1.3 Responding to button click |
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Written by kksou
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Wednesday, 12 March 2008 |
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Objective
We've displayed a button in the previous example. Now we will respond to button clicks.
Overview
- When a user presses the button, a signal clicked is generated. Think of signal as something php-gtk generates to inform you that something has occurred, in this example, the user has clicked the button.
- By connecting the signal to a callback function, every time there is a 'clicked' signal, php-gtk will automatically call the callback function that you have connected.
Sample Output
Sample Code
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| <?php
$window = new GtkWindow();
$window->connect_simple('destroy',array('Gtk','main_quit'));
$button = new GtkButton("click me!");
$button->connect('clicked', 'on_click'); // note 1
$window->add($button);
$window->show_all();
Gtk::main();
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Explanation
- Connects the signal 'clicked' to the callback function
on_click().
- This is the callback function that is called when the user clicks on the button. Here we simply echo the words "button clicked!" to the command window.
Note
- Different signals are generated by a widget for different types of events. Each signal has a unique name assigned to it. E.g. for GtkButton:
- the signal clicked is emitted when the user clicks the button.
- the signal pressed is emitted when the button is being pressed
- the signal released is emitted when the button is being released.
- You will sometimes see people referring callback functions as signal handlers, since these callback functions are used to handle signals.
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