There was a subtle reftest failure on Mac in RTL text-overflow tests.
I tracked it down to RTL overflow:auto areas being automatically scrolled by a subpixel amount.
This was because we try to set scrollbar "curpos" attributes to an integer number of CSS pixels representing
the scroll amount, relative to the top-left of GetScrolledRect, which is a noninteger number of CSS pixels
in this case. Then in ReflowFinished() we scroll to the saved curpos values plus the top-left of GetScrolledRect.
This patch fixes the problem by making CurPosAttributeChanged pass an allowed scroll range to
ScrollToWithOrigin. We allow any scroll destination that, when rounded to CSS pixels, would give the same
value as "curpos".
This fixes the bug, ensuring that ReflowFinished's call to CurPosAttributeChanged will not normally need
to scroll because the current position will be in the acceptable range. Also, it means that code that
scrolls by setting the "curpos" attribute will be optimized to try to hit a layer pixel boundary.
--HG--
extra : rebase_source : 3a768883feee4ff2b88fe3c729ea1058e911f2ea
When asked to scroll a 1,1 appunit rectangle into view, ScrollFrameRectIntoView will now actually
succeed!
For example if the window is 6000 appunits high and we ask to scroll a 1x1 rect at 0,6000 into view,
before bug 681192 was fixed we'd actually fail to do so. We'd compute a desired scroll destination of 0,1,
and ScrollTo would round that to 0,0 and we wouldn't scroll at all.
Now, we compute a desired scroll destination of 0,1 but also an allowed scroll range for y of
"1 to <someting large>", so ScrollFrameRectIntoView will scroll down by a full pixel to 0,60. This is correct ---
it gets the subpixel area into view, which the previous code didn't --- but it's not really what DoAutoScroll
wants, at least the way test_mousecapture.xul is written. test_mousecapture.xul expects DoAutoScroll to scroll
windowheight+N into view by scrolling down by exactly N pixels, so the desired point is exactly at the bottom
edge of the window rect. Using a zero-sized rect achieves this.
--HG--
extra : rebase_source : 5d3d8cc4417c35dc88ad296a4f13e01d2c1c9233
It is possible to have a JSContext with no global object and no frames on the
stack, yet still be within a request. In that case, xpc_UnmarkGrayContext will
trigger an exception "nothing active on context" when it attempts to access the
inner object of the cx's NULL global.
