From 081ce883fb6fbfb4607ded0f569772e4362cd759 Mon Sep 17 00:00:00 2001
From: bartvde <bartvde@osgis.nl>
Date: Tue, 17 Nov 2009 07:34:51 +0000
Subject: [PATCH] create an option to cancel adding a layer, r=tschaub (closes
 #2121)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@9802 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
---
 lib/OpenLayers/Map.js |  4 +++-
 tests/Map.html        | 15 ++++++++++++++-
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/lib/OpenLayers/Map.js b/lib/OpenLayers/Map.js
index db66c0f0fa..e197d230eb 100644
--- a/lib/OpenLayers/Map.js
+++ b/lib/OpenLayers/Map.js
@@ -906,7 +906,9 @@ OpenLayers.Map = OpenLayers.Class({
             layer.isBaseLayer = false;
         }
 
-        this.events.triggerEvent("preaddlayer", {layer: layer});
+        if (this.events.triggerEvent("preaddlayer", {layer: layer}) === false) {
+            return;
+        }
         
         layer.div.className = "olLayerDiv";
         layer.div.style.overflow = "";
diff --git a/tests/Map.html b/tests/Map.html
index 28afb022c6..16b954dda1 100644
--- a/tests/Map.html
+++ b/tests/Map.html
@@ -84,7 +84,7 @@
     }
 
     function test_Map_add_layers(t) {
-        t.plan(6);
+        t.plan(8);
         map = new OpenLayers.Map('map');
         var layer1 = new OpenLayers.Layer.WMS("Layer 1", 
             "http://octo.metacarta.com/cgi-bin/mapserv?",
@@ -101,6 +101,19 @@
                 "layer1 zIndex is set" );
         t.eq( parseInt(layer2.div.style.zIndex), map.Z_INDEX_BASE['BaseLayer'] + 5, 
                 "layer2 zIndex is set" );
+
+        map.events.register('preaddlayer', this, function(evt) {
+            return !(evt.layer.name === 'donotadd');
+        });
+        var layer3 = new OpenLayers.Layer.WMS("donotadd",
+            "http://octo.metacarta.com/cgi-bin/mapserv?",
+            {map: "/mapdata/vmap_wms.map", layers: "basic"});
+        map.addLayers([layer3]);
+        t.eq(map.layers.length, 2, "layer is not added since preaddlayer returns false");
+        layer3.name = 'pleaseadd';
+        map.addLayers([layer3]);
+        t.eq(map.layers.length, 3, "layer is added since preaddlayer returns true");
+       
     }
 
     function test_Map_options(t) {