Re: Font lookup ranges [was Re: Notes on Pango Xft backend]

[Owen Taylor <otaylor redhat com>]

Yao Zhang <yaoz vidar niaaa nih gov> writes:

> From your coverage map, it is easy to tell which category the font is in.
> But in my opinion, combining different Chinese fonts together to get
> a bigger coverage is generally not a good idea.  I see this kind of thing
> happens in Mozilla, GTK+ 2.  When I see it, the only effect is that it tells
> me I should change my font settings, the same as I see undisplayable, square
> substitute showing on my screen.  So why go through all the trouble to
> implement something no one will like.

The question being discussed here is not combining multiple fonts ... 
Pango already does this; it's pretty much a requirement if you
want to be able display multilingual text. (The alternative is
that the document creator knows exactly what fonts the user
has on their system and specifies those fonts.)

The question is how to combine multiple fonts in a way that avoids
the "mixed" appearance that you are seeing.

Frequently, we do know the language of the text, either because
the text is tagged with the language, or because we can assume that
it matches the user's settings.

In these cases we should prefer fonts that include all the characters
of the language, so we don't have to use additional fonts that
don't match the style of the original text.

Regards,
                                        Owen