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Extension Features

There are several additional requirements that are addressed by the extension.

Extension popup


By default, the extension uses the browser's locale to display any <mapml-viewer> UI in the user's locale. Note that if the UI is not localized to your browser's language, it is likely because there currently exists no translation of the UI strings for your locale. Localization contributions are welcome. Languages that are available at the time of writing are english, french and swedish.

Feature Indexing

When turned on through the extension, enables a square in the middle of the map to enable a keyboard index menu of features located inside the square.

Feature Index Example

Announce Zoom Level

When toggled through the extension, announces the zoom level through screen readers (this is on by default).

Announce Scale

Announces the map scale through screen readers in metric or imperial units (metric is selected by default).

Render MapML resources

When turned on through the extension popup (it is on by default as shown above, but can be turned off), the extension enables the rendering of map documents that have no host document, just as browsers can render image resources (image/*) that have no host document, by synthesizing a host document at run time. The feature will recognize documents that are served to a browser tab (a top level browsing context) that are served with the "text/mapml" or "application/xml" Content-Type header. In the latter case, the extension will "sniff" for a root <mapml- xmlns=""> element.

Set a coordinate system for copy operations

By default, the coordinate system (cs) for copying the map extent using the map context menu is projected coordinates (PCRS), and that for copying locations is by default geodetic (GCRS). When changed to another through the extension user interface, the selected cs will be used for subsequent copy operations.


Report problems with these requirements on GitHub

requirementenhancementimpracticalundecidedunder discussion

The GeoWeb - proposed Epic
Client-side Mapping API Capabilities (6.0)