1391014 - CSS Grid Inspector: Bug, doesn't respect transformation on `html` element

Status: RESOLVED FIXED

(DevTools :: Inspector, defect, P2)

Description

[Jen Simmons [:jensimmons]]

If I apply a margin on a document's HTML element, the Grid Inspector miscalculates where to draw the boxes for a Grid.

Here's an example: 
1) Open this in Firefox Nightly: https://s.codepen.io/jensimmons/debug/GvyJWV, and open up the Grid Inspector
2) See that the Grid is drawn in the wrong place, https://monosnap.com/file/RJqv4iIr9QktnaPHAlRNmvJsyIPDVS.png
3) Remove the margin from the HTML element, and see that the Grid is now in the correct place.

Here's the full code for the example so you can see the CSS: https://codepen.io/jensimmons/pen/GvyJWV?editors=1100#0
Note — it works *inside* CodePen itself, because the document structure is different.

Comment 1

[Matteo Ferretti [:zer0] [:matteo]]

Attachment: Bug 1391014 - take in account the ancestor's transformation too for the current matrix;

Review commit: https://reviewboard.mozilla.org/r/177746/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/177746/

Comment 2

[Matteo Ferretti [:zer0] [:matteo]]

This patch should do the trick.

Basically the matrix we applied to the grid was everything up to the `documentElement` (our ancestor), but it didn't consider any transformation - rotation, translation, scale, etc - applied to the `documentElement` itself (`margin` and `top`, `left` etc are considering a "translation" in the matrix).

Comment 3

[Gabriel Luong [:gl] (ΦωΦ)]

Comment on attachment 8905989 [details]
Bug 1391014 - take in account the ancestor's transformation too for the current matrix;

https://reviewboard.mozilla.org/r/177746/#review182818

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/76eda7d1476e
take in account the ancestor's transformation too for the current matrix; r=gl

Comment 5

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/mozilla-central/rev/76eda7d1476e

Comment 6

[Jen Simmons [:jensimmons]]

This looks fixed to me:
https://monosnap.com/file/6R4wxjbhmmW45Ise3f8aoERdqP7sTW.png

Fantastic! Thank you.

Comment 7

[Saheda Reza [:Antora]]

I have reproduced this bug according to (2017-08-16)

Fixing bug is verified on Latest Nightly--
Build ID   :20170914220209
User Agent  :Mozilla/5.0 (Windows NT 6.1; rv:57.0) Gecko/20100101 Firefox/57.0

Tested OS-- WIndows7 32bit