Thanks to you John (and John D) for shedding some light on this.

But if it's a hardware issue that's holding DWrite back in FF, I fail to see how the same hardware issues won't put the kabosh on CFF DWrite rendering, too.
The font flavor sounds irrelevant to the underlying problem.

Also, isn't it a big surprise that Microsoft seems to have the leg up on getting DWrite to work?
Hee, hee, hee, ha, ha, ha, ho, ho, ho.

Like Mel Brooks said in History Of The World Part I: "It's good ta be da king".

Hardware issues aside, we issued an update to compensate for the rendering issue John identifies in the second paragraph... http://support.microsoft.com/kb/2545698

Cheers, Si

Rich: But if it's a hardware issue that's holding DWrite back in FF, I fail to see how the same hardware issues won't put the kabosh on CFF DWrite rendering, too.

The second paragraph of John D's comments indicates that this is not fundamentally a hardware/driver issue, but a design decision, i.e. that it would be possible to enable DWrite by default ‘whether hardware acceleration is enabled or not’ (presuming an OS that supports DWrite). He further suggests that specific (TTF) fonts can be excluded by name, so what I'm wondering is if other (CFF) fonts could be included by flavour.

Also, isn't it a big surprise that Microsoft seems to have the leg up on getting DWrite to work?

MS invest in massive hardware testing and maintain a very extensive driver registry, so of course they have an advantage over companies that don't do the same level of hardware and driver testing.

@jh

Or who can't do the same level of hardware and driver testing.
It's Windows' world, pal, we're all just livin' in it.
So with envy and admiration I say again: it really is good ta be da king.

Obviously I might have missed an angle to what JD said. Will read harder.

@sii

Thanks for the link. Important to know.

rich

IE always uses D2D/DWrite. Only if there are known problems with graphics card or driver, IE9 will use D2D software rendering. This should produce the same (although slower) layout and rendering results as hardware accelerated mode, incuding ClearType with subpixel positioning.

Here is relevant post on IE team blog:

http://blogs.msdn.com/b/ie/archive/2011/04/01/getting-the-most-from-ie9-and-your-gpu.aspx

Besides rendering quality, compatibility of layout is also very important (e.g. same site laid out using pixel-aligned or subpixel glyph metrics). Having different layout results depending on user's hardware would be support nighmare, we went through this. It is not clear from John's response if this actually happens in FireFox.

Thanks,
Sergey

>>>One immediate thought that I have regarding this is that perhaps Mozilla could find a way to enable DWrite by default for CFF fonts? I don't think anyone is going to complain that this is worse than the old PS rasteriser rendering!

John, what results are you seeing for otf fonts in FF5? In some tests I am seeing DirectWrite ClearType rendering.

Mike, I've not had an opportunity to test FF5 yet (too busy), but my understanding of John Daggett's comments is that you will see DWrite rendering of both CFF and TTF fonts in both FF4 and FF5 if hardware acceleration is enabled, but that some core TTF fonts are currently excluded due to negative user feedback on the rendering (perhaps fixed, according to Si's comment).

So what I take away from this is that what you will see in FF4 and 5 will depend on both the machine being used and which specific font is used.

My suggestion was that if, as John D suggests, it would be possible to support DWrite regardless of hardware acceleration, but there are concerns about rendering of some TTFs and hence the possibility of using DWrite for some fonts and GDI for others, it might be possible to first apply default DWrite rendering to CFF fonts, since they will more surely benefit relative to the old PS rendering.

I understand reasoning why decision about subpixel rendering can be based on font/size, but using hardware capabilities for this purpose is strange (you can use it for other puuposes, of course). Results on screen produced by DWrite should not depend on whether you use hardware or software rendering. And the other way around, DWrite provides ability to produce both subpixel ClearType or GDI-compatible rendering, independent from hardware mode. Would be interesting to hear what John D think.