%META:TOPICPARENT{name="Plugins"}%
---+!! Wysiwyg Plugin
<!--
   * Set SHORTDESCRIPTION = Translator framework for Wysiwyg editors
-->
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%SHORTDESCRIPTION%

Support for the integration of WYSIWYG (What-You-See-Is-What-You-Get) editors. On its own, the only thing this plugin gives you is a stand-alone HTML to TML (topic markup language) translator script. For WYSIWYG editing in Foswiki and Foswiki, you will also need to install a specific editor package such as Foswiki:Extensions.TinyMCEPlugin.

This plugin provides a generic framework that supports editing of topics using any browser-based HTML editor. It works by transforming TML into HTML for the editor, and then transforming HTML back into TML on save.

%TOC%

---++ Features
   * Supports the input of malformed HTML
   * Full round-trip (TML -> XHTML -> TML)
   * Framework is editor-agnostic

---++ Details
---+++ What's in the package
The package includes the following pieces:
   * TML (topic markup language) to HTML translator
   * HTML to TML translator (with stand-alone script)
   * Generic plugin for automating the translation during editing

---+++ How it works
The plugin works by translating the topic text into HTML when someone edits a topic. The HTML is then fed to the WYSIWYG editor. On save, the edited HTML is run through the reverse translation before saving to the topic. TML is used in preference to HTML in the stored topic wherever possible, though HTML may be used if the translator can't find a suitable TML equivalent.

The default rendering that Foswiki uses to generate HTML for display in browsers is 'lossy' - information in the TML is lost in the HTML output, and a round-trip (recovering the original TML from the HTML) is impossible. To solve this problem the plugin instead uses its own translation of TML to XHTML. The generated XHTML is annotated with CSS classes that support the accurate recovery of the original TML.

_Before you ask the obvious question, yes, the translator *could* be used to replace the Foswiki rendering pipeline for generating HTML pages. In fact, the translator is taken almost directly from the implementation of the rendering pipeline for the TWiki-4 release_

Translation of the HTML back to TML uses the CPAN:HTML::Parser. This parser is used in preference to a more modern XML parser, because the WYSIWYG editor may not generate fully compliant XHTML. A strict parser would risk losing content. CPAN:HTML::Parser is better at handling malformed HTML.

There is also the advantage that the translator can be used to *import* HTML from other sources - for example, existing web pages. Due to the simple nature of TML and the potential complexity of web pages, this translation is often lossy - i.e. there will be HTML features that can be entered by editors that will be lost in this translation step. This is especially noticeable with HTML tables.

---+++ Using the translators from Perl scripts

Both translators can be used directly from Perl scripts, for example to build your own stand-alone translators.

A stand-alone convertor script for HTML to TML is included in the installation. It can be found in =tools/html2tml.pl=.

---+++ Integrating a HTML Editor
The plugin can be used to integrate an HTML editor in a number of different ways.
   1 The HTML for the content-to-be-edited can be generated directly in the standard edit template.
   1 The HTML for the content-to-be-edited can be generated directly in a specialised edit template.
   1 A URL can be used to fetch the content-to-be-edited from the server, for use in an IFRAME.
   1 REST handlers can be called from Javascript to convert content.

---++++ Generating content directly in the standard edit template
This is the technique used by WYSIWYG editors that can sit on top of HTML
textareas, such as !TinyMCE. The topic content is pre-converted to HTML before inclusion in the standard edit template. These editors use plugins that have a =beforeEditHandler= and an =afterEditHandler=. These handlers are responsible for the conversion of topic text to HTML, and post-conversion of HTML back to TML.
   1 User hits "edit".
   1 Editor-specific plugin =beforeEditHandler= converts topic content to HTML by calling =Foswiki::Plugins::WysiwygPlugin::TranslateTML2HTML=.
   1 User edits and saves
   1 Editor-specific plugin =afterEditHandler= converts HTML back to TML by calling =Foswiki::Plugins::WysiwygPlugin::TranslateHTML2TML=.
   * !WysiwygPlugin should *not* be enabled in =configure=.
   * =WYSIWYGPLUGIN_WYSIWYGSKIN= should *not* be set.
   * Your plugin should set the =textareas_hijacked= context id, to signal to skins to suppress their textarea manipulation functions.
This is the recommended integration technique, if your editor can support it.

---++++ Generating content directly in a specialised edit template
This technique is useful when the editor requires the topic content in a variety of different formats at the same time. In this scenario the editor uses a custom edit template. The WYSIWYG content is made available for instantiation in that template in a number of different formats. =WYSIWYGPLUGIN_WYSIWYGSKIN= *must* be set for this to work.

The flow of control is as follows:
   1 User hits "edit" with the skin (or cover) set the same as =WYSIWYGPLUGIN_WYSIWYGSKIN=.
   1 The !WysiwygPlugin =beforeEditHandler= determines if the topic is WYSIWYG editable, and vetos the edit if not by redirecting to the standard edit skin.
 the edit
   1 The =edit= template containing the JS editor is instantiated.
   1 The following macros are available for expansion in the template:
      * =%<nop>WYSIWYG_TEXT%= expands to the HTML of the content-to-be-edited. This is suitable for use in a =textarea=.
      * =%<nop>JAVASCRIPT_TEXT%= expands to the HTML of the content-to-be-edited in a javascript constant.
   1 User edits and saves
   1 The =afterEditHandler= in the !WyswiygPlugin sees that =wysiwyg_edit= is set, which triggers the conversion back to TML.

   * The HTML form in the edit template *must* include an =&lt;input= called =wysiwyg_edit= and set it to 1, to trigger the conversion from HTML back to TML.
   * =WYSIWYGPLUGIN_WYSIWYGSKIN= must be set to the name of the skin used for WYSIWYG editing. This is often the name of the editor e.g. =xinha=.

---++++ Fetching content from a URL
In this scenario, the edit template is generated *without* the content-to-be-edited. The content is retrieved from the server using a URL e.g. from an =IFRAME=.

The flow of control is as follows:
   1 As _Generating content directly in a specialised edit template_
   1 As _Generating content directly in a specialised edit template_
   1 As _Generating content directly in a specialised edit template_
   1 When the document loads in the browser, the JS editor invokes a content URL (using an =IFRAME= or a =XmlHttpRequest=) to obtain the HTML document to be edited
      * The content URL is just a Foswiki =view= URL with the =wysiwyg_edit=
        parameter set.
      * The !WysiwygPlugin recognises the =wysiwyg_edit= parameter and uses the
        TML2HTML translator to prepare the text, which is then returned
        as =text/plain= to the browser.
      * Two macros, =%<nop>OWEB%= and =%<nop>OTOPIC%=, can be used in the content URL in the edit template to refer to the source topic for the content.
   1 After edit handling is as for _Generating content directly in a specialised edit template_

---+++ Other techniques
---++++ Asynchronous saves
Editors can use =XmlHttpRequest= to perform saves, by POSTing to the Foswiki =save= script with the =wysiwyg_edit= parameter set to =1=. This parameter tells the =beforeSaveHandler= in the !WysiwygPlugin to convert the content back to TML. See %SYSTEMWEB%.CommandAndCGIScripts for details of the other parameters to the =save= script.

Once the save script has completed it responds with a redirect, either to an Oops page if the save failed, or to the appropriate post-save URL (usually a =view=). The editor must be ready to handle this redirect.

---++++ Handling Attachments
Attachment uploads can be handled by URL requests from the editor template to the Foswiki
=upload= script. The =upload= script normally redirects to the containing topic; a behaviour that you usually don't want in an editor! There are two ways to handle this:
   * If the uploads are done in an =IFRAME= or via =XmlHttpRequest=, then the
     302 redirect at the end of the upload can simply be ignored.
   * You can pass =noredirect= to the =upload= script to suppress the redirect. In this case
     you will get a =text/plain= response of =OK= followed by a message if everything went well, or an error message if it did not.

---++++ REST handlers
If you are confident in Javascript you can use REST handlers with =XmlHttpRequest= to convert content from TML to HTML and back again.

The plugin defines the following REST handlers:

=.../rest/WysiwygPlugin/html2tml?topic=Web.Topic;text=htmltexttotranslate=

Converts the HTML text to TML. =topic= *must* be specified.

=.../rest/WysiwygPlugin/tml2html?topic=Web.Topic;text=tmltexttotranslate=

Converts the TML text to HTML. =topic= *must* be specified. The response is a =text/plain= page of converted content.

---++ Plugin Installation Instructions
You do not need to install anything in the browser to use this extension. The following instructions are for the administrator who installs the extension on the server.

Open configure, and open the "Extensions" section. Use "Find More Extensions" to get a list of available extensions. Select "Install".

If you have any problems, or if the extension isn't available in =configure=, then you can still install manually from the command-line. See http://foswiki.org/Support/ManuallyInstallingExtensions for more help.


---++ Plugin Configuration Settings

---+++ Translator control
%INCLUDE{"%SYSTEMWEB%.WysiwygPluginSettings"}%

*Implementors note* if you are using your own before/after edit handlers, you can call =Foswiki::Plugins::WysiwygPlugin::isWysiwygEditable()= to check these controls.

---++ Known issues

---+++ Incompatible with "non-standard" syntax
WysiwygPlugin is incompatible with plugins that expand non-standard syntax e.g. Foswiki:Extensions.MathModePlugin (WysiwygPlugin)

Plugins that extend the syntax using macros, such as =%MYMACRO%=, should work fine.

*Implementors note* plugins that use XML-like tags may call [[%SCRIPTURLPATH{view}%/%SYSTEMWEB%/PerlDoc?module=Foswiki::Plugins::WysiwygPlugin][Foswiki::Plugins::WysiwygPlugin::addXMLTag()]] from their =initPlugin= handlers to make WysiwygPlugin protect the content between XML-like tags, just like it does for macros. 

---+++ Overlapping styles
Because Foswiki uses a "best guess" approach to some formatting, it allows overlapping of tags in a way forbidden by HTML, and it is impossible to guarantee 100% that formating in the original Foswiki document will still be there when the same document is loaded and then saved through the WysiwygPlugin. The most obvious case of this is to do with styles. For example, the sentence
<verbatim>
*bold _bold-italic* italic_
</verbatim>
is legal in TML, but in HTML is represented by
<verbatim>
<strong>bold <em>bold-italic</em></strong> <em>italic</em>
</verbatim>
which gets translated back to TML as
<verbatim>
*bold _bold-italic_* _italic_
</verbatim>
which is correct by construction, but does not render correctly in Foswiki. This problem is unfortunately unavoidable due to the way TML works.

---+++ Flattening of =&lt;div&gt;= tags
The "Normal" format command in the current release of TinyMCEPlugin depends on WysiwygPlugin flattening =&lt;div&gt;= tags. If you have a customised =WYSIWYGPLUGIN_STICKYBITS= set, check that plain =&lt;div&gt;= tags will be flattened if you expect this feature to work. It is expected that this requirement will be removed in a future release of TinyMCEPlugin.

---++ Plugin Info

This plugin is brought to you by a [[http://wikiring.com][WikiRing <a href="http://wikiring.com"><img src="%ATTACHURLPATH%/wikiringlogo20x20.png" title="WikiRing: Professional Wiki Innovation and Support" /></a>]] partner - working together to improve your wiki experience!

Many thanks to the following sponsors for supporting this work:
   * [[http://ilog.fr][ILOG]]
   * [[http://www.carrier.com][Carrier Corporation]]
   * [[http://twiki.net][TWIKI.NET]]

|  Author: | [[http://c-dot.co.uk][Crawford Currie]] |
|  Copyright | &copy; ILOG 2005 http://www.ilog.fr |
|  License | [[http://www.gnu.org/licenses/gpl.html][GPL (Gnu General Public License)]] |
|  Version: | 6068 (2010-01-17) |
|  Release: | 17 Jan 2010 |
|  Change History: | |
|  17 Jan 2010 | Foswikitask:Item2337: ATTACHFILESIZELIMIT check fails confusingly if value is "0 " |
|  08 Dec 2009 | Foswikitask:Item2447: Add TinyMCEPlugin's &lt;div&gt; flattening requirement to Known Issues <br/> Foswikitask:Item2352: Use Foswiki's regex instead of a hard-coded regex, so that WysiwygPlugin will always "see" macros in the same way as Foswiki's renderer<br/> Foswikitask:Item2286: Cleaning up missing calls to Foswiki::finish() |
|  22 Oct 2009 | Foswikitask:Item2183: Protect div style= by default |
|  18 Sep 2009 | Foswikitask:Item1980: Prevent dataloss when saving a topic in Wysiwyg where there are a pair of sticky tags inside verbatim tags |
|  28 Jun 2009 | Foswikitask:Item1770: Protect XML tags registered by plugins, and not just the content between them (Michael Tempest) |
|  06 Jun 2009 | Foswikitask:Item1013: Correct dependency on HTML::Parser (Will Norris) Foswikitask:Item1397: Foswikitask:Item1535: Foswikitask:Item1666: Correct processing of colour and typewriter-text in several situations, include application to bold text and table cells (Michael Tempest) Foswikitask:Item1667: Remove unwanted extra &lt;sticky&gt; tags (Michael Tempest) Foswikitask:Item1674: Let plugins register XML tags that should be protected like macros |
|  10 Apr 2009 | Foswikitask:Item1394: fixed colour handling |
|  03 Dec 2008 | Foswikitask:Item6041: fixed empty bullet list problem. Foswiki version |
|  22 Oct 2008 | Fixed TWikibug:Item5961 (emphasis), TWikibug:Item6089 (backslash in verbatim) |
|  07 Aug 2008 | Fixed TWikibug:Item5707 (mod_perl) |
|  03 Aug 2008 | TWiki 4.2.1 release version |
|  25 May 2008 | TWikibug:Item5457: TWikibug:Item5528: TWikibug:Item5626: using a debug simulation, I believe I have finally fixed all the complexities of using international character sets with the translator. |
|  13 Apr 2008 | TWikibug:Item4946: TWikibug:Item5530: I think I have finally fixed non-iso-8859-1 character sets. Painful. TWikibug:Item5393: removed spurious DIV generated by IE inside LI tags |
|  31 Mar 2008 | TWikibug:Item5314: TWikibug:Item5457: Fixed pickaxe mode for editing UTF-8. Characters above 255 are converted to entitites, which is a bit of a PITA, but at least it no longer corrupts topics. |
|  28 Mar 2008 | TWikibug:Item5294: fixed angle brackets in plain text and promoted sticky to be higher priority than any other tag, solving several problems in one go |
|  24 Jan 2008 | TWikibug:Item5257: remove extra spaces at end of Set lines |
|  20 Dec 2007 | TWikibug:Item5022: made TT font size same as verbatim. Had to add a new style to do it, as TMCE didn't want to play with TT or CODE tags. TWikibug:Item5138: post-conversion of 8-bit entities to characters to aid searching etc. |
| 19 Dec 2007 | TWikibug:Item4836: make the parser tolerant of META, so pasting OO docs works TWikibug:Item4969: autoclose BR and HR tags TWikibug:Item5132: fixed IMG tags TWikibug:Item5076: fixed line-sensitive TML embedded in tables |
|  8 Nov 2007 | TWikibug:Item4923: fixed blocking of table conversion due to empty attributes TWikibug:Item4936: An em embedded in an em was getting eaten TWikibug:Item4817: added typewriter text button TWikibug:Item4850: added font colour controls TWikibug:Item4645: added REST handlers for upload and fetching lists of attachments |
|  2 Nov 2007 | TWikibug:Item4903: corrected over-enthusiastive interpretation of ! as an escape |
|  21 Oct 2007 | TWikibug:Item4788: fixed unbalanced protect, which could cause loss of protected status TWikibug:Item4811: noautolink *looks* like an HTML construct but in fact is not; the tag is infact an "on-off" switch and does not imply any HTML structure, so cannot be converted to a DIV or a span, so has to be removed. TWikibug:Item4747: added &lt;sticky&gt; to try to overcome limitations in translation TWikibug:Item4831: added increased flexibility in deciding what HTML get converted to TML, and what does not. Analysed all the HTML4 tags to establish initial settings. TWikibug:Item4847: don't call non-existent function with older HTML::Parser releases TWikibug:Item4844: Saving a table from IE didn't convert it back to TML TWikibug:Item4855: table rows generated from TWiki variables were being eaten |
|  6 Oct 2007 | TWikibug:Item4700: fixed colspans TWikibug:Item4701: removed extra line between %TABLE and the table TWikibug:Item4705: fixed spacing around literal and verbatim blocks TWikibug:Item4706: merge adjacent verbatim blocks separated only by whitespace TWikibug:Item4712: fixed eating of noautolink and literal TWikibug:Item4763: list items spanning multiple lines fixed TWikibug:Item4867: released tml2html |
|  17 Sep 2007 | TWikibug:Item4647: TWikibug:Item4652: problems related to DIV fixed. TWikibug:Item4653: fixed multi-line twiki variables |
|  16 Sep 2007 | TWikibug:Item4630: polished up the way the secret string is done, to ensure synch between perl and JS. Item4622: added UTF-8 handling steps that fixup malformed UTF8 strings before presenting them to the editor (saves Moz) and stops the editor passing them back to TWiki (saves IE). Removed extra entity decoding steps that were causing problems. TWikibug:Item4629: fixed issues with verbatim, highlighted by previous mangling of this topic |
|  13 Sep 2007 | TWikibug:Item4613 cleaned up spurious message when navigating away TWikibug:Item4615 fixed incorrect rendering of emphasis next to br |
|  12 Sep 2007 | TWikibug:Item4604 Fixes to REST handler, and add ability to trigger HTML2TML conversion from a content comment alone (required for some editors) TWikibug:Item4588 fixes to conversion of double-character emphases |
|  7 Sep 2007 | TWikibug:Item4503 excess empty lines TWikibug:Item4486 no toc headers with unofficial syntax TWikibug:Item4560: empty lines lost TWikibug:Item4566: corrupted table on save TWikibug:Item4550 section tags being eaten |
|  4 Sep 2007 | TWikibug:Item4534 TWikibug:Item4535 fixed |
| See Subversion logs for earlier revisions ||
|  Dependencies: | <table class="foswikiTable" border="1"><tr><th>Name</th><th>Version</th><th>Description</th></tr><tr><td align="left">HTML::Parser</td><td align="left">&gt;=3.28</td><td align="left">Required. Available from [[http://cpan.uwinnipeg.ca/search?query=HTML%3A%3AParser&mode=dist][CPAN]].</td></tr><tr><td align="left">HTML::Entities</td><td align="left">&gt;=1.25</td><td align="left">Required. Available from [[http://cpan.uwinnipeg.ca/search?query=HTML%3A%3AEntities&mode=dist][CPAN]].</td></tr><tr><td align="left">Encode</td><td align="left">&gt;=2.01</td><td align="left">Required.</td></tr></table> |
|  Plugin Home: | http://foswiki.org/Extensions/%TOPIC% |
|  Support: | http://foswiki.org/Support/%TOPIC% |

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