1529219 - The left edge of scrollable overflow rect on RTL frame looks wrong (to me)

Status: RESOLVED INVALID

(Core :: Layout: Scrolling and Overflow, defect, P3)

Description

[Hiroyuki Ikezoe (:hiro)]

Attachment: rtl-scroll.html

The scrollable overflow rect in the attaching sample is currently;

scr-overflow=-42000,0,60000,11280

But I supposed it's (-60000, 0, 60000, 11280) instead. I did debug where the '-42000' comes from, it's from at the end of ssAbsoluteContainingBlock::ReflowAbsoluteFrame, and the |r| rect value comes from here.

Anyway, my question is, is this intentional behavior?

Comment 1

[Hiroyuki Ikezoe (:hiro)]

Jonathan and Botond?

Comment 2

[Jonathan Kew [:jfkthame]]

This seems correct to me, I think. The #scroller div is 300px wide. The scrollable overflow rect is 1000px wide (because of the width of the #spacer div inside there), and extends 700px to the left of the #scroller. Its (physical) coordinate system is that of the #scroller, with origin at the bottom left of the #scroller div, and so then the overflow rect runs from -700px to +300px in that space.

(A scrollable overflow rect of (-60000, 0, 60000, 11280) would mean the scrollable area is 1000px wide but lies completely to the left of the enclosing #scroller.)

Comment 3

[Hiroyuki Ikezoe (:hiro)]

Thank you, Jonathan. So the right edge x value is 300px in the case. It's odd to me (given that LTR scroll frame starts with 0px). Anyway I will wait for Botond's reply.

Comment 4

[Kartikaya Gupta (email:[e-mail])]

Botond is away this week so his reply might be delayed. But this behaviour matches my expectations as well, and is what APZ expects/handles.

Comment 5

[Botond Ballo [:botond]]

Yep, the numbers make sense to me too. Even though it's an RTL scroll frame, the scrollable overflow rect is still relative to the top left corner of the scroll port.

Comment 6

[Hiroyuki Ikezoe (:hiro)]

Thank you all, then I have to tweak the value in bug 1373833.