From 2bb08aa5896e65036e457ccf911e308868438310 Mon Sep 17 00:00:00 2001
From: 
 "https://www.google.com/accounts/o8/id?id=AItOawlSFgIlytGZgMLh_Cw4IA011V8pLKk5dVg"
 <Brian@web>
Date: Thu, 28 Nov 2013 16:56:28 -0400
Subject: Possible code for converting static assets

---
 doc/plugins/write/discussion.mdwn | 44 ++++++++++++++++++++++++---------------
 1 file changed, 27 insertions(+), 17 deletions(-)

(limited to 'doc/plugins/write')

diff --git a/doc/plugins/write/discussion.mdwn b/doc/plugins/write/discussion.mdwn
index d4d8f57a3..5afe95f2a 100644
--- a/doc/plugins/write/discussion.mdwn
+++ b/doc/plugins/write/discussion.mdwn
@@ -45,23 +45,33 @@ distributed wiki.
 
 Since there's no mailing list, I'll post my request for help here :-)
 
-I would like to use ikiwiki to build a static site which needs some transformations to be made on binary assets. A simple example is to translate a .odp presentation to .pdf using (e.g.) unoconv. I'd probably make a plugin with a config which maps extensions to shell commands. But what's the right place to hook in to do this?
-
-I can see that binary assets are normally hardlinked or copied verbatim. The logic from `sub render` in `IkiWiki/Render.pm` is:
-
-* If the private hash $rendered{$file} is already set, skip
-* If the extension is known to pagetype(), i.e. it has been registered for the htmlize hook, send content through the full cycle of `genpage(htmlize(linkify(preprocess(filter(readfile)))))`
-* ...except for extensions which start with underscore, in which case the processing is aborted before the write
-* Any file whose extension is unknown to pagetype() is either hardlinked or copied directly to the target directory
-
-Options I can see are:
-
-* Register .odp as a htmlize extension, use the scan hook(), inside there write out the file and alter the page name so that it has an underscore (xxx.odp -> xxx._odp)
-* Use the scan() hook, write out the file, directly manipulate the private %rendered hash to stop `sub render` handling it
-* use needsbuild to build the page as a side effect and at the same time remove it from the list of pages to be built
-* other way??
-
-It's not clear to me which of these is the right way to go, taking into account all the existing logic for rebuilding pages on demand. (For example: if I git add and push a new .odp to the repository, I want the .pdf to be generated automatically in the output site through the post-commit hook)
+I would like to use ikiwiki to build a static site which needs some transformations to be made on binary assets. A simple example is to translate a .odp presentation to .pdf using (e.g.) unoconv. If I add a new .odp attachment, or push one into the repo, I want the corresponding .pdf to appear in the generated site. What's the right place to hook in to do this?
+
+I've made an experimental prototype which hooks into needsbuild, builds the pages then and there, and at the same time removes them from the list of pages to be built.
+
+~~~
+sub needsbuild {
+    my $files=shift;
+    my $nfiles=[];
+    foreach my $f (@$files) {
+        if ($f =~ /\.odp$/) {
+            my $g = $f;
+            $g =~ s/\.odp$/\.pdf/;
+            debug("building $f to $g");
+            will_render($f, $g);
+            if (system("unoconv","-f","pdf","-o",IkiWiki::dirname("$config{destdir}/$g"),srcfile($f)) != 0) {
+                error("unoconv: failed to translate $f to $g");
+            }
+        }
+        else {
+            push @$nfiles, $f;
+        }
+    };
+    return $nfiles;
+}
+~~~
+
+It appears to work, but is this the right way to do it, bearing in mind ikiwiki's dependency tracking and the like? And is the usage of will_render() correct?
 
 [[BrianCandler]]
 
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