Desktop Applications in PHP

							Desktop Applications in PHP

       by Nirav Mehta
 CEO, MagNet WebPublishing Pvt.
             Ltd.
Goals for this session
• Understand what is PHP-GTK
• Basics of PHP-GTK
• Applications available
• Future
• Keep you awake!
What is PHP
•   PHP Hypertext Preprocessor
•   Embedded in HTML
•   Available on 10 million+ domains
•   Competes with Perl, ASP, JSP, CFM
•   Open Source
•   About 100 Extensions
•   Good base for all kinds of functionality
More about PHP
•   Structural Programming roots
•   Increasing OO support
•   Strong database support
•   C + HTML
•   Syntax similar to Perl
•   Very easy to learn
•   More of a general purpose language now
A simple PHP script
<?php
$str[] = “Hello!”;
$str[] = “How are you?”;
$str[] = “Good bye!”;
for($i=0; $i<count($str); $i++)
 echo “$str[$i]<br>”;
?>

Hello
How are you?
Good bye!
What is GTK+
• GTK stands for GIMP Tool Kit
• GIMP (GNU Image Manipulation
  Program) - popular image manipulation
  software on Linux
• GTK: core of Gnome desktop
  environment
• Ported to Windows and BeOS
• Collection of libraries that provide object
  oriented framework to develop graphical
  user interfaces – GTK, GDK, GLib
What is PHP-GTK
•   An object-oriented PHP extension
    providing bindings to GTK+
•   Probably the largest PHP extension:
    –   95 classes, 970 methods, 600
        constants
•   Developed by Andrei Zmievski
•   First stable release: January 2002
•   Inspired from PyGTK
What can it do?
• Developed as proof-of-concept, getting
  better now
• Example Applications
  – PHPMole
  – Teak
  – Agata Report
  – NewzRider
  – PhpGFtp
  – and a lot more…
PHPMole – Modular IDE
Teak – IMAP Mail Client
Agata Report – GUI DB Client
NewzRider – NNTP Client
PhpGFtp – FTP Client
Other applications
• Development Related
• Games
• Internet Related
• Site Management
• Utilities

http://gtk.php.net/apps/
Web vs. Desktop
• Different ballgame
• Web
  – Request / Response
  – Top-down execution
  – HTML / Interface limitations
• Desktop
  – Event driven
  – Anything possible with GUI
Hello World!
• Let’s see what it takes to do a “Hello
 World” in PHP-GTK
  – hello.php
Loading PHP-GTK Extension
• Typically dynamically loaded
• Determine the OS, load extension
• GTK Class


if (!class_exists('gtk')) {
    if (strtoupper(substr(PHP_OS, 0, 3)) == 'WIN')
        dl('php_gtk.dll');
    else
        dl('php_gtk.so');
}
Widgets
•   Any GUI component: text box, label,
    window, button
•   Similar to Controls
•   Derived from GtkWidget class
•   Lifecycle consists of 5 parts:
    –   Creation
    –   Placement
    –   Signal connection
    –   Display
    –   Destruction
Lifecycle of a Widget
• Creation
    <? $button = &new GtkButton('Ok');
    ?>
•   Placement
    <? $container->add($button); ?>
•   Signal connection
    <? $button->connect('clicked',
    'on_clicked'); ?>
•   Display
    <? $button->show(); ?>
•   Destruction
Containers
•   Widget that can contain another widget
•   Examples: window, table, box
•   Derived from GtkContainer
•   A container can contain another container,
    which in turn can contain containers or
    widgets!
Signals
• Signals emitted on events – click, double
  click, mouse over, destroy etc.
• Both user actions and system events
• Inherited from parents, can define own
• Signal-like events generated by the
 window system - expose_event,
 button_press_event etc.
Callbacks
• Functions invoked on signals
• Normal PHP functions
• Every signal can be connected to one or
  more callback functions
• The 1st parameter is always the widget
  that emitted the signal
• Varying number of parameters depending
  on the signal
• Callback can be a method of an object
Connecting signals to callbacks
• connect() or connect_object() methods
• First parameter is the signal name, second -
    callback name
•   Simple connection:
    <? $button->connect('clicked',
    'on_button_clicked'); ?>
•   Multiple connections:
    <?
    $text->connect('changed',
    'update_status');
    $text->connect('changed',
    'save_text');
    ?>
Connecting signals…
• Passing your own parameters
  <?
  $button->connect('clicked',
  'on_button_clicked', $variable);
  function
  on_button_clicked($button,
  $variable);
  ?>
• When object reference not required –
  connect_object
  – Associating one function with many signals or
    many widgets
Sample PHP-GTK Apps
• Calendar
• File Selection
• Fonts
• Calculator
• Menu Bar
• Tree
• Notebook
• Scribble
Glade / libglade
• Building GUI by hand is complex
• Glade is GTK+ User Interface Builder
• libglade generates GTK+ widgets on
 runtime using Glade’s XML files
• gladeXT – tool to convert the Glade XML
 file into PHP code
• Can also use GladeXML class directly
Glade screenshot
Example Application
• So what shall we build?
PHP-GTK Extensions
•   Extension support makes it easy to add
    newer widgets and functionalities
•   Currently available extensions:
    –   libglade
    –   scintilla - source code editing widget
    –   GtkHtml - HTML rendering and editing
        widget
    –   GdkPixbuf - loading and rendering of images
    –   ComboButton, PieMenu, SPaned, SQPane,
        ScrollPane
Limitations of PHP-GTK
•       Main limitation due to current Zend Engine
    –     reliance on &new
    –     cannot invoke methods on object properties
    –     class properties cannot store references
    –     objects are not destroyed until the app is shut down
    –     lack of threading
•       Cannot write new widgets from scratch
•       IDEs not available
•       Installation problems
•       Everybody can see the code!
Our Experience with PHP-GTK
•   PHPGale
•   PhpGFtp
•   Incomplete manual
•   Learning curve
•   Interface building
•   Overall, good start
What's new on PHP-GTK
• Threads
• bcompiler
• GTK 2
• Zend Engine 2 integration
Endless Possibilities
•   PHP on both web and desktop
•   Backend management tools
•   Reporting tools
•   Palm applications
•   Pitching against Java?
Resources
•   http://www.php.net/
•   http://gtk.php.net/
•   http://www.gtk.org/
•   http://gtk.miester.org/
Thank you!
Nirav Mehta
nirav@magnet-i.com
http://www.magnet-i.com

• Credits
  – Andrei Zmievski
  – MagNet, PhpGFTP team