Centered text in PDF

Question

Hi
I am new to this Acrobat SDK forum. I am trying to write a PDF code, but I have problems centering text. Below is a short "program" that writes the text "Centered text" starting at position x=100, y=600. But how do I center this text at some position, say x=200, y=600 ?  Can anyone help?
- gullipeX
%PDF-1.4
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      /Outlines 2 0 R
      /Pages 3 0 R
   >>
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      /Resources << /ProcSet 6 0 R
                  /Font << /F1 7 0 R >>
                  >>
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   << /Length 73 >>
stream
BT
   /F1 24 Tf
   100 600 Td
   ( Centered text ) Tj
ET
endstream
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6 0 obj
   [ /PDF /Text ]
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7 0 obj
   << /Type /Font
      /Subtype /Type1
      /Name /F1
      /BaseFont /Helvetica
      /Encoding /MacRomanEncoding
   >>
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625
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Answer 1

Hi, Irosenth and others again.
To try to solve my problem (because I do not know how to do this in PDF), I made a short PostScript program to check the length of the characters in Helvetiva 10 pt. A part of the program is shown below. If I have the length, I can calculate the centered position of the text in my C or Fortran program, that makes the PDF file.  This investigation gave, for instance, the lengths for A, B and W as:
A:  6.66797
F:  6.10840
W: 9.43945
When I placed the EPS file into Adobe InDesign a bit different values came out:
A:  6.66959
F:  6.10963
W: 9.43942
... and still different in Adobe Photoshop:
A:  6.67081
F:  6.11075
W: 9.44115
I have the feeling that character lengths are given as integers in the font file (not as real numbers) and I actually have to multiply these lengths (for 10 pt. Helvetica)  with some unknown value to find the "correct" lengths of the given characters. Does anyone know the actual length of the character A in Helvetica for instance?
PostScript program:
/Helvetica findfont
dup length dict begin
  {1 index /FID ne {def} {pop pop} ifelse} forall
  /Encoding ISOLatin1Encoding def
  currentdict
end
/Helvetica-ANSI exch definefont pop
gsave
/str 20 string def
/Helvetica-ANSI findfont 10 scalefont setfont
(A ) 50  750 moveto show
(A)  stringwidth pop str cvs  80 750 moveto show
(F ) 50  700 moveto show
(F)  stringwidth pop str cvs  80 700 moveto show
(W ) 50  650 moveto show
(W)  stringwidth pop str cvs  80 650 moveto show
grestore