make the fetching of the default profile photo hookable, and document the hook

Zotlabs/Module/Photo.php

@@ -60,19 +60,32 @@ class Photo extends \Zotlabs\Web\Controller {
 	
 			$uid = $person;
 
-			$r = q("SELECT * FROM photo WHERE imgscale = %d AND uid = %d AND photo_usage = %d LIMIT 1",
+			$d = [ 'imgscale' => $resolution, 'channel_id' => $uid, 'default' => $default, 'data'  => '', 'mimetype' => '' ];
-				intval($resolution),
+			call_hooks('get_profile_photo',$d);
-				intval($uid),
+
-				intval(PHOTO_PROFILE)
+			$resolution = $d['resolution'];
-			);
+			$uid        = $d['channel_id']; 	
-			if($r) {
+			$default    = $d['default'];
-				$data = dbunescbin($r[0]['content']);
+			$data       = $d['data'];
-				$mimetype = $r[0]['mimetype'];
+			$mimetype   = $d['mimetype'];
+
+			if(! $data) {
+				$r = q("SELECT * FROM photo WHERE imgscale = %d AND uid = %d AND photo_usage = %d LIMIT 1",
+					intval($resolution),
+					intval($uid),
+					intval(PHOTO_PROFILE)
+				);
+				if($r) {
+					$data = dbunescbin($r[0]['content']);
+					$mimetype = $r[0]['mimetype'];
+				}
+				if(intval($r[0]['os_storage']))
+					$data = file_get_contents($data);
 			}
-			if(intval($r[0]['os_storage']))
+			if(! $data) {
-				$data = file_get_contents($data);
-			if(! isset($data)) {
 				$data = file_get_contents($default);
+			}
+			if(! $mimetype) {
 				$mimetype = 'image/png';
 			}
 		}
@@ -88,6 +101,7 @@ class Photo extends \Zotlabs\Web\Controller {
 			   Project link: https://github.com/Retina-Images/Retina-Images
 			   License link: http://creativecommons.org/licenses/by/3.0/
 			*/
+
 			$cookie_value = false;
 			if (isset($_COOKIE['devicePixelRatio'])) {
 			  $cookie_value = intval($_COOKIE['devicePixelRatio']);
@@ -114,15 +128,15 @@ class Photo extends \Zotlabs\Web\Controller {
 			}
 			
 			// If using resolution 1, make sure it exists before proceeding:
-			if ($resolution == 1)
+			if($resolution == 1) {
-			  {
 			    $r = q("SELECT uid FROM photo WHERE resource_id = '%s' AND imgscale = %d LIMIT 1",
 				   dbesc($photo),
 				   intval($resolution)
-				   );
+				);
-			    if (!($r))
+			    if(! $r) {
 			      $resolution = 2;
-			  }
+				}
+			}
 	
 			$r = q("SELECT uid FROM photo WHERE resource_id = '%s' AND imgscale = %d LIMIT 1",
 				dbesc($photo),

doc/hook/get_profile_photo.bb

@@ -0,0 +1,18 @@
+[h2]get_profile_photo[/h2]
+
+Called when fetching the content of the default profile photo for a local channel in mod_photo.
+
+
+Hook arguments:
+
+'imgscale'   => integer resolution requested (4, 5, or 6)
+'channel_id' => channel_id of requested profile photo
+'default'    => filename of default profile photo of this imgscale
+'data'       => empty string
+'mimetype'   => empty string
+
+
+If 'data' is set, this data will be used instead of the data obtained from the database search for the profile photo.
+If 'mimetype' is set, this mimetype will be used instead of the mimetype obtained from the database or the default profile photo mimetype.
+
+

doc/hooklist.bb

@@ -236,6 +236,9 @@ Hooks allow plugins/addons to "hook into" the code at many points and alter the
 [zrl=[baseurl]/help/hook/get_features]get_features[/zrl]
 	Called when get_features() is called
 
+[zrl=[baseurl]/help/hook/get_profile_photo]get_profile_photo[/zrl]
+	Called when local profile photo content is fetched in mod_photo
+
 [zrl=[baseurl]/help/hook/get_role_perms]get_role_perms[/zrl]
 	Called when get_role_perms() is called to obtain permissions for named permission roles