On Thu, Apr 28, 2011 at 11:24:43PM +0200, Nicolas Cellier wrote:
> 
> 2011/4/28 Chris Wright <cawright.99 at gmail.com>:
> >
> > running the example from the Pen class
> > Display restoreAfter:
> > [Pen new squareNib: 2; color: Color red; turn: 45;
> > ? ? ? ?print: 'The owl and the pussycat went to sea in a beautiful pea green
> > boat.' withFont: TextStyle defaultFont]
> >
> > draws a patterned red line at the correct angle, but with no recognisable text.
> >
> > same problem with the "Terse guide to squeak" Pen example.
> >
> > I'm not sure where to look to see if this is a known problem... and if
> > there's a fix :?
> >
> > and received the following reply from Jerome Peace (thanks!)
> >
> > I tried your code in a 4.3 squeak and got your described results. Went
> > back to a 3.9 squeak and got the results expected with the printing
> > actually working. So I suspect there is a problem. I suspect it is not
> > known. I wonder if the problem is that color is now setting both
> > foreground and background.
> >
> > I am not actively doing bug tracking in squeak right now. So hopefully
> > someone else will look to see what changed. Anyway you have found a
> > real bug. A good place to note it would be on the squeak-dev list and
> > the mantis bug tracker.
> > http://bugs.squeak.org/view_all_bug_page.php
> >
> > So, I'm posting, as instructed!
> >
> One way to understand what is going on is to debugIt
> It seems that Pen>>print:withFont: assumes that the background pixel
> code of the character form is zero.
> This does not happen to be true, is it an effect of anti-aliasing ?
> I join the
>     (form magnifyBy: 16) asMorph openInWorld
> of the first letter T.
> 
> The character form is currently of depth 16.
> In my 4.3 updated trunk image, background code seems to be 32767
> (I don't know why 15 bits when form depth is 16, maybe 5 bits per
> color channel...).
> 
> I guess the code was written for depth 1 forms (0 = pen up = white, 1
> = pen down = black).
> 
> Maybe we can try using this snippet:
>     backgroundColorCode := 1 << (form depth // 3 * 3) - 1.
> This would work both for depth 16 and 1...
> 
> Then use:
>     value = backgroundColorCode
> instead of:
>     value = 0
> 
> But I'm not sure this hack is general enough...
> 
> Anyway, the result still looks ugly.
> Again this is probably related to anti-aliasing.

The problem is also related to the font being used.

In 3.8, we have TextStyle defaultFont ==> a StrikeFontSet(Accuny12 12)
In Squeak trunk we are using TextStyle defaultFont ==> a StrikeFont(Bitmap DejaVu Sans 9 14)
And if we use the same font as was used in Squeak 3.8, the example works:

  sq38Font := StrikeFont familyName: 'Accuny' size: 12. " ==> a StrikeFontSet(Accuny12 12)"
  Display restoreAfter: [Pen new squareNib: 2; color: Color red; turn: 45;
	print: 'The owl and the pussycat went to sea in a beautiful pea green boat.'
	withFont: sq38Font]

I think it is somehow related to the bit peeker in Pen>>print:withFont:
which seems to be created incorrectly when using the DejaVu Sans font,
but I'm not sure why.

Dave