[UI] A small change... for a start

[Gary Chambers]

The current experiment works by double dispatch to "simple" methods that were previously the main entry point on Canvas, for compatibility.  So provides the flexibility of FillStyles to utilise the existing capabilities of various canvasses.

Ideally the whole thing could be restructured back to Canvas to efficiently deal with compositing. For the moment this achieves the overall aim without excessive redesign.

----- Original message -----
From: Igor Stasenko  <siguctua at gmail.com>
To: Squeak's User Interface  <ui at lists.squeakfoundation.org>
Sent: Fri, 21 Mar 2008, 23:13:43 GMT
Subject: Re: [UI] A small change... for a start
On 21/03/2008, Gary Chambers <gazzaguru2 at btinternet.com> wrote:
> P.S. Just rectangular fills as a proof of concept for the moment.
>
>
>  > -----Original Message-----
>  > From: ui-bounces at lists.squeakfoundation.org
>
> > [mailto:ui-bounces at lists.squeakfoundation.org]On Behalf Of Gary Chambers
>  > Sent: 21 March 2008 5:59 PM
>  > To: Squeak's User Interface
>
> > Subject: RE: [UI] A small change... for a start
>  >
>  >
>  > Pinesoft-Widgets-gvc.302 on SqueakMap. Nebraska not included in
>  > changes (may do a separate package for that if there is interest).
>  >
>  > Added CompositeFillStyle. Canvas double-dispatches to the
>  > fillstyle/color/infiniteForm.
>  > Should allow more complex fills through subclassing(like pieced
>  > together from forms for a button, top-left image, top image etc.).
>  >
>  > Have fun!
>  >

It looks double-dispatch needed from a BaloonEngine, not from Canvas.
A fillStyle needs method #registerFillWith: engine.

So, it will dispatch back to BalloonEngine with messages like:

^ engine registerSolidFill: self.  "For single color fill"

^ engine registerGradientFill: self "For gradient fill"

^ engine registerBitmapFill: self "For bitmap fill"

And BaloonEngine>>registerFill: aFill should look like:
^ aFill registerFillWith: self.

Otherwise we need to extend canvas protocol with methods:

#fillRectangle:color:
#fillRectangle:gradient:
#fillRectangle:bitmap:

I don't like that there is need in additional checking for fill type
later, after canvas receives
#fillRectangle:basicFillStyle:
i think it would be better to be precise after dispatch, what basic
fill type should be used.

>  > Gary
>  >
-- 
Best regards,
Igor Stasenko AKA sig.
_______________________________________________
UI mailing list
UI at lists.squeakfoundation.org
http://lists.squeakfoundation.org/mailman/listinfo/ui