1584680 - Distorted image when inside smaller container with overflow:auto and using an image map

Status: RESOLVED DUPLICATE of bug 1580922

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

Description

[Florens Verschelde :fvsch]

Attachment: screenshot-image-map-distortion.png

Could be a dupe of bug 1583090, but I couldn't reproduce with the STR there.

Since 2-4 weeks on Nightly I've been seeing distorted images on some image galleries where images use a <map>. Images render correctly initially, but as soon as some scrolling happens the image content appears stretched, while the <img> element itself keeps its size.

Steps to reproduce:

1. Open https://codepen.io/fvsch/pen/GRKaJOG
2. Scroll inside the DIV containing two images

Expected result:
Both images render identically.

Actual result:
Images render identically on initial load, then when scrolling (step #2) the second image gets distorted.

Conditions I've found for the distortion to happen:

• <img> has an image map
• image layout dimensions are taller or wider than the viewport, or an ancestor element with overflow:auto or overflow:scroll

Seen in Nightly on Linux, and according to about:support I have Compositing: WebRender. Haven't tested with webrender force-disabled yet.

Comment 1

[Florens Verschelde :fvsch]

Looks WebRender-specific.
I can't reproduce with Compositing: Basic.

Comment 2

[Timothy Nikkel (:tnikkel)]

I think Andrew has patches that change how image maps are rendered with webrender, perhaps they fix this?

Comment 3

[Timothy Nikkel (:tnikkel)]

(bug 1583235)

Comment 4

[Emilio Cobos Álvarez (:emilio)]

This looks a lot like bug 1580922, and also involves blob images, wdyt Jeff?

Comment 5

[Jeff Muizelaar [:jrmuizel]]

Yep this sounds like the same issue. The patches on bug 1580922 should fix the issue.

Comment 6

[Jeff Muizelaar [:jrmuizel]]

Do you still see this with the latest Nightly?

Comment 7

[Florens Verschelde :fvsch]

Not seeing it anymore on latest Nightly with WebRender on (Linux + macOS).
Closing as WORKSFORME, but feel free to dupe it against another bug if that's more relevant.