45.8.0b1 available with user agent switching (plus: Chrome on PowerPC?!)

45.8.0b1 is available (downloads, hashes). This was supposed to be in your hands last week, but I had a prolonged brownout (68VAC on the mains! thanks, So Cal Edison!) which finally pushed the G4 file server over the edge and ruined various other devices followed by two extended blackouts, so the G5 was just left completely off all week and I did work on my iBook G4 and i7 MBA until I was convinced I wasn't going to regret powering the Quad back on again. The other reason for the delay is because there's actually a lot of internal changes in this release: besides including the work so far on Operation Short Change (there is still a fair bit more to do, but this current snapshot improves benchmarks anywhere from four to eight percent depending on workload), this also has numerous minor bug fixes imported from later versions of Firefox and continues removing telemetry from UI-facing code to improve browser responsiveness. I also smoked out and fixed many variances from the JavaScript conformance test suite, mostly minor, but this now means we are fully compliant and some classes of glitchy bugs should just disappear.

But there are two other big changes in this release. The first is to font support. While updating the ATSUI font blacklist for Apple's newest crock of crap, the fallback font (Helvetica Neue) appeared strangely spaced, with words as much as a 1/6th of the page between them. This looks like it's due to the 10.4-compatible way we use for getting native font metrics; there appears to be some weird edge case in CGFontGetGlyphAdvances() that occasionally yields preposterous values, meaning we've pretty much shipped this problem since the very beginning of TenFourFox and no one either noticed or reported it. It's not clear to me why (or if) other glyphs are unaffected but in the meantime the workaround is to check if the space glyph's horizontal advance value is redonkulous and if it is, assuming the font metrics are not consistent with a non-proportional font, heuristically generate a more reasonable size. In the process I also tuned up font handling a little bit, so text run generation should be a tiny bit faster as well.

The second is this:

As promised, user agent switching is now built-in to TenFourFox; no extension is required (and you should disable any you have installed or they may conflict). I chose five alternatives which have been useful to me in the past for sites that balk at TenFourFox (including cloaking your Power Mac as Intel Firefox), or for lower-powered systems, including the default Classilla user agent. I thought about allowing an arbitrary string but frankly you could do that in about:config if you really wanted, and was somewhat more bookwork. However, I'm willing to entertain additional suggestions for user agent strings that work well on a variety of sites. For fun, open Google in one tab and the preferences pane in another, change the agent to a variety of settings, and watch what happens to Google as you reload it.

Note that the user agent switching feature is not intended to hide you're using TenFourFox; it's just for stupid sites that don't properly feature-sniff the browser (Chase Bank, I'm looking at yoooooouuuuu). The TenFourFox start page can still determine you're using TenFourFox for the purpose of checking if your browser is out of date by looking at navigator.isTenFourFox, which I added to 45.8 (it will only be defined in TenFourFox; the value is undefined in other browsers). And yes, there really are some sites that actually check for TenFourFox and serve specialized content, so this will preserve that functionality once they migrate to checking for the browser this way.

If you notice font rendering is awry in this version, please compare it with 45.7 before reporting it. Even if the bug is actually old I'd still like to fix it, but new regressions are more serious than something I've been shipping for awhile. Similarly, please advise on user agent strings you think are useful, and I will consider them (no promises). 45.8 is scheduled for release on March 7.

Finally, last but not least, who says you can't run Google Chrome on a Power Mac?

Okay, okay, this is the PowerPC equivalent of a stupid pet trick, but this is qemu 2.2.1 (the last version that did not require thread-local storage, which won't work with OS X 10.6 and earlier) running on the Quad as a 64-bit PC, booting Instant Web Kiosk into Chromium 53. It is incredibly, crust-of-the-earth-coolingly slow, and that nasty blue tint is an endian problem in the emulator I need to smoke out. But it actually can browse websites (eventually, with patience, after a fashion) and do web-browsery things, and I was even able to hack the emulator to run on 10.4, a target this version of qemu doesn't support.

So what's the point of running a ridiculously sluggish emulated web browser, particularly one I can't stand for philosophical reasons? Well, there's gotta be something I can work on "After TenFourFox"™ ...

Jokes aside, even though I see some optimization possibilities in the machine code qemu's code generator emits, those are likely to yield only marginal improvements. Emulation will obviously never be anywhere near as fast as native code. If I end up doing anything with this idea of emulation for future browser support, it would likely only be for high-end G5 systems, and it may never be practical even then. But, hey, Google, guess what: it only took seven years to get Chrome running on a Tiger Power Mac.