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Negative Letter Spacing handling in Firefox #3

Open GoogleCodeExporter opened 8 years ago

GoogleCodeExporter commented 8 years ago 
What steps will reproduce the problem?
Testcase for negative letter
spacing https://bugzilla.mozilla.org/attachment.cgi?id=719861

Please provide any additional information below.
Upstream: https://bugzilla.mozilla.org/show_bug.cgi?id=846617 

Kew's comment on Testcase in Firefox bug tracker:

"Indeed - this is behaving as designed. When the author specifies non-default 
letterspacing, we disable the 'liga' and 'clig' features, because it doesn't 
really make sense to use ligatures with letterspaced text.

(The word "office" with letterspacing should look like "o f f i c e", not "o f 
fi c e" or even "o ffi c e".)

So don't use letterspacing if you want all ligatures to be applied.

The root of the problem here is that the Myanmar3 font is using the 'liga' and 
'clig' features, which will only be used when the text is rendered with its 
"natural" spacing, to achieve "shaping" that actually needs to happen 
regardless of letterspacing modifications. If the font used the 'rlig' 
(required ligatures) feature instead, the ligatures would still be applied, as 
we do not disable 'rlig' even when letterspacing is present."

Original issue reported on code.google.com by hitmana...@gmail.com on 2 Mar 2013 at 7:55

GoogleCodeExporter commented 8 years ago 
Dear Arky, Thanks for your report. I've checked Firefox 18 and 19 on Mac. We 
can see Burmese font properly until 18. After installing Firefox 19, We can't 
see properly because. I found dotted circle in every marks. your example "o f f 
i c e" is still readable. We can't read anymore when we need to follow unicode 
storage order. I tried with AAT Font instead of OpenType Font. It doesn't work.

Let me explain you abit. We want to use specific opentype features for Myanmar. 
Microsoft didn't activate our script in uniscribe level rendering. We can try 
proper opentype features in only Microsoft Visual OpenType Layout Tools. We got 
the break thought from Cambodia. We can use Generic *liga*, *clig* and *rlig* 
features for Myanmar. We knew that is the best one. No choice at 2005-6. We 
tried out with those features and looking forward Microsoft Support.

In this case, It doesn't related with opentype features. It is totally related 
to Firefox rendering engine. We can have proper rendering for same file in 
other browser such as chrome, safari. Please check deeply in yours. Thanks any 
how.

Original comment by ngwes...@gmail.com on 2 Mar 2013 at 3:48