Support for right-to-left languages

[Phil Thompson]

On 14/06/2023 05:45, Caleb Rouleau wrote:
> Hi,
> 
> I really appreciate QScintilla. Thanks for writing it and maintaining 
> it!
> 
> I was wondering what the state of support for right-to-left languages 
> like
> Arabic and Hebrew should be in QScintilla. (I don't see any mention of
> support in the documentation but I may be missing it!) I'm also 
> wondering
> whether you plan to work to improve this support in the future. I see 
> on
> the Scintilla website (1) that Scintilla has "limited experimental" 
> support
> for these languages on Windows. I read this thread on GitHub (2) that 
> shows
> that this support might be desirable for other projects than just mine.
> 
> Here's an issue that I'm having with right-to-left languages:
> 1. On a Windows 10 machine, install Hebrew or Arabic language support.
> 2. Build the example application that comes with QScintilla against Qt 
> 5.15
> and QScintilla 2.14.0 and run it.
> 3. Use Windows UI to switch your keyboard to Hebrew or Arabic.
> 4. Type "asdf" on your keyboard into the example application. Since 
> your
> keyboard is in Arabic or Hebrew mode, this should type "شسيب" or 
> "שדגכ".
> However, no text is visible.
> 5. Switch your keyboard back to English.
> 6. Type "asdf". Suddenly the Arabic or Hebrew text appears and you 
> should
> see something like "שדגכasdf"
> 
> Is there something that I can do differently to make the right-to-left 
> text
> appear immediately instead of only showing when there is also 
> left-to-right
> text in the same box?
> 
> It seems likely that this issue happens on other versions of Qt and
> versions of Windows as well, but I haven't tested it yet.

At the moment this just isn't supported.  It has to be fully supported 
in the underlying Scintilla code.

QScintilla is based on a relatively old version of Scintilla - I haven't 
kept up to date because, IMHO, newer versions haven't added much that is 
generally useful. If the support was added to Scintilla then I'd 
consider updating to it.

Phil