Re: [Gimp-print-devel] Canon PIXMA iP7250

[Gernot H. <aik...@gm...>]

On Sun, Apr 16, 2017 at 9:31 PM, Ludwig TAUER <ta...@ao...> wrote:
> On Sonntag, 16. April 2017 03:21:57 CEST Gernot Hassenpflug wrote:
>> On Sat, Apr 15, 2017 at 9:43 PM, Gernot Hassenpflug
>>
> <snip>
>> Hello Ludwig,
>> I left out one critical function in the previous email.
>>
> <snip>
>
> Hello Gernot,
> seems that this omission further grayed my hair ;-)

Hello Ludwig,
Sorry about that! I have the same hair issue when looking at CD
printing though :-)

>> > (3) code is in print-canon.c, specifically functions:
>> > canon_size_type (setting of tray type codes, no changes needed)
>> > canon_init_setPageMargins2 (settings of page size and offsets, here is
>> > the place to experiment)
>
> Nothing I changed here made any visible difference.

Really. That is good news, it means it is not critical to get exact sizes maybe.

> <snip>
>> (5) adjustment in canon_setup_channels, requires adjustment also  in (4)
>> abvove.
>>
>>   if (print_cd) {
>>     privdata->cd_inner_radius = hub_size / 2;
>>     privdata->cd_outer_radius = stp_get_width(v) / 2;
>>     privdata->left = CANON_CD_X - privdata->cd_outer_radius +
>> stp_get_dimension_parameter(v, "CDXAdjustment");;
>>     privdata->top = CANON_CD_Y - privdata->cd_outer_radius +
>> stp_get_dimension_parameter(v, "CDYAdjustment");
>>     privdata->page_width = privdata->left + privdata->out_width;
>>     privdata->page_height = privdata->top + privdata->out_height;
>>
>> As you can see, the top is set according to CANON_CD_Y, so even if the
>> adjustments in (4) are correct for the overall page dimensions, the
>> shift you see might well be owing to CANON_CD_Y (in fact, very
>> likely).
>
> True. I now left adjust_tray_J_lengprivdata->leftth and
> adjust_tray_J_width untouched.
> In setup_page() I reduced privdata->left by 2 and privdata->top by 73.
> That gives the best result, though it seems slightly misaligned by
> half a point in the vertical direction, but since we have integers here...

Thanks for that correction, too bad half a point of misalignment remains.
Since we are intending to move the code to floating point, things will
improve for CD offsets.
I haven't begun on that task yet though. I'll have to check it it was
intended to do that for the current upcoming release or not.

I will note the changes you have fou nd necessary and see if I can
recode in a way that makes these changes applicable only to this tray
type.
It is a temporary solution until the new codebase for CD printing can be used.

/../
> Count on me for further testing but for the moment I am out of
> printable CDs, DVDs and BRs. Must order some so the further CD tray
> testing is delayed until 2nd half of the week.

I used to use the same CD each time, just print patterns in black or
cyan, and wipe off the ink after printing. Even a CD not intended for
CD printing is fine in that case.

Best regards,
Gernot Hassenpflug