17861 - Should use logical resolution from OS when higher than 96ppi

Status: VERIFIED FIXED

(Core Graveyard :: GFX, defect, P3)

Description

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

DESCRIPTION:  Currently Mac and Linux, by default (i.e., without the secret
browser.screen_resolution pref), do not use the logical resolution from the
operating system at all.  Instead, they assume 96ppi.  I think this is a bad
idea - they should only assume 96ppi when the operating system claims the
logical resolution is *less* than 96ppi.  If the OS gives a value *more* than
96ppi, then the OS value should be used.  (Users with poor vision, for example,
may have a high logical resolution set.  Or, for that matter, users with
high-res monitors.  The reason for doing this at all is that the Windows default
is 96ppi, and many web designers write pages with physical units that are
illegible with a logical resolution smaller than 96ppi, because the fonts become
too small to read.  Therefore, there's no reason to *lower* the logical
resolution to 96ppi -- it should only be raised to 96ppi.)  The code should also
respect the browser.screen_resolution pref above all.

I'll try to submit a patch that does this on Linux.  Sometime, that is...


QA:  I can verify this bug by looking at the code.  Steps to reproduce are too
hard...

Comment 1

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Attachment: patch to fix bug in GTK gfx code (Mac should be similar)

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Attachment: patch to fix bug in GTK gfx code (Mac should be similar)

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

I tested the patch each of the following ways with my X server's res set to
75dpi and then 117dpi.  It worked as expected (correct results given for 75 and
117):
 * viewer (96, 117)
 * apprunner, pref set to 91 (91, 91)
 * apprunner, pref set to 0 (75, 117)
 * apprunner, pref set to -1 (96, 117)
 * apprunner, no pref (96, 117)

Comment 4

[Erik van der Poel]

Created bug 20802 for the Mac. This bug is for Unix.

Comment 5

[Erik van der Poel]

Reviewed and checked in David's fix.

Comment 6

[Erik van der Poel]

Marking FIXED.

Comment 7

[Chris Petersen]

Marking verified fixed in the Feb 1 build.