Re: [ft] sub-glyph graphics-state question

[Dakai Liu]

Dear Mr. Lemberg,

Thanks for the suggestion. The flip switch, I am auto_flip in the graphics 
state, which is not reset before each rendering
of sub-glyphs. Actually I have copy and inserted a code snippet from ver 2.4.6:

/* Reset graphics state */
loader->exec->GS = ((TT_SIZE)loader->size)->GS;

into function: TT_Process_Simple_Glyph()
just before the if statement: if (n_ins > 0) ... , which I think is to execute 
the sub-glyphs' byte code.

This seems do the trick, and only affects Simbraille and some middle european 
fonts. What do you think of the hack?

Regards,
Dakai

________________________________________
From: Werner LEMBERG address@hidden
Sent: Thursday, October 27, 2011 4:52 AM
To: Dakai Liu
Cc: address@hidden
Subject: Re: [ft] sub-glyph graphics-state question

> I encountered a bug rendering a font called SimBraille.

I don't know this font!

> This font contains sub-glyphs, and the true glyph is assembled by
> selecting those sub glyphs.
>
> The problem is in each and every of the sub-glyph, the flip switch
> is turned off at some point, and the flip flag stayed in graphics
> state for all the subsequent sub-glyph rendering, which results in
> incorrect hinting.

What do you mean with `flip' switch?

> the flip switch is turned on in the beginning of "prep" code.  So my
> question is, should I restore this flag before each of the sub-glyph
> being interpreted?

Data of the `prep' table gets executed only if the font size (or the
rendering mode) changes.

> I think this bug is fixed by later versions of freetype library,
> however, unfortunately I am [not] allowed to port the later version
> into our product due to management decision.

I suggest to access the git repository of FreeType, using `git bisect'
to find out which commit fixes your problem so that you can manually
apply it.


    Werner
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