Activity icon colors are not accurate

[t-schroeder]

Describe the bug
The same problem currently exists in the core Boost theme in Moodle versions 4.4 and 4.5 and is described in https://tracker.moodle.org/browse/MDL-84306.

To Reproduce
Steps to reproduce the behavior:

1. Change theme setting activityiconcolorassessment to #5B40FF
2. Go to a course
3. Create an assignment
4. Open the assignment's page
5. Zoom the page to make the icon as bis as possible
6. Take a screenshot of the icon
7. Insert it in an image editor (e.g. GIMP)
8. Use the color picker to check which color the icon has
9. Notice the color differs significantly from the intended color.
   • Example: #7d4bff

Expected behavior
The color should be very near the intended color.

Screenshots

Please complete the following information:

• Moodle Version: 4.4/4.5
• Boost Union Version: latest 4.4/4.5
• OS: Windows
• Browser: Chrome

[wiebkemueller-hsh]

Hi @t-schroeder we are aware of this, have you tried to increase the colour fidelity by using the "many shot iterations" for the configuration (boost union/look/activity branding) to create a better colour match? We hope to see better results in the coming moodle versions, therefore we marked this as won't fix/waiting for core. Regards BU Team

[t-schroeder]

Hi @wiebkemueller-hsh ,

the fidelity is not the problem. The problem is that the filters only work for icons with black as their base color. With MDL-78284 the core activity icons got changed and now they have a base color of #212529 instead of the the #000000 required for the filters to work correctly. When I configure the color as #5B40FF in the boost_union settings, it produces #7D4BFF instead which looks noticeably different. Also: Third-party activities often use black icons, which get colored correctly, so you can end up with two activities having the same purpose but noticeably different colors. None of the Behat tests for boost_union found this issue because they don't test the actual color of the icons. They test whether the CSS filters that boost_union produces would result in that color given a black icon as the basis.

I already provided a pull request that fixes this, just haven't gotten around to making the Behat tests work with it. So I don't get why this got closed.

[t-schroeder]

I'm also aware of the fix to this in Moodle 5.0+ in MDL-83725 but that has its own problems like not working at all in Safari (see MDL-84630).

We tested that fix from MDL-83725 for a while and it would also randomly not work in Chrome and Firefox, but after a page refresh it would work again. All the icons would just be black (or near-black). The strange thing is, the CSS rules are correctly set according to the browser dev tools when that happens. If you uncheck and check any of these CSS rules, all the icons of that purpose suddenly have the correct color, no page reload needed. No idea what that's about, but we haven't had that problem with the current solution that stochastically approximates the CSS filters needed to create a color.