do not allow multiple identical wms layers

[richlv]

build 1566.
some time ago, wms plugin did not create a persistent layer - instead, choosing desired wms from the menu downloaded visible area. now, choosing wms source again, adds identical layer.

this should be prevented, preferably, with a popup message informing user.

now, if there's some use case where this is actually desired, added wms layers should have different name (like "Landsat 2", "Landsat 3" etc), and every identical wms layer past the first should default to "automatic downloading" off.

[skyper]

Imagery should also prevent to open the same layer (+ same settings) twice and name the layers properly not just the provider.

[Don-vip]

In 5458/josm:

fix #2519 - do not allow multiple identical imagery layers

[skyper]

Now it is impossible to have two layers of the same provider but with different shapen values set. I often use the same provider without shapening and with smooth shapening. The major disadvantage was that you did not see any difference in the layer list and had to aktivate them to know which one was with option.

As I already commented, please allow several layers of one provider but with different settings and chose adequate names for the layers.

Thanks.

[skyper]

Sorry for my English on the last comment.

I do not know how it works at the moment, but maybe layers with different sharpen option set can still use the same cache.

BTW I find the sharpen option quite unhandy hidden under the imagery main preferences. I often forget to set it back, but that is a different issue.

[Don-vip]

I don't know exactly how it works, I'll look into it tonight. If it's too complicated, I'll revert r5458.

Why exactly do you need to have the same layer with two different sharpening methods ? If it becomes possible to change sharpening on an existing layer, would it be OK for you to have only one instance of this layer ?

[skyper]

I mainly use it with lower quality images. I need it to get better contrast, so I use the sharpened pictures directly but also as underlayer below an unsharpened one.

It depends on several factors like colours, position of sun (shades), clouds/fog etc.

I could try if it would work with a single layer and a direct switch but I am not really sure about it.

[Don-vip]

In 5466/josm:

see #2519, see #7981 - revert r5458 to allow again several instances of a single imagery provider