Neat! That would make a great planet package,
Vincent At Sat, 25 Feb 2012 11:40:32 -0700, Kieron Hardy wrote: > > Hi all, > > I needed a GUI container that allows the contained components to choose > where they are placed in the container. i.e. A container that doesn't try > to stretch and re-'place' its containees, instead letting the containees > figure out where they want to be. > > I was surprised that this particular container/containee use-case wasn't > readily available in Racket (since it is 'the' fundamental layout > elsewhere), so I implemented a version and post it here in case it is > useful to others. (If I'm going about it wrong, then please do let me know.) > > Cheers, > > Kieron. > > p.s. I notice the canvas border is actually painted only on the top and > left (see capture-self-placeable). Should the border also be painted on the > bottom and right? > > **** > > #lang racket/gui > > ; Specify in an interface the methods that a containee needs to make it > self-placeable. > (define self-placeable-containee<%> > (interface () > get-preferred-x get-preferred-y get-preferred-x-y > set-preferred-x set-preferred-y set-preferred-x-y)) > > ; Define in a mixin the default implementations for a self-placeable > containee. > (define (self-placeable-containee%% %) > (class* % (self-placeable-containee<%>) > (super-new) > > (define preferred-x 0) > (define preferred-y 0) > > (define/public (get-preferred-x) > preferred-x) > (define/public (get-preferred-y) > preferred-y) > (define/public (get-preferred-x-y) > (values preferred-x preferred-y)) > > (define/public (set-preferred-x x) > (set! preferred-x x)) > (define/public (set-preferred-y y) > (set! preferred-y y)) > (define/public (set-preferred-x-y x y) > (set! preferred-x x) > (set! preferred-y y)) > )) > > ; Define a custom container panel that can place the self-placeable > containees. > (define placer-panel% > (class panel% > (inherit get-children min-width min-height) > > (super-new) > > ; container-size is called with each child's dimensions and > strechability, > ; and returns the container's required minimum dimensions. > ; In this case, the containee size's are ignored, > ; and the container's (previously set) minimum width and height are > returned. > [define/override (container-size containee-sizes) > ; (printf "container-size:~a\n" containee-sizes) > (values (min-width) (min-height))] > > ; place-children is called with each child's dimensions and > strechability, > ; and returns each child's location and dimensions. > ; In this case, each containee is simply asked where it wants to be > (previously set). > ; No adustments are made to a containee's size so as to use any empty > space in the container. > ; i.e. A containee's strechability is ignored, and each containee > remains the (previously set) minimum width and height. > [define/override (place-children containee-sizes container-width > container-height) > ; (printf "place-children:~a\n" containee-sizes) > (map (lambda (containee-size containee) > (let*-values ([(min-width min-height h-stretch? v-stretch?) > (apply values containee-size)] > [(x y) > (send containee get-preferred-x-y)] > ) > (list x y min-width min-height))) > containee-sizes > (get-children))] > )) > > (define self-placeable-canvas% > (class (self-placeable-containee%% canvas%) > (inherit set-preferred-x-y) > (init x y) > (super-new) > (set-preferred-x-y x y) > )) > > (define frame-1 (new frame% > [label "Self Placeable Containees"] > [x 30] > [y 30] > [min-width 800] > [min-height 600])) > > (define panel-1 (new placer-panel% > [parent frame-1] > )) > > (define canvas-1 (new self-placeable-canvas% > [parent panel-1] > [style (list 'border)] > [x 25] > [y 25] > [min-width 500] > [min-height 75])) > > (define canvas-2 (new self-placeable-canvas% > [parent panel-1] > [style (list 'border)] > [x 275] > [y 275] > [min-width 100] > [min-height 100])) > > (define canvas-3 (new self-placeable-canvas% > [parent panel-1] > [style (list 'border)] > [x 600] > [y 125] > [min-width 100] > [min-height 400])) > > (send frame-1 show #t) ____________________ Racket Users list: http://lists.racket-lang.org/users
