[texhax] [NTG-pdftex] \pdfximage : is there a transparency attribute or method ?

Paul Isambert zappathustra at free.fr
Wed Jan 5 00:35:43 CET 2011

Le 05/01/2011 00:09, Philip TAYLOR (Webmaster, Ret'd) a écrit :
> A supplementary question, if I may ?  The PdfTeX
> reference manual as found at Tug.Org has Chapter
> Eight entitled "Graphics and color", yet the
> chapter seems not to mention colour at all and
> focuses solely on graphics.  Section 7.12 says
> "\pdfliteral [ <pdfliteral spec> ] <general text>
> Like \special in normal TEX, this command inserts
> raw pdf code into the output. This allows support
> of color and text transformation." but as far as
> I can tell, there are no examples of suitable
> parameters for affecting the colour of (e.g.)
> rendered text.  May I ask if there is a supplementary
> manual that defines how colour is to be programmed
> through PdfTeX ?

With \pdfliteral, there is absolutely no "parameter": it's a real 
literal. What the manual means is that if you know how PDF works, you 
can write your own code. Even the colourstack mechanism (see section 
7.17) does little more than adding "q" and "Q" (PDF's \bgroup and 
\egroup), and you still have to input PDF graphic operators (Heiko might 
correct me on this, but I think I'm right).

So color is to be programmed in pdfTeX by writing PDF code... Which, as 
far as colors are concerned, is not extremely difficult, although it 
requires a little work.

(Oh, yes, there's one good reason to use color stacks instead of raw 
literals: the q/Q group doesn't nullify the width of the material you 
want to colorize.)


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