ikiwiki/doc/plugins/contrib/album.mdwn

[[!template id=plugin name=album author="[[Simon_McVittie|smcv]]"]]
[[!template id=gitbranch branch=smcv/album author="[[Simon_McVittie|smcv]]"]]
[[!tag type/chrome]]

Available from [[smcv]]'s git repository, in the `album` branch
([[users/smcv/gallery|users/smcv/gallery]] contains some older
thoughts about this plugin).

This plugin formats a collection of images into a photo album,
in the same way as many websites: good examples include the
PHP application [Gallery](http://gallery.menalto.com/), Flickr,
and Facebook's Photos "application".

I've called it `album` to distinguish it from
[[contrib/gallery|plugins/contrib/gallery]], although `gallery` might well be
a better name for this functionality.

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 album, 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.)

<h2 id="album"><code>album</code> directive</h2>

Each page containing an `album` directive is treated as a photo album.

Every image attached to an album or its subpages is considered to be part of
the album. A "viewer" page, with the wiki's default page extension, will be
generated to display the image, if there isn't already a page of the same
name as the image: for instance, if `debconf` is an album and
`debconf/tuesday/p100.jpg` exists, then `debconf/tuesday/p100.mdwn` might
be created.

There's currently a hard-coded list of extensions that are treated as images:
`png`, `gif`, `jpg`, `jpeg` or `mov` files. More image and video types could
be added in future. Videos aren't currently handled very well;
ideally, something like totem-video-thumbnailer would be used.

The `album` directive also produces an [[ikiwiki/directive/inline]] which
automatically includes all the viewers for this album, except those that
will appear in an <a href="#albumsection">albumsection</a> (if every image
is in a section, then the `album` directive won't have any visible effect).

The `inline` is in `archive` and `quick` mode, but can include some
extra information about the images, including file size and a thumbnail made
using [[ikiwiki/directive/img]]). The default template is `albumitem.tmpl`,
which takes advantage of these things.

<h2 id="albumsection"><code>albumsection</code> directive</h2>

The `albumsection` directive is used to split an album into sections. It can
only appear on a page that also has the <a href="#album">album</a> directive.

The `filter` parameter is a [[ikiwiki/PageSpec]] against which viewer pages
are matched. The `albumsection` directive displays all the images that match
the filter, and the `album` directive displays any leftover images, like
this:

    # Holiday photos

    \[[!album]]
    <!-- replaced with a list of any uncategorized photos, which might be
         empty -->

    ## People

    \[[!albumsection filter="tagged(people)"]]
    <!-- replaced with a list of photos tagged 'people', including
         any that are also tagged 'landscapes' -->

    ## Landscapes

    \[[!albumsection filter="tagged(landscapes)"]]
    <!-- replaced with a list of photos tagged 'landscapes', including
         any that are also tagged 'people' -->

<h2 id="albumimage"><code>albumimage</code> directive</h2>

Each viewer page produced by the <a href="#album">album</a> directive
contains an `albumimage` directive, which is replaced by an
[[ikiwiki/directive/img]], wrapped in some formatting using a
template (by default it's `albumviewer.tmpl`). That template can also include
links to the next photo, the previous photo and the album it's in; the default
template has all of these.

The next/previous links are themselves implemented by evaluating a template,
either `albumnext.tmpl` or `albumprev.tmpl` by default.

The directive can also have parameters:

* `title`, `copyright` and `date` are short-cuts for the corresponding
  [[ikiwiki/directive/meta]] directives

* `caption` sets a caption which is displayed in the album and viewer
  pages

The viewer page can also have other contents before or after the actual
image viewer.

## Bugs

* The plugin doesn't do anything special to handle albums that are subpages
  of each other. If, say, `debconf` and `debconf/monday` are both albums,
  then `debconf/monday/p100.jpg` will currently be assigned to one or the
  other, arbitrarily.

* The plugin doesn't do anything special to handle photos with similar names.
  If you have `p100.jpg` and `p100.png`, one will get a viewer page called
  `p100` and the other will be ignored.

* If there's no `albumimage` in a viewer page, one should probably be appended
  automatically.

## TODO

* The documentation should mention how to replicate the appearance of
  `album` and `albumsection` using an `inline` of viewer pages.

* The documentation should mention all the template variables and
  all the parameters.

* The generated viewer page should include most or all of the possible
  parameters to the `albumimage` directive, with empty values, as a
  template for editing.

* The generated viewer page should extract as much metadata as possible from
  the photo's EXIF tags (creation/modification dates, author, title, caption,
  copyright). [[smcv]] has a half-written implementation which runs
  `scanimage` hooks, and has an `exiftool` plugin using [[!cpan Image::ExifTool]]
  as a reference implementation of that hook.

* There should be an option to reduce the size of photos and write them into
  an underlay, for this workflow:

  * your laptop's local ikiwiki has two underlays, `photos` and `webphotos`
  * `photos` contains full resolution photos with EXIF tags
  * for each photo that exists in `photos` but not in `webphotos`, the album
    plugin automatically resamples it down to a web-compatible resolution
    ([[smcv]] uses up to 640x640), optimizes it with `jpegoptim`, strips out
    all EXIF tags, and and writes it into the corresponding location
    in `webphotos`
  * `webphotos` is what you rsync to the web server
  * the web server's ikiwiki only has `webphotos` as an underlay

* Eventually, there could be a specialized CGI user interface to batch-edit
  all the photos of an album (so for each photo, you get an edit box each for
  title, author, copyright etc.) - this would work by making programmatic
  edits to all the `albumimage` directives.