Comment 3 for bug 548918

Thanks Alvin, I'll test it and let you know.

Neil

On Sun, Mar 28, 2010 at 4:21 PM, Alvin Penner <email address hidden> wrote:
> to use this, you will need to copy both the .inx file and the .py file
> into the share\extensions directory.
>
> ** Attachment added: "hpgl_output.inx"
>   http://launchpadlibrarian.net/42324509/hpgl_output.inx
>
> --
> HPGL output scaling incorrect
> https://bugs.launchpad.net/bugs/548918
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> of the bug.
>
> Status in Inkscape: A Vector Drawing Tool: New
>
> Bug description:
> The scaling factor used to generate hpgl output is slightly incorrect. Inkscape version 0.47.
>
> In hpgl_output.py, the scaling is set to 1016/90. This assumes 40 plotter units per mm.
>
> In fact, there are 40.2 plotter units per mm.
>
> The following text is reproduced from the HP7475A interfacing and programming manual page 2-5:
>
> "The plotting area is divided into plotter units; one plotter unit equals 0.025 mm (0.00098 in). There are approximately 40.2 plotter units per millimeter, or approximately 1021 plotter units per inch."
>
> On this plotter, if I plot an object of a known size, and then measure it with a ruler, the size is incorrect. I modified the scale factor in hpgl_output.py to be 1021/90 instead of 1016/90 and repeated the experiment. This caused the object to measure correctly.
>
> I don't know if any other plotters use this same value. It might be useful to allow the user to specify the number of plotter units per inch for their specific plotter in the dialog that appears when saving as hpgl.
>
> Anyway, at least for the HP 7475A, the correct number is 1021, not 1016.
>
> Neil Baylis
>
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