Index: openacs-4/packages/xowiki/tcl/form-field-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xowiki/tcl/form-field-procs.tcl,v
diff -u -r1.284.2.25 -r1.284.2.26
--- openacs-4/packages/xowiki/tcl/form-field-procs.tcl	29 Aug 2019 10:24:58 -0000	1.284.2.25
+++ openacs-4/packages/xowiki/tcl/form-field-procs.tcl	2 Sep 2019 17:00:08 -0000	1.284.2.26
@@ -1509,14 +1509,21 @@
   Class create author -superclass user_id -parameter {
     {photo_size 54}
     {with_photo true}
+    {with_gravatar true}
     {with_user_link false}
     {label #xowiki.formfield-author#}
   }
   author instproc pretty_value {v} {
     if {$v ne ""} {
       acs_user::get -user_id $v -array user
-      if {[:with_photo]} {
-        set src "/shared/portrait-bits.tcl?user_id=$v"
+      if {${:with_photo}} {
+        set portrait_id [acs_user::get_portrait_id -user_id $v]
+        if {$portrait_id == 0 && ${:with_gravatar}} {
+          set src [::xowiki::includelet::gravatar url \
+                       -email $user(email) -size ${:photo_size}]
+        } else {
+          set src "/shared/portrait-bits.tcl?user_id=$v"
+        }
         set photo "<img width='[:photo_size]' class='photo' src='[ns_quotehtml $src]'>"
         set photo_class "photo"
       } else {
Index: openacs-4/packages/xowiki/tcl/includelet-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xowiki/tcl/includelet-procs.tcl,v
diff -u -r1.239.2.17 -r1.239.2.18
--- openacs-4/packages/xowiki/tcl/includelet-procs.tcl	31 Aug 2019 08:46:07 -0000	1.239.2.17
+++ openacs-4/packages/xowiki/tcl/includelet-procs.tcl	2 Sep 2019 17:00:08 -0000	1.239.2.18
@@ -4603,7 +4603,7 @@
         }}
       }
 
-  gravatar proc url {-email {-size 80}} {
+  gravatar proc url {-email {-size 80} {-default mp}} {
     # reusable helper proc to compute a gravatar URL
     if {[info commands ns_md5] ne ""} {
       set md5 [string tolower [ns_md5 $email]]
@@ -4612,7 +4612,7 @@
       set md5 [string tolower [md5::Hex [md5::md5 -- $email]]]
     }
     security::csp::require img-src www.gravatar.com
-    return //www.gravatar.com/avatar/$md5?size=$size
+    return //www.gravatar.com/avatar/$md5?size=$size&d=$default
   }
 
   gravatar instproc render {} {