Using PHP-GTK to rapidly develop

Internet enabled desktop applications

Hong Kong. March 2001

Alan Knowles <alan@akbkhome.com>

http://www.akbkhome.com

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Introduction

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Alan Knowles - Background

• Teletext editor (6502 assembler in early 80's)
• C & Autolisp (early 90's)
• VBCCE - ccmail (late 90's)
• contributor to TWIG (php webmail application)
• set up a Linux Consulting company during dotcom boom
• contributor to Midgard (C Mysql php extension)
• Large scale php application user interface to midgard

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Phpmole the Project

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The Need

• Dreamweaver Quality HTML editor on linux
• Midgard interface (Content managment)
• Editor that access files using scp/ssh
• Learn and expand knowledge of PHP

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PHP-GTK Pros and Cons

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Advantages

• Open Source :)
• simple powerfull object orientated language
• large user base = lots of potential contributors
• easy to build extensions
• cross platform - works on windows (well sometimes)
• scripting -> compiled -> run = fast at runtime, negligable startup penalty

Disadvantages

• threading
• forking and sockets available though
• incomplete widgets
• gnome etc. - not available on windows anyway.
           

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Initial efforts and PHPIDE

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Initial Efforts

• initial efforts where hacking moleskine (added file tree to moleskine)
• python object model not as intuative
• at the same time Andrei released php-gtkscintilla in cvs
• Original PHPMole very much a straight port of moleskine into PHP
• Only major change was not doing this as it was confusing to read.

class phpinterface extends scintilla {
        
              
      
            

PHPIDE

• Aims
• Modular enviroment
• PEAR based (with PEAR standards)
• Problems
• Project lacked resources
• Ideas good.
• first effort at phpmole
• already allowed editing documents
• but not very modular.
   

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Modulizing the mole

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Display Modules (modules)

• Scintilla
• Now has : Gtkhtml (WYSIWYG html editor), plain text, database,xml and forms/midgard

Transport Modules (transports)

• File
• Scp
• Midgard (HTTP + Curl)
• Database

Parser/Language Modules (languages)

• XML,
• HTML/PHP

Extensions (plugin extras)

• Help Viewer, Directory/Image tools, dictionary client, simple and full debugger, phppresents

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Extending PHP-GTK - adding GTKHTML

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GtkHTML = gtk widget 

• Browing Web pages
• Editing Web pages in a WYSIWYG manner
• Understanding the design of GtkHTML

Limitations

• Strips HTML!
• Not very cross platform (cschtml? or gtkhtml2 or gtk2 text widget)

   

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Writing a PHP & PHP-GTK Extension

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Principle :

• Auto generated C code - try not to do the hard work

php-gtk/generator/generator.php                   
        
                    

Defs file

• The defs file generator (/php-gtk/generator/h2defs.py)
• .h files converted to 'scheme/lisp format'

(object HTML 
          
  (in-module Gtk)
          
  (parent Layout (Gtk))
          
  (c-name GtkHTML)
          
)
          
                    
          

        
                    

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Writing a PHP & PHP-GTK Extension

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Overrides file

• The C code that can not be generated

Makefiles and config files

• Like all PHP modules - Makefile.in, config.m4

Zend/PHP API

• Alot of C Macros
• php functions/methods become short and simple C functions

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GTKHTML - the source

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PHP_FUNCTION(gtk_html_get_paragraph_style)
{
    long php_retval;
    NOT_STATIC_METHOD();
    if (!php_gtk_parse_args(ZEND_NUM_ARGS(), ""))
      
    return;
      
    php_retval = gtk_html_get_paragraph_style(
        GTK_HTML(PHP_GTK_GET(this_ptr)));
      
    RETURN_LONG(php_retval);
      
}
                
    
                

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GTKHTML - the widget

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Creating the widget

•  must be inside a scrolled window!

$scrolly = &new gtkscrolledwindow()
$gtkhtml = &new gtkhtml();
$scrolly->add($gtkhtml); 

Loading the html data

$stream = $gtkhtml->begin();
$gtkhtml->write($stream,$data,strlen($data));       
$gtkhtml->end($stream,GTK_HTML_STREAM_OK);

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GTKHTML - the widget

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Connect the callbacks

$gtkhtml->connect(""link_clicked","callback_link_clicked"); 
$this->gtkhtml->connect_url_request("callback_url_request");

Callback functions

• all callbacks call function with widget, then other variables eg.

function callback_url_request($widget,$stream) {        
    $data = .....get image......
    $widget->write($stream, $data, $size_of_data);                 
}
                  

Saving the data

$gtkhtml->save(array(&$this,"mymethod"));
      
                  

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Phpmole Modules

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Developing modulized class based desktop apps.

• module manager
• responsible for relaying messages to modules
• no single module could expect another one to be there
• all messages must be sent to module manager.
• extensive use of

call_user_function(array(&$something,"method"),$args) 
    
                

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PHP-GTK Tips & Tricks  

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the & sign

• essential to create and use references of classes
• useful for sharing data between different classes - eg. the transports and editors.
• avoid copying data as this is slower!

$object = &$other_object;   // reference
    
$object = $other_object;    // copy
    

  
              

•       If you copy a gtk object - it will break

$widget->connect("clicked",array(&$this,"some_method"));
    

  
              

• Call backs on classes should use &$this, otherwise you will end up with referencing a copy of the object at the time the 'connect' was called

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PHP-GTK Tips & Tricks  

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  while (gtk::events_pending) gtk::main_iteration();

• php is multitasking not threaded
• if your program is busy - you can use this to let the interface have control breifly
• most applications do not require threading - it also introduces other issues - like locking
• re-entrant methods - what happens when methods are called inside themselves.

       

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PHP-GTK Tips & Tricks  

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signal connecting

• avoid accidently connecting twice.

$widget->connect("clicked",array(&$this,"some_method"));
$widget->connect("clicked",array(&$this,"some_method"));                  

• will call some_method twice
• fix:

$ref = $widget->connect("clicked",array(&$this,"some_method")); 
$widget->connect("clicked",array(&$this,"some_method"));
$widget->connect($ref);

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PHP-GTK Tips & Tricks  

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use glade - the gtk interface builder

• saves time developing interfaces
• you can load parts of a glade file and merge it with your interface
• simple phplibglade layer in phpmole to get arround win32 libglade bugs
• phpmole uses configuration dialogs
• automatically map config vars to widget names
• adding config options involves 
• modifying the glade file.
• adding config names to default config file

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PHP-GTK Tips & Tricks  

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extending gtk objects

• common trick is to use $this->widget to refer to managed widget
• make code clearer (loses some benifits of object extending)
• reuse of classes like scintilla...

class mywidget extends gtknotebook {
    function mywidget() {
    //initialize the widget
        $this->set_sensitive(FALSE);
    }
      
}
//or this may be clearer, however more typing! 
class mywidget   {
    var $widget;
    function mywidget() {
        //initialize the widget
	$this->widget = &new GtkNotebook();
	$this->widget->set_sensitive(FALSE);
    }
      
}
      

                    

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PHP-GTK Tips & Tricks  

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storing extra information on widgets

• lists, trees and notebooks  it is usefull to store extra data with a widget

$widget->set_data("key","value") 
        

        

        
$widget->connect("pressed","some_function");
        

        
function some_function($w){
        
	echo $w->get_data("key"); 
        
}
        

      
                      

       

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PHP-GTK Tips & Tricks

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Drawing areas (Drawing Graphics- lines, text etc.)

• most complex part of gtk1.2 (although gtk2 has gtktextview as competition)
• useful for displaying images, or doing drawing diagrams, pdfs..... etc.
• off screen pixmap, painted on to screen using  expose_event callbacks
• configure_event callback sets up the pixmap
• pixmap can be drawn to seperatly from displaying it.
• explicity tell display to draw pixmap. (or part of pixmap) on drawing area

Look at tests/scribble.php for more details

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PHP-GTK Tips & Tricks

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Drag and Drop

• very difficult to do in web enviroment ( php's origin )
• does not work on php-gtk for windows (as of 0.5.0)
• not usefull for non-mouse driven displays

source widget

$widget->drag_source_set(
	GDK_BUTTON1_MASK|GDK_BUTTON3_MASK, 
	array(array('text/plain', 0, -1)),
	GDK_ACTION_COPY);
$widget->connect('drag_data_get', array(&$this,'dnd_drag_data_get')); 
                    

destination widget

$widget->drag_dest_set(GTK_DEST_DEFAULT_ALL, 
	array(array('text/plain', 0, -1)) ,
	GDK_ACTION_COPY);
$widget->connect('drag_data_received', array(&$this,"drop_recieved"));
       
                    

see tests/test.php for more details

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Content Management - Web Services

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Midgard Integration (Web Services)

• Midgard is CMS engine - managed C API interface to mysql
• phpmole uses a simplified XML transport layer to get send data to midgard server
• can be used as an abstract form eding layer - eg. sourceforge, bugtracker etc.
• in the future it will use XMLRPC



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Phpmole the Future

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Other plans

• real php debugger : APD - added socket support -   PROTOTYPE WORKING!
• real builder/executer/runner  -   PROTOTYPE WORKING!
• start make
• more parsers C, C++..   
• replace Gtkhtml?  -   PROTOTYPE STARTED!

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Conclusion

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   Developing on php-gtk is FAST!