[Patch] Synchronized access to MapView#layers

[michael2402]

The OpenGL plugin should support asynchronous layer drawing (not in sync with the AWT threads). Currently, the layers are not synchronized anywhere, but this is required for the plugin.

[bastiK]

In 8551/josm:

applied #11631 new enhancement - Synchronized access to MapView#layers (patch by michael2402)

[bastiK]

Great work!

• in moveLayer, there was an unused variable (oldEditLayer)
• I've not applied the changes to getVisibleLayersInZOrder: The idea is to move the active data layer on top of any number of (inactive) data layers that come directly above. (Not sure if the current code does that, but anyway...)

[Don-vip]

Milestone renamed

[wiktorn]

@michael2402

You need to verify changes in [8646], if they provide needed level of synchronization.

[michael2402]

For me, they provide enough synchronisation. This should at least solve the issues I got (ConcurrentModificationException, ...).

I am not sure about plugins. Especially calling layer.destroy(); before fireLayerRemoved(layer); seems to be unsafe.

I think we could move this whole block out of the synchronized statement:

layer.removePropertyChangeListener(this);
layer.destroy();
AudioPlayer.reset();

[Don-vip]

In 8925/josm:

see #11631 - see #11689 - remove commented code causing javadoc warnings