Re: Unicode and Encoding Problems in Browsers

From: Christopher John Fynn (cfynn@gmx.net)
Date: Thu Feb 20 2003 - 02:09:20 EST

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     "Muhammad Asif" <mdasif@wol.net.pk> wrote:
    > can it be problem with Uniscribe (USP10.dll) shiped with Windows2000 and
    > IE? ie. may be characters appearing as rectangles are not supported in
    > particualar version of Uniscribe.
    >
    > But then why Netscape is rendering these properly?
    >
    > Asif

    I doubt that this is a problem with Uniscribe.

    Glyphs appearing as rectangles usually means that the font being used to display the document does not contain the glyphs to display those characters (- or sometimes that there are errors in the glyph outlines which can prevent them from being properly rendered on some systems).

    This problem will often occur if the character set being used to display the web page is wrong (misinterpreted by the browser) - since the font may not contain glyphs for *that* character set. When a glyph outline for a particular character is not present in a font then the "default glyph" defined in that font (usually an empty rectangle) is displayed for that character.

    An OpenType font should contain glyphs for the nominal forms of all the Unicode characters it supports - and these nominal glyph forms should be mapped directly to the corresponding Unicode codepoints. Thus, even without Uniscribe, the nominal glyphs for those characters should be displayed by the basic font rendering system - though you won't get any of the contextual shaping relying on OpenType lookups which under Windows are handled by Uniscribe.
     
    - Chris



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