1 CAPI Reference Entries

button-panel

Class

Summary

The classbutton-panel is a pane containing a number of buttons that are laid out in a particular style, and that have group behavior.

Superclasses

choice titled-pane

Subclasses

push-button-panel radio-button-panel check-button-panel

Slots

layout-class: The type of layout for the buttons.
layout-args: Initialization arguments for the layout.
callbacks: The selection callbacks for each button.

Description

The classbutton-panel inherits most of its behavior fromchoice, which is an abstract class providing support for handling items and selections. By default, a button panel is single selection (meaning that only one of the buttons can be selected at any one time), but this can be changed by specifying an interaction.

The subclassespush-button-panel,radio-button-panel andcheck-button-panel are provided as convenience classes, but they are just button panels with different interactions (:no-selection,:single-selection and:multiple-selection respectively).

The layout of the buttons is controlled by a layout of classlayout-class (which defaults torow-layout) but this can be changed to be any other CAPI layout. When the layout is created, the list of keyword argumentslayout-args is passed to themake-instance.

Each button uses the callbacks specified for the button panel itself, unless the argumentcallbacks is specified. This should be a list of callbacks (one per button) which if non-nil will be used for theselection-callback.

Forbutton-panel and its subclasses, the items supplied to the:itemsinitarg and(setf collection-items) function can contain button objects. In this case, the button is used directly in the button panel rather than a button being created by the CAPI.

This allows button size and spacing to be controlled explicitly. Note that the button must be of the appropriate type for the subclass ofbutton-panel being used, as shown in the following table:

Table 1.1 Button and panel classes
Button panel class	Button class
push-button-panel	push-button
radio-button-panel	radio-button
check-button-panel	check-button

For example,

(let ((button1 (make-instance 'capi:push-button
                              :text "button1"
                              :internal-border 20
                              :min-width 200))
      (button2 (make-instance 'capi:push-button
                              :text "button2"
                              :internal-border 20
                              :min-width 200)))
  (capi:contain (make-instance 'capi:push-button-panel
                           :items (list button1 button2)
                           :layout-args '(:x-gap 30))))

Compatibility Note
: Button panels now default to having a maximum size constrained to their minimum size as this is useful when attempting to layout button panels into arbitrary spaces without them changing size. To get the old behavior, specify:max-width nil in themake-instance.
Example

(capi:contain (make-instance 
               'capi:button-panel
               :items '(:red :green :blue)
               :print-function 'string-capitalize))

(setq buttons (capi:contain
               (make-instance
                'capi:button-panel
                :items '(:red :green :blue)
                :print-function 'string-capitalize
                :interaction :multiple-selection)))

(setf (capi:choice-selected-items buttons) 
       '(:red :green))

(capi:contain (make-instance 
               'capi:button-panel
               :items '(1 2 3 4 5 6 7 8 9)
               :layout-class 'capi:grid-layout
               :layout-args '(:columns 3)))

See also
: radio-button
check-button
push-button
set-button-panel-enabled-items