LablGTK2 2.18.10 : an interface to the GIMP Tool Kit
ocaml-4.05 or more
gtk+-2.x (gtk+-2.16.x for full functionality)
findlib 1.2.1 or more (for default install)
GNU make (there is no standard for conditionals)
LablGtk2 is now pretty stable.
An important change in gtk-2 is the use of unicode (utf8) for
all strings. If you use non-ascii strings, you must imperatively
convert them to unicode. This can be done with the
[Glib.Convert.locale_to_utf8] function. If your input is already in
utf8, it is still a good idea to validate it with
Glib.Utf8.validate, as malformed utf8 strings may cause segmentation
Note that setlocale is now always called (except if you set
GTK_SETLOCALE to 0 in the environment), but LC_NUMERIC is reverted
to "C" to avoid problems with floating point conversion in Caml.
Note that some widgets are only supported in newer versions of GTK+.
If you use them in older versions, you will get a runtime error:
Failure "Gobject.unsafe_create : type GtkActionGroup is not yet defined"
For unsupported methods, the error message is a bit clearer:
Failure "gdk_pixbuf_get_file_info unsupported in Gtk 2.x < 2.4"
How to compile:
You should normally not need to modify Makefiles.
In case you are using the SVN version you may have to first type
"aclocal && autoconf".
./configure && make world
to compile with all supported options enabled (libgl, libglade,
libgnomecanvas, librsvg, native compilation, thread support).
You may use "./configure --help" to check for the different
Lablgtk2 specific options are:
--with-libdir=/path: install libs in /path/lablgtk2
--with-gl --without-gl: override autodetected GtkGLArea support.
--with-glade --without-glade: override autodetected libglade support
--with-rsvg --without-rsvg: override autodetected librsvg support
override autodetected libgnomecanvas support
override autodetected libgnomeui support
override autodetected libpanelapplet support
override autodetected gtkspell support
override autodetected gtksourceview support
override autodetected gtksourceview2 support
--enable-debug: enable debug mode
Type "make install" to install using findlib.
The commands lablgtk2, gdk_pixbuf_mlsource, and lablgladecc2,
are copied directly to the configured executable directory.
The following findlib packages are provided (according to configuration):
You can alternatively use "make old-install" or
"make old-install DESTDIR=/my/prefix" to use the old
installation procedure, which does not rely on findlib.
By default, the library is installed at +lablgtk2.
All installation paths are prefixed by DESTDIR when given.
gdk.ml low-level interface to the General Drawing Kit
gtk.ml low-level interface to the GIMP Tool Kit
gtkThread.ml main loop for threaded version
g[A-Z]*.ml object-oriented interface to GTK
gdkObj.ml object-oriented interface to GDK
examples/*.ml various examples
applications/browser an ongoing port of ocamlbrowser
applications/camlirc an IRC client (by Nobuaki Yoshida)
How to run the examples:
In the examples directory just type:
If you want to run them before installing lablgtk2 you have to use -localdir:
../src/lablgtk2 -localdir ???.ml
How to link them:
The lablgtk2 script loads an extra module GtkInit, whose only contents is:
let locale = GtkMain.Main.init ()
You must either add this line, or add this module to your link, before
calling any Gtk function. With ocamlfind, use
ocamlfind ocamlc -package lablgtk2.auto-init -linkpkg -w s ???.ml -o ???
Otherwise, use something similar to:
ocamlc -I +lablgtk2 -w s lablgtk.cma gtkInit.cmo ???.ml -o ???
How to use the threaded toplevel:
% lablgtk2 -thread
Objective Caml version 3.09
# let w = GWindow.window ~show:true ();;
# let b = GButton.button ~packing:w#add ~label:"Hello!" ();;
You should at once see a window appear, and then a button.
The GTK main loop is running in a separate thread. Any command
is immediately reflected by the system.
For Windows and OSX/Quartz, there are restrictions on which
commands can be used in which thread. See the windows port section
lower for how to use them.
When using threads in a stand-alone application, you must link with
gtkThread.cmo and call GtkThread.main in place of GMain.main.
Since 2.16.0, busy waiting is no longer necessary with systems
threads. (I.e., CPU usage is 0% if nothing occurs.)
If you use VM threads, you have to enable busy waiting by hand,
otherwise other threads won't be executed (cf. gtkThread.mli).
Beware that with VM threads, you cannot switch threads within
a callback. The only thread related command you may use in a
callback is Thread.create. Calling blocking operations may cause
deadlocks. On the other hand, all newly created threads will be run
outside of the callback, so they can use all thread operations.
Structure of the (raw) Gtk* modules:
These modules are composed of one submodule for each class.
Signals specific to a widget are in a Signals inner module.
A setter function is defined to give access to set_param functions.
Structure of the G[A-Z]* modules:
These modules provide classes to wrap the raw function calls.
Here are the widget classes contained in each module:
GPango Pango font handling
GDraw Gdk pixmaps, etc...
GObj gtkobj, widget, style
GData data, adjustment, tooltips
GContainer container, item_container
GWindow window, dialog, color_selection_dialog, file_selection, plug
GPack box, button_box, table, fixed, layout, packer, paned, notebook
GBin scrolled_window, event_box, handle_box, frame,
aspect_frame, viewport, socket
GButton button, toggle_button, check_button, radio_button, toolbar
GMenu menu_item, tearoff_item, check_menu_item, radio_menu_item,
menu_shell, menu, option_menu, menu_bar, factory
GMisc separator, statusbar, calendar, drawing_area,
misc, arrow, image, pixmap, label, tips_query,
GTree tree_item, tree, view (also tree/list_store, model)
GList list_item, liste, clist
GEdit editable, entry, spin_button, combo
GRange progress, progress_bar, range, scale, scrollbar
GText view (also buffer, iter, mark, tag, tagtable)
While subtyping follows the Gtk widget hierarchy, you cannot always
use width subtyping (i.e. #super is not unifiable with all the
subclasses of super). Still, it works for some classes, like
#widget and #container, and allows subtyping without coercion towards
these classes (cf. #container in examples/pousse.ml for instance).
Practically, each widget class is composed of:
* a coerce method, returning the object coerced to the type widget.
* an as_widget method, returning the raw Gtk widget used for packing, etc...
* a destroy method, sending the destroy signal to the object.
* a get_oid method, the equivalent of Oo.id for Gtk objects.
* a connect sub-object, allowing one to widget specific
signals (this is what prevents width subtyping in subclasses.)
* a misc sub-object, giving access to miscellanous functionality of
the basic gtkwidget class, and a misc#connect sub-object.
* an event sub-object, for Xevent related functions (only if the widget
has an Xwindow), and an event#connect sub-object.
* a drag sub-object, containing drag and drop functions,
and a drag#connect sub-object.
* widget specific methods.
Here is a diagram of the structure (- for methods, + for sub-objects)
- coerce : widget
- as_widget : Gtk.widget obj
- destroy : unit -> unit
- get_oid : int
+ connect : mywidget_signals
| - after
| - signal_name : callback:(... -> ...) -> GtkSignal.id
+ misc : misc_ops
| - show, hide, disconnect, ...
| + connect : misc_signals
+ drag : drag_ops
| - ...
| + connect : drag_signals
+ event : event_ops
| - add, ...
| + connect : event_signals
You create a widget by [<Module>.<widget name> options ... ()].
Many optional arguments are admitted. The last two of them, packing:
and show:, allow you respectively to call a function on your newly
created widget, and to decide wether to show it immediately or not.
By default all widgets except toplevel windows (GWindow module) are
For many constructor or method arguments, default values are provided.
Generally, this default value is defined by GTK, and you must refer
to GTK's documentation.
For ML defined defaults, usually default values are either false, 0, None
or `NONE, according to the expected type.
Important exceptions are ~show, which default to true in all widgets
except those in GWindow, and ~fill, which defaults to true or `BOTH.
Note about unit as method argument:
O'Caml introduces no distinction between methods having side-effects
and methods simply returning a value. In practice, this is
confusing, and awkward when used as callbacks. For this reason all
methods having noticeable side-effects should take arguments, and
unit if they have no argument.
The GUtil module provides two kinds of utilities: a memo table, to be
able to dynamically cast widgets to their original class, and more
interesting ML-side signals.
With ML-side signals, you can combine LablGTK widgets into your own
components, and add signals to them. Later you can connect to these
signals, just like GTK signals. This proved very efficient to
develop complex applications, abstracting the plumbing between
various components. Explanations are provided in GUtil.mli.
The GToolbox module contains contributed components to help you build
Important efforts have been dedicated to cooperate with Gtk's
reference counting mechanism. As a result you should generally be
able to use Gdk/Gtk data structures without caring about memory
management. They will be freed when nobody points to them any more.
This also means that you do not need to pay too much attention to
whether a data structure is still alive or not. If it is not, you
should get an error rather than a core dump.
The case of Gtk objects deserves special care. Since they are
interactive, we cannot just destroy them when they are no longer
referenced. They have to be explicitely destroyed. If a widget was
added to a container widget, it will automatically be destroyed when
its last container is destroyed. For this reason you need only
destroy toplevel widgets.
Since too frequent GC can severely degrade performance, since 2.18.4
it is possible to change the contribution of custom blocks to the
GC cycle, using the function GMain.Gc.set_speed. The default is 10%
of what it was in 2.18.3. If you set it to 0, custom block allocation
has no impact, and you should consider running the Gc by hand.
IMPORTANT: Some Gtk data structures are allocated in the Caml heap,
and their use in signals (Gtk functions internally cally callbacks)
relies on their address being stable during a function call. For
this reason automatic compation is disabled in GtkMain. If you need
it, you may use compaction through Gc.compact where it is safe
(timeouts, other threads...), but do not enable automatic compaction.
There is support for Glade generated XML UI description files, using
libglade. You can read in a file, access to widgets, and define
A tool for extracting widget definitions from glade description is
provided. It generates a wrapper class, and you can then generate an
object corresponding to the intended layout, and access individual
widgets through its methods. Example:
% lablgladecc2 project1.glade > project1.ml
% lablgtk2 -thread
# #use "project1.ml" ;;
class window1 : ...
# let w1 = new window1 () ;;
# w1#bind ~name:"on_paste1_activate"
~callback:(fun () -> w1#text1#insert "some text\n");;
See lablgladecc2 -help for other features (tracing and source
The executable must be linked with lablglade.cma.
You can use lablgtk in combination with LablGL
* get and install lablGL 1.05 from
* get and install gtkglarea-1.99.0.tar.gz from
or any other gnome mirror site
You can then use the widget GlGtk.gl_area as an OpenGL window.
Some examples are in examples/GL, but basically any LablGL example
can be easily ported.
The executable must be linked with both lablgl.cma and
This binding was contributed by Olivier Andrieu.
It requires librsvg-2.x (preferably 2.2.x).
See an example in examples/rsvg.
The executable must be linked with lablrsvg.cma.
This binding was also contributed by Olivier Andrieu.
It requires libgnomecanvas-2.x.
See examples in examples/canvas.
The executable must be linked with lablgnomecanvas.cma.
GtkSourceView 1 support:
This binding was contributed by Maxence Guesdon and Stefano Zacchiroli.
It requires libgtksourceview-1.x.
See examples in examples/sourceview.
The executable must be linked with lablgtksourceview.cma.
GtkSourceView 2 support:
This binding was contributed by Benjamin Monate: it is based on
the aforementioned GtksourceView 1 support.
It requires libgtksourceview-2.x.
See examples in examples/sourceview/*2.ml
The executable must be linked with lablgtksourceview2.cma.
See README.win32 for detailed information on installation.
If you want to use threads, you must be aware of windows specific
restrictions; see for instance:
I.e. all GTK related calls must occur in the same thread, the one
that runs the main loop. If you want to call them from other threads
you need to do some forwarding. Fortunately, with a functional
language this is easy. Two functions,
val async : ('a -> unit) -> 'a -> unit
val sync : ('a -> 'b) -> 'a -> 'b
are available in the GtkThread module to help you. They will forward
your call to the main thread (between handling two GUI events). This
can be either asynchronous or synchronous. In the synchronous case,
beware of deadlocks (the trivial case, when you are calling from the
same thread, is properly avoided). Note also that since callbacks
are always called from the main loop thread, you can freely use GTK
in them. Also, non-graphical operations are thread-safe.
Here is an example using the lablgtk toplevel with threads:
% lablgtk2.bat -thread
Objective Caml version 3.09
# open GtkThread;;
# let w = sync (GWindow.window ~show:true) ();;
# let b = sync (GButton.button ~packing:w#add ~label:"Hello!") ();;
# b#connect#clicked (fun () -> prerr_endline "Hello");;
Since Darwin is Unix, this port compiles as usual.
Note however that Quartz imposes even stronger restrictions than
Windows on threads: only the main thread of the application can do
GUI work. Just apply the same techniques as described above, being
careful to ensure that your first call to GtkThread.main occurs in
the main thread. This is done automatically in the threaded toplvel.
Jacques Garrigue <firstname.lastname@example.org>
Benjamin Monate <email@example.com>
Olivier Andrieu <firstname.lastname@example.org>
Adrien Nader <email@example.com>
Jun Furuse <firstname.lastname@example.org>
Maxence Guesdon <email@example.com>
Stefano Zacchiroli <firstname.lastname@example.org>
Hubert Fauque <email@example.com>
Koji Kagawa <firstname.lastname@example.org>