implement dynamic offset (pass in calculateOffset() function) and implement dynamic alpha-safe sizing. I realize some tests still fail. I have to run out for some errands, will be back in 3-4 hours to fix this (namely text layer still has issues. fear not, i will fix these)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@450 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Icon.js

@@ -15,28 +15,30 @@ OpenLayers.Icon.prototype = {
     * @type OpenLayers.Pixel */
     offset: null,    
     
+    /** Function to calculate the offset (based on the size) 
+     * @type OpenLayers.Pixel */
+    calculateOffset: null,    
+    
     /** @type DOMElement */
-    image: null,
+    imageDiv: null,
+
+    /** @type OpenLayers.Pixel */
+    px: null,
     
     /** 
     * @constructor
     *
     * @param {String} url
     * @param {OpenLayers.Size} size
-    * @param {OpenLayers.Pixel} offset
+    * @param {Function} calculateOffset
     */
-    initialize: function(url, size, offset) {
-        this.size = size;
+    initialize: function(url, size, offset, calculateOffset) {
         this.url = url;
-        this.offset = (offset) ? offset 
-                               : new OpenLayers.Pixel(0,0); 
+        this.size = size;
+        this.offset = (offset) ? offset : new OpenLayers.Pixel(0,0);
+        this.calculateOffset = calculateOffset;
 
-        this.image = OpenLayers.Util.createAlphaImageDiv(null,
-                                                 null,
-                                                 this.size,
-                                                 this.url,
-                                                 "absolute"
-                                                );
+        this.imageDiv = OpenLayers.Util.createAlphaImageDiv();
     },
 
     /** 
@@ -47,6 +49,16 @@ OpenLayers.Icon.prototype = {
         return new OpenLayers.Icon(this.size, this.url, this.offset);
     },
     
+    /**
+     * @param {OpenLayers.Size} size
+     */
+    setSize: function(size) {
+        if (size != null) {
+            this.size = size;
+        }
+        this.draw();
+    },
+
     /** 
     * @param {OpenLayers.Pixel} px
     * 
@@ -54,18 +66,31 @@ OpenLayers.Icon.prototype = {
     * @type DOMElement
     */
     draw: function(px) {
+        OpenLayers.Util.modifyAlphaImageDiv(this.imageDiv, 
+                                            null, 
+                                            null, 
+                                            this.size, 
+                                            this.url, 
+                                            "absolute");
         this.moveTo(px);
-        return this.image;
+        return this.imageDiv;
     }, 
 
     /**
     * @param {OpenLayers.Pixel} px
     */
     moveTo: function (px) {
-        if ((px != null) && (this.image != null)) {
-            offsetPx = px.offset(this.offset);
-            this.image.style.left = offsetPx.x + "px"; 
-            this.image.style.top = offsetPx.y + "px"
+        //if no px passed in, use stored location
+        if (px != null) {
+            this.px = px;
+        }
+
+        if ((this.px != null) && (this.imageDiv != null)) {
+            if (this.calculateOffset) {
+                this.offset = this.calculateOffset(this.size);  
+            }
+            var offsetPx = this.px.offset(this.offset);
+            OpenLayers.Util.modifyAlphaImageDiv(this.imageDiv, null, offsetPx);
         }
     },