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diff --git a/doc/users/smcv/gallery.mdwn b/doc/users/smcv/gallery.mdwn new file mode 100644 index 000000000..b6b8de79f --- /dev/null +++ b/doc/users/smcv/gallery.mdwn @@ -0,0 +1,342 @@ +[[!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 next/previous part this plugin overlaps with [[todo/wikitrails]]. + +A \[[!galleryimg]] directive to assign metadata to images might be necessary, so +the gallery page can contain something like: + + \[[!galleryimg p1010001.jpg title="..." caption="..." tags="foo"]] + \[[!galleryimg p1010002.jpg title="..." caption="..." tags="foo bar"]] + +However, allowing other pages to push in metadata like that will make +dependency tracking difficult. + +Making the viewer pages could be rather tricky. Here are some options: +"synthesize source pages for viewers" is the one I'm leaning towards at the +moment. + +### Viewers' source page is the gallery + +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; however, that would +require hacking up both `IkiWiki::htmllink` and `IkiWiki::urlto` to redirect +links to the image (e.g. from the \[[!map]] on a tag page) to become links to +the viewer page. + +Modifications to the comments plugin would also be required, to make it allow +comments written to `foo/bar/comment_1._comment` even though the page foo/bar +does not really exist, and display comments on the viewer pages even though +they're not real pages. (Writing comments to `foo/bar.jpg/*._comment` is not +an option!) + +### Synthesize source pages for 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]]... + +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. + +Perhaps a better approach would be to have a setupfile option that names a +particular underlay directory (meeting the objective of not having large +photos under source code control) and generates a source page for each file +in that directory during the refresh hook. The source pages could be in the +underlay until they are edited (e.g. tagged), at which point they would be +copied into the source-code-controlled version in the usual way. + +The synthetic source pages can be very simple, using the same trick as my +[[plugins/comments]] plugin (a dedicated [[directive|ikiwiki/directives]] +encapsulating everything the plugin needs). If the plugin automatically +gathers information like file size, pixel size, date etc. from the images, then +only the human-edited information and a filename reference need to be present +in the source page; with some clever lookup rules based on the filename of +the source page, not even the photo's filename is necessarily needed. + + \[[!meta title="..."]] + \[[!meta date="..."]] + \[[!meta copyright="..."]] + \[[!tag ...]] + + \[[!galleryimageviewer p1010001.jpg]] + +However, this would mean that editing tags and other metadata would require +editing pages individually. Rather than trying to "fix" that, perhaps it would +be better to have a special CGI interface for bulk tagging/metadata editing. +This could even be combined with a bulk upload form (a reasonable number of +file upload controls - maybe 20 - with metadata alongside each). + +Uploading multiple images is necessarily awkward due to restrictions placed on +file upload controls by browsers for security reasons - sites like Facebook +allow whole directories to be uploaded at the same time, but they achieve this +by using a signed Java applet with privileged access to the user's filesystem. + +I've found that it's often useful to be able to force the creation time of +photos (my camera's battery isn't very reliable, and it frequently decides that +the date is 0000-00-00 00:00:00), so treating the \[[!meta date]] of the source +page and the creation date of the photo as synonymous would be useful. + +### Images are the viewer's source - special filename extension + +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). + +### Images are the viewer's source - alter `ispage()` + +It might be possible to hack up `ispage()` so some, but not all, images are +considered to "be a page": + +* srcdir/not-a-photo.jpg → destdir/not-a-photo.jpg +* srcdir/gallery/photo.jpg → destdir/gallery/photo/index.html + +Perhaps one way to do this would be for the photos to appear in a particular +underlay directory, which would also fulfil the objective of having photos not +be version-controlled: + +* srcdir/not-a-photo.jpg → destdir/not-a-photo.jpg +* underlay/gallery/photo.jpg → destdir/gallery/photo/index.html + +## Proof-of-concept implementation of "viewers' source page is the gallery" + + #!/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 |