[XeTeX] Diacritics in color (was Re: XETEX cannot access OpenType features in PUA?)

[Ross Moore]

Hi Heiko,

On 29/11/2011, at 9:29 AM, Heiko Oberdiek wrote:

> The same also works in XeLaTeX:
> 
> \documentclass{minimal}
> \usepackage{fontspec}
> \usepackage{color}
> \pagestyle{empty}
> 
> \begin{document}
> \fontsize{100pt}{100pt}\selectfont
> \noindent
> ^^^^00e4\\
> a^^^^0308\\
> a\textcolor{red}{^^^^0308}
> \end{document}
> 
>  stream
>   q 1 0 0 1 72 769.89 cm 0 G 0 g 0 G 0 g 0 G 0 g BT /F1 99.626 Tf 0 -63.86
>  Td[<00a0>]TJ 0 -99.63 Td[<001c00ee>]TJ 0 -99.62 Td[<001c>]TJ ET 1 0 0 RG 1
>  0 0 rg BT /F1 99.626 Tf 45.73 -263.11 Td[<00ee>]TJ ET 0 G 0 g 0 G 0 g 0 G
>  0 g Q
> 
>  endstream


Yes, this is OK with lower-case letters.
But try with uppers:

\begin{document}
\fontsize{100pt}{100pt}\selectfont
\noindent
^^^^00e4\\
a^^^^0308\\
a\textcolor{red}{^^^^0308}\"a
U\textcolor{red}{^^^^0308}\"U

\end{document}


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Both the vertical and horizontal position are now wrong.

stream
 q 1 0 0 1 72 769.89 cm 0 G 0 g 0 G 0 g 0 G 0 g BT /F1 99.626 Tf 0 -63.86 Td[<00a0>]TJ 0 -99.63 Td[<001c00ee>]TJ 0 -99.62 Td[<001c>]TJ ET 1 0 0 RG 1 0 0 rg BT /F1 99.626 Tf 45.73 -263.11 Td[<00ee>]TJ ET 0 G 0 g BT /F1 99.626 Tf 45.73 -263.11 Td[<00a0>-301<006c>]TJ ET 1 0 0 RG 1 0 0 rg BT /F1 99.626 Tf 190.59 -263.11 Td[<00ee>]TJ ET 0 G 0 g BT /F1 99.626 Tf 190.59 -263.11 Td[<0242>]TJ ET 0 G 0 g 0 G 0 g Q

endstream

Note also that those <HEX> codes are glyph IDs, not Unicode points.
There is a CMap that decodes these.

5 beginbfchar
<001C> <0061>   % a
<006C> <0055>   % U
<00A0> <00E4>   % ?
<00EE> <0308>   % ??
<0242> <00DC>   % ?
endbfchar
endcmap
CMapName currentdict /CMap defineresource pop


It is not at all clear how to obtain correct positioning 
information for the coloured glyph, and put it in place
once known.
 
One would hope to not have to go back to positioning the
accent in its own box, above the character --- ensuring that
it comes later, rather than earlier, within the PDF stream.
Maybe this *is* the only way to go?


Also, you cannot start with the precomposed glyph (<0242> here)
without also having the knowledge of how to decompose(!) it.



> 
> Yours sincerely
>  Heiko Oberdiek



Cheers,

	Ross

------------------------------------------------------------------------
Ross Moore                                       ross.moore at mq.edu.au 
Mathematics Department                           office: E7A-419      
Macquarie University                             tel: +61 (0)2 9850 8955
Sydney, Australia  2109                          fax: +61 (0)2 9850 8114
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