1870474 - SVG X and Y rounding issues when scale transformation is used

Status: UNCONFIRMED

(Core :: Graphics: WebRender, defect, P3)

Description

[tarquinwj]

Attachment: ffsvgrounding.svg

Steps to reproduce:

120.0.1 (64-bit) stable on Windows 10.
http://www.howtocreate.co.uk/working/ffsvgrounding.svg

1. Create a shape with whatever dimensions it should have.
2. <use> that shape in a group, and transform="scale" the <use> with a scale that has several decimal places, below 0.1
3. <use> that scaled version, and set the x and y positions in the <use> to positions that also have several decimal places, less than 1.

Actual results:

Firefox rounds or truncates positions somewhere, causing the shapes to be misplaced. As the x and y values are changed, the error in the resulting position suddenly jumps by more than the change in coordinate, showing that some rounding is taking place.

This issue is not seen in Chromium.

Expected results:

The shapes should have been correctly positioned.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::Graphics: WebRender' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Brad Werth [:bradwerth]]

I can reproduce on my macOS setup as well. Nical, would you please take a look?

Comment 3

[tarquinwj]

Is there perhaps someone that can look into this? It's breaking some stuff I cannot realistically recode without making the SVG enormous (it gets used repeatedly at different scales), and I couldn't find any useful workarounds.

Comment 4

[tarquinwj]

2 months in. I understand that development time is precious, but this is still sitting in "unconfirmed" in spite of me providing a reduced testcase, and someone else having reproduced the bug. Surely this can be confirmed and assigned by now. Is this sort of delay normal?