I've noticed this on a few sites -- the rdio collections circle/bubble graph, and now the flash at http://www.logitech.com/en-us/speakers-audio -- the text is not antialiased, though it looks like it tried to do AA but was instead forced to 100% opacity somehow. Could be flash thinking it has a surface with an alpha channel and us not giving it one, not sure. Bad (Firefox 4 nightly): http://i.imgur.com/VPLCs.png Good: http://i.imgur.com/5bHKJ.png

Regression window: Works; http://hg.mozilla.org/mozilla-central/rev/212a391d3b79 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b8pre) Gecko/20101109 Firefox/4.0b8pre ID:20101110052514 Fails: http://hg.mozilla.org/mozilla-central/rev/bdbef533364f Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b8pre) Gecko/20101109 Firefox/4.0b8pre ID:20101110081923 Pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=212a391d3b79&tochange=bdbef533364f

Did you try this after bug 611698 landed (past two days)?

(In reply to comment #2) > Did you try this after bug 611698 landed (past two days)? Yes, Latest m^c nightly. And confirmed again on http://hg.mozilla.org/mozilla-central/rev/413eb50d4b81 Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b10pre) Gecko/20110116 Firefox/4.0b10pre ID:20110116030325

This sounds like the espn.com issue I reported in bug 611698.

For me, turning Cleartype off doesn't affect the bad rendering -- still stays bad. Problem sounds/looks to be very similar to bug 611698, though.

Also, the espn.com poll looks fine to me here. Marking this related to 611698, though.

If you try with OOPP disabled and Cleartype manually disabled, do you see the same problem?

Confirmed - seeing issue mentioned in comment 0. Although, for me, all sites mentioned in bug 611698 work fine.

FYI Switching tab or scrolling up/down helps for upper sample(espn.com).

To answer my own question: no, that does not trigger the problem.

(In reply to comment #7) > If you try with OOPP disabled and Cleartype manually disabled, do you see the > same problem? OOPP disabled : The problem does not happen Cleartype manually disabled : The problem happens.

I meant both at the same time.

(In reply to comment #12) > I meant both at the same time. Disabled both; http://www.logitech.com/en-us/speakers-audio : The problem does not happen espn.com: The problem does not happen, but the font is thin than that of disabled OOPP only

OK I've figured out what the problem is. The problem is that Flash recomposites its entire internal buffer over our own irrespective of what rectangle we asked it to paint. In PluginInstanceChild::PaintRectToSurface we only clear the rectangle that we're asking Flash to paint into. So Flash ends up recompositing text outside the repaint region over and over itself, which eventually saturates any pixels that were partially touched by the text. The best way to fix this is to set the GDI clip rect to the rectangle we expect Flash to paint into.

This fixes it.

Setting the clip rect like this might speed up Flash's final BitBlt too, for some performance gain.

Patch applied locally looks great, Rob.