Working on overconstrained geometry

[Jeremias Maerki <de...@jeremias-maerki.ch>]

I'm currently working on overconstrained geometry (5.3.4, XSL 1.0) and
I'm unsure what to do with the following situation:

Assume a reference IPD of 5in.
Assume an fo:block with start-indent="3in" end-indent="2.5in".

--> 5in - 3in - 2.5in = -0.5in (for content area IPD)

inline-progression-dimension is defined to treat negative lengths as
"0pt" in 7.14.5. I can see that this applies to the property and not
(directly) to the trait. Still negative values for the i-p-d trait seem
to be unwanted.

5.3.4 dictates that in this case that start-indent + end-indent +
content IPD = reference IPD.

Now, if the content IPD is forced to "0pt", the above equation doesn't
fit anymore and 5.3.4 says that end-indent is adjusted accordingly. In
this case, end-indent is set to "2in". So far, everything is clear IMO.
This was just to get you started.

Now, considering a content IPD of "0pt". What shall we do with it? I'm
currently letting it through. This produces block areas with very large
BPD due to the many breaks, i.e. each break is chosen as concrete break.
Text is painted outside the content rectangle. I know such a situation
is almost certainly a bug in the stylesheet and this situation somewhat
esotheric but still... I'm not sure what to do. The other idea is to
skip the FO if the available IPD for its contents is 0pt.

If anyone has some cool ideas, I'd be grateful, but don't waste too
much time thinking about it. :-)

Jeremias Maerki

Re: Working on overconstrained geometry

[Andreas L Delmelle <a_...@pandora.be>]

On Dec 1, 2005, at 20:26, Jeremias Maerki wrote:

> Hmm, but the 0pt is not explicit, it is implicit, derived from
> calculations. And what is "auto" in this case?
>
> Anyway, to provide the user with the means to detect problems in his
> stylesheet we'd need much more code that detects overflows, for  
> example
> if a word doesn't fit in the available space, nothing happens  
> currently.
> The word is simply painted beyond the available space.

Well, explicit in the sense that it is derived from explicitly  
specified properties. Anyway, "auto" could refer to the maximum- 
available-ipd. If even that is zero or too little, then clipping/ 
dropping the content seems to be the only viable option indeed.


Cheers,

Andreas

Re: Working on overconstrained geometry

[Jeremias Maerki <de...@jeremias-maerki.ch>]

Hmm, but the 0pt is not explicit, it is implicit, derived from
calculations. And what is "auto" in this case?

Anyway, to provide the user with the means to detect problems in his
stylesheet we'd need much more code that detects overflows, for example
if a word doesn't fit in the available space, nothing happens currently.
The word is simply painted beyond the available space.

On 01.12.2005 19:11:07 Andreas L Delmelle wrote:
> On Dec 1, 2005, at 18:13, Jeremias Maerki wrote:
> 
> Hi,
> 
> <snip />
> > Now, considering a content IPD of "0pt". What shall we do with it? I'm
> > currently letting it through. This produces block areas with very  
> > large
> > BPD due to the many breaks, i.e. each break is chosen as concrete  
> > break.
> > Text is painted outside the content rectangle. I know such a situation
> > is almost certainly a bug in the stylesheet and this situation  
> > somewhat
> > esotheric but still... I'm not sure what to do. The other idea is to
> > skip the FO if the available IPD for its contents is 0pt.
> 
> How about interpreting an explicit "0pt" as "auto"? The result will  
> still look acceptable in most cases. Combined with a warning that  
> this fallback is used, this would enable the user to locate the  
> problem. If the fallback doesn't bug him, but he wants FOP to stop  
> complaining, he will still know what to look for in his XSL-FO source.
> 
> >
> > If anyone has some cool ideas, I'd be grateful,...
> 
> Something like the above? :-)




Jeremias Maerki

Re: Working on overconstrained geometry

[Andreas L Delmelle <a_...@pandora.be>]

On Dec 1, 2005, at 18:13, Jeremias Maerki wrote:

Hi,

<snip />
> Now, considering a content IPD of "0pt". What shall we do with it? I'm
> currently letting it through. This produces block areas with very  
> large
> BPD due to the many breaks, i.e. each break is chosen as concrete  
> break.
> Text is painted outside the content rectangle. I know such a situation
> is almost certainly a bug in the stylesheet and this situation  
> somewhat
> esotheric but still... I'm not sure what to do. The other idea is to
> skip the FO if the available IPD for its contents is 0pt.

How about interpreting an explicit "0pt" as "auto"? The result will  
still look acceptable in most cases. Combined with a warning that  
this fallback is used, this would enable the user to locate the  
problem. If the fallback doesn't bug him, but he wants FOP to stop  
complaining, he will still know what to look for in his XSL-FO source.

>
> If anyone has some cool ideas, I'd be grateful,...

Something like the above? :-)


Cheers,

Andreas