macOS packaging: Add better rasterization of icon

[fwcd]

As a small follow-up to #4545, this PR adds a better rasterization of the macOS icon.

The version added in the original PR used an ICNS that was generated by downscaling a 1024x1024 render of the icon. This works fine for most use-cases and with the widespread use of high dpi displays usually isn't really a big issue. However, on non-retina displays there are some noticeable artifacts with the smaller versions. For example, consider the Mixxx icon in this dialog:

The icon noticeably lacks its gray border. Contrast this with e.g. the icons for Preview or GIMP, which feature crisp borders that are optimized for the smaller icon size.

This PR addresses this by rendering every size individually from the source SVG into the ICNS (using this script). With the new ICNS, the icon renders properly at all sizes:

[daschuer]

Cool, thank you for taking care.
Can you also put the script in the Mixxx's tool folder?

[ronso0]

Can you also put the script in the Mixxx's tool folder?

I couldn't find clear info on gist licenses.
Can someone clarify this before the script (based on another script) is included in Mixxx?

[daschuer]

So we need to ask the original author. @fwcd can you do it?

https://zebracatzebra.com/oss/getting-the-gist-of-github-gist-licensing/
... explains it and has even a template message.

[fwcd]

Not a lawyer, but isn't the snippet sufficiently trivial to not be copyright-protectable?

[fwcd]

If you'd like, I could rewrite it from scratch for Mixxx (it would in any case probably require a few tweaks to the paths)

[fwcd]

I have added a new version of the script in packaging/macos/regenerate_icns.sh that is

• written from scratch
• tailored to Mixxx's paths
• only based on the inkscape man pages and this Stackoverflow post

Thus there hopefully shouldn't be any licensing issues.

[daschuer]

LGTM, Thank you.