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Problem Note: This is a series of examples to show you how to change tab orders in PHP-GTK2.
Ready for something more challenging? Suppose now you have 12 buttons arranged in a circle. You would like to change the tab order to start from the top right button and traverse round the circle, just like that in a monopoly, as shown below:
Solution Here are the rules to use GtkContainer::set_focus_chain() again:.
- The method takes only one argument - an array of GtkWidgets.
- All the widgets in the array must be direct descedents of the container.
- It's not necessary to define the tab orders of all levels.
Because of Rule #2 above, there are much rework to be done. Based on the way we want the tab order to be, we have repacked the 12 buttons into the following hboxes and vboxes:
hbox_top_row to hold buttons 1 to 4.hbox_bottom_row to hold three vboxes.vbox_column1 holds buttons 5, 6 and 7.vbox_column2 holds only one button: buttons 8.vbox_column3 holds only one button: buttons 9.vbox_column4 holds buttons 10, 11 and 12.
Once you have the hboxes and vboxes in place, you then apply GtkContainer::set_focus_chain():
- To change the tab order to
hbox_top_row so that it goes from left to right.
- To change the tab order to
vbox_column4 so that it goes from bottom to top.
That's it! The rest of the tab order are defaults. So using Rule #3, we do not need to define any of them!
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| <?php
$window = new GtkWindow();
$window->set_title($argv[0]);
$window->set_size_request(480, 240);
$window->connect_simple('destroy', array('Gtk','main_quit'));
$window->add($vbox = new GtkVBox());
// display title
$title = new GtkLabel("Set tab order - Example 4");
$title->modify_font(new PangoFontDescription("Times New Roman Italic 10"));
$title->modify_fg(Gtk::STATE_NORMAL, GdkColor::parse("#0000ff"));
$title->set_size_request(-1, 40);
$title->set_justify(Gtk::JUSTIFY_CENTER);
$alignment = new GtkAlignment(0.5, 0.5, 0, 0);
$alignment->add($title);
$vbox->pack_start($alignment, 0);
$alignment = new GtkAlignment(0.5, 0.5, 0, 0);
$alignment->add($label = new GtkLabel(
"The tab orders are as indicated on the button.\n".
"It starts from the top right button and traverse ".
"round the circle like the monopoly"));
$label->set_justify(Gtk::JUSTIFY_CENTER);
$vbox->pack_start($alignment);
$vbox->pack_start(new GtkLabel(), 0);
$button_hbox = array();
$vbox->pack_start($hbox_top_row = new GtkHBox(), 0);
setup_buttons($hbox_top_row, array(4,3,2,1));
$vbox->pack_start($hbox_bottom_row = new GtkHBox(), 0);
$hbox_bottom_row->pack_start($vbox_column1 = new GtkVBox(), 0);
setup_buttons($vbox_column1, array(5,6,7));
$hbox_bottom_row->pack_start($vbox_column2 = new GtkVBox(), 0);
setup_buttons($vbox_column2, array('', '', 8));
$hbox_bottom_row->pack_start($vbox_column3 = new GtkVBox(), 0);
setup_buttons($vbox_column3, array('', '', 9));
$hbox_bottom_row->pack_start($vbox_column4 = new GtkVBox(), 0);
setup_buttons($vbox_column4, array(12, 11, 10));
// set the tab order
$hbox_top_row->set_focus_chain(array($button_hbox[1], // note 1
$button_hbox[2], $button_hbox[3], $button_hbox[4]));
$vbox_column4->set_focus_chain(array($button_hbox[10], // note 2
$button_hbox[11], $button_hbox[12]));
$window->show_all();
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- Note that this is only 70% of the sample code. You have to be a registered member to see the entire sample code. Please login or register.
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- Have some doubt about the registration? Please read this forum article.
Explanation
- Set the tab order of
hbox_top_row to go from right to left. Note the use of $button_box instead of $button, because the direct descendent is $button_box and not $button. Try changing it to $button. You will find that it won't work.
- Set the tab order of
vbox_column4 to go from bottom to top. Note the use of $button_box instead of $button, because the direct descendent is $button_box and not $button.
- In case you're wondering, I pack the button inside another layer of hbox to make it easy to create the "four holes" at the centre of the monopoly.
- Pay particular attention to this. We need the pointer to the hbox when setting the tab order.
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