Improve printout resolution

In order to create paper printout of graph i’m doing the following

  1. Create Photon window, size 1024X768.
  2. Create PtRaw widget inside the window.
  3. Draw graph on PtRaw by calling to PgDrawILine function several
    times, Black color strokeWidth 1.
  4. Send the window widget to printer by snapshot or PpPrintContex
    mechanism, using or Pp.pcl filter, Letter paper, 1200 DPI printer

The problem is that the draw line on paper is thick, Since I’m using
1200 DPI printer resolution I expected to better paper printout.

How can I decrease the line thickness on my paper printout ?
Notice that I don’t need to preview my output before printing.
I’m using QNX 4.25x Photon 1.13x and .

Please advise.