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class Fl_Choice

Class Hierarchy

Fl_Menu_
   |
   +----Fl_Choice

Include Files

#include <FL/Fl_Choice.H>

Description

This is a button that when pushed pops up a menu (or hierarchy of menus) defined by an array of Fl_Menu_Item objects. Motif calls this an OptionButton.

The only difference between this and a Fl_Menu_Button is that the name of the most recent chosen menu item is displayed inside the box, while the label is displayed outside the box. However, since the use of this is most often to control a single variable rather than do individual callbacks, some of the Fl_Menu_Button methods are redescribed here in those terms.

When the user picks an item off the menu the value() is set to that item and then the item's callback is done with the menu_button as the Fl_Widget* argument. If the item does not have a callback the menu_button's callback is done instead.

All three mouse buttons pop up the menu. The Forms behavior of the first two buttons to increment/decrement the choice is not implemented. This could be added with a subclass, however.

The menu will also pop up in response to shortcuts indicated by putting a '&' character in the label(). See Fl_Button for a description of this.

Typing the shortcut() of any of the items will do exactly the same as when you pick the item with the mouse. The '&' character in item names are only looked at when the menu is popped up, however.

Fl_Choice widget.

Fl_Choice::Fl_Choice(int x, int y, int w, int h, const char *label = 0)

Creates a new Fl_Choice widget using the given position, size, and label string. The default boxtype is FL_UP_BOX.

The constructor sets menu() to NULL. See Fl_Menu_ for the methods to set or change the menu.

virtual Fl_Choice::~Fl_Choice()

The destructor removes the Fl_Choice widget and all of its menu items.

int Fl_Choice::value() const
int Fl_Choice::value(int)
int Fl_Choice::value(const Fl_Menu *)

The value is the index into the Fl_Menu array of the last item chosen by the user. It is zero initially. You can set it as an integer, or set it with a pointer to a menu item. The set routines return non-zero if the new value is different than the old one. Changing it causes a redraw().

int Fl_Widget::changed() const

This value is true if the user picks a different value. It is turned off by value() and just before doing a callback (the callback can turn it back on if desired).

void Fl_Widget::set_changed()

This method sets the changed() flag.

void Fl_Widget::clear_changed()

This method clears the changed() flag.

Fl_Boxtype Fl_Choice::down_box() const
void Fl_Choice::down_box(Fl_Boxtype b)

The first form gets the current down box, which is used when the menu is popped up. The default down box type is FL_DOWN_BOX The

User Comments [ Add Comment ]

From eb, 05:39 Jul 25, 2007 (score=3)

what if we have 2000 lines for menus ? I cannot find the option setting a scrollbar for this widget.
[ Reply ]

From eb, 05:39 Jul 25, 2007 (score=3)

what if we have 2000 lines for menus ? I cannot find the option setting a scrollbar for this widget.
[ Reply ]

From greg.ercolano, 12:25 Jul 07, 2009 (score=3)

When there are many items in the chooser, it doesn't use scrollbars to scroll the list, you move the mouse to the extreme top or bottom of the list, and it auto-scrolls.
[ Reply ]

From Jon, 18:20 Jan 06, 2005 (score=3)

When the user picks an item off the Choice, it is not clearly documented what callback is done. The behavior seems to be the same as is documented for Fl_Menu_Button, namely:

When the user picks an item off the menu, the item's callback is done with the menu_button as the Fl_Widget* argument. If the item does not have a callback the menu_button's callback is done instead.
[ Reply ]