[Freebangfont-devel] [Bug 118302] New - ZWJ and ZWNJ not passed to indic shaper

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http://bugzilla.gnome.org/show_bug.cgi?id=118302

Changed by address@hidden

--- shadow/118302       Fri Jul 25 10:37:11 2003
+++ shadow/118302.tmp.24536     Fri Jul 25 10:37:11 2003
@@ -0,0 +1,75 @@
+Bug#: 118302
+Product: pango
+Version: 1.2.x
+OS: Linux
+OS Details: 
+Status: NEW   
+Resolution: 
+Severity: normal
+Priority: Normal
+Component: general
+AssignedTo: address@hidden                            
+ReportedBy: address@hidden               
+TargetMilestone: ---
+URL: 
+Cc: address@hidden,address@hidden,address@hidden
+Summary: ZWJ and ZWNJ not passed to indic shaper
+
+Trying to keep track of the four different issues in 
+bug 113551 was pretty much impossible for me, so splitting
+up the comments into separate bug reports.
+
+* address@hidden (Sayamindu Dasgupta):
+
+3. ZWNJ & ZWJ
+---------------------
+
+Rendering of certain strings have led us to believe that Pango is somehow
+confusing between Zero Width Non Joiner (ZWNJ) and Zero Width Joiner (ZWJ).
+<consonant> <halant> <ZWJ> <consonant> is rendered in the exact same way as
+<consonant> <halant> <ZWNJ> <consonant>. This should not happen - as the
+screenshot taken in Yudit shows. <consonant> <halant> <ZWJ> should render
+the "half form" of the consonant, while Pango is rendering the "halant
+form" instead (or it may be simply putting the consonant followed by the
+halant - I am not very sure). This issue becomes important when we handle
+the khanda-ta character in Bengali - a short write-up on this can be found
+in the Unicode Indic FAQ.
+
+* Additional Comments From Taneem Ahmed 2003-06-01 01:05
+
+Owen, can you please take a look at the third issue? It seems like a word 
+with ZWJ or ZWNJ are broken into three items (in pango_itemize), and 
+then treated alike. 
+
+* Additional Comments From Owen Taylor 2003-06-01 04:04
+
+Your issue 3. is bug 91542 .. in Pango currently, 
+every character has to be assigned to *some* script.
+
+Is there an easy workaround short of fixing 91542?
+
+We can't assign ZWNJ to indic-fc, because it is
+needed, e.g., for displaying Persian in Arabic
+script, but perhaps we can add ZWJ to the list of
+characters that indic-fc.c handles? As it turns
+out, that won't work either because the Indic engine
+advertises itself as one engine for each different
+Indic language. So, only one Indic script can
+get ZWJ...
+
+So, in the end, I don't have any idea other than fixing
+bug 91542.
+
+* Additional Comments From Taneem Ahmed 2003-06-01 04:54
+
+As for 3, today was my first day hacking pango... no way I can make a 
+meaningful comment on this one. The only idea that crossed my mind is 
+to consider ZWJ as part of the language left (or right in case of LTR) to it. 
+Most of the code in indic directory seems to be checking for 
+CC_ZERO_WIDTH_MARK, but currently this case can not happen. I am 
+not sure about other engines. 
+
+* Additional Comments From Taneem Ahmed 2003-06-01 16:50
+
+Issue 3 is quite important for Bengali at least. Unicode 4.0 seems to be 
+using ZWJ/ZWNJ to deal with few commonly used cases.