1828224 - Text in SVG shifts up-and-down when mouse is hovered over the interactive part of the SVG

Status: NEW

(Core :: Graphics: WebRender, defect)

Description

[thomas.smailus]

Attachment: Contains the SVG file demonstrating the issue, and images to show where to mouse and what SVG content is modified by mouseover.

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Firefox/102.0

Steps to reproduce:

Open the SVG graphic in the browser, the mouse over the region indicated (in MouseZone-Example.PNG) - it is a js driven 'hotspot', which changes the visibility of an orange rectangle behind the part. Moving off and on that 'hotspot' will turn on and off the highlighted orange rectangle - which is done by changing the 'visibility' attribute of the group the rectangle is in. (section illustrated in MouseZone-ObjectWithVisabilityChanging.PNG )

Actual results:

As you move on/off the region and the highlighting turns on/off, the mere changing of the visibility of a rectangle, causes all of the text on the SVG to move slightly up and down, even though nothing in the text is modified.

The recomputation/rendering seems to be shifting/rounding error? the text - and only the text. Lines are not affected.

Expected results:

The text should NOT move at all; only the orange highlight should come on and off - nothing more. Chrome/Edge do not have this issue - only Firefox.

Comment 1

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

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

Comment 2

[Mayank Bansal]

Can repro.
Regression Range:
Bug 1686654 - Track CompositorHitTestInfo accross blob groups. r=jrmuizel
Differential Revision: https://phabricator.services.mozilla.com/D145358

Comment 3

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

Set release status flags based on info from the regressing bug 1686654

:nical, since you are the author of the regressor, bug 1686654, could you take a look? Also, could you set the severity field?

For more information, please visit auto_nag documentation.

Comment 4

[Nicolas Silva [:nical]]

This is caused by rendering differences when layerization of the blobs plays out differently because something in the middle is turned into an WR display item. Could be a snapping issue or some precision loss on some transform somewhere. The regressing patch made it so some images in SVGs are rendered with WR display items instead of blobs.

I won't have time to investigate this for a long while. In case anyone was waiting on me it's up for grabs.