[ENH] Bob's World Gradient (was: Re: Code Challenge !!!)

Raab, Andreas Andreas.Raab at disney.com
Sat Mar 25 09:50:47 UTC 2000

Doug - Just to make my point, enclosed is a change set that does what you
want (it'll be in the next bunch of updates). File it in, go to 8bpp display
depth and execute:

0 to: 255 do:[:i|
	(FormCanvas on: Display) 
		fillRectangle: (0 at 0 extent: 400 at 400) 
		color:(Color gray: i / 255.0).
	i printString displayAt: 0 at 0.
	(Delay forMilliseconds: 100) wait].

[Note - for comparison you may want to try this without the update]

Have fun,


> -----Original Message-----
> From: Raab, Andreas [mailto:Andreas.Raab at disney.com]
> Sent: Friday, March 24, 2000 5:53 PM
> To: squeak at cs.uiuc.edu
> Cc: recipient list not shown
> Subject: RE: [ENH] Bob's World Gradient (was: Re: Code Challenge !!!)
> > Maybe I'll try to work on this at some point.  Hmm, now where in the
> > FillStyle hierarchy would HalftoneFillStyle be most appropriate...
> From my point of view - nowhere. You were talking about a 
> *very* specific
> representation of Colors for a pixel based output device and 
> there is no
> point in specifying a pixel pattern if you really mean a 
> color (that's what
> you mean, isn't it?!) If you want to do halftoning on the fly 
> the right
> place to do this is in class FormCanvas and nowhere else. So that, for
> instance, a PostScriptCanvas gets what is intended - the 
> color - rather than
> some yet-to-be-guessed-at pixel pattern. In fact, I have 
> already submitted a
> change set that tries to get rid of such a usage (for colors 
> as well as
> combination rules) because it is absolutely necessary to 
> state what you
> -mean- rather than handing in some obscure bits. If you mean 
> a color, then
> pass a color. The canvas is the thing you want to make smart enough to
> realize that on an 8bit form it might be a good idea to use a 
> dither pattern
> rather than the nearest color.
>   - Andreas

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