Add legend for WMS

[nkamapper]

It would be great to see legends for WMS imageries.

For example, for the Trafikverket road network endpoint in Sweden, and for the "Hastighetsgrans" (maxspeed) layer, there are only colours for each maxspeed but no number, so interpreting the layer is not easy.

However, in the GetCapabilities the WMS layer defines in the LegendURL element the following link to a legend: ​https://geo-netinfo.trafikverket.se/mapservice/wms.axd/NetInfo?service=WMS&request=GetLegendGraphic&version=1.3.0&sld_version=1.1.0&format=image/png&layer=Hastighetsgrans&width=171&height=128

The legend could be a pop-up window available from the list of layers.

[stoecker]

terms-of-use-url A link that is opened, when the user clicks on the terms-of-use text
terms-of-use-text Customized text for the terms of use link (default is "Background Terms of Use")

What about simply reusing these two maps info fields? Should be displayed at the bottom of the page. Add the link there and call it "Legend" ;-)

[nkamapper]

The link is different for each layer.

[stoecker]

Is legendurl a widespread usage or only a special case? In the second case I'd recommend to make multiple maps entries for each layer or create a webpage which joins all legends into one linkable page.

In the first case JOSM should support it.

[nkamapper]

I think legendurl is a standard feature of most WMS. Something that one would expect to see.
Not related only to the example above but a particular problem there because there are so many different layers.

[stoecker]

Well, WMS has a large amount of features. Most of them seldom used or not very helpful or badly configured or ...
So the question for implementation is always if there is a benefit for multiple systems or only for very few.

[nkamapper]

Agree, but a large number of WMS services use colour coding and symbols which are not easy to guess - I think the majority in my region (Scandinavia), so it certainly would be helpful. There recently was a discussion on the Swedish community on how to interpret the example above.
And many WMS browsers are using the imageurl.