Fixes #1528

 * Also adding in product doc about parameters to the Simple Image Tracking code

core/Tracker/Visit.php

@@ -85,6 +85,15 @@ function setRequest($requestArray)
 			throw new Exception('Invalid idSite');
 		}
 		$this->idsite = $idsite;
+
+		// When the 'url' and referer url parameter are not given, we might be in the 'Simple Image Tracker' mode.
+		// The URL can default to the Referer, which will be in this case 
+		// the URL of the page containing the Simple Image beacon
+		if(empty($this->request['urlref'])
+			&& empty($this->request['url']))
+		{
+    		$this->request['url'] = @$_SERVER['HTTP_REFERER'];
+		}
 	}
 
 	/**
@@ -972,7 +981,7 @@ public function getRefererInformation()
 
 		// get the urls and parse them
 		$refererUrl	= Piwik_Common::getRequestVar( 'urlref', '', 'string', $this->request);
-		$currentUrl	= Piwik_Common::getRequestVar( 'url', '', 'string', $this->request);
+		$currentUrl	= Piwik_Common::getRequestVar( 'url', $defaultUrl, 'string', $this->request);
 
 		$this->refererUrl = $refererUrl;
 		$this->refererUrlParse = @parse_url(Piwik_Common::unsanitizeInputValue($refererUrl));

misc/tracker_simpleImageTracker.php

@@ -0,0 +1,3 @@
+This page loads a Simple Tracker request to Piwik website id=1
+
+<img src='http://localhost/trunk/piwik.php?idsite=1&rec=1'>

plugins/SitesManager/templates/DisplayAlternativeTags.tpl

@@ -14,6 +14,13 @@ The Simple Image Tracker tag can be used when Javascript is disallowed.
 &lt;img src="{$piwikUrl}piwik.php?idsite={$idSite}&rec=1" style="border:0" alt="" /&gt;<br/>
 &lt;!-- End Piwik --&gt;<br/>
 </code>
+<br/>
+The following parameters can also be passed to the image URL:
+<ul> 
+	<li><i>action_name</i> - Defines the custom Page Title for this page view</li>
+	<li><i>idgoal</i> - The request will trigger the given Goal</li>
+	<li><i>revenue</i> - Used with idgoal, defines the custom revenue for this conversion</li>
+</ul>
 </div>
 
 <h3>Piwik Tracking API (Advanced users)</h3>