Wrong spacing using stretch effect

Wrong spacing using stretch effect

[Marco Patzer]

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Hi,

the stretch effect does not take the final width of the string into
account. Is this a bug or a limitation? Example:

\starttext
  (\effect[stretch]{fftabc})\par  %% “c” collides with “)”
  (\kerncharacters[.05]fftabc)    %% no collision
\stoptext

Marco

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Re: Wrong spacing using stretch effect

[Hans Hagen]

On 9/25/2013 12:32 PM, Marco Patzer wrote:
> Hi,
>
> the stretch effect does not take the final width of the string into
> account. Is this a bug or a limitation? Example:
>
> \starttext
>    (\effect[stretch]{fftabc})\par  %% “c” collides with “)”
>    (\kerncharacters[.05]fftabc)    %% no collision
> \stoptext

these are unrelated mechanisms where the first one just does some pdf 
magic ... no feedback to tex about widths (ok, i could write something 
better but never had and still don't have a reason for that kind of low 
level pdf based approach to be really deeply integrated)

a better test is this:

   (\effect[stretch]{\dorecurse{50}{x}})\par  %% “c” collides with “)”


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                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
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                                              | www.pragma-pod.nl
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Re: Wrong spacing using stretch effect

[Marco Patzer]

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On 2013–09–30 Hans Hagen wrote:

> these are unrelated mechanisms where the first one just does some
> pdf magic ... no feedback to tex about widths (ok, i could write
> something better but never had and still don't have a reason for
> that kind of low level pdf based approach to be really deeply
> integrated)

Thanks for the explanation. I was looking for a way to do slight
letter spacing without breaking ligatures and thought I could
leverage the stretch effect for that.

Marco

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Re: Wrong spacing using stretch effect

[Hans Hagen]

On 10/1/2013 10:05 AM, Marco Patzer wrote:
> On 2013–09–30 Hans Hagen wrote:
>
>> these are unrelated mechanisms where the first one just does some
>> pdf magic ... no feedback to tex about widths (ok, i could write
>> something better but never had and still don't have a reason for
>> that kind of low level pdf based approach to be really deeply
>> integrated)
>
> Thanks for the explanation. I was looking for a way to do slight
> letter spacing without breaking ligatures and thought I could
> leverage the stretch effect for that.

well, we break ligatures because ligatures make no sense in that kind of 
kerned text (if they make sense at all, but that's a different issue

Hans

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                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
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Re: Wrong spacing using stretch effect

[Khaled Hosny]

On Tue, Oct 01, 2013 at 11:20:52AM +0200, Hans Hagen wrote:
> On 10/1/2013 10:05 AM, Marco Patzer wrote:
> >On 2013–09–30 Hans Hagen wrote:
> >
> >>these are unrelated mechanisms where the first one just does some
> >>pdf magic ... no feedback to tex about widths (ok, i could write
> >>something better but never had and still don't have a reason for
> >>that kind of low level pdf based approach to be really deeply
> >>integrated)
> >
> >Thanks for the explanation. I was looking for a way to do slight
> >letter spacing without breaking ligatures and thought I could
> >leverage the stretch effect for that.
> 
> well, we break ligatures because ligatures make no sense in that
> kind of kerned text (if they make sense at all, but that's a
> different issue

Some ligatures should not be broken in letter-spaced text, typically
represented by rlig in OpenType, e.g. Fraktur ch, ck, ſt and tz
ligatures:
http://unifraktur.sourceforge.net/letterspacing.html

Regards,
Khaled
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Re: Wrong spacing using stretch effect

[Philipp Gesang]

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···<date: 2013-10-01, Tuesday>···<from: Khaled Hosny>···

> On Tue, Oct 01, 2013 at 11:20:52AM +0200, Hans Hagen wrote:
> > On 10/1/2013 10:05 AM, Marco Patzer wrote:
> > >On 2013–09–30 Hans Hagen wrote:
> > >
> > >>these are unrelated mechanisms where the first one just does some
> > >>pdf magic ... no feedback to tex about widths (ok, i could write
> > >>something better but never had and still don't have a reason for
> > >>that kind of low level pdf based approach to be really deeply
> > >>integrated)
> > >
> > >Thanks for the explanation. I was looking for a way to do slight
> > >letter spacing without breaking ligatures and thought I could
> > >leverage the stretch effect for that.
> > 
> > well, we break ligatures because ligatures make no sense in that
> > kind of kerned text (if they make sense at all, but that's a
> > different issue
> 
> Some ligatures should not be broken in letter-spaced text, typically
> represented by rlig in OpenType, e.g. Fraktur ch, ck, ſt and tz
> ligatures:
> http://unifraktur.sourceforge.net/letterspacing.html
 

When using the characterkerning method you can exempt ligatures
and character pairs from being letterspaced by defining the
functions typesetters.kerns.keepligature (<liganode>) and
typesetters.kerns.keeptogether (<prevglyph>, <glyph>),
respectively. If the function returns a truish value for the
given input, ligatures won’t be decomposed and no extra kerning
will be applied.

Best regards
Philipp



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Re: Wrong spacing using stretch effect

[Marco Patzer]

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On 2013–10–01 Philipp Gesang wrote:

> When using the characterkerning method you can exempt ligatures
> and character pairs from being letterspaced by defining the
> functions typesetters.kerns.keepligature (<liganode>) and
> typesetters.kerns.keeptogether (<prevglyph>, <glyph>),
> respectively. If the function returns a truish value for the
> given input, ligatures won’t be decomposed and no extra kerning
> will be applied.

I didn't know ConTeXt supports that. And it's even highly
customizable. Thank you very much.

Marco

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Re: Wrong spacing using stretch effect

[Hans Hagen]

On 10/1/2013 12:17 PM, Marco Patzer wrote:
> On 2013–10–01 Philipp Gesang wrote:
>
>> When using the characterkerning method you can exempt ligatures
>> and character pairs from being letterspaced by defining the
>> functions typesetters.kerns.keepligature (<liganode>) and
>> typesetters.kerns.keeptogether (<prevglyph>, <glyph>),
>> respectively. If the function returns a truish value for the
>> given input, ligatures won’t be decomposed and no extra kerning
>> will be applied.
>
> I didn't know ConTeXt supports that. And it's even highly
> customizable. Thank you very much.

in next beta

\starttext

     \definefontfeature[unifraktur][default][goodies=unifraktur]

     \definedfont[UnifrakturCook*unifraktur]

     ſitzen / ch ck ſt tz fi

     \start \kerncharacters[.5]
         ſitzen / ch ck ſt tz fi
     \stop
     ‍
\stoptext

It's a somewhat messy area (e.g. in unifraktur names we see zwj's being 
injected in names) so we control it via a goodie file (predictable at 
least).

Hans

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                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
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Re: Wrong spacing using stretch effect

[Hans Hagen]

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On 10/1/2013 7:58 PM, Hans Hagen wrote:
> On 10/1/2013 12:17 PM, Marco Patzer wrote:
>> On 2013–10–01 Philipp Gesang wrote:
>>
>>> When using the characterkerning method you can exempt ligatures
>>> and character pairs from being letterspaced by defining the
>>> functions typesetters.kerns.keepligature (<liganode>) and
>>> typesetters.kerns.keeptogether (<prevglyph>, <glyph>),
>>> respectively. If the function returns a truish value for the
>>> given input, ligatures won’t be decomposed and no extra kerning
>>> will be applied.
>>
>> I didn't know ConTeXt supports that. And it's even highly
>> customizable. Thank you very much.

I've added a slightly more advanced control ... not yet uploaded (as 
Idris has to test something else first). See attached. I'm still in 
doubt if we have to add ccmp to the default feature set.

Hans

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                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------

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