Re: [Freetype] how does freetype handle combining character for unicode

[Ziying Sherwin]

Thanks for the response to my email. Here are some reasons why we are looking
for the normalization capabilities in freetype fonts: 

1. Our application have a java applet-based unicode keyboard, which takes the 
   key input and convert it into unicode in different languages. The layout
   of the keyboards are based on what the keyboards look like in different
   countries. It is inevitable that combining character sequence will be
   used. Because the application is an applet, building normalization into
   the keyboard application itself would bloat the code and impact the 
   efficiency. 

2. The combination of character sequence is defined in Unicode standard. If
   Freetype library handles unicode, it should be able to handle the 
   normalization or at least provide the option for user to use the 
   normalization function. In any case, it does not make sense to display
   a combining diacritics alone as a character in the respect of rendering 
   proper glyphs.

If freetype library does not provide the normalization for unicode yet, do
you know any toolkit or library which have this functionalities? We are 
checking ICU as a workaround, but it would be nice to try something smaller.

Many thanks for the help.

Ziying Sherwin




On Wed, 18 Sep 2002, Vadim Plessky wrote:

> On Tuesday 17 September 2002 8:00 pm, Ziying Sherwin wrote:
> |  We installed php 4.2.2 with freetype 1.3.1 on our solaris 2.8 machine.  We
> |  are using function imagettftext to convert UTF8 string to image file for
> |  Internet display. However, it seems that this function does not handle the
> |  combining characters properly.  For instance, the sequence of unicode
> |  characters U+0061(a) and U+0308 (combining diacritics) is display as two
> |  characters: a and a square indicating not displayable. The correct result
> | should be a character identical to U+00E4.
> 
> What is the problem to render adieresis (U+00E4) character itself?
> This character is not extremly difficult, and present in many fonts.
> 
> As about combining U+0061(a) and U+0308 (combining diacritics) glyphs into 
> one 
> character - this should be done in font editor (preferable in your case, 
> IMO), or in advanced layout library.
> Whne you export such font to PostScript Type1 fotmat - character will have 
> calls to subroutines displaying U+0061(a) and U+0308 (combining diacritics) 
> [in your case].
> TrueType format also supports combined glyphs (references).
> 
> |
> |  We are wondering where the normalization is handled in this case, freetype
> |  library or inside imagettftext php function? Is it a bug in freetype
> | library? If not, how can we fix it?
> 
> I hardly see it as a FreeType bug.
> 
> |
> |  Thanks,
> |
> |  Ziying Sherwin
> |
> |  P.S. I am not on the mailing list, please send your response to
> |  address@hidden
> |
> 
> You should subscribe! :-)
> 
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> -- 
> 
> Vadim Plessky
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