B4J Library CodeMirror Javascript Code editor wrapper - proof of concept.

This proof of concept is now deprecated, for a more useful implementation see the CodeMirrorWrapper / CodeEditor Library

This is a proof of concept test for the javascript library CodeMirror.

I still like RichtextFX, but it is limited to Java 8, so I went in search of an alternative. Code Mirror seems very comprehensive and will do the simple task I want it for admirably. It is a huge project. If you want to use it I suggest you prepare yourself to do some reading.

I have added a mode for B4x, but it is only currently a copy of the vbscript mode, and needs a lot of work. But it is fine just to prove to myself that it will work as I want it to. CodeMirror supports 100 different languages out of the box.

The code includes wrappers for Webengine and Worker classes as well as a WebViewWrapper I wrote a few years ago to make interfacing B4j and Javascript more manageable.

Unfortunately the full project is too large to upload, so I have removed the codemirror js library and zipped it for convenience, which you can download from my dropbox here: https://www.dropbox.com/s/577qj8bf0225v7s/codemirror.zip?dl=0

It is version 5.58.3 which is the latest.

Just copy that into your projects Files directory as is, it will be unzipped when the program runs.


Screen shot as requested. (updated)

Update to V1.1
If you have downloaded the first version, you will need to download the new version of the CodeMirror library from my dropbox, comment out the check for the existing library so it can be overwritten: Line 50 of WebCodeEditor

'CodeMirror js files, only copied once. Updates not yet managed.
'    If File.IsDirectory(XUI.DefaultFolder,"codemirror-5.58.3") = False Then
        Dim Arc As Archiver
        Log(Arc.UnZip(XUI.DefaultFolder,"codemirror.zip",XUI.DefaultFolder,"") & "Files unzipped")
'    End If

Then Uncomment it so it doesn't unzip the file every time it runs.

Update to V1.2
  • changed HTML template for better loading and consistency.
  • Implemented encodebase64 for text transfer
  • now a proper wrapper, all required calls are in the CodeEditorWrapper
  • improved syntax highlighting

Update to V1.3
  • Added access to most of the available languages
  • Added b4x.js to the proper structure within CodeMirror mode folder and Meta.js
  • Added new code module to Map Language Names to mime types
  • Added and implemented autoLoad addon to select language by MimeType
  • Changes to the CodeMirror library - requires downloading new version

Upgrade to V1.4
  • Added doc.clearHistory to setCode to stop undo removing the new code
  • Added #javacompilerpath to ide parameter words.
  • requires download of codemirrorlib
  • Moved the InitializeFiles sub to the WebCodeEditor class where it belongs.

Don't forget to download the codemirror library and save it in the projects Files folder as is. https://www.dropbox.com/s/577qj8bf0225v7s/codemirror.zip?dl=0

This will be the last update to this version of the code mirror wrapper, it has proven useful to me but is tied too closely with the WebCodeEditor class, so I will be changing the way the wrapper works to make it easier to integrate into other projects and will release it as a new version once completed.

Known issues:

  • Sometimes the scrollbars do not disappear, resulting in the last line of the file being covered. if this is a problem for you then an extra empty line at the end will sort this out until a solution is found. - This seems to no longer be an issue, let me know if you see it.
  • Smart strings are only parsed to 1 level, so it doesn't handle nested smart strings. If you know javascript well (which I don't) I'm sure you could sort this out. If you do, please share.

Now added a b4xlib with the required files

There is a full manual and some examples on their website if you want to explore or find other functions CodeMirror.

Let me know how you get on with it.



  • CodeEditorWrapper1.4.zip
    23.5 KB · Views: 182
  • CodeEditorWrapper.b4xlib
    14.1 KB · Views: 180
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Licensed User
Longtime User
There is not much to see, but I've added a screen shot for you.


Licensed User
Longtime User
I think this is going to make a nice replacement for RichtextFX The editing feels nicer and more stable. I've added a couple of more functions (see first post) Will now set about replacing RichTextFX in a project, so there may be some more improvements along the way. If you do anything with this, feel free to share.
Last edited:


Licensed User
Longtime User
Updated to v1.2

see first post


Active Member
Licensed User
Longtime User
Thanks for the work, steve. I may use some of the code to create a rich text editor based on webview.

Currently, I am using RichTexrFX to style tags and spaces for a translation editor:



Licensed User
Longtime User
@xulihang That's great, let me know how it goes.


Licensed User
Longtime User
Updated to v1.3

see first post