markdown-preview: Add Markdown preview plugin

[vkareh]

This plugin uses the new right pane in Pluma to display a real-time rendering/preview of a Markdown file. It uses WebKit2 and only relies on core markdown plugins in python.

Needs python3-markdown (or whatever the lib is named in your distro).

Also moved the sourcecodebrowser plugin to the new right panel.

Needs mate-desktop/pluma#718

Markdown Preview plugin:

Source code browser plugin on right side:

[Cyrille37]

Yeah! That's a so great feature 💌

[lukefromdc]

Is there a test file for this? This is one of those things I don't know anything about

[vkareh]

@lukefromdc

Is there a test file for this? This is one of those things I don't know anything about

Try the README.md file in this repo. The .md extension is for Markdown, which is what we generaly use in MATE.

[lukefromdc]

I was unable to build pluma-plugins due to a libpeas issue blocking the build at the word-completion plugin:

                 from pluma-word-completion-plugin.c:29:
/usr/include/libpeas-1.0/libpeas/peas-extension.h:26:10: fatal error: girepository.h: No such file or directory
   26 | #include <girepository.h>
      |          ^~~~~~~~~~~~~~~~

Debian has rebuit libpeas 1.36.0 (1.36.0-8) to declare "breaks" against current eom and eog prior to a certain commit. I don't know much about libpeas but pluma without the plugins package is working fine with libpeas 1.36.0-5

libpeas (1.36.0-8) unstable; urgency=medium

  * Team upload
  * d/control: Increase version of Breaks on eom and pluma.
    Version 1.28.0-1 of each package was uploaded to unstable, so we'll
    need a correspondingly newer upload with the changes for #1118496
    and #1118497.
  * Release to unstable (transition: #1118613) (Closes: #1118363)

libpeas (1.36.0-5)

[vkareh]

@lukefromdc I think your solution for the time being may be to install libgirepository1.0-dev to work around those Debian changes.

Long term I think pluma-plugins (and possibly other packages in MATE) need to explicitly depend on girepository (and handle 1.0 or 2.0 gracefully, or through a build flag)

[vkareh]

This should work now with the latest commit from Pluma (I've rebased mate-desktop/pluma#718 from master)

[lukefromdc]

Got this error on an attempted test build during configuration:

configure.ac:28: installing './compile'
configure.ac:22: installing './missing'
configure.ac: error: AM_GNU_GETTEXT used but SUBDIRS not defined
plugins/bookmarks/Makefile.am: installing './depcomp'
autoreconf: error: automake failed with exit status: 1

[vkareh]

The AM_GNU_GETTEXT used but SUBDIRS not defined error usually happens when gettext's infrastructure isn't properly initialized before running autoreconf.

I think having both autopoint and gettext-devel is necessary here. Can you reproduce this in master?

[lukefromdc]

A build from git master just went fine, and then from the same directory switching to this branch , configuring again, and building again also appeared to work but (EDIT) it did NOT. The terminal text completed and did not show an error, but none of the binary files actually got built. In master they showed up fine

[mbkma]

Looks very nice, I compiled and ran it today. An issue I found was when clicking on a link in the markdown preview, the website opened inside the markdown preview. Expected would be in a web browser.

[vkareh]

@mbkma good catch, thanks for pointing that out!
I added a signal catch to make sure any navigation happens outside in the default browser app. I also cleaned up a few things in the plugin code.

[mbkma]

The links now open in the browser as expected.

However, there are still issues with the Markdown plugin:

• When opening a Markdown file, the preview does not appear immediately. I need to close and reopen the file for the preview to show.
• When closing a .md file, the preview remains visible instead of being cleared.

Both behaviors should be addressed.

[vkareh]

@mbkma just added a function to show the pane when the active document is markdown and a call to load the placeholder text when the active document is not markdown.