--- /dev/null
+[[!template id=plugin name=smcvgallery author="[[Simon_McVittie|smcv]]"]]
+[[!tag type/chrome]]
+
+This plugin has not yet been written; this page is an experiment in
+design-by-documentation :-)
+
+## Requirements
+
+This plugin formats a collection of images into a photo gallery,
+in the same way as many websites: good examples include the
+PHP application [Gallery](http://gallery.menalto.com/), Flickr,
+and Facebook's Photos "application".
+
+The web UI I'm trying to achieve consists of one
+[HTML page of thumbnails](http://www.pseudorandom.co.uk/2008/2008-03-08-panic-cell-gig/)
+as an entry point to the gallery, where each thumbnail
+links to
+[a "viewer" HTML page](http://www.pseudorandom.co.uk/2008/2008-03-08-panic-cell-gig/img_0068/)
+with a full size image, next/previous thumbnail links, and [[plugins/comments]].
+
+(The Summer of Code [[plugins/contrib/gallery]] plugin does the
+next/previous UI in Javascript using Lightbox, which means that
+individual photos can't be bookmarked in a meaningful way, and
+the best it can do as a fallback for non-Javascript browsers
+is to provide a direct link to the image.)
+
+Other features that would be good to have:
+
+* minimizing the number of separate operations needed to make a gallery -
+ editing one source file per gallery is acceptable, editing one
+ source file per photo is not
+
+* keeping photos outside source code control, for instance in an
+ underlay
+
+* assigning [[tags|ikiwiki/directive/tag]] to photos, providing a
+ superset of Facebook's "show tagged photos of this person" functionality
+
+* constructing galleries entirely via the web by uploading attachments
+
+* inserting grouping (section headings) within a gallery; as in the example
+ linked above, I'd like this to split up the thumbnails but not the
+ next/previous trail
+
+* rendering an `<object>/<embed>` arrangement to display videos, and possibly
+ thumbnailing them in the same way as totem-video-thumbnailer
+ (my camera can record short videos, so some of my web photo galleries contain
+ them)
+
+My plan is to have these directives:
+
+* \[[!gallery]] registers the page it's on as a gallery, and displays all photos
+ that are part of this gallery but not part of a \[[!gallerysection]] (below).
+
+ All images (i.e. `*.png *.jpg *.gif`) that are attachments to the gallery page
+ or its subpages are considered to be part of the gallery.
+
+ Optional arguments:
+
+ * filter="[[ikiwiki/PageSpec]]": only consider images to be part of the
+ gallery if they also match this filter
+
+ * sort="date|filename": order in which to sort the images
+
+* \[[!gallerysection filter="[[ikiwiki/PageSpec]]"]] displays all photos in the
+ gallery that match the filter
+
+So, [the gallery I'm using as an example](http://www.pseudorandom.co.uk/2008/2008-03-08-panic-cell-gig/)
+could look something like this:
+
+ \[[!gallery]]
+ <!-- replaced with one uncategorized photo -->
+
+ # Gamarra
+
+ \[[!gallerysection filter="link(sometag)"]]
+ <!-- all the Gamarra photos -->
+
+ # Smokescreen
+
+ \[[!gallerysection filter="link(someothertag)"]]
+ <!-- all the Smokescreen photos -->
+
+ <!-- ... -->
+
+## Implementation ideas
+
+The photo galleries I have at the moment, like the Panic Cell example above,
+are made by using an external script to parse XML gallery descriptions (lists
+of image filenames, with metadata such as titles), and using this to write IkiWiki
+markup into a directory which is then used as an underlay. This is a hack, but it
+works. The use of XML is left over from a previous attempt at solving the same
+problem using Django.
+
+The next/previous part this plugin overlaps with [[todo/wikitrails]].
+
+A \[[!galleryimg]] directive to assign metadata to images is probably necessary, so
+the gallery page can contain something like:
+
+ \[[!galleryimg p1010001.jpg title="..." caption="..." tags="foo"]]
+ \[[!galleryimg p1010002.jpg title="..." caption="..." tags="foo bar"]]
+
+Making the viewer pages could be rather tricky.
+
+One possibility is to write out the viewer pages as a side-effect of preprocessing
+the \[[!gallery]] directive. The proof-of-concept implementation below does this.
+However, this does mean the viewer pages can't have tags or metadata of their own
+and can't be matched by [[pagespecs|ikiwiki/pagespec]] or
+[[wikilinks|ikiwiki/wikilink]]. It might be possible to implement tagging by
+using \[[!galleryimg]] to assign the metadata to the *images* instead of their
+viewers,
+
+Another is to synthesize source pages for the viewers. This means they can have
+tags and metadata, but trying to arrange for them to be scanned etc. correctly
+without needing another refresh run is somewhat terrifying.
+[[plugins/autoindex]] can safely create source pages because it runs in
+the refresh hook, but I don't really like the idea of a refresh hook that scans
+all source pages to see if they contain \[[!gallery]]...
+
+Making the image be the source page (and generate HTML itself) would be possible,
+but I wouldn't want to generate a HTML viewer for every `.jpg` on a site, so
+either the images would have to have a special extension (awkward for uploads from
+Windows users) or the plugin would have to be able to change whether HTML was
+generated in some way (not currently possible).
+
+## Proof-of-concept
+
+ #!/usr/bin/perl
+ package IkiWiki::Plugin::gallery;
+
+ use warnings;
+ use strict;
+ use IkiWiki 2.00;
+
+ sub import {
+ hook(type => "getsetup", id => "gallery", call => \&getsetup);
+ hook(type => "checkconfig", id => "gallery", call => \&checkconfig);
+ hook(type => "preprocess", id => "gallery",
+ call => \&preprocess_gallery, scan => 1);
+ hook(type => "preprocess", id => "gallerysection",
+ call => \&preprocess_gallerysection, scan => 1);
+ hook(type => "preprocess", id => "galleryimg",
+ call => \&preprocess_galleryimg, scan => 1);
+ }
+
+ sub getsetup () {
+ return
+ plugin => {
+ safe => 1,
+ rebuild => undef,
+ },
+ }
+
+ sub checkconfig () {
+ }
+
+ # page that is a gallery => array of images
+ my %galleries;
+ # page that is a gallery => array of filters
+ my %sections;
+ # page that is an image => page name of generated "viewer"
+ my %viewers;
+
+ sub preprocess_gallery {
+ # \[[!gallery filter="!*/cover.jpg"]]
+ my %params=@_;
+
+ my $subpage = qr/^\Q$params{page}\E\//;
+
+ my @images;
+
+ foreach my $page (keys %pagesources) {
+ # Reject anything not a subpage or attachment of this page
+ next unless $page =~ $subpage;
+
+ # Reject non-images
+ # FIXME: hard-coded list of extensions
+ next unless $page =~ /\.(jpg|gif|png|mov)$/;
+
+ # Reject according to the filter, if any
+ next if (exists $params{filter} &&
+ !pagespec_match($page, $params{filter},
+ location => $params{page}));
+
+ # OK, we'll have that one
+ push @images, $page;
+
+ my $viewername = $page;
+ $viewername =~ s/\.[^.]+$//;
+ $viewers{$page} = $viewername;
+
+ my $filename = htmlpage($viewername);
+ will_render($params{page}, $filename);
+ }
+
+ $galleries{$params{page}} = \@images;
+
+ # If we're just scanning, don't bother producing output
+ return unless defined wantarray;
+
+ # actually render the viewers
+ foreach my $img (@images) {
+ my $filename = htmlpage($viewers{$img});
+ debug("rendering image viewer $filename for $img");
+ writefile($filename, $config{destdir}, "# placeholder");
+ }
+
+ # display a list of "loose" images (those that are in no section);
+ # this works because we collected the sections' filters during the
+ # scan stage
+
+ my @loose = @images;
+
+ foreach my $filter (@{$sections{$params{page}}}) {
+ my $_;
+ @loose = grep { !pagespec_match($_, $filter,
+ location => $params{page}) } @loose;
+ }
+
+ my $_;
+ my $ret = "<ul>\n";
+ foreach my $img (@loose) {
+ $ret .= "<li>";
+ $ret .= "<a href=\"" . urlto($viewers{$img}, $params{page});
+ $ret .= "\">$img</a></li>\n"
+ }
+ return "$ret</ul>\n";
+ }
+
+ sub preprocess_gallerysection {
+ # \[[!gallerysection filter="friday/*"]]
+ my %params=@_;
+
+ # remember the filter for this section so the "loose images" section
+ # won't include these images
+ push @{$sections{$params{page}}}, $params{filter};
+
+ # If we're just scanning, don't bother producing output
+ return unless defined wantarray;
+
+ # this relies on the fact that we ran preprocess_gallery once
+ # already, during the scan stage
+ my @images = @{$galleries{$params{page}}};
+ @images = grep { pagespec_match($_, $params{filter},
+ location => $params{page}) } @images;
+
+ my $_;
+ my $ret = "<ul>\n";
+ foreach my $img (@images) {
+ $ret .= "<li>";
+ $ret .= htmllink($params{page}, $params{destpage},
+ $viewers{$img});
+ $ret .= "</li>";
+ }
+ return "$ret</ul>\n";
+ }
+
+ sub preprocess_galleryimg {
+ # \[[!galleryimg p1010001.jpg title="" caption="" tags=""]]
+ my $file = $_[0];
+ my %params=@_;
+
+ return "";
+ }
+
+ 1
sipb-www / ikiwiki.git / commitdiff
