -- a resource file containing the "hand point" cursor conditionally linked into applications.
• PJHotLabel.hlp -- the Delphi IDE compatible component help file.
• pjhotlbl.htm -- this file.

Compatibility

TPJHotLabel has been tested Delphi 4, 6 and 7 and should work with all 32 bit versions of Delphi (i.e. versions 2 to 7). The component is not suitable for use with Delphi 1

Installation

In these instructions $(DELPHI) is to be taken to represent the path where the appropriate version of Delphi was installed. For example, if you have Delphi 4 installed on the default installation path then $(DELPHI) is equivalent to C:\Program Files\Borland\Delphi4.

The installation procedue for Delphi 3-7 differs from that for Delphi 2. Separate instructions for each type of installation follows. (The Delphi 2 instructions are towards the end of the section).

Installation with Delphi 3 & later

These instructions assume you wish to install the component into an existing package. To install into a new package, create a new, empty design time package, install it into Delphi and then follow these instructions to add this component to the package.

1. Unzip the .zip file containing the component into a folder, preserving the directory structure.
2. Copy PJHotLabel.pas, PJHotLabel.res and PJHotLabel.dcr to the folder from where you wish to install the component into the Delphi Component Palette. This will probably be a sub-folder of the $(DELPHI)\lib folder.
3. Install the component into the palette by chosing the Component | Install Component menu option.
• Select the "Into exisiting package" page of the Install Components dialog box.
• Browse to the folder where you saved PJHotLabel.pas and select the file.
• Choose a package into which to install the component.
• Accept that the package will be rebuilt.
• A dialog box should be displayed saying that TPJHotLabel has been added to the component palette.
4. You can now delete PJHotLabel.pas from the place where you copied it if you wish. The component will appear on a palette called DelphiDabbler. You can move the component to a different palette if required.
5. The simplest way to install the help file is to use my Component Help Installer Expert. To install manually, proceed as follows:
   • Copy PJHotLabel.hlp to whichever folder you wish to install it to.
   • In Delphi 3 to 6 (where X is the Delphi version 3..6):
     • Edit DelphiX.ohl (in $(DELPHI)\Help), adding the line :Link PJHotLabel.hlp to the end of the section labelled "Third party help".
     • Edit DelphiX.ohi (in $(DELPHI)\Help), adding the line :Index DelphiDabbler Hot Label Component=PJHotLabel.hlp towards the end of the index section.
     • Edit DelphiX.cnt (in $(DELPHI)\Help), ensuring that the lines :Include delphiX.ohi and :Include delphiX.ohl appear somewhere in the file.
   • In Delphi 7
     • Edit D7.ohl (in $(DELPHI)\Help), adding the line :Link PJHotLabel.hlp to the end of the section labelled "Third party help".
     • Edit D7.ohi (in $(DELPHI)\Help), adding the line :Index DelphiDabbler Hot Label Component=PJHotLabel.hlp towards the end of the index section.
     • Edit D7.cnt (in $(DELPHI)\Help), ensuring that the lines :Include d7.ohi and :Include d7.ohl appear somewhere in the file.
6. Using RegEdit open the key HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\Help and add a new string value named PJHotLabel.hlp whose value is the path where you copied the help file (probably ($DELPHI)\Help).

Installation with Delphi 2

To install the component, proceed as follows:

1. Unzip the .zip file containing the component into a folder, preserving the directory structure.
2. Copy PJHotLabel.pas, PJHotLabel.res and PJHotLabel.dcr to the folder from where you wish to install the component into the Delphi Component Palette. This will probably be a sub-folder of the $(DELPHI)\lib folder.
3. Start Delphi. Select the Components | Install menu option. Click the Add button, then the Browse button and navigate to PJHotLabel.pas in the folder where you placed it. Click OK to recompile the component library.
4. You can now delete PJHotLabel.pas from the place where you copied it if you wish. The component will appear on a palette named DelphiDabbler. You can move it to a different palette as required.

Please note that the supplied help file does not integrate into the Delphi 2 IDE (it only integrates with Delphi 3 onwards). The help file can be used stand-alone, but the help file contains links into other Delphi help files that will not work when run stand-alone.

Known Issues

No known outstanding issues.

Update History

Release 2.0 of 02 November 2003
HotLabel v2.0 of 02 November 2003

• Added separate URL property to enable caption to be different to URL accessed.
• Added ability to highlight label text when cursor passes over it.
• Added ability to display URL in hint or to display custom hints set by handling the new OnCustomHint event.
• Now uses built in hand point cursor for Delphi 4 and higher while still loading a custom cursor from resources for earlier compilers.
• Moved error messages to resource strings for Delphi 3 and later while using constants for Delphi 2.
• Now recognises the https:// protocol as valid.
• Changed default URL to http://localhost/.
• Rewrote help file to be compatible with Delphi 3 and later IDEs. Help file is no longer compatible with Delphi 2 IDE.

Release 1.0.1 of 28 November 1999
HotLabel v1.0 of 25 October 1999

• Updated HTML documentation to include installation notes for Delphi 3/4 and added update history.

Release 1.0 of 25 October 1999
HotLabel v1.0 of 25 October 1999

• Original version with HTML documentation.

License & Disclaimer

This component is copyright © P.D.Johnson, 1999-2003.

The source code and help file can be freely distributed on a not-for-profit basis providing that:

1. The source code is not altered.
2. This readme file is distributed with it unchanged.

By not-for-profit I mean that you may recover out of pocket expenses incurred in distributing the code, but should not make a profit from this.

If you discover any bugs in this implementation, or if you have any update suggestions, please contact me via my website.

Please do modify the code for you own use. I'd like to see any changes you make - I could incorporate them into future versions. Please notify me of changes on at the above e-mail address.

This software is provided as is - no warranty is given as to its suitability for any purposes to which you may wish to put it.

About the Author

I'm Peter Johnson - a hobbyist programmer living in Ceredigion in West Wales, UK. I write mainly in Delphi. My programs are available for download on my web-site: http://www.delphidabbler.com/.

I can be contacted via the website.