[Lazarus] Arabic beta tester for SynEdit needed

[Martin]

On 14/12/2012 21:15, patspiper wrote:
> On 14/12/12 21:33, Martin wrote:
>> On 13/12/2012 14:39, Martin wrote:
>>>
>>> Ok, bad news, I did some more testing myself, and it turns out, that 
>>> WIndows allocates the extra space (song connection line) just 
>>> anywhere in the word, or at the end of it, but not always where the 
>>> ligation is.
>>>
>> .....
>>> So what's next.
>>> The only way to support this, is to make SynEdit aware of the 
>>> ligatures. And that is a lot of work, so it will take more time. And 
>>> I don't yet know when I will schedule it....
>>
>> Ok, I found a quick way to get a use-able behaviour.
> :)
>>
>> *  it is currently WINDOWS ONLY
> :(

For GTK, I believe this functionhttp://developer.gnome.org/pango/stable/pango-Text-Processing.html#pango-get-log-attrs   can deliver the information needed.
But in addition there may be a need for further fixes/improvements in ExtTextOut (widgetset)

Other WidgetSets: No idea

If anyone wants to give GTK a try, I will mail what needs to be done.


>> - ligatures are handled as follows.
>>    There is  no middle caret
>>    Depending on the caret being before or after (and accordingly 
>> backspace or delete being used) the first or 2nd char is deleted
>>   # So it is 2 chars, but any caret move will just be translated into 
>> skipping the middle pos
>
> When you mention ligatures, do you mean any 2 connected characters 
> (ex: ???), or characters that combine such as Lam Alef (??)?
Lam Alef

combining codepoints (such as dots or accents added to chars) are 
handled diferrently (SynEdit knows them for Arabic Only):
- Backspace (from behind the char), deletes one codepoint
- Delete (from before the char) deletes char + all combining (leaving 
the dot without the char makes little sense?)

combining codepoints not known to synedit (none arabic), will act like 
ligatures.

>
> I tested the behaviour of Libre Office Writer (Ubuntu):
>
> - Damma or shadda or similar will combine with the affected character 
> and form one character as far as the cursor movement is concerned. 
> Backspace after the combined character will remove the damma. Delete 
> before the character will remove both.
See above
>
> - Lam Alef produced by pressing a single keyboard key (?) acts as a 
> single character in all aspects.
>
> - Lam followed by Alef will combine visually into one character (??) 
> but acts as 2 characters in all aspects.

I can not test (I don't know haw to write Arabic, except for hitting 
random keys on an Arabic layout). If the single keystroke, produces a 
single utf8 char, then yes.

SynEdit works on Utf8 Codepoints. Except where it finds combining 
Codepoints, if they are in the list of combining, that SynEdit includes.

----------
On addition, it asks Windows, if any sequence of codepoints is drawn as 
a single glyph. This is used to calculate the position of the caret, in 
relation to each glyph, as well as the length of the line, and where to 
apply highlights.


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