Arne Götje (高盛華) wrote (in another thread, replying to Rich Felker):
> In this case, *you* need to *define* which combinations you > need and *how* they should be displayed. and (replying to Andries Brouwer): > But please, if you do so, provide the necessary information > (which combinations are possible and how they should display) > to the font maintainer... Do you really mean that in order to make fonts suitable for rendering strings containing "combining accents", all possible combinations have to be known *in advance*? This seems a tall order. Are you absolutely sure this is correct? Apart from the difficulty of doing this, in my view this would defeat the whole purpose of having "combining accents" (which should be usable when combined with just about any character, in order to create "new" characters which Unicode does not specify). I am beginning to think that the responsibility for correct "combining accents" behaviour rests primarily with the rendering engine, rather than with the fonts. The fonts must, of course, include the combining accents, otherwise the accents will be borrowed from other fonts; but I doubt that they really need anchors or GPOS. E.g. say I am a rendering engine; I see a character which, from its Unicode range, is either -- a "top" accent -- a "bottom" accent [-- a left accent if such things exist, a right accent, etc.,] Then I can place it to the top, bottom, etc., of the previous character; based on the "top", "bottom", etc., coordinates of the previous base character (which I know, or at least can calculate). So I do not need anchors! After, e.g., placing a "top" accent on a base character, I could increment the "top" coordinate by a certain amount, so a following "stacked" character can also be placed correctly (but it seems not even pango does this). Couldn't this work? Perhaps it really works like that in practice (I also hope to see some comment by the "pango guys"!) It would at least explain some of the puzzling "luck" we now see when trying to display combining accents using anchor-less fonts. Regards, Jan -- Linux-UTF8: i18n of Linux on all levels Archive: http://mail.nl.linux.org/linux-utf8/
