[HotFix] [SVCS-918] Use White Background For Zoomed Images

[cslzchen]

Ticket

https://openscience.atlassian.net/browse/SVCS-918

Purpose

cc and h/t @Johnetordoff for discovering this

Fix the issue where zooming does not work properly for .GIFs with transparent background. Here is the example on staging OSF. This bug only affects non-exported types: .GIF and .ICO. For exported ones, the export type .JPEG does not have transparency so the background is set to white by default.

Normal

Zoom - Before

Changes

• The fix simply set a white background when the zoom image's style class is generated on the page.

Zoom - After

Side effects

No

QA Notes

Test that image rendering and zooming works as expected.

• .GIF with transparent background: https://staging.osf.io/3ca45/
• .GIF with non-transparent background: https://staging.osf.io/3r9m7/
• Plus a few other static images

Deployment Notes

No

[coveralls]

Coverage remained the same at 71.117% when pulling 4ba1f1a447fe915bedd3253968994d7c8abc43a5 on cslzchen:hotfix/image-zoom-gif into ead3389dd0363333778ab53fc2c64211a141c90c on CenterForOpenScience:develop.