SqueakGTK. Gwenael Casaccio. ESUG 2008, Amsterdam

1. SqueakGTK
Gwenael Casaccio

2. SqueakGTK
• Presentation of GTK+
• GLib
• GDK, Pango, Cairo
• GTK+
• SqueakGTK tools (Omnibrowser, launcher)
• To do
• Conclusions

3. GTK+
• Open source toolkit (LGPL)
• Created for the GIMP
• Written in C
• Multi platform

4. GTK+
X11 Win32 (Quartz)
GLib
GDK Pango Cairo
Figure 2.9: The GTK+ stack
All parts of the GTK+ stack are written in C, and hence there is no support for object-orientation
features in the language. GTK+ still boasts itself as an object-oriented toolkit. This is thanks to
GObject, which is a part of GLib.
GObject is an object system which is used extensively by GTK+. It is designed to be easy to be
used by other programming languages, both interpreted and compiled.
GObject supports object inheritance as well as interfaces. Objects can also have named properties.
There also exists a general purpose notification mechanism for objects called signals.
GTK+ Stack

5. GLib
• Cross platform utility
• Linked list, hash tables, binary trees, ...
• C object model : GObject
• Fundamental types (Float, String, ...)
• Enumeration

6. GObject
• Single inherited class structure
• Signals
• Independent type system (GType)
• Memory management : reference counting

7. GDK
• Drawing : pixmaps, drawables, graphic
pattern
• Events : mouse, keyboard, window, ...
• Fonts : metrics

8. Pango
• Rendering text
• Internationalized
• Different font backends
• Integration with Cairo

9. Cairo
• Vector graphic-based
• Device-independant API
• 2D
• Several backends (PDF, PostScript, SVG, ...)
• GTK+ integration

10. Cairo
• Shape rendering
• Alpha blending
• Gradient drawing
• OpenGL acceleration

11. GTK+
• Now code our first application

12. GTK+
• First create a window

13. GTK+
• Now how to add a widget ?

14. Widgets

15. Widgets
• ...

16. Layout
• GtkFixed

17. Layouts
• GtkVBox

18. Layouts
• GtkTable

19. GTK+ Events
• when: anEvent send: aMessage to: anObject
• when: anEvent do: aBloc

20. inside GTK+
• Each GtkWidget inherit from GPointer
• C pointer store in a ByteArray
• Each Gtk classes call primitives

21. inside GTK+ events
• Handle events :
• Do we have an event ?
• Handle events

22. GTK+
• Events
• Active waiting for events (morphs, ...)
• GTK+ events handling
first process :
[self waitForEvents] repeat.
Second process :
[self handleEvents] repeat.

23. SqueakGTK
• Omnibrowser
• Launcher
• Inspector
• Browser

24. To do
• Restore the state of the interface
• Write tutorials
• Improve the tools
• Create a desktop
• Support of GObjectInspector
• ...

25. Conclusion
• Support multiple operating system
• Powerful and flexible user interface
• Stable
• http://code.google.com/p/squeakgtk/