[racket] Changing the background color of a GUI button.

You could change the button child of the GUI and bring in a completely new button with a different color. -- Matthias



On Feb 21, 2012, at 12:53 PM, Matthew Flatt wrote:

> The idea of `set-state-normal' and `set-state-selected' sounds like a
> `check-box%' rather than a `button%'.
> 
> Otherwise, there's no way to change the background color of a `button%'
> instance. Classes like `button%' correspond to platform-specific GUI
> widgets that typically either don't support or strongly discourage the
> possibility of changing a button's background (because button colors
> are normally determined by a theme). You can create a `canvas%' that
> draws a custom button image, in which case you have complete control
> over how the button looks and reacts, but there isn't much of an
> in-between level of customization in the current toolkit.
> 
> At Tue, 21 Feb 2012 00:25:52 -0700, Kieron Hardy wrote:
>> Hi all,
>> 
>> How do I change the background color (and/or style of border etc.) of a GUI
>> button? Given the code below, what should I put in the set-state-x methods
>> to indicate a difference between a normal and selected button?
>> 
>> Also any comments on program style and/or substance are appreciated (I
>> apologize in advance if the layout offends).
>> 
>> Cheers,
>> 
>> Kieron.
>> 
>> ****
>> 
>> #lang racket/gui
>> 
>> (define color-button%
>>  (class button%
>>    (inherit refresh)
>> 
>>    (define toggle
>>      (let ([f #f])
>>        (lambda ()
>>          (set! f (not f))
>>          f
>>          )
>>        )
>>      )
>> 
>>    (define (set-state-normal)
>>      (printf "color-button%: set-state-normal:\n")
>>      ; ??? ; set background color to normal
>>      (refresh)
>>      )
>> 
>>    (define (set-state-selected)
>>      (printf "color-button%: set-state-selected:\n")
>>      ; ??? ; set background color to red
>>      (refresh)
>>      )
>> 
>>    (define click-callback
>>      (lambda (button control-event)
>>        (printf "color-button%: click-callback:\n")
>>        (if (toggle)
>>          (set-state-selected)
>>          (set-state-normal)
>>          )
>>        )
>>      )
>> 
>>    (super-new (callback click-callback))
>> 
>>    )
>>  )
>> 
>> (define f (new frame%
>>               [label "Colored Button"]
>>               [min-width 100]
>>               [min-height 200]
>>               )
>>  )
>> 
>> (define b (new color-button%
>>              [parent f]
>>              [label "push me"]
>>              )
>>  )
>> 
>> (send f show #t)
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