PDF: How starting Position is Calculated through TM and TD

Question

I reading PDF Specification and unable to calculate the starting offset of x axis the visible text is as under:

Preface            vii
Acknowledgments    ix

INTRODUCTION       3

PDF Text uncompress stream text as under:

10 0 0 10 99 475.09 Tm        <-New setting fontsize=10 and x and y axis
-.2 Tc                        <-Character spacing
[(            P)-207(r)-181(e)-211(f)-187(a)-207(c)-191(e)-200(   )-500(  )-500(  )]TJ
^Array having text

/F2 1 Tf        <-New font is set
7.5 0 0 7.5 137.289 475.09 Tm   <-New settings Fontsize=7.5 and x and Y axis
.002 Tc        <-Character spacing
(vii)Tj        <-Text String

/F6 1 Tf     <-New Font
10 0 0 10 144.857 475.09 Tm    <-New settings Fontsize=10 and x and Y axis
-.2 Tc      <-Character spacing
(   )Tj     <-Text String

What would be new x axis and y axis now

-4.5857 -1.3 TD        <- What x-axis?
 [(      A)-226(c)-190(k)-202(n)-201(o)-197(w)-192(l)
  -199(e)-200(d)-211(g)-216(m)-200(e)-201(n)-204(t)-201(s)
   -200(   )-500(  )-500(  )]TJ

 /F2 1 Tf     <- New Font
 7.5 0 0 7.5 178.759 462.09 Tm    <-New Text Matrix
 0 Tc                    <-Character spacing
 (ix)Tj                 <- text string

 /F6 1 Tf
 10 0 0 10 184.309 462.09 Tm
 -.2 Tc
 (   )Tj

Means x axis must be equal to 462.09? But how it is calculated

 /F2 1 Tf
 7 0 0 7 99.4 434.09 Tm
 .1599 Tc
 -.3799 Tw
 [(         IN)-19.1(T)-10.1(R)1.9(ODUCT)-20.1(I)6.9(O)6.9(N)-.1(  )-660(  )-660(  )]TJ

 /F2 1 Tf
-5.5427 -1.8857 TD
-.22 Tc
[(       )-42.9(  )]TJ
7 0 0 7 99.6 407.69 Tm
.1663 Tc
[(CH)5.3(APT)-13.7(E)2.3(R)6.3( )]TJ

Again the Same thing repeting but how to calculate x axis position

You might want to look [here](http://stackoverflow.com/a/16483429/1729265) for more information. — mkl, Feb 19 '15 at 10:44

score 6 · Accepted Answer · answered Feb 19 '15 at 10:11

You are missing that Tm sets a matrix, not just the font size:

10 0 0 10 144.857 475.09 Tm   <-New settings Fontsize=7.5 and x and Y axis

In addition to the font scale, this also sets the origin at 137.289 475.09. Next, the instruction

-4.5857 -1.3 TD        <- What x-axis?

moves -4.5857 'units' across and -1.3 'units' down. The size of the units is in text space, that is, scaled horizontally by 10 and vertically by 10 -- two separate calculations. That comes down to horizontally -45.857 and vertically -13 units, in graphics space and relative to the origin:

137.289 + 10*-4.5857 = 91.432 (horizontal)
475.09  + 10*-1.3    = 462.09 (vertical)

PDF: How starting Position is Calculated through TM and TD

1 Answers1