1682197 - [non WebRender] OOP iframe contents gets incorrectly minus offset-ed without layerization on Fission

Status: RESOLVED FIXED

(Core :: Panning and Zooming, defect)

Description

[Hiroyuki Ikezoe (:hiro)]

Attachment: a test case

Steps to reproduce;

1. Enable fission and disable WebRender
2. Open the attaching file
3. Pinch zoom in
4. The contents in the iframe will go outside the iframe's viewport

If the iframe has will-change: transform style, it works properly.

Comment 1

[Hiroyuki Ikezoe (:hiro)]

Probably this is not a high priority issue for Fission because it only happens without WebRender.

Comment 2

[Chris Peterson [:cpeterson]]

Fission Future. We only support Fission with WebRender for now.

Comment 3

[Botond Ballo [:botond]]

S4 for a bug in a configuration we are not intending to ship.

Comment 4

[Hiroyuki Ikezoe (:hiro)]

Attachment: Fix for simple OOP iframe case

I happened to notice where the problem underlies. The problem is here in nsDisplayRemote::BuildLayer to get the remote iframe offset. When the desktop zoom is applied, the offset should be multiplied by the zoom value.

Attaching file is a fix for simple OOP iframe case, it doesn't fix nested iframe cases unfortunately we need a way to get the desktop zoom value in OOP contents. I will introduce the way in bug 1649447.

An interesting thing (at least for me) is that we use the same offset for WebRender as well, but the rendering results on WebRender looks correct. (note that hit testing is incorrect on WebRender).

Comment 5

[Hiroyuki Ikezoe (:hiro)]

Attachment: A scale iframe case that you can see the issue without zooming

The issue is not a desktop zoom specific issue, it's an issue that we don't scale the offset to the iframe because we use PreScale. Using PostScale seems to fix this issue.

Comment 6

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 1682197 - Scale the offset to remote iframe in nsDisplayRemote::BuildLayer. r?mattwoodrow!,botond

When the iframe is inside a scaled container, the offset to the reference frame
needs to be scaled.

This change fixes both a rendering issue (bug 1682197) and a hit-testing issue
(bug 1682200) altogether for non WebRender.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/1f6d62f03dd7
Scale the offset to remote iframe in nsDisplayRemote::BuildLayer. r=mattwoodrow

Comment 8

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/1f6d62f03dd7