add a bit more attribution so it's clearer what Joey wrote

[ikiwiki] / doc / plugins / contrib / album / discussion.mdwn

thanks for this plugin.  it might help me in my application, which is to provide album/galleries which can be edited (ie. new images added, taken away, etc.) through web interface.

> That's my goal eventually, too. Perhaps you can help to
> design/write this plugin? At the moment I'm mostly
> waiting for a design "sanity check" from [[Joey]],
> but any feedback you can provide on the design would
> also be helpful. --[[smcv]]

i have two challenges: firstly, for installation, i'm not sure what all the files are that need to be downloaded (because of my setup i can't easily pull the repo).  so far i have Ikiwiki/Plugins/album.pm; ikiwiki-album; and 4 files in templates/  any others?

> Those are all the added files; ikiwiki-album isn't strictly
> needed (IkiWiki itself doesn't use that code, but you can
> use it to turn a directory full of images into correct
> input for the album plugin).
>
> You probably also want the album plugin's expanded version of
> style.css (or put its extra rules in your local.css).
> Without that, your albums will be quite ugly.
>
> There aren't currently any other files modified by my branch.
> --[[smcv]]

secondly: barring the CGI interface for editing the album, which would be great, is there at least a way to use attachment plugin or any other to manually add images and then create viewers for them?

> Images are just attachments, and viewers are pages (any supported
> format, but .html will be fastest to render). Attach each image,
> then write a page for each image containing the
> \[[!albumimage]] directive (usually it will *only* contain that
> directive).
>
> The script ikiwiki-album can help you to do this in a git/svn/etc.
> tree; doing it over the web will be a lot of work (until I get
> the CGI interface written), but it should already be possible!
>
> The structure is something like this:
> 
> * album.mdwn (contains the \[[!album]] directive, and perhaps also
>   some \[[!albumsection]] directives)
> * album/a.jpg
> * album/a.html (contains the \[[!albumimage]] directive for a.jpg)
> * album/b.jpg
> * album/b.html (contains the \[[!albumimage]] directive for b.jpg)
>
> Have a look at ikiwiki-album to see how the directives are meant to
> work in practice.
>
> --[[smcv]]

i'm new to ikiwiki, apologies if this is dealt with elsewhere.  -brush

> This plugin is pretty ambitious, and is unfinished, so I'd recommend
> playing with  a normal IkiWiki installation for a bit, then trying
> out this plugin when you've mastered the basics of IkiWiki. --[[smcv]]

----

You had wanted my feedback on the design of this. I have not looked at the
code or tried it yet, but here goes. --[[Joey]] 

* Needing to create the albumimage "viewer" pages for each photo
  seems like it will become a pain. Everyone will need to come up
  with their own automation for it, and then there's the question
  of how to automate it when uploading attachments. -J

> There's already a script (ikiwiki-album) to populate a git
> checkout with skeleton "viewer" pages; I was planning to make a
> specialized CGI interface for albums after getting feedback from
> you (since the requirements for that CGI interface change depending
> on the implementation). I agree that this is ugly, though. -s

>> Would you accept a version where the albumimage "viewer" pages
>> could be 0 bytes long, at least until metadata gets added? -s

* With each viewer page having next/prev links, I can see how you
  were having the scalability issues with ikiwiki's data structures
  earlier! -J

> Yeah, I think they're a basic requirement from a UI point of view
> though (although they don't necessarily have to be full wikilinks).
> -s

>> I think that with the new dependency types system, the dependencies for
>> these can be presence dependencies, which will probably help with
>> avoiding rebuilds of a page if the next/prev page is changed.
>> (Unless you use img to make the thumbnails for those links, then it
>> would rebuild the thumbnails anyway. Have not looked at the code.) --[[Joey]]

* And doesn't each viewer page really depend on every other page in the
  same albumsection? If a new page is added, the next/prev links
  may need to be updated, for example. If so, there will be much
  unnecessary rebuilding. -J

> albumsections are just a way to insert headings into the flow of
> photos, so they don't actually affect dependencies.
>
> One non-obvious constraint of ikiwiki's current design is that
> everything "off-page" necessary to build any page has to happen
> at scan time, which has caused a few strange design decisions,
> like the fact that each viewer controls what album it's in.
>
> It's difficult for the contents of the album to just be a
> pagespec, like for inline, because pagespecs can depend on
> metadata, which is gathered in arbitrary order at scan time;
> so the earliest you can safely apply a pagespec to the wiki
> contents to get a concrete list of pages is at rebuild time.
>
> (This stalled my attempt at a trail plugin, too.) -s

>> Not sure I understand why these need to look at pagespecs at scan time?
>> Also, note that it is fairly doable to detect if a pagespec uses such
>> metadata. Er, I mean, I have a cheezy hack in `add_depends` now that does
>> it to deal with a similar case. --[[Joey]] 

>>> I think I was misunderstanding how early you have to call `add_depends`?
>>> The critical thing I missed was that if you're scanning a page, you're
>>> going to rebuild it in a moment anyway, so it doesn't matter if you
>>> have no idea what it depends on until the rebuild phase. -s

* One thing I do like about having individual pages per image is
  that they can each have their own comments, etc. -J

> Yes; also, they can be wikilinked. I consider those to be
> UI requirements. -s

* Seems possibly backwards that the albumimage controls what album
  an image appears in. Two use cases -- 1: I may want to make a locked
  album, but then anyone who can write to any other page on the wiki can
  add an image to it. 2: I may want an image to appear in more than one
  album. Think tags. So it seems it would be better to have the album
  directive control what pages it includes (a la inline). -J

> I'm inclined to fix this by constraining images to be subpages of exactly
> one album: if they're subpages of 2+ nested albums then they're only
> considered to be in the deepest-nested one (i.e. longest URL), and if
> they're not in any album then that's a usage error. This would
> also make prev/next links sane.
>
> If you want to reference images from elsewhere in the wiki and display
> them as if in an album, then you can use an ordinary inline with
> the same template that the album would use, and I'll make sure the
> templates are set up so this works.
>
> (Implementation detail: this means that an image X/Y/Z/W/V, where X and
> Y are albums, Z does not exist and W exists but is not an album,
> would have a content dependency on Y, a presence dependency on Z
> and a content dependency on W.)
>
> Perhaps I should just restrict to having the album images be direct
> subpages of the album, although that would mean breaking some URLs
> on the existing website I'm doing all this work for... -s

* Putting a few of the above thoughts together, my ideal album system
  seems to be one where I can just drop the images into a directory and
  have them appear in the album index, as well as each generate their own wiki
  page. Plus some way I can, later, edit metadata for captions,
  etc. (Real pity we can't just put arbitrary metadata into the images
  themselves.) This is almost pointing toward making the images first-class
  wiki page sources. Hey, it worked for po! :) But the metadata and editing
  problems probably don't really allow that. -J

> Putting a JPEG in the web form is not an option from my point of
> view :-) but perhaps there could just be a "web-editable" flag supplied
> by plugins, and things could be changed to respect it.

>> Replying to myself: would you accept patches to support
>> `hook(type => 'htmlize', editable => 0, ...)` in editpage? This would
>> essentially mean "this is an opaque binary: you can delete it
>> or rename it, and it might have its own special editing UI, but you
>> can never get it in a web form".
>>
>> On the other hand, that essentially means we need to reimplement
>> editpage in order to edit the sidecar files that contain the metadata.
>> Having already done one partial reimplementation of editpage (for
>> comments) I'm in no hurry to do another.
>>
>> I suppose another possibility would be to register hook
>> functions to be called by editpage when it loads and saves the
>> file. In this case, the loading hook would be to discard
>> the binary and use filter() instead, and the saving conversion
>> would be to write the edited content into the metadata sidecar
>> (creating it if necessary).
>>
>> I'd also need to make editpage (and also comments!) not allow the
>> creation of a file of type albumjpg, albumgif etc., which is something
>> I previously missed; and I'd need to make attachment able to
>> upload-and-rename.
>> -s

> In a way, what you really want for metadata is to have it in the album
> page, so you can batch-edit the whole lot by editing one file (this
> does mean that editing the album necessarily causes each of its viewers
> to be rebuilt, but in practice that happens anyway). -s

>> Replying to myself: in practice that *doesn't* happen anyway. Having
>> the metadata in the album page is somewhat harmful because it means
>> that changing the title of one image causes every viewer in the album
>> to be rebuilt, whereas if you have a metadata file per image, only
>> the album itself, plus the next and previous viewers, need
>> rebuilding. So, I think a file per image is the way to go.
>>
>> Ideally we'd have some way to "batch-edit" the metadata of all
>> images in an album at once, except that would make conflict
>> resolution much more complicated to deal with; maybe just
>> give up and scream about mid-air collisions in that case?
>> (That's apparently good enough for Bugzilla, but not really
>> for ikiwiki). -s

>> Yes, [all metadata in one file] would make some sense.. It also allows putting one image in
>> two albums, with different caption etc. (Maybe for different audiences.)
>> --[[Joey]]

>>> Eek. No, that's not what I had in mind at all; the metadata ends up
>>> in the "viewer" page, so it's necessarily the same for all albums. -s

>> It would probably be possible to add a new dependency type, and thus
>> make ikiwiki smart about noticing whether the metadata has actually
>> changed, and only update those viewers where it has. But the dependency
>> type stuff is still very new, and not plugin friendly .. so only just
>> possible, --[[Joey]] 

----

Trying to use the "special extension" design:

Suppose that each viewer is a JPEG-or-GIF-or-something, with extension
".albumimage". We have a gallery "memes" with three images, badger,
mushroom and snake.

> An alternative might be to use ".album.jpg", and ".album.gif"
> etc as the htmlize extensions. May need some fixes to ikiwiki to support
> that. --[[Joey]] 

>> foo.albumjpg (etc.) for images, and foo._albummeta (with
>> `keepextension => 1`) for sidecar metadata files, seems viable. -s

Files in git repo:

* index.mdwn
* memes.mdwn
* memes/badger.albumjpg (a renamed JPEG)
* memes/badger/comment_1._comment
* memes/badger/comment_2._comment
* memes/mushroom.albumgif (a renamed GIF)
* memes/mushroom._albummeta (sidecar file with metadata)
* memes/snake.albummov (a renamed video)

Files in web content:

* index.html
* memes/index.html
* memes/96x96-badger.jpg (from img)
* memes/96x96-mushroom.gif (from img)
* memes/96x96-snake.jpg (from img, hacked up to use totem-video-thumbnailer :-) )
* memes/badger/index.html (including comments)
* memes/badger.jpg
* memes/mushroom/index.html
* memes/mushroom.gif
* memes/snake/index.html
* memes/snake.mov

ispage("memes/badger") (etc.) must be true, to make the above rendering
happen, so albumimage needs to be a "page" extension.

To not confuse other plugins, album should probably have a filter() hook
that turns .albumimage files into HTML? That'd probably be a reasonable
way to get them rendered anyway.

> I guess that is needed to avoid preprocess, scan, etc trying to process
> the image, as well as eg, smiley trying to munge it in sanitize.
> --[[Joey]] 

>> As long as nothing has a filter() hook that assumes it's already
>> text... filters are run in arbitrary order. We seem to be OK so far
>> though.
>>
>> If this is the route I take, I propose to have the result of filter()
>> be the contents of the sidecar metadata file (empty string if none),
>> with the `\[[!albumimage]]` directive (which no longer requires
>> arguments) prepended if not already present. This would mean that
>> meta directives in the metadata file would work as normal, and it
>> would be possible to insert text both before and after the viewer
>> if desired. The result of filter() would also be a sensible starting
>> point for editing, and the result of editing could be diverted into
>> the metadata file. -s

do=edit&page=memes/badger needs to not put the JPG in a text box: somehow
divert or override the normal edit CGI by telling it that .albumimage
files are not editable in the usual way?

> Something I missed here is that editpage also needs to be told that
> creating new files of type albumjpg, albumgif etc. is not allowed
> either! -s

Every image needs to depend on, and link to, the next and previous images,
which is a bit tricky. In previous thinking about this I'd been applying
the overly strict constraint that the ordered sequence of pages in each
album must be known at scan time. However, that's not *necessarily* needed:
the album and each photo could collect an unordered superset of dependencies
at scan time, and at rebuild time that could be refined to be the exact set,
in order.

> Why do you need to collect this info at scan time? You can determine it
> at build time via `pagespec_match_list`, surely .. maybe with some
> memoization to avoid each image in an album building the same list.
> I sense that I may be missing a subtelty though. --[[Joey]] 

>> I think I was misunderstanding how early you have to call `add_depends`
>> as mentioned above. -s

Perhaps restricting to "the images in an album A must match A/*"
would be useful; then the unordered superset could just be "A/*". Your
"albums via tags" idea would be nice too though, particularly for feature
parity with e.g. Facebook: "photos of Joey" -> "tags/joey and albumimage()"
maybe?

If images are allowed to be considered to be part of more than one album,
then a pretty and usable UI becomes harder - "next/previous" expands into
"next photo in holidays/2009/germany / next photo in tagged/smcv / ..."
and it could get quite hard to navigate. Perhaps next/previous links could
be displayed only for the closest ancestor (in URL space) that is an
album, or something?

> Ugh, yeah, that is a problem. Perhaps wanting to support that was just
> too ambitious. --[[Joey]] 

>> I propose to restrict to having images be subpages of albums, as
>> described above. -s

Requiring renaming is awkward for non-technical Windows/Mac users, with both
platforms' defaults being to hide extensions; however, this could be
circumvented by adding some sort of hook in attachment to turn things into
a .albumimage at upload time, and declaring that using git/svn/... without
extensions visible is a "don't do that then" situation :-)

> Or extend `pagetype` so it can do the necessary matching without
> renaming. Maybe by allowing a subdirectory to be specified along
> with an extension. (Or allow specifying a full pagespec,
> but I hesitate to seriously suggest that.) --[[Joey]] 

>> I think that might be a terrifying idea for another day. If we can
>> mutate the extension during the `attach` upload, that'd be enough;
>> I don't think people who are skilled enough to use git/svn/...,
>> but not skilled enough to tell Explorer to show file extensions,
>> represent a major use case. -s

Ideally attachment could also be configured to upload into a specified
underlay, so that photos don't have to be in your source-code control
(you might want that, but I don't!).

> Replying to myself: perhaps best done as an orthogonal extension
> to attach? -s

Things that would be nice, and are probably possible:

* make the "Edit page" link on viewers divert to album-specific CGI instead
  of just failing or not appearing (probably possible via pagetemplate)

* some way to deep-link to memes/badger.jpg with a wikilink, without knowing a
  priori that it's secretly a JPEG (probably harder than it looks - you'd
  have to make a directive for it and it's probably not worth it)