allowed images to be loaded from plugins.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@2662 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/Functions.java

@@ -8,6 +8,7 @@ import hudson.model.Run;
 import hudson.model.Items;
 import hudson.model.JobPropertyDescriptor;
 import hudson.model.Job;
+import hudson.model.Action;
 import org.kohsuke.stapler.Ancestor;
 import org.kohsuke.stapler.StaplerRequest;
 import org.kohsuke.stapler.StaplerResponse;
@@ -353,4 +354,16 @@ public class Functions {
     public static List<JobPropertyDescriptor> getJobPropertyDescriptors(Class<? extends Job> clazz) {
         return JobPropertyDescriptor.getPropertyDescriptors(clazz);
     }
+
+    /**
+     * Computes the path to the icon of the given action
+     * from the context path.
+     */
+    public static String getIconFilePath(Action a) {
+        String name = a.getIconFileName();
+        if(name.startsWith("/"))
+            return name.substring(1);
+        else
+            return "images/24x24/"+name;
+    }
 }