Last (goddam) Resort Font

I wrote CoBro back in 2012 with the original intent of "releasing" it for public use (i.e. making it known on the the comics subreddit) but because of QWebKit instabilities as well as problems packaging it with either PyInstaller or cx_freeze, I put that off until I could re-do it for Qt5 and Python 3.

Now I've done that it still is plagued by QWebKit issues (and still breaks cx_freeze, and PyInstaller still doesn't support Python 3). Among the instabilities is a very intermittent tendency to throw a blizzard of messages like this: 2014-03-14 15:06:59.270 Python[6570:d07] Critical failure: the LastResort font is unavailable.

This is a Python log message, not a Qt one that I could maybe stifle with the technique mentioned in the prior post. And "Critical" at that! So what's going on?

Turning to The Google I find that a lot of people encountered this message with a variety of different apps, but mostly back in 2010 or 2011 when Snow Leopard was new. But some information emerged.

What is the Last Resort font? The official explanation from Unicode.org is that it is a font to use when the system needs to print a Unicode glyph and all available fonts lack values for that code position.

if the font cannot represent any particular Unicode character, the appropriate "missing" glyph from the Last Resort font is used instead. This provides users with the ability to tell what sort of character it is, and gives them a clue as to what type of font they would need to display the characters correctly.

This explains why the message comes only rarely but in a flurry: it happens when a comic web page has a glyph that isn't in any available font. That doesn't happen all the time, but if it does, the site is likely to have a string of such glyphs; hence the multiple messages. But why can't the WebKit browser find the font? With a little poking around on my system (and absolutely no help from the Finder, whose search function insists there is nothing to match that name) I did find that /System/Library/Fonts/LastResort.ttf exists and had 644 permissions. So...

Finally I found this FontGeek post about Safari having the same problem. They claim that because of "sandboxing" the browser can't access the folder where LastResort resides. I'm dubious about the explanation; and the fix they offer isn't directly applicable to the Qt WebKit code as far as I can tell. But it's the best explanation I've seen.

What to do? One possibility: get a copy of LastResort.ttf and include it in the app. I've already got code in PPQT V1 to load a font bundled with the app and add it to the QFontDatabase. I need to think about this, also I need to find a web comic that will trigger the issue reliably.