Re: Representative glyphs for combining kannada signs

From: Philippe Verdy (verdy_p@wanadoo.fr)
Date: Mon Mar 20 2006 - 03:28:13 CST

  • Next message: Antoine Leca: "Re: Representative glyphs for combining kannada signs"

    From: "Peter Constable" <petercon@microsoft.com>
    >> Unfortunately, "Arial Unicode MS" pretends supporting Bengali, Oriya,
    >> Telugu and Malayalam (for Oriya, it just contains the national digit
    >> characters, and for the 3 others it has enough glyphs but lacks the
    >> OpenType layout and shaping tables).
    >
    >Your statement about Oriya and only "national digit characters" is simply
    >incorrect, as evidenced by the attached screenshot.

    It is correct. Only Oriya digits are assigned to Unicode code point poisitions. Other glyphs are not accessible from these codepoints (and FireFox then fails to access to any of those glyphs). See attached "charmap" screenshot.

    If I select Group by "All" in charmap, these glyphs are also not visible, simply because they don't even have any PUA assignment. The glyphs may be accessible only though some complex OpenType tables, only if Oriya features are enabled.

    May be it's a bug in the "charmap" tool, but the fact that no glyph can be found for Oriya letters means that the font has a compatibility problem if it works with Viewglyph.

    Your screenshot seems to display glyphs in a font, not the codepoints to whichthey are assignedinternally.

    >> In other words, no font should mix simple scripts and complex scripts,
    >> unless complex scripts are fully supported. Arial Unicode MS (and a few
    >> others like Tahoma regarding Arabic and Hebrew scripts) is such a
    >> defective font
    >
    >Tahoma supports Hebrew and Arabic - it is not a "defective font".

    Supports may be, but not completely. And I have the same problem with this font because even when I select another complete font for Hebrew or Arabic, the "Arial Unicode MS" font "takes the hand" on the rendered script, if there are any Latin letters in the containing HTML element before Hebrew or Arabic letters, and even if the rendered anonymous text element ONLY contains Arabic or Hebrew and NO Latin letters (for example rendering a Hebrew or Arabic <span> or <div> embedded within elements containing Latin.

    This means that supplementary points not found in "Arial Unicode MS" will berendered as the "missing glyph box", even though another complete font is selected in the stylesheet, and comes FIRST in the list of fonts for the "font-family:" CSS style of the stylesheet.

    In that case, the ONLY way to get the other complete font is to select a specific style class for EVERY occurence of <span> of Arabic or Hebrew text, and in that class, set only ONE font for the "font-family:" style. This looks also like a bug in interpreting the CSS style hierarchy.

    > Notepad does not have *any* logic for doing any kind of script or character fallback.

    Normal: its text renderer uses a common Windows component that has this fallback logic but Notepad does not setup a Uniscribe text breaker for its rendering (all is done in the component), unlike IE that attempts to control those fallbacks as it needs a higher control on the page layout, and on line breaks (word-breakers, justification, determination of the line-height according to the composite elements extracted from the word breaker and so on...).

    > Just out of curiousity I copied your web page with charts for 0000-0FFF and
    > pasted it into Notepad on XP with it set to display using a font that supports
    > only Oriya and Latin-1: there was no noticeable delay, and the system displayed
    > all of the scripts except for Lao and Tibetan, which aren't supported on XP.

    Hmmm. I get NO problem on XP for Lao and Tibetan. I just need fonts for them, but these extra fonts are installed. And I did not say that I had problems in Notepad, given that it does not setup a stylesheet with multiple fonts in a CSS-like font-family.

    But with Oriya text, if I choose "Arial Unicode MS"(installed from a retail French version of Office 2003) as the font, NO oriya letter is displayed (only digits).

    I have the same conclusion: we don't run the same Windows.


    Oriya.PNG

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