Feature Index

[Malvoz]

Experiment: https://maps4html.org/experiments/screenreader/feature-index/

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A Feature Index exposes all features currently in view, in a list. It has the following benefits:

1. Users can tell what a feature is about without first interacting with it:

   • Visual users can see the features' names in the Feature Index (even if they couldn't see the feature itself on the map due to poor contrast, small size, etc.). This is enabled by having the Feature Index visible on screen (perhaps a control can be provided to toggle the Feature Index between sr-only and "visible to all").

   • Non-visual users can have their screen reader announce the items in the Feature Index. This is enabled by making the Feature Index a Live Region element (whether it's sr-only or "visible to all" does not matter to a non-visual user).

2. Allows interacting with overlapping interactive features (Otherwise, for example, if you have 2 clickable features overlapping, only 1 can be clicked using a mouse pointer or touch. So enables more easily interacting with the desired feature for all types of users (including users who use speech recognition to control a cursor, which is not on that list)):

   • For keyboard users this would be enabled by having each item in the Feature Index assigned a keyboard shortcut (usually 1-8 (9 exposes "more results" - items that can't initially fit in the Feature Index's container).

   • For users on a touch device, with no access to keyboard shortcuts, this would be enabled by having each item in the Feature Index clickable (perhaps the actual feature on the map is too small to interact with, the user can instead click the corresponding feature item in the Feature Index).
     Note: neither Esri's a11y-map, the Google Maps site nor the proposed implementation for MapBox's Accessibility Plugin has this feature, may raise an issue with the former to discuss usefulness and potential issues.

3. Allows querying any number of layers (I believe, if they can somehow be exposed in the Feature Index. I think this means that queries must have identifiers, e.g. <link rel="query" title="...">.)

For reference, here are screenshots of Feature Indexes as implemented by the Google Maps site (instructions), Esri's a11y-map and the experimental implementation for MapBox's Accessibility Plugin:

[Malvoz]

I've updated the initial comment as it was a bit vague and left out important details.

Also, I'd like to note that it's not immediately clear to me at this moment if a Feature Index as described in this issue can make sense without #396. OTOH #396 does not necessarily depend on a Feature Index, see 5. Features in view should be announced options a) and b).

[Malvoz]

• Need to resolve Feature index #636 (comment):

Users on touch devices (using e.g. TalkBack, VoiceOver) can't use the feature index in the demo because it remains aria-hidden="true".

[prushforth]

@Malvoz I think that the key buttons in the feature index should be actual buttons, so that mobile / touch device users can press them without access to a keyboard. WDYT?