Define logo origin on the Toolbar

I think it would be great to make the logo customizable. The minimal version could be that it lives with a twig template that the site's subtheme can customize. But we discourage runtime subtheming ;)

I think an admin theme settings screen would be useful. The existing site logo upload is for the frontend and global to all themes, right?

> The existing site logo upload is for the frontend and global to all themes, right?

I thought that the logo upload is per theme, because there is also the checkbox on theme settings that lets you just use the default logo provided by the theme. When left unchecked, you can upload your own logo, which then gets stored into theme settings. I could be wrong, but seems like this could just use the same theme settings that Drupal already supports, provide the `logo.svg` and let it be overridden. It might be helpful to provide additional context on this specific theme's logo upload form to specify ideal dimensions, image formats (eg PNG &SVG preferred) or any color requirements (eg white on transparent bg).

The existing site logo upload is for the frontend and global to all themes, right?

I would assume so. Maybe as an MVP we could go with the front-end logo, but it scares me what you can face with "scaled square-forced" logos (prepared to be printed way bigger on the front-end). So I'd rather keep the Drupal logo...

I think an admin theme settings screen would be useful.

Good point. Maybe the logo on a theme, when it's admin, can be used there? But I'm a bit afraid of relying on external themes for that, because not even Claro has this logo now. Another alternative is something generic like "Administration settings" under "User interface" in config, created by this module itself?

I think we definitely want to have the logo customizable. I also think it needs to go through the image style process so it looks and loads quickly.

Whatever route/path we put this on, we also need to think of other future settings like colors, dark mode, etc that hopefully will be coming down the line. My initial thought is somewhere in system settings.

What I'm currently missing is an easy way to provide a site-specific SVG logo that can consider dark/light mode. The only way (I think) to do this is by changing the logo to an inline SVG with embedded CSS styles like this:

<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64">
   <style>
        path {
            fill: black;
        }
        @media (prefers-color-scheme: dark) {
            path { fill: white; }
        }
    </style>
    <path d="..."/>
</svg>

And the only way to achieve that would be to override a template, to allow uploading an SVG through a text field (doesn't sound like a good idea) or if an SVG image is uploaded, to inline it instead of rendering as an <img> tag (sounds insecure).

📌 Support admin theme logo Needs review was opened as a duplicate but has code to implement swapping the logo from the admin theme settings. I'll close this and carry over credits to there.