1661294 - Retrieve Native Resolution (DPI/PPI) Information For nsIPrinter

Status: NEW

(Core :: Printing: Setup, task, P5)

Description

[Erik Nordin [:nordzilla]]

In order to reduce the amount of pixelation in situations where we need to rasterize images forprinting, we need to query printers for their native resolutions so that we can set the print settings accordingly.

Comment 1

[Erik Nordin [:nordzilla]]

Attachment: Bug 1661294 - Add nsIPrinter.minimumOptimalResolution attribute r=jwatt,alaskanemily,bobowen

This adds an attribute to nsIPrinter that will return the minimum
optimal resolution supported by this printer.

This value will be an integer factor of the printer's native resolution
and will also be greater than or equal to the
print.preferred_minimum_dpi pref if possible.

If the printer's native resolution is less than the preferred minimum
DPI, or if the preferred minimum DPI is invalid (e.g. negative), then
the promise will be resolved with the printer's closest unaltered native
DPI.

Comment 2

[Jonathan Watt [:jwatt]]

While I remember, we should make this compatible with printers that have different resolutions in the X and Y directions. See bug 1444078 for example.

Comment 3

[Jonathan Watt [:jwatt]]

I mean bug 1444078.

Comment 4

[Erik Nordin [:nordzilla]]

Attachment: Bug 1661294 - Retrieve optimal X and Y Resolutions (WIP)

Comment 5

[Jonathan Watt [:jwatt]]

Erik, do you recall if there were resolution issues that are worse in the new printing UI than the old one? I think there were, but don't recall the details.

Comment 6

[Erik Nordin [:nordzilla]]

jwatt,

I can't think of one off the top of my head. The one that comes to mind is this one: Bug 1444078

But that bug is much older than the new print UI.

One of the issues I've been having with this bug is that my printer offers 300 or 600 DPI, but I haven't seen an observable difference between either of them in numerous physical prints.

For what its worth, I haven't observed a difference when I try 300 vs. 600 in Google Chrome for my printer either.

Comment 7

[Erik Nordin [:nordzilla]]

After exploring this functionality on both macOS and on Linux, I am not convinced that we will be able to implement this behavior at this time.

I am making the decision to not land the prefs for this functionality so that we don't bloat Firefox with prefs that are not connected to any functionality.

Unfortunately, I and people whom I asked to help me test the functionality (dholbert, alaskanemily, heycam), were unable to see any differences in physical prints after changing the resolution.

At the time of writing, the resolution selections also appear to have no effect in Google Chrome, either.

The existing patch is able to query the printer for its list of native resolutions, and set them via a pref; unfortunately, setting the resolutions appears to have no effect on prints.