Re: [Gimp-print-devel] Advice on how to add the Epson SL-D700

[Solomon P. <pi...@sh...>]

On Sun, Aug 08, 2021 at 07:03:33PM -0400, Robert Krawitz wrote:
> initialVerticalOffset and blackInitialVerticalOffset may be what you 
> want (you'll need to set both in the model file).  They're expressed 
> in units of baseSeparation, which is 360; 1374 would be 343.5, so 
> you'd have to use either 343 or 344 for this purpose.  If that's not 
> good enough -- if you really need it more precise -- we'll have to 
> come up with something else.

Hmm, initialVerticalOffset seems to only be used as an input to ESC(c, 
which I'd commented out.  Re-enabling it and plugging both positive and 
negative numbers in seems to have no effect on the printer behavior:

   1b  (  c 08 00 82 fa ff ff 5a 19 00 00
   1b  (  c 08 00 18 01 00 00 5a 19 00 00 

So that's not going to work.  However, I discovered what we really want 
is pd->printing_initial_vertical_offset, but there is no way to set it 
via XML and it is currently hardcoded to 0.  Force-setting that to an 
appropriate value works great, so I added the code to read it from the 
model XML.

Since that value needs to be specified in terms of base_res * 2, which 
varies based on the print resolution. it either needs to be specified in 
resolution-independent units (and get converted) or has to be pushed 
made into a <resolution> parameter.  Which is your preference?

BTW, I don't get the results I want until I push the offset out slightly 
over an inch.  Chalk it all up to margin differences with the Windows 
driver.

So, the hacks I still have in my code:

 * Always bypass sending ESC(c and ESC(C
 * Always send ESC(g based on paper height
 * Disable the special case for 720x360 in adjusted_vertical_resolution()

I think the prudent thing to do is add some sort of model flag that says 
a model is roll-only, and those first two things can key off of that?
 
I suspect we'll need something similar for print size 
selection/filtering; this model is most commonly used to produce 
standard photo sizes (eg 5x7, 6x8, 8x10) but thanks to the roll-only 
media even under Windows it supports arbitrary print lengths.

 - Solomon
-- 
Solomon Peachy			      pizza at shaftnet dot org (email&xmpp)
                                      @pizza:shaftnet dot org   (matrix)
High Springs, FL                      speachy (libra.chat)