Item14977: add support for native lazy-loading

also:

* added showhidden parameter to exclude hidden images from the gallery
* added warn toggle to disable warinings

data/System/ImageGalleryPlugin.txt

@@ -32,12 +32,14 @@ below).
 | frontend | select gallery interface, possible values are =default=, =slimbox=, =prettyphoto=, =photoswipe= | photoswipe, prettyphoto or slimbox (in the given prioirty) |
 | header | header part of the gallery | =<div class="$class clearfix" data-item-selector=".imageSimple">= |
 | include | regular expression an image must match to be part of the gallery | |
+| showhidden | boolean flag to include images that are hidden; set to off to hide hidden images | on |
 | layout | thumbnail layout algorithm, can be either =packery= (using Foswiki:Extensions/JQPackeryContrib) or =masonry= or undefined | |
 | limit | maximum number of images to display | 0, meaning no limit | 
 | reverse | invert the initial order of the images, can be on or off | off |
 | size | the thumbnail size, the actual geometries of a size can be configured below; possible values: tiny, small, medium, large, huge  (default: medium) |
 | sort | set the initial order of the images, can be name, date, size or comment | date |
 | titles | toggles image and thumnail titles on and off | off |
+| warn | toogles display of error messages, i.e. when no image was found | on |
 
 ---+++ Frontends
 
@@ -111,6 +113,8 @@ Note, that the $comment variable will only display =<comment>= , that is w
 
 ---++ Change History
 %TABLE{columnwidths="7em" tablewidth="100%"}%
+|  26 Oct 2020 | added support for native lazy loading of images; \
+                 added =showhidden= parameter to exclude hidden images from the gallery |
 |  27 Jul 2017 | massive rewrite using Foswiki:Extensions/ImagePlugin as a backend now; \
                  removed <nop>NRIMAGES macro; \
                  oo-ified implementation; \
@@ -158,8 +162,8 @@ Note, that the $comment variable will only display =&lt;comment&gt;= , that is w
                  added refresh query parameter to recompute images |
 |  09 May 2005 | fixed errors reported by Marcel Trap; \
                  added support for multiple topics (proposed by Martin Cleaver; \
-                 added %<nop>NRIMAGES% tag |
-|  &nbsp;      | fix error when called from within rename view |
+                 added %<nop>NRIMAGES% tag; \
+                 fix error when called from within rename view |
 |  03 May 2005 | fixed thumbnail resizing; reintroduced =titles= parameter;  \
                  support for multiple galleries per topic |
 |  27 Apr 2005 | complete rewrite |
@@ -173,7 +177,7 @@ Note, that the $comment variable will only display =&lt;comment&gt;= , that is w
 %META:FIELD{name="Release" title="Release" value="%25$RELEASE%25"}%
 %META:FIELD{name="Description" title="Description" value="%25$SHORTDESCRIPTION%25"}%
 %META:FIELD{name="Repository" title="Repository" value="https://github.com/foswiki/%25TOPIC%25"}%
-%META:FIELD{name="Copyright" title="Copyright" value="2002-2009, Will Norris; 2005-2017, Michael Daum http://michaeldaumconsulting.com"}%
+%META:FIELD{name="Copyright" title="Copyright" value="&copy; 2002-2009, Will Norris, 2005-2020, Michael Daum"}%
 %META:FIELD{name="License" title="License" value="GPL ([[http://www.gnu.org/copyleft/gpl.html][GNU General Public License]])"}%
 %META:FIELD{name="Home" title="Home" value="Foswiki:Extensions/%25TOPIC%25"}%
 %META:FIELD{name="Support" title="Support" value="Foswiki:Support/%25TOPIC%25"}%

lib/Foswiki/Plugins/ImageGalleryPlugin.pm

@@ -1,5 +1,5 @@
 # Copyright (C) 2002-2009 Will Norris. All Rights Reserved. (wbniv@saneasylumstudios.com)
-# Copyright (C) 2005-2017 Michael Daum http://michaeldaumconsulting.com
+# Copyright (C) 2005-2020 Michael Daum http://michaeldaumconsulting.com
 #
 # This program is free software; you can redistribute it and/or
 # modify it under the terms of the GNU General Public License
@@ -17,13 +17,12 @@ package Foswiki::Plugins::ImageGalleryPlugin;
 use strict;
 use warnings;
 
-our $VERSION = '8.01';
-our $RELEASE = '27 Jul 2017';
+our $VERSION = '8.20';
+our $RELEASE = '26 Oct 2020';
 our $NO_PREFS_IN_TOPIC = 1;
 our $SHORTDESCRIPTION = 'Displays image gallery with auto-generated thumbnails from attachments';
 our $core;
 
-###############################################################################
 sub initPlugin {
   #my ($topic, $web, $user, $installWeb) = @_;
 
@@ -36,14 +35,12 @@ sub initPlugin {
   return 1;
 }
 
-###############################################################################
 sub finishPlugin {
 
   $core->finish() if defined $core;
   #undef $core; # EXPERIMENTAL: keep it in memory
 }
 
-###############################################################################
 sub getCore {
 
   unless (defined $core) {

lib/Foswiki/Plugins/ImageGalleryPlugin/Core.pm

@@ -1,7 +1,7 @@
 # Plugin for Foswiki - The Free and Open Source Wiki, http://foswiki.org/
 #
 # Copyright (C) 2002-2009 Will Norris. All Rights Reserved. (wbniv@saneasylumstudios.com)
-# Copyright (C) 2005-2017 Michael Daum http://michaeldaumconsulting.com
+# Copyright (C) 2005-2020 Michael Daum http://michaeldaumconsulting.com
 #
 # This program is free software; you can redistribute it and/or
 # modify it under the terms of the GNU General Public License
@@ -67,14 +67,14 @@ sub handleIMAGEGALLERY {
   $params->{crop} //= "on";
   $params->{tooltip} = Foswiki::Func::isTrue($params->{tooltip} // "off", 0)?"on":"off";
   $params->{titles} = Foswiki::Func::isTrue($params->{titles} // "off", 0);
-  $params->{lazyload} = Foswiki::Func::isTrue($params->{lazyload} // "on", 1);
-  $params->{format} //= '%IMAGE{"$name" topic="$web.$topic" align="left" size="$size" crop="$crop" caption="$title" tooltip="$tooltip" filter="$filter"}%';
+  $params->{format} //= '%IMAGE{"$name" topic="$web.$topic" align="left" size="$size" crop="$crop" caption="$title" tooltip="$tooltip" filter="$filter" lazyload="on"}%';
   $params->{header} //= '<noautolink><div class="$class clearfix" data-item-selector=".imageSimple">';
   $params->{footer} //= '</div></noautolink>';
   $params->{separator} //= '';
   $params->{limit} //= 0;
   $params->{skip} //= 0;
   $params->{filter} //= '';
+  $params->{showhidden} //= 'on';
 
   $params->{filter} = '' if $params->{filter} eq 'none';
 
@@ -150,11 +150,6 @@ sub handleIMAGEGALLERY {
 
   $this->addToZone();
 
-  if ($params->{lazyload} && $context->{'LazyLoadPluginEnabled'}) {
-    Foswiki::Plugins::JQueryPlugin::createPlugin("lazyload");
-    $result = '%STARTLAZYLOAD%'.$result.'%ENDLAZYLOAD%';
-  }
-
   return Foswiki::Func::decodeFormatTokens($result);
 }
 
@@ -193,9 +188,10 @@ sub getImages {
     }
 
     foreach my $attachment ($meta->find('FILEATTACHMENT')) {
-      next unless $this->isImage($attachment->{name});
+      next if $params->{showhidden} ne 'on' && $attachment->{attr} =~ /h/;
       next if $params->{exclude} && $attachment->{$params->{field}} =~ /$params->{exclude}/;
       next if $params->{include} && $attachment->{$params->{field}} !~ /$params->{include}/;
+      next unless $this->isImage($attachment->{name});
       push @images, {
         web => $theWeb,
         topic => $theTopic,