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

[Robert K. <rl...@al...>]

On 8/8/21 5:54 PM, Solomon Peachy wrote:
> On Sun, Aug 08, 2021 at 01:22:45PM -0400, Solomon Peachy wrote:
>>   <resolution translate="text" name="720x360sw" text="720 x 360">
>>    <physicalResolution>720 360</physicalResolution>
>>    <parameter type="integer" name="escp2_base_res">360</parameter>
>>   </resolution>
> 
> FWIW, there's a special-case in adjusted_vertical_resolution() that seems to
> things on this printer for 720x360.  I commented it out for now.

Yeah, we'll get that fixed.

>>     1b  (  g 04 00 30 2d 00 00   # sent after the "print method" and "dot size" commands
> 
> This turns out to be the cutter control, in units of 2880 rows/inch.  
> Without it the printer cuts and stops after something like a single 
> inch.

That's what I was thinking too; our emails on the subject crossed.

> The good news is that with some hacked-in changes, I'm now able to 
> print, and the color channels appear to be correct!  The bad news is 
> that the ink drop/density levels are _quite_ wonky, but that was 
> expected.

Right.  That's one of the two final problems to solve (the other being the light/dark ratios, but
there's a good chance that those will match other UltraChrome inks).

> More seriously, there is a major page margin definition problem in play, 
> and I'm not sure how to tackle it.
> 
> I think I need to add about an inch of vertical margin to start of the 
> printed page, eg a 6x8" print becomes a 6x9", but with the first inch 
> blank. This seems to jive with what I see in the windows dump, with the 
> first vertical position command at position 1374:
> 
>    1b  (  v 04 00  5e 05 00 00   # == 1374
> 
> But from gutenprint it's this:
> 
>    1b  (  v 04 00 00 00 00 00
> 
> Interestingly, this extra inch-ish gets automatically cut off by the 
> printer, and that explicit (g cutter control is relative to this first 
> cut point, so as far as the user is concerned, what comes out is a 
> perfect 6x8" print.

More like 0.954166, presumably expressed in base units.

> Is there a simple way to force-add this margin from within the escp2 
> driver in a way that won't get reported back to the user as a page 
> margin?

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.

This was designed for a different purpose, printers with offset heads, where the offset is negative;
I've never tried it with a positive offset.