[Freebangfont-devel] [Bug 113551] New - Bugs in the Bengali rendering system of Pango.

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http://bugzilla.gnome.org/show_bug.cgi?id=113551

Changed by address@hidden

--- shadow/113551       Thu May 22 15:36:05 2003
+++ shadow/113551.tmp.27040     Thu May 22 15:36:06 2003
@@ -0,0 +1,91 @@
+Bug#: 113551
+Product: pango
+Version: 1.2.x
+OS: All
+OS Details: 
+Status: NEW   
+Resolution: 
+Severity: normal
+Priority: Normal
+Component: general
+AssignedTo: address@hidden                            
+ReportedBy: address@hidden               
+TargetMilestone: ---
+URL: 
+Cc: address@hidden
+Summary: Bugs in the Bengali rendering system of Pango.
+
+Hello,
+Thanks for the work on the Bengali rendering in Pango. 
+However, there are a few bugs which we have come across while working on
+font development and Bengali l10n.
+I am listing them below, and there are two screenshots -
+http://www.nongnu.org/freebangfont/pango_bugs/shot_bugs_gedit.jpg showing
+the problem strings as rendered in Gedit2, and the other
+http://www.nongnu.org/freebangfont/pango_bugs/shot_bugs_yudit.jpg showing
+the correct rendering via Yudit. The file used for generating the
+screenshots is also downloadable from
+http://www.nongnu.org/freebangfont/pango_bugs/bugs.txt . (Note that I am
+using Pango version 1.2.1 - the one provided with Mandrake 9.1)
+
+1. Yaphala
+---------------
+
+a. The string য্য is rendered incorrectly. For some reasons, 
the Yafala mark
+is getting rendered twice.    
+    More information on yaphala can be found at
+    http://www.microsoft.com/typography/otfntdev/bengalot/features.htm
+    (section on "Post-base form of consonant")
+
+b. The sequence 0985 09CD 09AF 09BE (অ্যা) is not 
rendered properly.
+
+    I quote from the Unicode Indic FAQ.
+
+       Q: What are the Bengali characters used to transcribe the sound "a" (as 
in
+English "bat") in Unicode?
+
+       A: In Bengali, the sequence "zophola" (U+09CD U+09AF) + the "aa" matra
+(U+09BE) is used for transcribing the          English "a" in "bat". This
+zophola_aa can be seen as a special "composite" matra to write a new
+Bengali sound,           imported from English. Represent these sequences 
using a
+halant (virama):
+
+               Vowel_A_zophola_AA = 0985 09CD 09AF 09BE ( a- halant ya -aa )
+               Vowel_E_zophola_AA = 098F 09CD 09AF 09BE ( e- halant ya -aa )
+       
+       If you need to add a candrabindu or other combining mark in the 
sequence,
+represent the sequence as:
+
+               Vowel_A_zophola_AA + candrabindu = 0985 09CD 09AF 09BE 0981 ( 
a- halant
+ya -aa candrabindu )
+    
+
+2. Baphala
+---------------
+
+Pango, for some reasons is confusing between the sequence 09AC 09CD. This
+sequence can be substituted by two different lookups  - pres, and blws.
+Examples are given below.
+
+pres - জব্দ 
+blws - জ্বদ 
+
+I have attached a screenshot of how the above two examples look in Yudit.
+More details on blws can be found at
+http://www.microsoft.com/typography/otfntdev/bengalot/features.htm
+(section on Below-base substitutions)
+
+
+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.