Readium demo not working reliably

[robertknight]

The Readium EPUB demo is not working reliably.

In Safari, selecting text in the ebook content doesn't show the Annotate / Highlight actions. There is also a spurious cross-origin access error in the browser console that doesn't affect execution.

In Chrome, the adder does appear when selecting text, but all the annotations orphan and after ~30 seconds, the following errors appear in the console:

In Firefox the result is the same as in Chrome.

The issue in Chrome and Firefox looks the issue described and resolved in #4144.

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Update 2022-02-07:

The initial issue described in Chrome/Firefox was fixed, but there are still three issues present:

• Some annotations are missing highlights, despite apparently being anchored - Readium demo not working reliably #4153 (comment)
• Some annotations whose URLs do not match the current content frame URL are orphaned. See Readium demo not working reliably #4153 (comment)
• The adder doesn't appear when selecting text in Safari (Fixed by Build and load annotator bundle as a non-module script #4353)

[robertknight]

#4144 is now resolved, and some of the annotations now anchor in Chrome / Firefox. Some others do not however. Comparing the JSON data of the annotations which anchor vs those that do not, it looks like the annotations have different associated URLs. It looks like those annotations whose primary URL matches the <link rel="canonical>" URL of the book content anchor, but others do not. I think what is happening here relates to the limitation described in #4131 where annotations are not sent to a non-main frame unless the annotation's URL exactly matches the current frame URL.

[robertknight]

Additional problems seen after resolving #4144:

• The problem in Safari where selecting text does not show the Annotate/Highlight buttons persists
• In Chrome/Firefox, highlights are missing for some annotations, even though they apparently anchored. For example this annotation:

See that the text "Corlears hook" is not highlighted on the left, though it appears to have anchored.

[robertknight]

The issue with the adder not appearing in Safari was a general issue for XHTML documents. It was fixed by #4353.

[robertknight]

See #4283 (comment).