A single radio button performs the same basic function as a GtkCheckButton,
as its position in the object hierarchy reflects. It is only when multiple
radio buttons are grouped together that they become a different user
interface component in their own right.
Every radio button is a member of some group of radio buttons. When one is selected, all other
radio buttons in the same group are deselected. A GtkRadioButton is one way
of giving the user a choice from many options. Radio button widgets are created with gtkRadioButtonNew, passing NULL
as the argument if this is the first radio button in a group. In subsequent
calls, the group you wish to add this button to should be passed as an
argument. Optionally, gtkRadioButtonNewWithLabel can be used if you
want a text label on the radio button. Alternatively, when adding widgets to an existing group of radio buttons,
use gtkRadioButtonNewFromWidget with a GtkRadioButton that already
has a group assigned to it. The convenience function
gtkRadioButtonNewWithLabelFromWidget is also provided. To retrieve the group a GtkRadioButton is assigned to, use
gtkRadioButtonGetGroup. To remove a GtkRadioButton from one group and make it part of a new one, use gtkRadioButtonSetGroup. The group list does not need to be freed, as each GtkRadioButton will remove
itself and its list item when it is destroyed. How to create a group of two radio buttons.
# Creating two radio buttons
create_radio_buttons <- function() { window <- gtkWindow("toplevel", show = F)
box <- gtkVBoxNew(TRUE, 2) ## Create a radio button with a GtkEntry widget
radio1 <- gtkRadioButton()
entry <- gtkEntry()
radio1$add(entry) ## Create a radio button with a label
radio2 <- gtkRadioButtonNewWithLabelFromWidget(radio1,
"I'm the second radio button.") ## Pack them into a box, then show all the widgets
box$packStart(radio1, TRUE, TRUE, 2)
box$packStart(radio2, TRUE, TRUE, 2)
window$add(box)
window$showAll()
}
When an unselected button in the group is clicked the clicked button
receives the "toggled" signal, as does the previously selected button.
Inside the "toggled" handler, gtkToggleButtonGetActive can be used
to determine if the button has been selected or deselected.