Printing through Elmer found two things. Black and white came out grey
while the preview stayed in colour: 0.2.6.2 only told the driver. And
right-clicking a picture in a lesson and choosing Print printed the whole
page around it, where some pictures cannot be opened on their own at all.
Black and white is now made before the preview. Ghostscript makes a grey
copy, the preview shows it, and CUPS is given that same file, still with
ColorModel=Grayscale so Elmer's PCL 6 driver prints with pxlmono. Measured
first: Ghostscript's own grey of the colour original and of the copy give
the same greys (Elmer's driver is Ghostscript); poppler's do not. It takes
up to 4.4 s for a lesson page of pictures, so it runs in the background
with a minute to finish, is made once and kept, and a failure is said so
and never printed in colour instead. Ghostscript is now a named dependency;
cups-filters already brought it.
Right-click asks the engine's hit test: on a picture or a canvas it offers
Print image and Print page, elsewhere only Print page. The picture comes
from the engine's own copy image — the only one of five ways measured that
worked for a signed-in picture, a hotlink-protected one, a one-time
address, blob:, data:, another site's, a canvas and WebP — and it fetches
nothing, so the teacher's sign-in is not needed again. It goes through the
clipboard, which is kept and put back; measured under KWin with another
program owning it. A picture that never arrives is said so; the page is
not printed in its place. It then gets the 0.2.6.2 picture layout.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
The black bars above and below a printed picture were neither in the
picture nor in the layout. A PNG or JPEG in a tab of its own is shown by
the engine on a viewer page whose background is rgb(14, 14, 14), and Qt
prints page backgrounds by default; 0.2.6.1 printed that page.
A picture is now taken as itself — drawn onto white, capped at 300 dpi
across Letter — and laid out on the printer's paper by the preview, with
Size (as large as fits down to 25%), Position (nine squares), Paper
(automatic, upright, sideways) and Fill the whole page, which says it
cuts the edges off and is never the default. The preview is the PDF that
prints, laid out again after each change. Worksheet PDFs and lesson pages
get no picture controls and are unchanged.
Page backgrounds are no longer printed for lesson pages either, as in
Chrome; Blink darkens light text when it does that, so a white-on-black
page prints readable grey on white. "Colour" is "Color" in the print
interface and the manual.
Lab: 135 print checks, now including eight picture layouts measured on
the job file CUPS kept — byte-identical to the preview, within 1 point of
where asked, no ink anywhere else. Printed from the real session with the
pointer: 50% top left, Elmer-66, the same. Not yet on paper.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
The tab strip is drawn from the classroom's own palette, the one the
panel, Parent Call and Presentations read: larger titles, an accent
under the active tab, worksheets marked with a document icon. Its one
corner widget is the lesson's size and Print — not a new-tab button. With
one tab the strip stays hidden, as before; a change of size shows a
moment's badge instead, and the right-click menu and keys still work.
The window is named "Lesson — Wonder Ink" and carries its own icon.
The print preview showed "Page 1 could not be shown" in the real
session while printing correctly: poppler 25.03 does not write to stdout
when asked for "-" — it writes a file called "-.png" into the current
directory, which for Wonder Ink is the teacher's home. Pages are now
rendered into a directory of their own, and the lab print check fails
any preview that does not draw its page.
The teacher's manual has lesson size and printing.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
Little Waders, 0.2.2: SIGSEGV in QPrinter::resolution() every time a
teacher confirmed a print job. QWebEngineView.print() keeps the raw
QPrinter pointer and returns; Qt's didPrintPage() reads
printer->resolution() once Chromium has rendered the page, and by then
PyQt had deleted the printer, which print_view() held only as a local.
Reproduced in the lab with the 0.2.2 code, same backtrace, no job.
Keeping the printer alive fixed the crash and was measured, and Qt's
path was still not a print path: a worksheet PDF tab printed as one
blank page, a lesson went as 24.6 MB of 300 dpi pictures with no text,
and a queue refusing jobs was reported as printed.
Print is now: make a PDF (a worksheet already is one; a lesson page is
printToPdf'd onto the printer's own paper; an inline PDF is downloaded
and opened as a worksheet), show it in a preview with printer, pages,
copies and colour, and hand it to CUPS with lp — Chrome's route in the
same rooms. Nothing asynchronous holds a printer. Black and white uses
the driver's ColorModel=Grayscale, because Elmer's generic PCL 6 driver
ignores print-color-mode.
An exception escaping any slot no longer aborts Wonder Ink: PyQt6's
default is to kill the process, and it is now logged instead.
tests/test-classroom-printing.sh: 50 checks. tools/lab/wonderink-print-
check: 39 checks over 13 scenarios in the lab, against a queue built
from Elmer's PPD, judged by what CUPS received. Not yet on paper.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
