Missing captioned images feature in TinyMCE and Plone5 - tinymce

Question

I'm missing the function to enable captioned images in TinyMCE/Plone5. It was possible to enable that in the control panel with Plone4 (https://plone.org/documentation/manual/plone-4-user-manual/using-tinymce-as-visual-editor/images).
Now I'm using the new Plone5rc3 with TinyMCE 1.4.3, but the properties of TinyMCE in the control panel don't have the needed checkbox.
Does anybody know how to get that?
Thanks a lot!

Answer 1

So here's an answer in parts: you need several things for the captions to work:
Your <img> tags need to have the class captioned. I still need to find a good way to do that. The image picker will remove all other classes everytime you open it, so I guess a good way would be to change the classes that are added by the inline/left/right selection, but I've not easily found where those are defined.
You need the output filter, but fortunately, that is still there. However, the filter wants to see an IImageCaptioningEnabler, which is essentially a flag to turn the captioning mechanism on, and the old editors used to have that and currently, nothing in standard Plone does provide such a beast. If you're comfortable with add-on development, the class you want is
from plone.outputfilters.filters.resolveuid_and_caption import IImageCaptioningEnabler
from zope.interface import implements
class CaptioningAlwaysEnabled(object):
implements(IImageCaptioningEnabler)
available = True
with corresponding configure.zcml stanza
<utility factory=".resolveuid_and_caption.CaptioningAlwaysEnabled"
name="plone5-captions-always-enabled"
zcml:condition="have plone-5" />
(you can tell I patched buildout-cache/plone.outputfilters-2.1-py2.7.egg/plone/outputfilters/filters/configure.zcml and resolveuid_and_caption.py to include that, but of course, you shouldn't do that.)
If you're not comfortable with add-on development, you could, bizarrely enough, see if another editor provides that global switch, you don't need to have it set as your editor or the default editor. (Products.kupu would, but it doesn't install in 5.0. collective.ckeditor might, I can't try that right now due to missing dependencies.)
So, summary: no, you can't easily turn it on; you can turn it on with a bit of hacking; and if you file it as a feature request, it's the kind of thing that takes about fifteen minutes to fix for somebody who knows their way around the code.