This was moved into the `src/display/`-folder in PR 15110, for the initial editor-a11y patch. However, with the changes in PR 15237 we're again only using `binarySearchFirstItem` in the `web/`-folder and it thus seem reasonable to move it back there.
The primary reason for moving it back is that `binarySearchFirstItem` is currently exposed in the public API, and we always want to avoid that unless it's either PDF-related functionality or code that simply must be shared between the `src/`- and `web/`-folders. In this case, `binarySearchFirstItem` is a general helper function that doesn't really satisfy either of those alternatives.
Currently when the `TextAccessibilityManager.enabled` method is called, we'll update `aria-owns` for any pre-existing elements. This obviously makes sense when e.g. zooming/rotating in the viewer, since the annotationLayer/annotationEditorLayer is kept in those cases.
However when the page is *fully* reset, e.g. as result of going out-of-view and thus being evicted from the cache, we still keep the `#textNodes`-Map around. This causes us to set the `aria-owns` attribute (in the textLayer) for an element that doesn't actually exist any more, which as far as I'm concerned seems incorrect. In this case the element will simply, as already implemented, be re-inserted when the annotationLayer/annotationEditorLayer renders again.
This patch doesn't structurally change the text layer: it just adds some aria-owns
attributes to some spans.
The aria-owns attribute expect to have an element id, hence it's why it adds back an
id on the element rendering an annotation, but this id is built in using crypto.randomUUID
to avoid any potential issues with the hash in the url.
The elements in the annotation layer are moved into the DOM in order to have them in the
same "order" as they visually are.
The overall goal is to help screen readers to present to the user the annotations as
they visually are and as they come in the text flow.
It is clearly not perfect, but it should improve readability for some people with visual
disabilities.
