ruby-****@lists*****
ruby-****@lists*****
2003年 8月 10日 (日) 00:37:07 JST
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REMOTE_ADDR = 217.117.37.226
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URL = http://ruby-gnome2.sourceforge.jp/?tut-gtk2-signals-callbacks
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= Mechanism of signals and callbacks
Before looking at the "Hello World" program in details, we should study a bit how GTK handles signals and
callbacks.
In the same way as your system delivers a signal to processes upon shutdown
((-Note that GTK signals are not related in any way with UNIX signals. The GTK toolkit has been conceived
to be independant of the underlying system. -)), GTK sends a signal to the main loop (Gtk.main) when a
special event occured. The main loop will therefore call back the appropriate function of the widget.
Until a signal is received, the main loop will sleep.
In order to tell a GTK widget that it has to catch a specific signal, and then execute appropriate code,
we need to set a signal handler.
This can be done with the GLib::Instantiatable#signal_connect method, which is part of the Ruby/GLib library
(do not forget that GTK is built on GLib):
GLib::Instantiatable#signal_connect("signal name") do
# Code to execute when "signal name" has been catched.
end
GLib::Instantiatable#signal_connect needs 2 things:
* the name of the signal that the widget should catch;
* a block code that will be executed upon reception of the given signal.
The block code can take an optional parameter as follows:
GLib::Instantiatable#signal_connect("signal name") do |w|
# ...
end
The widget which issues the signal will be therefore substituted by the parameter w.