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Topic: Keep track of X and Y coordinates for Tm
Conf: (P-PDF) Beginners, Msg: 168732
From: er300905
Date: 2/3/2009 09:42 AM

Hello,

I am trying to develop a tool (in VB.net) that will read from a PDF file and store the data into variables for later use.
When reading the file, the tool reads every single command into a temp variable (I.e. BT, cm, Tm, Td, etc). It also reads the numbers preceding each command (i.e. 35.88 54.79 18.48 173.28 re).
The PDFs I'm reading the data from are in table format, and I need to keep this format. Which means that the tool needs to "remember" which values were in the same column and same row.
My idea at first was to make a struct with 3 values: col, row and val. 'Val' was supposed to hold the actual text value, and 'col' & 'row' the X & Y coordinates given prior to each "re." But here's where my problem begins.
Sometimes the PDFs do not have a "re" in between each "BT" and "ET" but instead they have "Tm" "cm" "Td" or "TD."
I have been reading the PDF Reference 1.5 for more info about this but I am very confused.
I understand that as soon as BT starts, it initializes "Tm" to the identity matrix, and therefore I know that anything given to Tm right after BT is straight forward.
I.e.
0 16.08 -16.08 0 50.2809 129.4394 Tm
means that the X and Y values are 50.2809 and 129.4394

The issue begins when I have more than one "Tm" (or "cm" or "Td" or "TD") between BT and ET.

For example

BT
0 7.92 -7.92 0 47.8809 697.2794 Tm
(Here i know what X and Y are)
0 g
0.0198 Tc
"Some Text" TJ
-85.7576 -1.7576 TD
(What happened to X and Y here?)
-0.0053 Tc
"Some Text" TJ
5.2121 -61.303 TD
(And here?)
0.0104 Tc
0.0051 Tw
"Some Text" TJ
0 10.08 -10.08 0 549.0009 395.8394 Tm
(Now I really lost track of X and Y)

Does anyone know a formula or a way to keep track of X and Y every time?

Please help me, I have been struggling with this for over a week now and I'm very frustrated.

Thanks


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