Changeset 10508 in josm for trunk/src/org/openstreetmap/josm/gui/layer

Timestamp:

2016-07-03T18:26:16+02:00 (8 years ago)

Author:

Don-vip

Message:

fix #13078 - Add new listener that fires before first layer is added and after last one is removed (patch by michael2402) - gsoc-core

File:

• trunk/src/org/openstreetmap/josm/gui/layer/MainLayerManager.java (modified) (6 diffs)

trunk/src/org/openstreetmap/josm/gui/layer/MainLayerManager.java

@@ -96 +96 @@
 
     /**
+     * This event is fired for {@link LayerAvailabilityListener}
+     * @author Michael Zangl
+     * @since 10508
+     */
+    public class LayerAvailabilityEvent extends LayerManagerEvent {
+        private final boolean hasLayers;
+
+        LayerAvailabilityEvent(LayerManager source, boolean hasLayers) {
+            super(source);
+            this.hasLayers = hasLayers;
+        }
+
+        /**
+         * Checks if this layer manager will have layers afterwards
+         * @return true if layers will be added.
+         */
+        public boolean hasLayers() {
+            return hasLayers;
+        }
+    }
+
+    /**
+     * A listener that gets informed before any layer is displayed and after all layers are removed.
+     * @author Michael Zangl
+     * @since 10508
+     */
+    public interface LayerAvailabilityListener {
+        /**
+         * This method is called in the UI thread right before the first layer is added.
+         * @param e The event.
+         */
+        void beforeFirstLayerAdded(LayerAvailabilityEvent e);
+
+        /**
+         * This method is called in the UI thread after the last layer was removed.
+         * @param e The event.
+         */
+        void afterLastLayerRemoved(LayerAvailabilityEvent e);
+    }
+
+    /**
      * The layer from the layers list that is currently active.
      */
@@ -106 +147 @@
 
     private final List<ActiveLayerChangeListener> activeLayerChangeListeners = new CopyOnWriteArrayList<>();
+    private final List<LayerAvailabilityListener> layerAvailabilityListeners = new CopyOnWriteArrayList<>();
 
     /**
@@ -154 +196 @@
         }
         activeLayerChangeListeners.remove(listener);
+    }
+
+    /**
+     * Add a new {@link LayerAvailabilityListener}.
+     * @param listener The listener
+     * @since 10508
+     */
+    public synchronized void addLayerAvailabilityListener(LayerAvailabilityListener listener) {
+        if (!layerAvailabilityListeners.add(listener)) {
+            throw new IllegalArgumentException("Attempted to add listener that was already in list: " + listener);
+        }
+    }
+
+    /**
+     * Remove an {@link LayerAvailabilityListener}.
+     * @param listener The listener
+     * @since 10508
+     */
+    public synchronized void removeLayerAvailabilityListener(LayerAvailabilityListener listener) {
+        if (!layerAvailabilityListeners.remove(listener)) {
+            throw new IllegalArgumentException("Attempted to remove listener that was not in list: " + listener);
+        }
     }
 
@@ -199 +263 @@
     @Override
     protected synchronized void realAddLayer(Layer layer) {
+        if (getLayers().isEmpty()) {
+            LayerAvailabilityEvent e = new LayerAvailabilityEvent(this, true);
+            for (LayerAvailabilityListener l : layerAvailabilityListeners) {
+                l.beforeFirstLayerAdded(e);
+            }
+        }
         super.realAddLayer(layer);
 
@@ -214 +284 @@
         }
 
-        return super.realRemoveSingleLayer(layer);
+        Collection<Layer> toDelete = super.realRemoveSingleLayer(layer);
+        if (getLayers().isEmpty()) {
+            LayerAvailabilityEvent e = new LayerAvailabilityEvent(this, false);
+            for (LayerAvailabilityListener l : layerAvailabilityListeners) {
+                l.afterLastLayerRemoved(e);
+            }
+        }
+        return toDelete;
     }
 
@@ -320 +397 @@
 
         activeLayerChangeListeners.clear();
+        layerAvailabilityListeners.clear();
     }
 }