Feature request: Preserve media overlay CSS

[noteon]

"Delete unused stylesheet selectors" deletes things that are not "used" in the .epub, but are still needed by the reading system.

If this appears in the .opf:

<meta property="media:active-class">-epub-media-overlay-active</meta>

It means this book has readaloud highlighting. Deleting the associated selector from .css will defeat that feature:

.-epub-media-overlay-active {
background-color: #FFFF00;
}

The selector can be called anything. "-epub-media-overlay-active" is most common.

Maybe a check box in the "Delete Styles" dialogue that says "Preserve media overlay CSS?"

[KevinH]

Please show me where in the epub3.3 spec this "feature" is described or supported?

What reading systems support this "feature"?

What namespace is "media:" from in the opf?

I really need to see the exact specification for any of this.

[KevinH]

Also the delete unused selectors shows a list of the selectors to be deleted and the user can the make the decision if kept or not.

[BeckyEbook]

https://www.w3.org/TR/epub/#app-overlays-vocab

[noteon]

Originally Posted by KevinH

Please show me where in the epub3.3 spec this "feature" is described or supported?

https://www.w3.org/TR/epub/#sec-media-overlays

What reading systems support this "feature"?

All of them? Apple Books, Adobe Digital Editions, Thorium, Colibrio... Those are the ones I test on, but I'm guessing any current EPUB reader. Apple Books and Colibrio only support it with fixed-layout, though, not reflowable. Readium supports it, too.

What namespace is "media:" from in the opf?

I'm not sure how to answer this, but this is what InDesign puts in a reflowable:

xmlns="http://www.w3.org/1999/xhtml

and in a fixed-layout:

xmlns="http://www.idpf.org/2007/opf

Read-aloud EPUBs have been a huge part of my ebook conversion work for years, so from my perspective, it's nothing odd.

[KevinH]

Originally Posted by BeckyEbook

https://www.w3.org/TR/epub/#app-overlays-vocab

Thanks! That helps.

From reading that spec, there is no xmlns for the media prefix. There is also a playback-active-class meta property that would need the same treatment (I think).

noteon and BeckyEbook, is that your interpretation as well?

[noteon]

Originally Posted by KevinH

There is also a playback-active-class meta property that would need the same treatment (I think).

noteon and BeckyEbook, is that your interpretation as well?

I haven't played with playback-active-class, but I think so.

[BeckyEbook]

I've never done it, but I found a sample file that has entries with the prefix 'media' in the opf file.
https://github.com/IDPF/epub3-sample...y-dick-mo.epub

[KevinH]

Okay as long as the OPF defines the media:active-class or media:playback-active-class
in an epub3 meta property, those specific class selectors will no longer be considered to be "unused" for the purposes of the Delete Unused Selectors tool.

Note this only works for **pure class** selectors with the class names provided by the OPF metadata.

I have now pushed this to master. This feature will be part of the next release.

I tested with the moby dick test case BeckyEbook found and it appears to work correctly.

[noteon]

Originally Posted by KevinH

Okay as long as the OPF defines the media:active-class or medialayback-active-class
in an epub3 meta property, those specific class selectors will no longer be considered to be "unused" for the purposes of the Delete Unused Selectors tool.

Note this only works for **pure class** selectors with the class names provided by the OPF metadata.

I have now pushed this to master. This feature will be part of the next release.

I tested with the moby dick test case BeckyEbook found and it appears to work correctly.

Thank you!