[devel] XLFD font naming convention

[Lucien Gentis]

Le 04/03/2019 à 18:18, Ilya Anfimov a écrit :
> On Mon, Mar 04, 2019 at 05:29:10PM +0100, Lucien Gentis wrote:
>> Le 04/03/2019 ?? 16:20, Ilya Anfimov a ??crit :
>>> On Fri, Mar 01, 2019 at 06:09:02PM +0100, Lucien Gentis wrote:
> [skipped]
>
>>>> we get scalable fonts with fields 7,8,12 at "0" like :
>>>>
>>>> -bitstream-charter-medium-i-normal--0-0-75-75-p-0-iso8859-1
>>>> -dec-terminal-medium-r-normal--0-0-75-75-c-0-dec-dectech
>>>>
>>>> but if we call :
>>>>
>>>> XListFonts(serveur, "-*-*-*-*-*-*-0-*-*-*-*-*-*-*", 10000, &nbFonts);
>>>>
>>>> we also get fonts with only field 7 at "0" like :
>>>>
>>>> -bitstream-charter-bold-r-normal--0-120-100-100-p-0-iso8859-1
>>>> -adobe-new century schoolbook-bold-r-normal--0-120-100-100-p-0-iso10646-1
>>>>
>>>> what about these fonts ?
>>>    Well, X Logical Font Description Conventions
>>>                   Version 1.5
>>> 		says (section 5):
>>>
>>>     "For a scalable font source, a scalable font name for each
>>>     character set is included in the list.  In addition to
>>>     the scalable font name, specific derived instance names
>>>     may also be included in the list."
>>>     ...
>>>     "Because some existing applications rely on seeing a collection
>>>     of point and pixel sizes, server vendors are strongly
>>>     encouraged in the near term to provide a mechanism for
>>>     including, for each scalable font name, a set of specific
>>>     derived instance names. For font sources that contain a set of
>>>     specific derived instance names."
>>>
>>>    So  it  is OK to have that in font list. It must be --0-0-  base
>>> name for every such font, and if it is not -- there is  an  error
>>> somewhere in your X server or font server, and probably should be
>>> fixed. If there are base entries -- then you  don't need them.
>> But how to determine if a font is scalable or not when its fields 7, 8 and
>> 12 are not at "0" ?
>   Why do you need it?
>   Usually you can safely assume, that this font is not scalable.

I don't really need it, existing choice is big enough !

But I only wanted to know the signification of "0" field in -adobe-new 
century schoolbook-bold-r-normal--0-120-100-100-p-0-iso10646-1

I did these (easy to reproduce) tests with xfontsel and xlsfonts commands :

*xfontsel :*

- if we select a point size of 120, it's impossible to select a pixel 
size of 0

- if we select a pixel size of 0, we only have the choice between * or 0 
for point size

*xlsfonts :*

- xlsfonts -fn "-*-*-*-*-*-*-0-*-*-*-*-*-*-*" (pixel size of 0) : we can 
see scalable fonts and fonts like -adobe-new century 
schoolbook-bold-r-normal--0-120-100-100-p-0-iso10646-1

- xlsfonts -fn "-*-*-*-*-*-*-0-120-*-*-*-*-*-*" (pixel size of 0, point 
size of 120) : we can see fonts like -adobe-new century 
schoolbook-bold-r-normal--0-120-100-100-p-0-iso10646-1

- xlsfonts -fn "-*-*-*-*-*-*-*-120-*-*-*-*-*-*" (point size of 120) :we 
don't see anymore fonts like -adobe-new century 
schoolbook-bold-r-normal--0-120-100-100-p-0-iso10646-1, which is 
confusing because "-*-120-" also matches "-0-120-"


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