1919414 - Pages-per-sheet count is double-applied (squared), if you print via system print dialog

Status: VERIFIED FIXED

(Core :: Printing: Setup, defect)

Description

[Daniel Holbert [:dholbert]]

STR:

1. Load attached testcase (a 2-page document) in Firefox Nightly on Linux, using a fresh profile
2. Ctrl+P
3. Choose "Print using the System Print Dialog"
4. Click the "Page Setup" tab and choose "Pages-per-side: 2" and then proceed with your print operation. (Note: this probably requires a real printer -- Pages-per-side isn't available in the system print dialog if you're using the "Print to file" print target)
5. Click "Print" and look at the results.

EXPECTED RESULTS:
The printout should have a 2-pages-per-sheet layout (with my 2 portrait pages side by side, filling a landscape-orientation sheet).

ACTUAL RESULTS:
The printout has a 4-pages-per-sheet layout (with my 2 portrait-oriented pages side-by-side at the top of a portrait-oriented sheet, with the bottom half blank [or filled in with more pages if you perform these STR with a longer document].)

mozregression range:
Last good revision: 7ff758e0d08b4bdf0ce3bd2abe84a1bff3be8ff4 (2022-12-14)
First bad revision: 440856ffde519ea98b6c1fca7d461c20cc55a90c (2022-12-15)
Pushlog: https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=7ff758e0d08b4bdf0ce3bd2abe84a1bff3be8ff4&tochange=440856ffde519ea98b6c1fca7d461c20cc55a90c

In that range, I think this would have been from bug 1805716 -- that's the only print-related change in there.

There's also an interesting connection here to bug 1755974 whose patch coincidentally landed on the previous day (just before the regression range) -- at first I suspected that as the regressor, but now I don't since its patch was included in the "last-good" build here. I'll post more notes about that one in another comment so that this initial one isn't too long.

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: testcase 1 (simple 2-page document with just a solid border around the whole body)

Comment 2

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 1805716

:jwatt, since you are the author of the regressor, bug 1805716, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 3

[Daniel Holbert [:dholbert]]

(In reply to Daniel Holbert [:dholbert] from comment #0)

There's also an interesting connection here to bug 1755974 whose patch coincidentally landed on the previous day (just before the regression range) -- at first I suspected that as the regressor, but now I don't since its patch was included in the "last-good" build here. I'll post more notes about that one in another comment so that this initial one isn't too long.

Following up on this: I think the patch that we landed in bug 1755974 didn't actually fix it, and then the patch we landed in bug 1805716 made it reproduce more readily.

To illustrate this, I tested 3 consecutive Nightlies:

• 2022-12-13 (baseline)
• 2022-12-14 (includes the patch that landed for bug 1755974)
• 2022-12-15 (includes the patch that landed for bug 1805716)

...and I tested each of those in 3 situations, printing the attached testcase (I'm listing an abbreviation for each, for the benefit of the results-table below):

• A.PPS-in-Firefox: set "pages-per-sheet:2" in Firefox's own print dialog, and then click out to System Print Dialog and proceed with the print.
• B.PPS-in-System: leave "pages-per-sheet" at the default 1 in Firefox's own print dialog, and then click out to System Print Dialog and choose "Pages-per-side: 2" (in Page Setup tab) and then print.
• C.PPS-in-Both: set pages-per-sheet to 2 in Firefox's own print dialog, then click out to system print dialog and set it to 2 there as well, and then Print.

Here are the results (the pages-per-sheet count we actually render with):

                     A.PPS-in-Firefox  B.PPS-in-System  C.PPS-in-Both
Nightly 2022-12-13          2                 2               4
Nightly 2022-12-14          2                 2               4
Nightly 2022-12-15          4                 4               4

So: Nightly 2022-12-13 and 2022-12-14 give the same results, which lead me to believe bug 1755974's patch didn't actually help, unfortunately. (I would have expected it to drop the page-count to 2 in situation C.)

And Nightly 2022-12-15 gives 4 pages across the board, but that's because A/B/C are all essentially the same situation there, because starting with that Nightly, we copy the settings from Firefox's print dialog to the system-print dialog. (So setting pages-per-sheet:2 in Firefox's print dialog means we automatically show pages-per-sheet:2 in the system print dialog as well.)

Comment 4

[Daniel Holbert [:dholbert]]

FWIW this bug came across my radar because someone requested the ability to do 2-pages-per-sheet with reversed page-ordering:
https://connect.mozilla.org/t5/ideas/add-pdf-page-order-setting-when-printing/idi-p/70668

That reversed-order feature is arguably in the category of rarely-used-power-features that we can let users find in the system print dialog if they really need it, in the interests of keeping Firefox's own print dialog easy-to-use and uncluttered. (Pages-per-sheet itself is rarely-used; and reverse-order-pages-per-sheet is presumably even more of a niche thing.) And on Linux at least, there is a reversed-page-ordering feature available in the system print dialog (nice!), and it works as-expected in Nightly 2022-12-13 and 2022-12-14 (hooray!), but it's not really usable in Nightlies after that point, due to this bug here -- since just using the system print dialog at all causes the pages-per-sheet count to be applied twice, i.e. squared.

Comment 5

[Daniel Holbert [:dholbert]]

Triaging as S3 given that this doesn't affect our built-in print dialog, and it's probably linux-specific, and we've been shipping for years without anyone noticing. :)

Still feels pretty broken & like something we should fix soonish, though.

Comment 6

[Daniel Holbert [:dholbert]]

[clarifying bug title -- in current Nightly (and really any Nightly after 2022-12-15), this bug reproduces regardless of whether you choose 2-pages-per-sheet in the Firefox print dialog vs. the system print dialog. All that matters is that you chose 2 pages per sheet somewhere, and that you actually choose a real or real-enough CUPS printer (not the "Print to File" special print target in the system print dialog).]

Comment 7

[Daniel Holbert [:dholbert]]

Clearing ni=jwatt since I don't think the regression status means he needs to change course & jump on this [as bugbot semi-assumes by default].

Ideally someone with print-internals knowledge (which could be either of two or another teammate) should take a look here before too long though.

Comment 8

[Daniel Holbert [:dholbert]]

I tested to be sure this doesn't repro on macOS or Windows, and this particular issue doesn't repro, but it turns out we hit different bugs (about page-orientation) if I perform the STR there. I filed those as:
on mac: bug 1919917
on windows: bug 1919925

Comment 10

[Emilio Cobos Álvarez [:emilio]]

Attachment: Bug 1919414 - Don't use Gecko's pages per sheet code in the native print dialog. r=dholbert,jwatt

Comment 11

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/32adfbef0de1
Don't use Gecko's pages per sheet code in the native print dialog. r=dholbert

Comment 12

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/32adfbef0de1

Comment 13

[BugBot [:suhaib / :marco]]

The patch landed in nightly and beta is affected.
:emilio, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
• If no, please set status-firefox134 to wontfix.

For more information, please visit BugBot documentation.

Comment 14

[Daniel Bodea [:danibodea]]

I can verify that using the steps in comment 0, the printer will print 2 portrait pages on a landscape-oriented sheet of papper, as expected. This has been verified in Ubuntu 22 in the Nightly v135.0a1 and Beta v135.0b4. Closing as verified. Thank you.

Comment 15

[Ryan VanderMeulen [:RyanVM]]

This seems worth fixing for ESR users and grafts cleanly. Please nominate for uplift unless you feel strongly otherwise :-)

Comment 16

[Emilio Cobos Álvarez [:emilio]]

Comment on attachment 9444554 [details]
Bug 1919414 - Don't use Gecko's pages per sheet code in the native print dialog. r=dholbert,jwatt

ESR Uplift Approval Request

• If this is not a sec:{high,crit} bug, please state case for ESR consideration: see above
• User impact if declined: comment 0
• Fix Landed on Version: 135
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Simple fix

Comment 17

[Ryan VanderMeulen [:RyanVM]]

Comment on attachment 9444554 [details]
Bug 1919414 - Don't use Gecko's pages per sheet code in the native print dialog. r=dholbert,jwatt

Approved for 128.7esr.

Comment 18

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-esr128/rev/2081421a876e

Comment 19

[Daniel Bodea [:danibodea]]

This fix has also been verified in Firefox ESR v128.7.0esr on Ubuntu 22.