Alpha channel not rendered on images?

[Gargaj]

Describe the bug

Playing http://www.digshot.com/gameinfopage.php?g=2657 causes a few obvious alpha channel issues - unfortunately they're most visible at the last level, but here's a playthrough video to help you get there: https://www.youtube.com/watch?v=YrlqziJOmW0

Expected behavior

It looks to me that the alpha channel on some images isn't honored correctly; the hands on the screenshot should not have the white rectangle around them, and the "END" sign shouldn't have the black background.

Affected platform

Browser's extension

Operating system

Windows 10

Browser

Firefox 104.0.1

Additional information

No response

[torokati44]

Looking at the problematic images in ffdec I see them the same way: on a solid background, without any alpha.
Additionally, they are defined using plain DefineBits (6) tags, which have no support for any transparency.
When running the SWF in the desktop player with RUST_LOG=warn set, I get a couple messages like these:

[2022-09-05T15:57:25Z WARN  ruffle_core::display_object] Blend mode 'screen' is unsupported and will not render correctly.
[2022-09-05T15:57:25Z WARN  ruffle_core::display_object] Blend mode 'lighten' is unsupported and will not render correctly.

So, this is likely just another case of #58.

[Lord-McSweeney]

The blend modes PR fixes this issue.

[torokati44]

Cross-referencing: #8262, #9134

[torokati44]

This is fixed now, at least on desktop, and in WebGL 2-capable browsers.