248837 - Percentage font sizes of 1px result in 13px sized text

Status: RESOLVED FIXED

(Core Graveyard :: GFX: Mac, defect)

Description

[Informity]

User-Agent:       Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.7) Gecko/20040517 Camino/0.8b
Build Identifier: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.7) Gecko/20040517 Camino/0.8

When you set the font-size attribute of an element through CSS to 1px, then
inside that set the text to any percentage value (such as 90%), the text renders
at 13px. This only appears on the macintosh, and is happening with Camino,
Mozilla and Firefox.

Reproducible: Always
Steps to Reproduce:
<span style="font-size: 1px; font-family: verdana">
	<span style="font-size: 90%">
		90% of 1px
	</span>
</span>
<span style="font-size: 13px; font-family: verdana">
	is apparently 13px?
</span>
Actual Results:  
All text was rendered at 13px

Expected Results:  
Only second piece of text should be 13px - '90% of 1px' should be very small.

I'm using Mac OS X version 10.3.4

Comment 1

[Simon Fraser [no longer active]]

Attachment: Testcase

Testcase that doesn't show the issue for me.

Do you have a min font size set in the prefs?

Comment 2

[Informity]

No minimum font size set. Your test case --  the 1px font renders at 1px, but
the 90% of 1px still renders at 13px. Doesn't appear to be any kind of
system-wide setting as other browsers (any not based on Gecko) render it fine.

Comment 3

[Informity]

Attachment: Gecko/Camino at top, KHTML/Safari at bottom

Screenshot of what I see added

Comment 4

[Felix Miata]

Looks to me like bug 53995 and/or bug 187889.

Comment 5

[jhp (no longer active)]

I can confirm this bug with Simon's testcase.  If I set the minimum font size in
Firefox to it's lowest setting (6), then the testcase works as expected.  So
we're probably not handling a less than 1px case somewhere.

Comment 6

[Simon Fraser [no longer active]]

Javier, do you have time to work on this? I don't, alas.

Comment 7

[jhp (no longer active)]

Attachment: patch

This one line was setting textSize to 0 in this case, and when ::TextSize is
called with 0, it sets the font size to the system default (usually 12 points).

Comment 8

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

Comment on attachment 152031 [details] [diff] [review]
patch

It might be a little cleaner not to put the division inside the PR_MAX macro. 
PR_MAX evaluates its arguments multiple times, and it's also probably simpler
to do integer < rather than floating-point <.

Comment 9

[jhp (no longer active)]

Attachment: patch v1.1

New patch per dbaron's comments.

Comment 10

[jhp (no longer active)]

Simon, can you take a look at the patch, so we can close out this bug?

Comment 11

[jhp (no longer active)]

Checked in on trunk.