[Lazarus] Arabic beta tester for SynEdit needed

[patspiper]

On 07/12/12 00:53, Martin wrote:
> A while ago, I started adding support for mixed LTR/RTL  text in SynEdit.
>
> The actual display of RTL text now works (that is, if you have some 
> arabic chars in the text, they display RTL, and the caret moves 
> accordingly / caret between RTL and LTR always means caret at LTR).
> uf8 LTR/RTL markers are not supported. This is absolute basics only.
This is ok in cases like the IDE editor where the document is mainly 
English. I suppose it will be somehow odd for documents with mainly RTL 
languages. Formatting (like indentation, bullets), where implemented, 
will suffer.
>
> Unfortunately with RTL came other unicode features, that sofar no one 
> had missed. Those are at the very least
> - combining codepoints
> - ligatures
> - maybe reordering of codepoints.
> - other?
> They are tasks of different extent. And I need to find out what is 
> mandatory, and what optional. So I can then decide, what does fit into 
> my schedule.
>
> The current state is:
> - combining: Only Arabic has been done (but they should be complete). 
> So none Arabic RTL will not work.
> - ligatures: see below
> - reordering: not researched, hopefully optional.
I am not aware of any need for reordering.
> "work"
> means, that the text is stable (except ligatures, only with 
> workaround), and does not expand/shrink, when selecting text, or 
> moving the caret. Also that the caret will be at the correct pos. A 
> newly inserted char will be where the caret was. Can be tested by 
> hitting the "end" key, and see if the caret is at the end of visual 
> text. If SynEdit thinks the text is shorter/longer than the actual 
> painted display, then there is an issue.
>
> ligatures:
> The editor does not handle ligatures yet. So it calculates 2 screen 
> cells, when only one is needed. However a stable "workaround" exists 
> (currently depends on config)
>
> On windows and windows only (others will be done, if that turns out to 
> be any good). In Options / Editor / Display / set "Extra CHAR spacing" 
> to 1
> This will slightly widen the script, ignore that, its temporary.
> Requires a proper monospaced font. (Deja vu mono)
>
> What it will do: It will tell windows, that the ligature is expected 
> to cover 2 display cells.
> Display: Arabic text is a script, glyphs are connected by a continuous 
> line. The ligature will be in one cell, the next cell will be empty, 
> except for the connecting line.
> Editing: The caret can be at either cell. Each cell stands for one of 
> the 2 chars in the ligature. So the 2nd char can be edited, if the 
> caret is at the empty cell
>
> ------------------
> I need feedback from people who actually speak (or at least read and 
> write) Arabic. I need to know, if the above situation is "useable".
>
> If so, then:
> - it can be fixed to work without the extra char spacing
> - on gtk, carbon, qt (well at least I hope)
> - combining can be added for other languages.
>
> If not, well I don't know yet.
I have tested on Linux/gtk2 (ubuntu 11.04), and courier new only:
- The attached snapshot (lines 29 and 30) shows an extra space before 
the 456.
- Long connecting lines are not what I would like, but this is a 
monospaced font afterall.
- The 456 should have come to the left of the Arabic words.
- If you put a shaddah or damma on a character, it gets displayed on top 
of the character (correct behaviour). Pressing backspace at this stage 
should only delete that addition, and not the character.

Stephano
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