391757 - moving divs leave odd droppings behind due to Windows ClearType

Status: NEW

(Core :: Layout, defect)

Description

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Not sure what's going on here -- this same issue happens in Firefox 2.  I only see it if Cleartype is enabled on windows.  I'm guessing this is cleartype droppings from the horizontal part of the "L" in "Layer", which is extending outside of the div bounding box when it's being drawn?

Note that you shuold see a smooth animation after a 1s pause after load; if you see an immediate jump, then you're hitting a different bug (that I was trying to create a testcase for), and you need to resize the window or fiddle around with it until you get the smooth animation for the droppings to show up.

Comment 1

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Attachment: testcase

testcase

Comment 2

[Eli Friedman]

Is this independent of Bug 96041?

Comment 3

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

I think so; I'm pretty sure those glyph bounds don't include cleartype extents, so not sure what we can do here, actually.

Comment 4

[Robert O'Callahan (:roc) (email my personal email if necessary)]

If the glyph bounds don't include the inked extents, that's a bug right? That's what I tend to mean by "glyph bounds"...

Comment 5

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Sure, but what if you can't get those bounds from the OS?  I'm pretty sure that the windows APIs won't give you the bounds of the cleartype'd area, for backwards compat purposes.

Comment 6

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Then how does any application work that needs to calculate the inked area?

I suppose we could just add one pixel or something, but we don't want to trigger overflow areas on every single text frame ... I did that on Mac accidentally, once, and it *sucked*.