3 UIs for the price of one code

3 UIs for the price of one code with YaST's libyui Katarína Machálková Software Engineer (YaST) [email_address]

Talk outline Introduction – why libyui (Hello World!) Brief Tour de Libyui internals My first libyui application Introducing different language bindings Sample non-C++ libyui application Documentation, useful links Questions, answers, ...

Intro & Motivation

The most famous app of all times ☺

Hello World in Qt ... int main(int argc, char *argv[]) { QApplication app(argc, argv); QPushButton hw("Hello World!"); hw.resize(75, 30); QObject::connect(&hw, SIGNAL(clicked()), &app, SLOT(quit())); hw.show(); return app.exec(); }

… in Gtk ... int main (int argc, char *argv[]) { GtkWidget *window; GtkWidget *button; gtk_init (&argc, &argv); window = gtk_window_new (GTK_WINDOW_TOPLEVEL); gtk_signal_connect (GTK_OBJECT (window), "destroy", GTK_SIGNAL_FUNC (destroy), NULL); gtk_container_border_width (GTK_CONTAINER (window), 10); button = gtk_button_new_with_label ("Hello World"); gtk_signal_connect (GTK_OBJECT (button), "clicked", GTK_SIGNAL_FUNC (hello), NULL); gtk_signal_connect_object (GTK_OBJECT (button), "clicked", GTK_SIGNAL_FUNC (gtk_widget_destroy), GTK_OBJECT (window)); gtk_container_add (GTK_CONTAINER (window), button); gtk_widget_show (button); gtk_widget_show (window); gtk_main (); return 0; }

… and in ncurses ... int main(void) { WINDOW * mainwin; if ( (mainwin = initscr()) == NULL ) { exit(EXIT_FAILURE); } mvaddstr(13, 33, "Hello, world!"); refresh(); sleep(3); delwin(mainwin); endwin(); refresh(); return EXIT_SUCCESS; }

One code, three user interfaces! #include "YUI.h" #include "YWidgetFactory.h" #include "YDialog.h" #include "YLayoutBox.h" #include "YEvent.h" int main( int argc, char **argv ) { YDialog *dialog = YUI::widgetFactory()->createPopupDialog(); YLayoutBox *vbox = YUI::widgetFactory()->createVBox( dialog); YUI::widgetFactory()->createLabel( vbox, "Hello, World!" ); YUI::widgetFactory()->createPushButton( vbox, "&OK" ); dialog->waitForEvent(); dialog->destroy(); }

Libyui from the inside

Introducing libyui
Library written in C++
Provides abstraction from GUI and TUI toolkits (Qt, Gtk, ncurses) in terms of widgets (UI elements) and events
YaST user interface engine
Independent of YCP (after major rewrite in 2006)
Independent of YaST core libraries and libzypp (dtto)
Dialogs, widgets + event handling

YaST UI Architecture

Widgets (dialog building blocks)
Parent widget
Properties (get/set)
Value (string, integer)
Items
Label
Current item
…
Widget id (optional)

Types of widgets
Simple
CheckBox, Label, InputField, PushButton, ...
Layout aids
VBox, HBox, VStretch,...
One-of-many, N-of-many “selectors”
ComboBox, SelectionBox, Table, Tree,...

Events (user input results)
Sample event loop
while(true)
{
YEvent *ev = dialog->waitForEvent();
do_something (ev);
}
User interaction with dialog causes waitForEvent (blocking call) to return
Each event has
Type (cancel event, widget event,...)
Reason (selection changed, widget was activated,...)
Pointer (or id) of the widget that broke the event loop

What libyui does not support
Multiple threads
Signals, slots, callbacks,...
Advanced graphics (3D, animations,...)
Non-blocking event handling

My first libyui application

Developer's check-list
Header files( yast2-libyui-devel )
Compiler ( gcc-c++ )
YaST UI package ( yast2-[qt|gtk|ncurses] )
Favourite text editor / IDE :)

Code it ... #include "YUI.h" #include "YWidgetFactory.h" #include "YDialog.h" #include "YLayoutBox.h" #include "YEvent.h" int main( int argc, char **argv ) { YDialog *dialog = YUI::widgetFactory()->createPopupDialog(); YLayoutBox *vbox = YUI::widgetFactory()->createVBox( dialog); YUI::widgetFactory()->createLabel( vbox, "Hello, World!" ); YUI::widgetFactory()->createPushButton( vbox, "&OK" ); dialog->waitForEvent(); dialog->destroy(); }

Compile & run it
' g++ -I/usr/include/YaST2/libyui -lyui
HelloWorld.cc -o HelloWorld'
Get Qt:
'./HelloWorld '
Get Gtk ( new in 11.2 )
'./HelloWorld --gtk'
Get ncurses:
'unset DISPLAY; ./HelloWorld '
Include libyui headers Link with libyui This emulates text-mode only env.

Hello World dissected, part I int main( int argc, char **argv ) { YDialog *dialog = YUI::widgetFactory()->createPopupDialog(); YLayoutBox *vbox = YUI::widgetFactory()->createVBox( dialog); 1 st call creates UI instance and w.factory instance Get widget pointer from w.factory Widget container (layout aid) Child of the main dialog

Hello World dissected, part II YUI::widgetFactory()->createLabel( vbox, "Hello, World!" ); YUI::widgetFactory()->createPushButton( vbox, "&OK" ); Create new widget, specify parent + property (string) Vert. container can have many children

Hello World dissected, part III dialog->waitForEvent(); dialog->destroy(); } Wait for user input Use this in event loops Close the dialog, do the final cleanup

But I don't speak C++ … ?

Other scripting language bindings Python Ruby Perl C++ bindings

Enter perl/python/ruby bindings
Independence on YCP and YaST core
Standard C++ (STL) data types (std::string, std::list,...)
Easy way to swig-generated language bindings
Currently for perl, python and ruby
' zypper in [perl|python|ruby]-yui ' (that's it ☺ )

Hello World with perl-yui !/usr/bin/perl # # Trivial read-write (not write-only :) # example of libyui used from Perl # use yui; my $factory = yui::YUI::widgetFactory; my $dialog = $factory->createPopupDialog; my $vbox = $factory->createVBox( $dialog ); $factory->createLabel( $vbox, "Hello,World!"); $factory->createPushButton( $vbox, "&OK" ); my $event = $dialog->waitForEvent(); $dialog->destroy();

Hello World with python-yui # Trivial usage of libyui # in pretty the same way # in python # #!/usr/bin/python import sys import yui factory = yui.YUI.widgetFactory() dialog = factory.createPopupDialog() vbox = factory.createVBox( dialog ) factory.createLabel( vbox, "Hello, World!" ) factory.createPushButton( vbox, "&OK" ) event = dialog.waitForEvent() dialog.destroy()

More complex non-C++ application

Simple zypp.conf editor with perl-yui (live demonstration)

When things don't work ...

Logs, debugging & co.
Redirect logs to file (avoid noise on stdout):
'yui::YUILog::setLogFileName( "/tmp/libyui-example.log" );'
Make logging more verbose
' yui::YUILog::enableDebugLogging(); '
Usual suspects: gdb, valgrind,...
Found a bug in libyui-(bindings)?
http://bugzilla.novell.com , YaST component

More Information

Where to get more information? On line dokumentace: http://www.suse.de/~ug/ On line dokumentace: http://www.suse.de/~ug/ On line dokumentace: http://www.suse.de/~ug/ On line dokumentace: http://www.suse.de/~ug/ On line dokumentace: http://www.suse.de/~ug/ *-yui package doc with examples: /usr/share/doc/packages/*-yui On line dokumentace: http://www.suse.de/~ug/ On line dokumentace: http://www.suse.de/~ug/ On line dokumentace: http://www.suse.de/~ug/ On line dokumentace: http://www.suse.de/~ug/ On line dokumentace: http://www.suse.de/~ug/ YaST development mailing list: [email_address] General YaST doc (incl. widget reference): http://forgeftp.novell.com/yast/doc/SL11 .1

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3 UIs for the price of one code

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