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.

>>>> Now added to ikiwiki, thanks! --[[Joey]] 

>>> 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]]

> 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. Hmm, I also can't find any copyright or license info in
> the zip file. --[[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]]

> Hmm, now that I've tried it, I notice that it does live preview by
> default, below the edit window. Which is nice, but then if I hit the
> preview button, I get two previews.. which is confusing. (Also, minor,
> but: the live preview is missing the "Page Preview:" header.) --[[Joey]] 

> I wonder how annoying it would be to add some kind of simplistic wikilink
> support to wmd's preview? And/or a wikilink button? While not supporting
> directies is fine, not supporting wikilinks in a wiki seems a bit
> lacking. It may also entice novide users to not use wikilinks and instead
> use the hyperlinks that wmd does support. --[[Joey]] 

> Bug: When I preview, all the text in the edit field seems to be
> converted from mdwn to html. I think that wmd is converting the mdwn
> into html when the form is posted, so it would also save like that.
> I assume that is designed for websites that do not use markdown
> internally. Doesn't it have a setting to leave it as markdown?
>> Found setting, fixed. --[[Joey]] 

>>> As I noted above, I've been working on the non-markdown page issue.
>>> Below is my a new javascript file that I'm using, and below that a patch
>>> to enable it.  This patch makes the normal usage prettier - you get
>>> a side panel with the live preview in it.  It also adds a new config
>>> option, `wmd_use101api`, which turns on code that tries to use the
>>> wmd api.  At the moment this code doesn't seem to work - moreover the
>>> code that uses the new API dies early, so any code after that point is
>>> completely untested.  I will not
>>> get a chance to look at this again soon though, so I thought I'd post
>>> my progress so far.  -- [[Will]]


Place the following file in `underlays/wmd/wmd-ikiwiki.js`.

----

    // This is some code to interface the WMD interface 1.0.1 with IkiWiki
    // The WMD interface is planned to change, so this file will likely need
    // updating in future.
    
    if (useWMDinterface) {
    	wmd_options = { autostart: false, output: "Markdown" };
    	var instance = null;
    
    	hook("onload", initwmd);
    } else {
    	var typeSelector = document.getElementById("type");
    	
    	var currentType = getType(typeSelector);
    	
    	if (currentType == "mdwn") {
    		wmd_options = { output: "Markdown" };
    		document.getElementById("wmd-preview-container").style.display = 'none';
    	} else {
    		wmd_options = { autostart: false };
    		document.getElementById("wmd-preview-container").style.display = 'block';
    	}
    }
    
    function initwmd() {
    	if (!Attacklab || !Attacklab.wmd) {
    		alert("WMD hasn't finished loading!");
    		return;
    	}
    	
    	var typeSelector = document.getElementById("type");
    	
    	var currentType = getType(typeSelector);
    	
    	if (currentType == "mdwn") {
    		window.setTimeout(enableWMD,10);
    	}
    	
    	typeSelector.onchange=function() {
    		var docType=getType(this);
    		
    		if (docType=="mdwn") {
    			enableWMD();
    		} else {
    			disableWMD();
    		}
    	}
    }
    
    function getType(typeSelector)
    {
    	if (typeSelector.nodeName.toLowerCase() == 'input') {
    		return typeSelector.getAttribute('value');
    	} else if (typeSelector.nodeName.toLowerCase() == 'select') {
    		return typeSelector.value;
    		// return typeSelector.options[typeSelector.selectedIndex].innerText;
    	}
    	return "";
    }
    
    function enableWMD()
    {
    	var editContent = document.getElementById("editcontent");
    	var previewDiv = document.getElementById("wmd-preview");
    	var previewDivContainer = document.getElementById("wmd-preview-container");
    	
    	previewDivContainer.style.display = 'block';
    	// editContent.style.width = previewDivContainer.style.width;
    	
    	/***** build the preview manager *****/
    	var panes = {input:editContent, preview:previewDiv, output:null};
    	var previewManager = new Attacklab.wmd.previewManager(panes);
    
    	/***** build the editor and tell it to refresh the preview after commands *****/
    	var editor = new Attacklab.wmd.editor(editContent,previewManager.refresh);
    
    	// save everything so we can destroy it all later
    	instance = {ta:editContent, div:previewDiv, ed:editor, pm:previewManager};
    }
    
    function disableWMD()
    {
    	document.getElementById("wmd-preview-container").style.display = 'none';
    
    	if (instance != null) {
    		instance.pm.destroy();
    		instance.ed.destroy();
    		// inst.ta.style.width='100%'
    	}
    	instance = null;
    }


----

    diff --git a/IkiWiki/Plugin/wmd.pm b/IkiWiki/Plugin/wmd.pm
    index 9ddd237..743a0b8 100644
    --- a/IkiWiki/Plugin/wmd.pm
    +++ b/IkiWiki/Plugin/wmd.pm
    @@ -17,6 +17,13 @@ sub getsetup () {
     	return
     		plugin => {
     			safe => 1,
    +			rebuild => 1,
    +		},
    +		wmd_use101api => {
    +			type => "boolean",
    +			description => "Use the advanced, but unstable, WMD api for markdown preview.",
    +			safe => 0,
    +			rebuild => 0,
     		},
     }
     
    @@ -24,29 +31,25 @@ sub formbuilder_setup (@) {
     	my %params=@_;
     	my $form=$params{form};
     
    -	return if ! defined $form->field("do");
    +	return unless defined $form->field("do");
     	
     	return unless $form->field("do") eq "edit" ||
    -			$form->field("do") eq "create" ||
    -			$form->field("do") eq "comment";
    -
    -	$form->tmpl_param("wmd_preview", "<div class=\"wmd-preview\"></div>\n".
    -		include_javascript(undef, 1));
    -}
    -
    -sub include_javascript ($;$) {
    -	my $page=shift;
    -	my $absolute=shift;
    -
    -	my $wmdjs=urlto("wmd/wmd.js", $page, $absolute);
    -	return <<"EOF"
    -<script type="text/javascript">
    -wmd_options = {
    -	output: "Markdown"
    -};
    -</script>
    -<script src="$wmdjs" type="text/javascript"></script>
    -EOF
    +				$form->field("do") eq "create" ||
    +				$form->field("do") eq "comment";
    +
    +	my $useAPI = $config{wmd_use101api}?'true':'false';
    +	my $ikiwikijs = urlto("ikiwiki.js", undef, 1);
    +	my $wmdIkiwikijs = urlto("wmd-ikiwiki.js", undef, 1);
    +	my $wmdjs = urlto("wmd.js", undef, 1);
    +
    +	my $previewScripts = <<"EOS";
    +		<script type="text/javascript">useWMDinterface=$useAPI;</script>
    +		<script src="$ikiwikijs" type="text/javascript"></script>
    +		<script src="$wmdIkiwikijs" type="text/javascript"></script>
    +		<script src="$wmdjs" type="text/javascript"></script>
    +EOS
    +
    +	$form->tmpl_param("wmd_preview", $previewScripts);
     }
     
     1
    diff --git a/doc/style.css b/doc/style.css
    index a6e6734..36c2b13
    --- a/doc/style.css
    +++ b/doc/style.css
    @@ -76,9 +76,16 @@ div.tags {
     	float: right;
     }
     
    +/*
     #editcontent {
     	width: 100%;
     }
    +*/
    +
    +#wmd-preview-container {
    +	width: 49%;
    +	float: right;
    +}
     
     img {
     	border-style: none;
    diff --git a/templates/editpage.tmpl b/templates/editpage.tmpl
    index b1cf015..1d2f080 100644
    --- a/templates/editpage.tmpl
    +++ b/templates/editpage.tmpl
    @@ -15,6 +15,14 @@ Page type: <TMPL_VAR FIELD-TYPE>
     <TMPL_VAR FIELD-PAGE>
     <TMPL_VAR FIELD-TYPE>
     </TMPL_IF>
    +<TMPL_IF NAME="WMD_PREVIEW">
    +<div id="wmd-preview-container">
    +<div  class="header">
    +<span>Live preview:</span>
    +</div>
    +<div class="wmd-preview" id="wmd-preview"></div>
    +</div>
    +</TMPL_IF>
     <TMPL_VAR FIELD-EDITCONTENT><br />
     <TMPL_IF NAME="CAN_COMMIT">
     Optional comment about this change:<br />
