Add event hooks for customizing ActivityObject output to Atom and JSON, and helpers for MicroAppPlugin.

New hooks:
* StartActivityObjectOutputAtom
* EndActivityObjectOutputAtom
	$obj ActivityObject
	$out XMLOutputter

* StartActivityObjectOutputJson
* EndActivityObjectOutputJson
	$obj ActivityObject
	&$out array

EVENTS.txt

@@ -1115,3 +1115,19 @@ StartGroupProfileElements: Start showing stuff about the group on its profile pa
 EndGroupProfileElements: Start showing stuff about the group on its profile page
 - $action: action being executed (for output and params)
 - $group: group for the page
+
+StartActivityObjectOutputAtom: Called at start of Atom XML output generation for ActivityObject chunks, just inside the <activity:object>. Cancel the event to take over its output completely (you're responsible for calling the matching End event if so)
+- $obj: ActivityObject
+- $out: XMLOutputter to append custom output
+
+EndActivityObjectOutputAtom: Called at end of Atom XML output generation for ActivityObject chunks, just inside the </activity:object>
+- $obj: ActivityObject
+- $out: XMLOutputter to append custom output
+
+StartActivityObjectOutputJson: Called at start of JSON output generation for ActivityObject chunks: the array has not yet been filled out. Cancel the event to take over its output completely (you're responsible for calling the matching End event if so)
+- $obj ActivityObject
+- &$out: array to be serialized; you're free to modify it
+
+EndActivityObjectOutputJson: Called at end of JSON output generation for ActivityObject chunks: the array has not yet been filled out.
+- $obj ActivityObject
+- &$out: array to be serialized; you're free to modify it

lib/activityobject.php

@@ -533,6 +533,7 @@ class ActivityObject
 			$xo->elementStart($tag);
 		}
 
+        if (Event::handle('StartActivityObjectOutputAtom', array($this, $xo))) {
             $xo->element('activity:object-type', null, $this->type);
 
             // <author> uses URI
@@ -620,6 +621,9 @@ class ActivityObject
                 $xo->element($extraTag, $attrs, $content);
             }
 
+            Event::handle('EndActivityObjectOutputAtom', array($this, $xo));
+        }
+
 		if (!empty($tag)) {
 			$xo->elementEnd($tag);
 		}
@@ -647,6 +651,7 @@ class ActivityObject
     {
         $object = array();
 
+        if (Event::handle('StartActivityObjectOutputJson', array($this, &$object))) {
             // XXX: attachedObjects are added by Activity
 
             // displayName
@@ -734,7 +739,8 @@ class ActivityObject
             if (!empty($this->poco)) {
                 $object['contact'] = $this->poco->asArray();
             }
-
+            Event::handle('EndActivityObjectOutputJson', array($this, &$object));
+        }
         return array_filter($object);
     }
 }

lib/microappplugin.php

@@ -212,6 +212,44 @@ abstract class MicroAppPlugin extends Plugin
                 in_array($activity->objects[0]->type, $types));
     }
 
+    /**
+     * Called when generating Atom XML ActivityStreams output from an
+     * ActivityObject belonging to this plugin. Gives the plugin
+     * a chance to add custom output.
+     *
+     * Note that you can only add output of additional XML elements,
+     * not change existing stuff here.
+     *
+     * If output is already handled by the base Activity classes,
+     * you can leave this base implementation as a no-op.
+     *
+     * @param ActivityObject $obj
+     * @param XMLOutputter $out to add elements at end of object
+     */
+    function activityObjectOutputAtom(ActivityObject $obj, XMLOutputter $out)
+    {
+        // default is a no-op
+    }
+
+    /**
+     * Called when generating JSON ActivityStreams output from an
+     * ActivityObject belonging to this plugin. Gives the plugin
+     * a chance to add custom output.
+     *
+     * Modify the array contents to your heart's content, and it'll
+     * all get serialized out as JSON.
+     *
+     * If output is already handled by the base Activity classes,
+     * you can leave this base implementation as a no-op.
+     *
+     * @param ActivityObject $obj
+     * @param array &$out JSON-targeted array which can be modified
+     */
+    public function activityObjectOutputJson(ActivityObject $obj, array &$out)
+    {
+        // default is a no-op
+    }
+
     /**
      * When a notice is deleted, delete the related objects
      * by calling the overridable $this->deleteRelated().
@@ -439,6 +477,46 @@ abstract class MicroAppPlugin extends Plugin
         return true;
     }
 
+    /**
+     * Event handler gives the plugin a chance to add custom
+     * Atom XML ActivityStreams output from a previously filled-out
+     * ActivityObject.
+     *
+     * The atomOutput method is called if it's one of
+     * our matching types.
+     *
+     * @param ActivityObject $obj
+     * @param XMLOutputter $out to add elements at end of object
+     * @return boolean hook return value
+     */
+    function onEndActivityObjectOutputAtom(ActivityObject $obj, XMLOutputter $out)
+    {
+        if (in_array($obj->type, $this->types())) {
+            $this->activityObjectOutputAtom($obj, $out);
+        }
+        return true;
+    }
+
+    /**
+     * Event handler gives the plugin a chance to add custom
+     * JSON ActivityStreams output from a previously filled-out
+     * ActivityObject.
+     *
+     * The activityObjectOutputJson method is called if it's one of
+     * our matching types.
+     *
+     * @param ActivityObject $obj
+     * @param array &$out JSON-targeted array which can be modified
+     * @return boolean hook return value
+     */
+    function onEndActivityObjectOutputJson(ActivityObject $obj, array &$out)
+    {
+        if (in_array($obj->type, $this->types())) {
+            $this->activityObjectOutputJson($obj, &$out);
+        }
+        return true;
+    }
+
     function onStartShowEntryForms(&$tabs)
     {
         $tabs[$this->tag()] = $this->appTitle();