Re: any small software to test the incremental loading feature?

[suzuki toshiya]

Hi,

The GhostScript developers replied, "GS had never used it,
and you can assume that the GS will not use it in the future."

https://ghostscript.com/pipermail/gs-devel/2023-May/010673.html

In addition, I found that the current t1cid driver requires
a trailing section of the binary data quoted by
"%%BeginData ... (Binary)... StartData %%EndData" structure
(see cidparse.c), which is a binary stream of the offset
tables and the glyph data.

The font dictionary created in the PostScript language space,
by the incremental definition (specified in PLRM), does not
have such a section (it uses the /GlyphDirectory array or
dictionary). So if we had a nice PostScript interpreter trying
to pass an incrementally-defined font dictionary to FreeType
as a completed stream, current FreeType could not accept it.

I cannot conclude that the incremental loading feature of
t1cid is solely for PostScript's incremental definition. But
disabling it by the default configuration may have little
impact on the existing clients.

After the improvement of FT_Get_CID_From_Glyph_Index() for
t1cid, I would make another MR to document the change and
disable it by default.

Regards,
mpsuzuki

P.S.
Personally I'm interested in the enhancement of t1cid to
accept the "incrementally-defined" CIDFontType0 font file,
which uses /GlyphDirectory and includes no binary section.
But I have to start from making a font data which GS and
genuine PostScript interpreter can accept.

On 2023/04/30 17:07, suzuki toshiya wrote:
> Dear Werner,
>
> Ah, I need more time to propose deprecating or removing
> the incremental loading feature in the t1cid driver.
>
> But there is room for improvement in this feature's
> documentation (or a tutorial). Just I've written to
> the ghostscript-devel mailing list and asked whether
> GhostScript has never been used and will never use.
>
> If they never use it, it may be possible to define our
> use case to clarify what we tested. Even if we decide
> to remove it in the future release, the "disabled-by-default"
> might be an appropriate next step.
>
> Anyway, for the improvement of FT_Get_CID_From_Glyph_Index(),
> I understand that there would be no urgent requirement to
> modify the part of the incremental loading. It is helpful
> information for me.
>
> Regards,
> mpsuzuki
>
> On 2023/04/29 22:48, Werner LEMBERG wrote:
> > > * In summary, the current GhostScript will never use the incremental
> > >     loading feature in the t1cid driver of FreeType.  In addition, I'm
> > >     questioning whether the incremental loading feature of t1cid is
> > >     helpful to render the PostScript document using the incremental
> > >     definition of the CIDFontType 0 dictionary.
> >
> > Thanks for your detailed analysis!  This sounds as if you favor the
> > removal of the code.  In case that is true: What about mentioning in
> > the `CHANGES` file that incremental loading gets removed from the
> > `t1cid` driver after the next release?
> >
> >
> >       Werner