Legend shows items with no GetLegend response

[jonathan-wcc]

A subjective one.

I have a layer enabled on my map that's not visible because it has a scale threshold and I'm outside that range.

However, when I print the map, MFP 2.0 shows the legend item below (Bus Stops):

What I think it should do is see that the GetLegend response doesn't actually include a graphic and then omit the legend item entirely.

[jbjonesjr]

Jonathan, I think the wms spec responds with a full list of features available, regardless if they are available in a single viewport or not. I do not think it is common for a "client" to keep track of what features are in view and update the legend accordingly.

Let me know if you have a contradictory example.

[jonathan-wcc]

Hey,
The GetLegend request doesn't seem to return a legend if the item is outside of viewing threshold. Instead, at least in the case of GeoServer, it returns an exception:
"java.lang.IllegalArgumentException: no legend passed
no legend passed"

My view is that on a printed map, a legend item shouldn't be printed if there is no legend item to print. From the end users perspective, having "Bus Stops" on a legend as in my original screenshot is worse than pointless - its taking up valuable map space to tell them absolutely nothing.

Incidentally, some clients do update the legend - I think its a common GeoExt thing. See:
http://lib.heron-mc.org/heron/0.73/examples/defaultnl/index.html
Try "streekpaden"
or "BAG - Verbilfsobjecten"
and zoom in/out.

They don't show the legend image itself (they can't, there isn't one at those scales), but they do still show the text.

[geekdenz]

If I understand this correctly, you don't want to print legend items that are not displayed on the map. This is a very similar requirement if not the same we have. Basically, when the map only displays 'class 1', 'class 3' and 'class 4', it should not show 'class 2' in the legend, right?

If this is what this issue is about, please confirm so that I can work against this.

So, GeoServer and MapServer actually return an exception if you give them a GetLegend request and the class is not defined for that extent? If yes, please detail how to configure this in MapServer as we are quite keen on this feature as well.

[jonathan-wcc]

Hi Tim,
Not quite. In this particular case there's a scale threshold on the layer. The layer is enabled but I am zoomed out too far for it to be rendered.

The legend shouldn't be shown because the layer isn't shown on the map.

From MFP's perspective it is simply amatter of noting that the response from the server was an exception rather than a PDF. If an exception has been received it shouldn't print any part of that particular legend item.

Hope that's clearer.

[geekdenz]

Yes it is and i think it would actually be reasonably simple to implement. However, I will need to find some time to do it.

[jonathan-wcc]

Has this been fixed but the ticket not closed? It doesn't seem to be happening in the 2.0.0 release.

[geekdenz]

Closing because @jonathan-wcc reports it to be fixed.