Created scale indicator based on Chris's Permalink.js.

git-svn-id: http://svn.openlayers.org/trunk/openlayers@923 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Control/Scale.js

@@ -0,0 +1,78 @@
+/* Copyright (c) 2006 MetaCarta, Inc., published under the BSD license.
+ * See http://svn.openlayers.org/trunk/openlayers/license.txt for the full
+ * text of the license. */
+
+// @require: OpenLayers/Control.js
+
+/**
+ * @class
+ */
+OpenLayers.Control.Scale = Class.create();
+OpenLayers.Control.Scale.prototype = 
+  Object.extend( new OpenLayers.Control(), {
+    INCHES_PER_UNIT: { // borrowed from MapServer mapscale.c
+	dd: 1.0,
+	ft: 12.0,
+	mi: 63360.0,
+	m: 39.3701,
+	km: 39370.1
+    },
+
+    /** @type DOMElement */
+    element: null,
+    
+    /** @type String */
+    base: '',
+
+    /** @type String */
+    units: 'dd',
+    
+    /** @type Integer */
+    dpi: 72,
+
+    /**
+     * @constructor
+     * 
+     * @param {DOMElement} element
+     * @param {String} base
+     */
+    initialize: function(element, base, units) {
+        OpenLayers.Control.prototype.initialize.apply(this, arguments);
+        this.element = element;        
+        if (base) this.base = base;
+        if (units) this.units = units;
+    },
+
+    /**
+     * @type DOMElement
+     */    
+    draw: function() {
+        OpenLayers.Control.prototype.draw.apply(this, arguments);
+        if (!this.element) {
+            this.element = document.createElement("div");
+            this.div.style.right = "3px";
+            this.div.style.bottom = "3px";
+            this.div.style.left = "";
+            this.div.style.top = "";
+            this.div.style.display = "block";
+            this.div.style.position = "absolute";
+            this.element.style.fontSize="smaller";
+            this.div.appendChild(this.element);
+        }
+        this.map.events.register( 'moveend', this, this.updateLink);
+        return this.div;
+    },
+   
+    /**
+     * 
+     */
+    updateLink: function() {
+        var res = this.map.getResolution();
+	var scale = 1 / (res * self.INCHES_PER_UNIT[self.units] * self.dpi);
+        this.element.innerHTML = "Scale = 1 : " + scale;
+    }, 
+    
+    /** @final @type String */
+    CLASS_NAME: "OpenLayers.Control.Scale"
+});
+