Wysiwyg Plugin
Translator framework for Wysiwyg editors
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 TWiki translator script. For WYSIWYG editing in TWiki, you will also need to install a specific editor package such as
TWiki:Plugins.KupuEditorContrib or
TWiki:Plugins.WikiwygContrib.
This plugin provides a generic framework that supports editing of TWiki topics using any browser-based HTML editor. It works by transforming TML (TWiki Meta Language) into HTML for the editor, and then transforming HTML back into TML on save.
Features
- Supports the input of malformed HTML
- Full round-trip (TML -> XHTML -> TWiki syntax)
- Framework is editor-agnostic
Details
What's in the package
The package includes the following pieces:
- TML (TWiki syntax) to HTML translator
- HTML to TML translator (with stand-alone script)
- Generic TWiki 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. TWiki syntax 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 TWiki uses to generate HTML for display in browsers is 'lossy' - information in the TWiki syntax is lost in the HTML output, and a round-trip (recovering the original TWiki syntax from the HTML) is impossible. To solve this problem the plugin instead uses its own translation of TWiki syntax to XHTML. The generated XHTML is annotated with CSS classes that support the accurate recovery of the original TWiki syntax.
Before you ask the obvious question, yes, the translator could be used to replace the TWiki 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 TWiki syntax 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 TWiki syntax 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 TWiki 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.
- The HTML for the content-to-be-edited can be generated directly in the standard edit template.
- The HTML for the content-to-be-edited can be generated directly in a specialised edit template.
- A URL can be used to fetch the content-to-be-edited from the server, for use in an IFRAME.
- REST handlers can be called from Javacript 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.
- User hits "edit".
- Editor-specific plugin
beforeEditHandler
converts topic content to HTML by calling TWiki::Plugins::WysiwygPlugin::TranslateTML2HTML
.
- User edits and saves
- Editor-specific plugin
afterEditHandler
converts HTML back to TML by calling TWiki::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:
- User hits "edit" with the skin (or cover) set the same as
WYSIWYGPLUGIN_WYSIWYGSKIN
.
- 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
- The
edit
template containing the JS editor is instantiated.
- The following variables are available for expansion in the template:
-
%WYSIWYG_TEXT%
expands to the HTML of the content-to-be-edited. This is suitable for use in a textarea
.
-
%JAVASCRIPT_TEXT%
expands to the HTML of the content-to-be-edited in a javascript constant.
- User edits and saves
- 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
<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 usually the name of the editor e.g. kupu
.
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:
- As Generating content directly in a specialised edit template
- As Generating content directly in a specialised edit template
- As Generating content directly in a specialised edit template
- 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 TWiki
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 TWiki variables,
%OWEB%
and %OTOPIC%=, can be used in the content URL in the edit template to refer to the source topic for the content.
- 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 TWiki
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
TWikiScripts 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 TWiki
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 where TWiki is running.
Like many other TWiki extensions, this module is shipped with a fully
automatic installer script written using the BuildContrib.
- If you have TWiki 4.2 or later, you can install from the
configure
interface (Go to Plugins->Find More Extensions)
- If you have any problems, then you can still install manually from the command-line:
- Download one of the
.zip
or .tgz
archives
- Unpack the archive in the root directory of your TWiki installation.
- Run the installer script (
perl <module>_installer
)
- Run
configure
and enable the module, if it is a plugin.
- Repeat for any missing dependencies.
- If you are still having problems, then instead of running the installer script:
- Make sure that the file permissions allow the webserver user to access all files.
- Check in any installed files that have existing
,v
files in your existing install (take care not to lock the files when you check in)
- Manually edit LocalSite.cfg to set any configuration variables.
Plugin Configuration Settings
Translator control
The
global TWiki Variable
WYSIWYG_EXCLUDE
can be set to make the plugin sensitive to what is in a topic, before allowing it to be edited. You can set it up to veto an edit if the topic contains:
-
html
- HTML tags (e.g. <div>
, not including <br>), or
-
variables
- simple variables (e.g. %VAR%
) or
-
calls
- TWiki variables with parameters e.g. %VARIABLE{...}%
-
pre
blocks (<pre>
)
- HTML
comments
(<!--
... -->
)
If the plugin detects an excluded construct in the topic, it will refuse to allow the edit and will redirect to the default editor.
If you excluded
calls
in
WYSIWYG_EXCLUDE
, you can still define a subset of TWiki variables that do
not block edits. this is done in the
global TWiki variable
WYSIWYG_EDITABLE_CALLS
, which should be a list of TWiki variable names separated by vertical bars, with no spaces, e.g:
* Set WYSIWYG_EDITABLE_CALLS = COMMENT|CALENDAR|INCLUDE
You should set
WYSIWYG_EXCLUDE
and
WYSIWYG_EDITABLE_CALLS
in
TWikiPreferences, or in
WebPreferences for each web.
You can define the global variable
WYSIWYGPLUGIN_STICKYBITS
to stop the
plugin from ever trying to convert specific HTML tags into
HTML when certain specific attributes are present on the tag. This is most
useful when you have styling or alignment information in tags that must be
preserved.
This variable is used to tell the translator which attributes, when present
on a tag, make it "stick" i.e. block conversion. For example, setting it to
table=background,lang;tr=valign
will stop the translator from trying to
handle any
table
tag that has
background
or
lang
attributes, and any
tr
tag that has a
valign
attribute.
You can use perl regular expressions to match tag and attribute names, so
.*=id,on.*
will ensure that any tag with an
on*
event handler is kept as HTML.
The default setting for this variable is:
.*=id,lang,title,dir,on.*;
A=accesskey,coords,shape,target;
BDO=dir;
BR=clear;
COL=char,charoff,span,valign,width;
COLGROUP=align,char,charoff,span,valign,width;
DIR=compact;
DIV=align;
DL=compact;
FONT=size,face;
H\d=align;
HR=align,noshade,size,width;
LEGEND=accesskey,align;
LI=type,value;
OL=compact,start,type;
P=align;
PARAM=name,type,value,valuetype;
PRE=width;
Q=cite;
TABLE=align,bgcolor,border,cellpadding,cellspacing,frame,rules,summary,width;
TBODY=align,char,charoff,valign;
TD=abbr,align,axis,bgcolor,char,charoff,colspan,headers,height,nowrap,rowspan,scope,valign,width;
TFOOT=align,char,charoff,valign;
TH=abbr,align,axis,bgcolor,char,charoff,colspan,height,nowrap,rowspan,scope,valign,width,headers;
THEAD=align,char,charoff,valign;
TR=bgcolor,char,charoff,valign;
UL=compact,type
If you edit using the plain-text editor, you can use the <sticky>..</sticky> tags to delimit HTML (or TML) that you do
not want to be WYSIWYG edited.
Implementors note if you are using your own before/after edit handlers, you can call
TWiki::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.
TWiki:Plugins.MathModePlugin (
WysiwygPlugin)
Plugins that extend the syntax using TWiki variables, such as
%MYVARIABLE%
, should work fine.
Overlapping styles
Because TWiki 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 TWiki 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
*bold _bold-italic* italic_
is legal in TML, but in HTML is represented by
<strong>bold <em>bold-italic</em></strong> <em>italic</em>
which gets translated back to TML as
*bold _bold-italic_* _italic_
which is correct by construction, but does not render correctly in TWiki. This problem is unfortunately unavoidable due to the way TWiki syntax works.
Plugin Info
This plugin is brought to you by a
WikiRing partner - working together to improve your wiki experience!
Many thanks to the following sponsors for supporting this work:
Plugin Authors: |
TWiki:Main.CrawfordCurrie http://www.c-dot.co.uk |
Copyright |
© ILOG 2005 http://www.ilog.fr |
License |
GPL (Gnu General Public License) |
Plugin Version: |
03 Aug 2008 17302 (04 Aug 2008) |
Change History: |
|
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 <sticky> 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: |
Name | Version | Description |
---|
HTML::Parser | >=3.28 | Required. Available from CPAN. | HTML::Entities | >=1.25 | Required. Available from CPAN. | |
Plugin Home: |
http://twiki.org/cgi-bin/view/Plugins/WysiwygPlugin |
Feedback: |
TWiki:Plugins/WysiwygPluginDev |
Appraisal: |
http://twiki.org/cgi-bin/view/Plugins/WysiwygPluginAppraisal |
Related Topics: TWikiPreferences,
TWikiPlugins