[Gnumed-devel] Printing forms

[Ian Haywood]

On Thu, 5 Dec 2002 07:08:09 +1100
Horst Herb <address@hidden> wrote:

> On Wed, 4 Dec 2002 23:26, Paolo Bizzarri wrote:
> > > two areas that need development are form input/printing.
> > > Ian Haywood has started some work on tables for this. This is
> > > a very important task that needs a good solution.
> >
> > I could work on this. Exactly what needs to be done ?
> 
> wxPython provides a low level printing framework. We would like a module 
> where 
> you can say something like "print_at(x,y, string)" where x and y are absolute 
> positions in mm on the print medium discounting the print margins.
I have been looking into this. Conversion of logical co-ordinates to physical
is not straightforward. PostScript has a conversion of 720 units to the inch.
On my HP DeskJet 500, this is from the paper edge, but the same PostScript
to a Canon BubbleJet 3000 seems to have a 'hard margin' of about 0.5cm 
from the top.

On Windows, you can query the driver for its maximum X and Y, but the docs
don't say this corresponds exactly to the paper edges. 

We may need to have a 'calibration' page, printing two dots at logical postions 
(1000, 1000) and (2000, 2000), the user takes a ruler and measures their
physical positions from the paper edge, from this the margins and scaling can
be calculated for that printer.

> The next step is than a module that parses an XML file with print 
> instructions 
> where the end user can position database elements on forms for printing 
> purposes
Why XML? It is favour of the month, but seems a bit excessive for what we want.
Also, a change to a form has to be updated to each client.
Alternatively, a few tables in the "gmoffice" service can hold the forms
and queries, shared across the database.

Ian



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