3.5. Buttons (cx-create-button)

This section describes how you can add a button to your interface.

3.5.1. Description

While dialog boxes come with standard OK and Cancel buttons, it can sometimes be useful to add additional buttons with different functionality than the OK button. To build a new button, you must use the cx-create-button macro.

3.5.2. Usage

(cx-create-button parent label callback row column)

Argument	Type	Description
parent	object	The name of the table that you are adding the button to
label	string	The name of the button to be displayed on the GUI
callback	symbol/function	The name of the function called when the button is clicked
row	symbol/int	When added to a table, signifies the row that the button is added to
column	symbol/int	When added to a table, signifies the column that the button is added to

Note: The row and column attributes are optional. If you leave out one or both of these attributes the button will be added to the first row/column of the parent attribute and overwrite anything that is already in that spot.

3.5.3. Button Example

This example shows how the cx-create-button macro is used to create a new button, and how the callback argument works. In the cx-create-button statement below, the 'activate-callback button-cb argument ensures that the button-cb procedure is called each time that the button is clicked. The button-cb function is set up with the line (define (button-cb . args), which is just like how the apply-cb and update-cb functions are set up in a fully functional dialog box (see Comprehensive Examples). Once you open the button-cb procedure with this line you can then write the code to give it functionality.

In this example, the variable counter is incremented by 1 each time the button is clicked and the number of times that the button has been clicked is output to a text entry field txtField. This dialog box does not do anything when the OK button is clicked because we have substituted Boolean values for the apply-cb and update-cb arguments, which would normally be function calls like the button-cb argument is in the cx-create-button line. For more information on the apply-cb and update-cb functions, see cx-create-panel.

(define (apply-cb) #t)
(define update-cb #f)

(define table)
(define txtField)

(define counter 0)
(define (button-cb . args)
  (set! counter (+ counter 1))
  (cx-set-text-entry txtField (string-append "Times Clicked: " (number->string counter)))
)

(define my-dialog-box (cx-create-panel "My Dialog Box" apply-cb update-cb))

(set! table (cx-create-table my-dialog-box "This is an example Dialog Box"))

(set! txtField (cx-create-text-entry table "" 'row 0 'col 0))
(cx-create-button table "Button" 'activate-callback button-cb 'row 1 'col 0)

(cx-show-panel my-dialog-box)

To view additional examples of buttons, see Comprehensive Examples.