Create a possibility to refresh a layer every N seconds: OpenLayers.Strategy.Refresh, excellent patch by krisgeus, r=me (closes #2317)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@9790 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
2009-11-09 14:43:58 +00:00
parent e77a804559
commit 01debb1c53
4 changed files with 303 additions and 0 deletions
--- a/lib/OpenLayers/Strategy/Refresh.js
+++ b/lib/OpenLayers/Strategy/Refresh.js
@@ -0,0 +1,139 @@
+/* Copyright (c) 2006-2009 MetaCarta, Inc., published under the Clear BSD
+ * license.  See http://svn.openlayers.org/trunk/openlayers/license.txt for the
+ * full text of the license. */
+
+/**
+ * @requires OpenLayers/Strategy.js
+ */
+
+/**
+ * Class: OpenLayers.Strategy.Refresh
+ * A strategy that refreshes the layer. By default the strategy waits for a
+ *     call to <refresh> before refreshing.  By configuring the strategy with 
+ *     the <interval> option, refreshing can take place automatically.
+ *
+ * Inherits from:
+ *  - <OpenLayers.Strategy>
+ */
+OpenLayers.Strategy.Refresh = OpenLayers.Class(OpenLayers.Strategy, {
+    
+    /**
+     * Property: force
+     * {Boolean} Force a refresh on the layer. Default is false.
+     */
+    force: false,
+
+    /**
+     * Property: interval
+     * {Number} Auto-refresh. Default is 0.  If > 0, layer will be refreshed 
+     *     every N milliseconds.
+     */
+    interval: 0,
+    
+    /**
+     * Property: timer
+     * {Number} The id of the timer.
+     */
+    timer: null,
+
+    /**
+     * Constructor: OpenLayers.Strategy.Refresh
+     * Create a new Refresh strategy.
+     *
+     * Parameters:
+     * options - {Object} Optional object whose properties will be set on the
+     *     instance.
+     */
+    initialize: function(options) {
+        OpenLayers.Strategy.prototype.initialize.apply(this, [options]);
+    },
+   
+    /**
+     * APIMethod: activate
+     * Activate the strategy. Register any listeners, do appropriate setup.
+     * 
+     * Returns:
+     * {Boolean} True if the strategy was successfully activated.
+     */
+    activate: function() {
+        var activated = OpenLayers.Strategy.prototype.activate.call(this);
+        if(activated) {
+            if(this.layer.visibility === true) {
+                this.start();
+            } 
+            this.layer.events.on({
+                "visibilitychanged": this.reset,
+                scope: this
+            });
+        }
+        return activated;
+    },
+    
+    /**
+     * APIMethod: deactivate
+     * Deactivate the strategy. Unregister any listeners, do appropriate
+     *     tear-down.
+     * 
+     * Returns:
+     * {Boolean} True if the strategy was successfully deactivated.
+     */
+    deactivate: function() {
+        var deactivated = OpenLayers.Strategy.prototype.deactivate.call(this);
+        if(deactivated) {
+            this.stop();
+        }
+        return deactivated;
+    },
+    
+    /**
+     * Method: reset
+     * Start or cancel the refresh interval depending on the visibility of 
+     *     the layer.
+     */
+    reset: function() {
+        if(this.layer.visibility === true) {
+            this.start();
+        } else {
+            this.stop();
+        }
+    },
+    
+    /**
+     * Method: start
+     * Start the refresh interval. 
+     */
+    start: function() {
+        if(this.interval && typeof this.interval === "number" && 
+            this.interval > 0) {
+
+            this.timer = window.setInterval(
+                OpenLayers.Function.bind(this.refresh, this),
+                this.interval);
+        }
+    },
+    
+    /**
+     * APIMethod: refresh
+     * Tell the strategy to refresh which will refresh the layer.
+     */
+    refresh: function() {
+        if (this.layer && this.layer.refresh && 
+            typeof this.layer.refresh == "function") {
+
+            this.layer.refresh({force: this.force});
+        }
+    },
+   
+    /**
+     * Method: stop
+     * Cancels the refresh interval. 
+     */
+    stop: function() {
+        if(this.timer !== null) {
+            window.clearInterval(this.timer);
+            this.timer = null;
+        }
+    },
+    
+    CLASS_NAME: "OpenLayers.Strategy.Refresh" 
+});