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Object
+--- Widget
+--- Container
+--- Box
+--- HBox
+--- Combo
The combo box is fairly simple widget that is really just a collection of other widgets. From the user's point of view, the widget consists of a text entry box and a pulldown menu from which the user can select one of a set of predefined entries. Alternatively, the user can type a different option directly into the text box.
The following extracts from the structure that defines a Combo
Box identifies several of the components:
Gtk::Combo
-> hbox
-> entry
-> button
-> popup
-> popwin
-> list
As you can see, the Combo Box has two principal parts that you really care about: an entry and a list.
First off, to create a combo box, use:
$combo = new Gtk::Combo();
Now, if you want to set the string in the entry section of the
combo box, this is done by manipulating the
entry
widget directly:
$combo->entry->set_text( "My String." );
To set the values in the popdown list, use the function:
$combo->set_popdown_strings( @strings );
Before you can do this, you have to assemble a list of the
strings that you want. Any Perl expression that can be
evaluated as a list can be use as an argument. A comma
seperated, double-quoted list of strings is most common. To
append to this list, use:
$combo->list = ( $combo->list, "append1", "append2", ... );
As suggested above, anything that you can do to a Perl list (which is a lot), you can also do to the Combo List.
Here's a typical code segment for creating a set of options:
@list = ( "String1", "String2", "String3" ); $combo->set_popdown_strings( "String1", "String2", "String3" );
Or, if you prefer terse code:
$combo->set_popdown_strings( @list );
If you want to let the user change the value in the entry using
the up/down arrow keys, use:
$combo->set_use_arrows( $use_arrows );
where
$use_arrows
is a true or false value. This doesn't bring up the list, but
rather replaces the current text in the entry with the next list
entry (up or down, as your key choice indicates). It does this
by searching in the list for the item corresponding to the
current value in the entry and selecting the previous/next item
accordingly. Usually in an entry the arrow keys are used to
change focus (you can do that anyway using TAB). Note that when
the current item is the last of the list and you press
arrow-down it changes the focus (the same applies with the first
item and arrow-up).
If the current value in the entry is not in the list, then the function of set_use_arrows() is disabled.
If you want the up/down arrow keys to cycle through the choices
in the dropdown list, except that it wraps around the values in
the list, use:
$combo->set_use_arrows_always( $use_arrows );
This will completely disable the use of the up and down arrow
keys for changing focus.
To determine whether GTK searches for entries in a case
sensitive manner or not, use:
$combo->set_case_sensitive( $case );
This is used when the Combo widget is asked to find a value from
the list using the current entry in the text box. This
completion can be performed in either a case sensitive or
insensitive manner, depending upon the use of this function. The
Combo widget can also simply complete the current entry if the
user presses the key combination MOD-1 and "Tab". MOD-1 is often
mapped to the "Alt" key, by the
xmodmap
utility. Note, however that some window managers also use this
key combination, which will override its use within GTK.
If you wish to specify whether the value entered into the entry
must be one of the items in the list, you can do so with:
$combo->set_value_in_list( $must_match, $ok_if_empty );
Where if
$must_match
is a true value, the value entered must be one of the values in
the list, and
$ok_if_empty
is a true or false value that determines if an empty field is
acceptable.
If an item in the list isn't a simple label, you might have to
tell GTK what that label is. You would do so with:
$combo->set_item_string( $item, $string );
where
$item
is the item in the list you wish to set, and
$string
is the label. Without this, GTK might not know what to put the
the entry field.
You can stop the Combo widget from showing the popup list when
the entry emits an
'activate' signal using:
$combo->disable_activate();
This could be useful if you want the Return key to close a
dialog instead. In most cases, though, you should leave it
alone.
Now that we have a combo box, tailored to look and act how we
want it, all that remains is being able to get data from the
combo box. This is relatively straightforward. Most of the
time, all you are going to care about getting data from is the
entry. The entry is accessed simply by
combo->entry
.
The two principal things that you are going to want to do with
it are attach to the activate signal, which indicates that the
user has pressed the Return or Enter key, and read the text. The
first is accomplished using something like:
$combo->entry->signal_connect( "activate", \&callback );
Getting the text at any arbitrary time is accomplished by simply
using the entry function:
$combo->entry->get_text();
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