The [StackOverflow](http://stackoverflow.com/) site uses markdown for markup.
It has a fancy javascript thing for showing a real-time preview of what the user
is editing. It would be nice if ikiwiki could support this, too. The thing they
use on StackOverflow is supposed to be free software, so it should be easy to
add to ikiwiki.

> See [[wikiwyg]]. Note that I do not have a copy of the code for that, or
> it'd be in ikiwiki already. --[[Joey]] 

>> I just had a brief look at the [[wikiwyg]] page and the link to the plugin was
>> broken.  The StackOverflow site uses the [WMD](http://wmd-editor.com/) editor,
>> which seems to be related to the [ShowDown](http://attacklab.net/showdown/)
>> javascript port of Markdown.  Interestingly, [WMD source](http://wmd.googlecode.com/)
>> is now available under an MIT license, though it is supposedly undergoing heavy
>> refactoring.  It looks like there was previous discussion ( [[todo/Add_showdown_GUI_input__47__edit]] )
>> about a showdown plugin.  Maybe a WMD plugin would be worthwhile.  I might
>> look into it if I have time on the weekend. -- [[Will]]

[[!tag wishlist]]

>>> Below is a simple plugin/[[patch]] to make use of the WMD editor.  Turns out it isn't hard at all to
>>> get a basic version going (which doesn't handle directives at all, nor does it swtich itself off when you're
>>> editing something other than Markdown source).  I've
>>> removed the done tag so this is visible as a patch. -- [[Will]]

>>>> Hmm, it would be good if it turned off for !mdwn. Although this could
>>>> be difficult for a new page, since there is a dropdown selector to
>>>> choose the markup language then. But it should be doable for editing an
>>>> existing page.

>>>>> I agree.  I'm working on this for for both new pages and existing pages.
>>>>> It shouldn't be hard once I get WMD going through the javascript API.
>>>>> At the moment that is inexplicably failing, and I haven't had time to have a good look at why.
>>>>> I may not get a chance to look at this again for a few weeks.

>>>> Can I get a license statement (ie, GPL-2+) ffrom you for the plugin?
>>>> --[[Joey]] 

>>>>> Certainly.  You're free to use the code I posted below under the GPL-2+ license.  You'll note
>>>>> however that I haven't said anything about the WMD code itself.  The WMD web page says:

>>>>>> "I'm refactoring the code, and will be releasing WMD under the MIT license soon. For now you can download the most recent release (wmd-1.0.1.zip) and use it freely."

>>>>> It might be best to contact <support@attacklab.net> to for an explicit license on that if you want to include it.
>>>>> -- [[Will]]

------

### Instructions:


Download the [WMD source](http://wmd-editor.com/downloads/wmd-1.0.1.zip).  In that zip file you'll
find a few example html files, a readme and `wmd` directory.  Move the `wmd` directory into the
ikiwiki `underlays` directory.  You should now have an `underlays/wmd/wmd.js` file as well as 
some other javascript files and an images directory in the same place.

> So, I wonder if I should add a copy of the WMD source to ikiwiki, or rely
> on the user or distribution providing it. It does not seem to be packaged
> for Debian yet. --[[Joey]] 

>> This is a good question.  My thought is that it will probably not be packaged any time soon,
>> so you're better off adding it to IkiWiki.  I'd contact the author of WMD and ask them.  They
>> may have more insight.  -- [[Will]]

Note that the WMD plugin does **not** handle directives.  For this reason the normal `preview` button
remains.  Some CSS to clean up the display of the live WMD preview would be good.

> Can you elucidate the CSS comment -- or will it be obvious what you mean
> when I try it? Is it what's needed for the live preview? --[[Joey]]

>> In the version of the plugin below, a new `div` is added just below the form.  WMD
>> populates this div with the HTML it generates from the Markdown source.  This is not very
>> pretty at the moment - it appears in the same place as the preview used to, but with no
>> header or anything.  Any standard IkiWiki preview will appear below the WMD live preview.
>> I recommend having a look at <http://wmd-editor.com/examples/splitscreen>
>> for what a little CSS could achieve.  -- [[Will]]

Install the following patch and plugin file.  Then enable the 'wmd' plugin.


    diff --git a/templates/editpage.tmpl b/templates/editpage.tmpl
    index 4b54db2..b1cf015 100644
    --- a/templates/editpage.tmpl
    +++ b/templates/editpage.tmpl
    @@ -37,6 +37,7 @@ Optional comment about this change:<br />
     </div>
     </TMPL_IF>
     <TMPL_VAR FORM-END>
    +<TMPL_VAR WMD_PREVIEW>
     
     <TMPL_IF NAME="PAGE_PREVIEW">
     <hr />

-----

    #!/usr/bin/perl
    package IkiWiki::Plugin::wmd;
    
    use warnings;
    use strict;
    use IkiWiki 3.00;
    use POSIX;
    use Encode;
    
    sub import {
    	add_underlay("wmd");
    	hook(type => "getsetup", id => "wmd", call => \&getsetup);
    	hook(type => "formbuilder_setup", id => "wmd", call => \&formbuilder_setup);
    }
    
    sub getsetup () {
    	return
    		plugin => {
    			safe => 1,
    			rebuild => 1,
    		},
    }
    
    sub formbuilder_setup (@) {
    	my %params=@_;
    	my $form=$params{form};
    
    	return if ! defined $form->field("do");
    	
    	return unless (($form->field("do") eq "edit") ||
    				($form->field("do") eq "create"));
    
    	$form->tmpl_param("wmd_preview", "<div class=\"wmd-preview\"></div>\n".include_javascript(undef, 1));
    }
    
    sub include_javascript ($;$) {
    	my $page=shift;
    	my $absolute=shift;
    	
    	return '<script src="'.urlto("wmd.js", $page, $absolute).
    		'" type="text/javascript"></script>'."\n";
    }
    
    1