852198 - Unicode mathematical symbols rendered as grey rectangles

Status: RESOLVED INCOMPLETE

(Firefox for Android Graveyard :: General, defect)

Description

[Chris Peterson [:cpeterson]]

Attachment: Firefox_screenshot.png

STR:
1. Load http://paulgraham.com/circling.html
2. See the grey rectangles where there should be (smart) quotation marks

See the attached screenshot.

Comment 1

[Chris Peterson [:cpeterson]]

btw, Chrome and the JB stock browser both render the smart quotes correctly.

Comment 2

[Jonathan Kew [:jfkthame]]

I don't see "smart quotes" there, what I see in those places (viewing the page on desktop) are "⟨" and "⟩", which are U+27E8/27E9 from one of the Unicode mathematical symbols blocks.

On a Nexus 10 in Firefox, I see gray boxes, suggesting we don't find a font for those. And in Chrome on the same device, I see...blanks. But not quotes.

Comment 3

[Chris Peterson [:cpeterson]]

oops! You are correct. This problem is not about smart quotes.

Comment 4

[Jonathan Kew [:jfkthame]]

Could you post a screenshot of that page in Chrome and/or stock browser on your device?

Comment 5

[Chris Peterson [:cpeterson]]

Attachment: JB_stock_browser_screenshot.png

JB stock browser screenshot.

Comment 6

[Chris Peterson [:cpeterson]]

Attachment: Chrome_screenshot.png

Chrome screenshot.

Comment 7

[Chris Peterson [:cpeterson]]

Since neither Chrome nor the JB stock browser can render these Unicode symbols, is this still even a bug we should fix? Is there a better fallback character we can render a grey rectangle or, like Chrome and stock, a blank space?

Comment 8

[Jonathan Kew [:jfkthame]]

OK, so this isn't a Firefox bug as such, it's a limitation of the fonts available on the device. If there were a font that supported the characters, we'd render them.

I don't think rendering -nothing- (or a small blank space, which is almost the same as "nothing" from a user's point of view) is better, in general, than a visible gray blob. It's better to show the user that there is -something- they're missing than to hide it completely. Though the gray boxes are ugly, I agree. Maybe we could just frame them instead of filling them?

For a "better" fix, we could consider adding a font to our product that includes glyphs for a wide range of the Unicode symbols that are not covered by the standard serif and sans-serif fonts. Maybe just the Regular face of DejaVu Sans - that would cover a huge number of symbols etc that are currently unavailable.

(Or if we finish up bug 619521, perhaps we could provide these via a font that is downloaded on demand.)

Comment 9

[Chris Peterson [:cpeterson]]

For comparison, I think desktop Firefox replaces missing Unicode glyphs with a rectangle (empty or containing a hex code) or a (upside-down?) question mark.

Comment 10

[Jonathan Kew [:jfkthame]]

Right. The code to draw a "hexbox" is explicitly disabled on mobile (probably for performance reasons, though I guess we could revisit that).

http://mxr.mozilla.org/mozilla-central/source/gfx/thebes/gfxFontMissingGlyphs.cpp#148
http://mxr.mozilla.org/mozilla-central/source/gfx/thebes/gfxFontMissingGlyphs.cpp#209

Comment 11

[:Margaret Leibovic]

Mass change to move Firefox for Android::Readability bugs to block bug 1129033. Filter on readability-mass-move.

Comment 12

[BMO Automation]

We have completed our launch of our new Firefox on Android. The development of the new versions use GitHub for issue tracking. If the bug report still reproduces in a current version of [Firefox on Android nightly](https://play.google.com/store/apps/details?id=org.mozilla.fenix) an issue can be reported at the [Fenix GitHub project](https://github.com/mozilla-mobile/fenix/). If you want to discuss your report please use [Mozilla's chat](https://wiki.mozilla.org/Matrix#Connect_to_Matrix) server https://chat.mozilla.org and join the [#fenix](https://chat.mozilla.org/#/room/#fenix:mozilla.org) channel.