[Lazarus] Arabic beta tester for SynEdit needed

[Mattias Gaertner]

On Fri, 07 Dec 2012 03:25:14 +0000
Martin <lazarus at mfriebe.de> wrote:

> On 07/12/2012 02:38, Mattias Gaertner wrote:
> > On Thu, 06 Dec 2012 22:53:12 +0000
> > Martin <lazarus at mfriebe.de> wrote:
> >> [...]
> >> 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".
> > Attached is a small example text and a screenshot showing, how Firefox
> > with font "serif"renders it, how synedit with "Courier New" renders it
> > and how synedit with "monospace" renders it.
> >
> > Firefox and the "monospace" synedit shows only one
> > ligature (??), combined of the two codepoints alif ? and lam ?.
> > Firefox allows to select the two independently.
> >
> > The "courier new" font shows another ligature:
> > The ??? are three letters in "monospace", while with "courier new" it
> > shows the two rightmost combined as one.
> >
> 
> Was the synedit picture taken with extra char spacing? Because without 
> that, you get the wrong behaviour (select line, char by char)

It was taken under Linux/gtk2 with ExtraCharSpace=0. Setting
ExtraCharSpace to 1 shows the characters separated.

 
> I know how it should be shown ideally.

Then you are ahead of most scientists. ;)

 
> The question is how far away from ideal would still be useful? And that 
> I can not tell for a script, that I do not use at all.
> Someone once said, some editors display the ligatures, as 2 chars. And 
> that would be accepted by many people. But I can not judge that.

The ligatures are not important at the beginning. Later at least
the alif+lam ligature is needed.
It is crucial that the connected characters are shown connected.


> The proper ligature handling is a lot more work. And it depends on the 
> font (or it may at least) On windows there is an API, that would allow 
> to get that info. However if not carefully done, it may have effect on 
> the speed of synedit (quite possible noticeable).
> On others, I wouldn't even know where to look for such an API. But 
> little point, until SynEdit is ready to use an external API in this 
> place. (That is it does not call it excessively)

Maybe it can be done by a plugin?
Then the LCL+synedit do not need to implement it fully, but users can
implement the subset they need.

 
> As for placing the caret in the middle of a char, that would require 90% 
> of the work to render proportional fonts (on the list, but not now)

IMO the placing in the middle is somewhat strange. Perhaps showing
a special caret or icon is doable. That has low priority.


> Below is with extra char spacing, and you can see a stretched bit of 
> horizontal line

I see a long connection between the second and third from the left
(the alif and the jim).
And I see the alif-lam ligature.
See the attachment.

 
> Without the etra char spacing, there is a gap, between the RTL and the 
> LTR spaces atthe end (use visible spaces, r type real latin text at the 
> end).
> Delete half the ligature, and it will go away, causing the LTR text to 
> move, even so the RTL has still the same length (ligature replaced by 
> remaining normal char)
> 
> So at the moment for synEdit the ligature are 2 chars, they must take to 
> cells on screen.
> 
> The  point is. It might be some time until I can add proper ligature 
> handling.
> But I can try to get the current behaviour without the extra char 
> spacing (if that current behaviour is of any use).
> It might be possible to force the splitting of the ligature, I do not 
> know that for sure. Also GTK2 will probably split it, others I do not 
> know. (GTK2, will have to pain every char on its own.)


Mattias
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