Tile opacity patch from tschaub: Fix for #235. Also includes tests to ensure

that code works.


git-svn-id: http://svn.openlayers.org/trunk/openlayers@1433 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Util.js

@@ -125,6 +125,19 @@ OpenLayers.Util.createImage = function(id, px, sz, imgURL, position, border,
     return image;
 };
 
+/**
+ * Set the opacity of a DOM Element
+ * Note that for this function to work in IE, elements must "have layout"
+ * according to:
+ * http://msdn.microsoft.com/workshop/author/dhtml/reference/properties/haslayout.asp
+ *
+ * @param {DOMElement} element Set the opacity on this DOM element
+ * @param {Float} opacity Opacity value (0.0 - 1.0)
+ */
+OpenLayers.Util.setOpacity = function(element, opacity) {
+    element.style.opacity = opacity;
+    element.style.filter = 'alpha(opacity=' + (opacity * 100) + ')';
+}
 
 OpenLayers.Util.onImageLoad = function() {
     this.style.backgroundColor = null;