Suport for tooltips on externalGraphics using the graphicTitle

symbolizer property. Only supported in IE and FF. Patch by zspitzer, 
modified by me (added some docs, moved code that sets the title tag so 
it gets executed for externalGraphics. p=zspitzer, r=me (closes #1946)


git-svn-id: http://svn.openlayers.org/trunk/openlayers@9097 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

examples/vector-features.html

@@ -62,6 +62,8 @@
             style_mark.graphicXOffset = -(style_mark.graphicWidth/2);  // this is the default value
             style_mark.graphicYOffset = -style_mark.graphicHeight;
             style_mark.externalGraphic = "../img/marker.png";
+            // graphicTitle only works in Firefox and Internet Explorer
+			style_mark.graphicTitle = "this is a test tooltip";
 
             var vectorLayer = new OpenLayers.Layer.Vector("Simple Geometry", {style: layer_style});
 

lib/OpenLayers/Feature/Vector.js

@@ -332,6 +332,7 @@ OpenLayers.Feature.Vector = OpenLayers.Class(OpenLayers.Feature, {
  * graphicZIndex - {Number} The integer z-index value to use in rendering.
  * graphicName - {String} Named graphic to use when rendering points.  Supported values include "circle" (default),
  *     "square", "star", "x", "cross", "triangle".
+ * graphicTitle - {String} Tooltip for an external graphic. Only supported in Firefox and Internet Explorer.
  * backgroundGraphic - {String} Url to a graphic to be used as the background under an externalGraphic.
  * backgroundGraphicZIndex - {Number} The integer z-index value to use in rendering the background graphic.
  * backgroundXOffset - {Number} The x offset (in pixels) for the background graphic.

lib/OpenLayers/Renderer/Canvas.js

@@ -191,6 +191,10 @@ OpenLayers.Renderer.Canvas = OpenLayers.Class(OpenLayers.Renderer, {
        var img = new Image();
        img.src = style.externalGraphic;
        
+       if(style.graphicTitle) {
+           img.title=style.graphicTitle;           
+       }
+
        var width = style.graphicWidth || style.graphicHeight;
        var height = style.graphicHeight || style.graphicWidth;
        width = width ? width : style.pointRadius*2;

lib/OpenLayers/Renderer/SVG.js

@@ -250,6 +250,9 @@ OpenLayers.Renderer.SVG = OpenLayers.Class(OpenLayers.Renderer.Elements, {
             if (style.externalGraphic) {
                 pos = this.getPosition(node);
                 
+        		if (style.graphicTitle) {
+                    node.setAttributeNS(null, "title", style.graphicTitle);
+                }
                 if (style.graphicWidth && style.graphicHeight) {
                   node.setAttributeNS(null, "preserveAspectRatio", "none");
                 }

lib/OpenLayers/Renderer/VML.js

@@ -199,6 +199,9 @@ OpenLayers.Renderer.VML = OpenLayers.Class(OpenLayers.Renderer.Elements, {
         if (node._geometryClass == "OpenLayers.Geometry.Point") {
             if (style.externalGraphic) {
                 this.drawGraphic(node, geometry, style);
+        		if (style.graphicTitle) {
+                    node.title=style.graphicTitle;
+                } 
                 // modify style/options for fill and stroke styling below
                 style.fillColor = "none";
                 options.isStroked = false;