Package: plone.outputfilters
Introductionplone.outputfiltersprovides a framework for registering filters that
get applied to text as it is rendered.By default, these filters are wired up to occur when text is transformed from
the text/html mimetype to the text/x-html-safe mimetype via the
PortalTransforms machinery.With  the RichText field ofplone.app.textfield, this transform is typically applied when the field value is first accessed.
The result of the transform is then cached in a volatile attribute for an hour or until the value is replaced.Included FiltersA default filter is included which provides the following features:Resolving UID-based linksAdding captions to images(These are implemented as one filter to avoid the overhead of parsing the HTML
twice.)These features used to be provided by similar transforms in both Products.kupu
and Products.TinyMCE.  New releases of these editors are being prepared which
depend on the transform in plone.outputfilters, so that bugs don’t need to be
fixed in multiple places.Resolving UID-based linksInternal links may be inserted with a UID reference rather than the real path
of the item being linked.  For example, a link might look like this:<a href="resolveuid/6992f1f6-ae36-11df-9adf-001ec2a8cdf1">Such URLs can be resolved by theresolveuidview, which resolves the UID to
an object and then redirects to its URL. However, resolving links in this way
requires an extra request after the redirect. The resolveuid filter avoids that
by replacing such URLs with the object’s actual full absolute URL as the link
is rendered.UIDs are resolved usingplone.app.uuid.utils.uuidToURL.The resolveuid filter is enabled if there is at least oneplone.outputfilters.filters.resolveuid_and_caption.IResolveUidsEnablerutility whoseavailableproperty returnsTrue.  This mechanism exists
for compatibility with TinyMCE and kupu, which both provide their own control
panel setting to enable the link-by-uid feature.Image captioningImage tags with the “captioned” class and asrcattribute that resolves to
an image object within the site will be wrapped in a definition list (DL) tag
which includes a caption based on the value of the image’sdescriptionfield, if any.For example, this image tag:<img src="path/to/image" class="captioned"/>might be transformed into:<dl class="captioned">
 <dt><img src="path/to/image"/></dt>
 <dd class="image-caption">Caption text</dd>
</dl>assuming the image found at “path/to/image” has the description “Caption text”.The captioning filter is enabled if there is at least oneplone.outputfilters.filters.resolveuid_and_caption.IImageCaptioningEnablerutility whoseavailableproperty returnsTrue.  This mechanism exists
for compatibility with TinyMCE and kupu, which both provide their own control
panel setting to enable the captioning feature.The captioned version of an image is rendered using the@@plone.outputfilters_captioned_imageview, which may be overridden to
customize the caption.  This view is passed the following kwargs:classThe CSS class on the image.originalwidthThewidthattribute of the image tag.originalaltThealtattribute of the image tag.url_pathThe path of the image, relative to the site root.captionThe image’s description.imageThe (possibly scaled) image object.fullimageThe original unscaled image object.tagA full HTML tag which displays the image.isfullsizeTrue ifimageisfullimage.widthThe width ofimage.Adding a custom filterAs an example, the following filter replaces all doubled hyphens (”–”) with em
dashes (“-“). (Don’t use the example verbatim, because it doesn’t parse HTML to
apply itself only to text nodes, so will mangle HTML comments.)A filter is a callable which accepts a UTF-8-encoded HTML string as input, and
returns a modified UTF-8-encoded HTML string. A return value ofNonemay be
used to indicate that the input should not be modified.Example:import re
from zope.interface import implementer
from plone.outputfilters.interfaces import IFilter

@implementer(IFilter)
class EmDashAdder(object):
    order = 1000

    def __init__(self, context, request):
        pass

    def is_enabled(self):
        return True

    pattern = re.compile(r'--')

    def __call__(self, data):
        return self.pattern.sub('—', data)Theorderattribute may be used to affect the order in which filters are
applied (higher values run later). The is_enabled method should return a boolean
indicating whether the filter should be applied.Filters are registered in ZCML as a named multi-adapter of the context and
request to IFilter:>>> from Zope2.App import zcml
>>> import Products.Five
>>> configure = """
... <configure
...     xmlns="http://namespaces.zope.org/zope">
...
...   <adapter
...     name="em_dash_adder"
...     provides="plone.outputfilters.interfaces.IFilter"
...     for="* *"
...     factory="plone.outputfilters.filters.example.EmDashAdder"
...     />
...
... </configure>
... """
>>> zcml.load_config("configure.zcml", Products.Five)
>>> zcml.load_string(configure)Now when text is transformed from text/html to text/x-html-safe, the filter will
be applied:>>> app = layer['app']
>>> portal = layer['portal']
>>> str(portal.portal_transforms.convertTo('text/x-html-safe',
...     'test--test', mimetype='text/html', context=portal))
'test—test'How it worksplone.outputfiltershooks into the PortalTransforms machinery by installing:a new mimetype (“text/x-plone-outputfilters-html”)a transform from text/html to text/x-plone-outputfilters-htmla null transform from text/x-plone-outputfilters-html back to text/htmla “transform policy” for the text/x-html-safe mimetype, which says that text
being transformed to text/x-html-safe must first be transformed to
text/x-plone-outputfilters-htmlThe filter adapters are looked up and applied during the execution of the
transform from step #2.This should be considered an implementation detail and may change at some point
in the future.Changelog5.0.4 (2023-07-13)Bug fixes:Call registry once per filter rather than for each img tag.
[gotcha] (less_call_to_registry)Internal:Update configuration files.
[plone devs] (7723aeaf)5.0.3 (2023-06-16)Bug fixes:Return a 404 Not Found response if the resolveuid view is called with no uuid. @davisagli (#43)5.0.2 (2023-04-14)Internal:Update configuration files.
[plone devs] (535edb14)5.0.1 (2023-03-21)Internal:Update configuration files.
[plone devs] (243ca9ec)5.0.0 (2022-11-17)Bug fixes:Use our new version of uuidToObject() from plone.app.uuid.utils
[anirudhhkashyap] (#52)5.0.0b3 (2022-09-30)Bug fixes:Do not return prettified soup after picture variants filter.
This prevents adding unneeded newlines.
[petschki] (#56)5.0.0b2 (2022-09-10)Bug fixes:isort, black, pyupgrade, manual six removal.
[jensens] (#53)5.0.0b1 (2022-06-23)New features:Add image_srcset output filter, to convert IMG tags into PICTURE tags with multiple source definitions as define in imaging control panel [MrTango] (#49)4.1.0 (2022-02-23)New features:Resolve UIDs in SRC= attribute of of SOURCE and IFRAME elements. (#47)4.0.2 (2020-09-28)Bug fixes:fix AttributeError: ‘NoneType’ object has no attribute ‘unwrap’ exception when a fullsize image is wrapped in an <a> tag. [flipmcf] (#39)Fixed deprecation warning for html_quote.
[maurits] (#3130)4.0.1 (2020-04-21)Bug fixes:Minor packaging updates. (#1)4.0.0 (2020-03-13)Breaking changes:Change the image caption template to use<figure>and<figcaption>.
[thet]New features:Add anImageCaptioningEnablerutility which can be enabled via the portal registry settingplone.image_captioning.
[thet]Bug fixes:Don’t check for hard coded image size in test.
[agitator]Fixed possible package install error with Python 3.6 when no system locale is set.
Seecoredev issue 642.
[maurits]3.1.2 (2019-03-21)Bug fixes:fix UnicodeDecodeError in Python 2 when uid-linked image has
non-ascii characters in title or description
[petschki]3.1.1 (2019-01-07)Bug fixes:bugfix for KeyError caused by <a> elements without href attribute
[ajung]3.1.0 (2018-11-02)New features:remove deprecated sgmllib and move to BeautifulSoup4
[tobiasherp, petschki]3.0.5 (2018-06-04)Bug fixes:Allow resolving of links with absolute path and host
[tomgross]Make plone.namedfile hard testing dependency
[tomgross]3.0.4 (2018-02-02)Bug fixes:Add Python 2 / 3 compatibility
[pbauer]3.0.3 (2017-08-04)Bug fixes:update test to reflect changes in PortalTransforms
[MrTango]3.0.2 (2017-07-03)Bug fixes:Remove unittest2 dependency
[kakshay21]3.0.1 (2017-02-05)Bug fixes:Do not transform a and img tags when inside script tag.
[gotcha]3.0.0 (2016-08-19)Breaking changes:Give up support of PortalTransforms 1.x with old style interfaces.
[jensens]Bug fixes:Handle unicode errors in img attributes
[vangheem]Cleanup: utf8-headers, isort, pep8
[jensens]Use zope.interface decorator.
[gforcada]2.1.5 (2016-06-07)Bug fixes:Make tests work with old and new safe HTML transform
[tomgross]2.1.4 (2016-05-10)Fixes:Explicitly excludemailto:links from being UID-resolved.
[thet]Fix test isolation problem.
[thet]2.1.3 (2016-03-07)New:Addedtel:to ignored link types.
[julianhandl]2.1.2 (2015-12-15)Fixes:Fixed error when uid resolving if object got didn’t have
absolute_url method.
[Gagaro]2.1.1 (2015-11-25)Fixes:Fixed case where unicode ends up getting used when resolving
img tags and (un)restrictedTraverse doesn’t work with unicode.
[vangheem]2.1 (2015-07-18)Remove kupu BBB code.
[gforcada]2.0 (2015-03-13)For full-size (non-scaled) plone.app.contenttypes images,
preserve height/width specified in img tag attributes.
[davisagli]Convert tests to plone.app.testing
[tomgross]1.14 (2014-04-22)for plone 5, always resolveuids
[vangheem]1.13 (2014-04-13)#12783 img tag referencing non existent scales leads to transform error
[anthonygerrard]1.12 (2014-01-27)Nothing changed yet.1.11.1 (2013-07-19)Fix README rst.
[gotcha]1.11 (2013-07-19)img unicode issue : fix resolve_image to avoid that it returns unicode
[gotcha]handle possibility of img tag being unicode to prevent unicode errors
[vangheem]1.10 (2013-05-23)Work around bug in SGMLParser to handle singleton tags correctly.
[tom_gross]1.9 (2013-04-06)If we have an image description it should go into the alt text of the img
tag
[ale-rt]1.8 (2012-12-10)Fix packaging issue.
[esteele]1.7 (2012-12-09)When resolving images, only look upward for the full image if the
image that was traversed is not a content item (i.e. is a scale).
[davisagli, datakurre]Also convert “resolveUid/” links (big ‘U’) that FCKeditor used to create.
[hacklschorsch]Also escape double quotes, fixes #13219
[maartenkling]1.6 (2012-08-16)Don’t break if an @@images scale can’t be resolved for some reason.
[davisagli]1.5 (2012-08-15)Restore compatibility with Plone 4.0 when plone.outputfilters is present.
[davisagli]1.4 (2012-08-04)Fix incompatibilities with plone.namedfile
[do3cc]1.3 (2012-05-25)Fixed testing error by moving the part of README.rst to
plone/outputfilters/README.txt.
[maurits]Small pep8 update
[pbdiode]1.2 - 2012-04-09Prevent transformation of links to anchors on the same page.
[davisagli]Fixed undefined uuid variable in kupu_resolveuid_hook branch
in resolveuid view.
[vincentfretin]Make sure links to expired objects can still be resolved by the resolveuid view.
[davisagli]alt/title attributes on img tags were not present if tinymce uid linking was not used
[iElectric]When making relative URIs absolute, use the parent as the relative
root when the context is not folderish.  Fixes an issue where
relative URLs from Plone 3, for example, had the wrong URLs under
Plone 4 when a default page was used for a folder.
[rossp]Fixed testing error when packaged with a missing README.rst.
[maurits]1.1 - 2011-11-21Fixed resolving of protected objects for AT content
[tom_gross]Fixed resolving of relative ../resolveuid/… links
[tom_gross]Respect implementation differences in Python 2.4 and
Python 2.6 sgmlparser
[tom_gross]Fixed resolving of images in protected folders for captioning
[mj]1.0 - 2011-05-13Release 1.0 Final.
[esteele]Add MANIFEST.in.
[WouterVH]1.0b5 - 2011-03-24Make captioning and linking work with new style image scales.
[elro]General refactoring of link resolution.
[elro]1.0b4 - 2011-03-22Add alt and title tags to images.
[elro]Get various image properties from the imaging view to work better with
Dexterity.
[elro]small fix so it is possible to create object without need of REQUEST or
without need of mocking it.
[garbas]1.0b3 - 2011-02-24Resolve image paths beginning with a slash relative to the Plone site root.
[davisagli]Support image captioning for new-style image scales using the @@images view.
[davisagli]1.0b2 - 2011-01-11Fix resolveuid so that uid resolution occurs after authentication.
[elro]Please remember to run tests before checking in!
[elro]Fix issue where resolving links with subpaths resulted in a reversed
subpath.
[elro]1.0b1 - 2011-01-25Fix issue with resolving resolveuid links with subpaths. This fixeshttp://dev.plone.org/plone/ticket/11426[davisagli]1.0a1 - 2011-01-03Initial implementation.
[davisagli]