[Fontconfig] font rendering priority and fontconfig font override

[Qianqian Fang]

hi everyone

I always get confused by the order that X(Freetype? Xft?) renders a
given symbol (encoded with unicode, for example). It seems to me that
scalable fonts always get the priority to render a character than
bitmap fonts if both match the encodings of the character. Can anyone
give me a hint or show me some useful webpages related to this?

Moverover, since it is very common for most existing Asian fonts
looking blurry on the screen due to anti-aliasing and no efficient
hinting method available, we have developed bitmap fonts to make
characters look nicer and sharper on the screen. However, when both the
bitmap and scalable fonts installed, the bitmap font never get chance
to be displayed (this is related to the priority question above). I
append the following rules into ~/.fonts.conf:

 <match target="font">
        <test compare="eq" name="family" qual="any" >
                <string>outline font name1</string>
                <string>outline font name2</string>
                .....
         </test>
         <test name="pixelsize" compare="eq">
                <double>12</double>
         </test>
         ...
         <edit name="family" mode="assign">
                <string>my bitmap font</string>
         </edit>
 </match>

unfortunately, it seems not effective at all. I start doubting if it is
possible to use fontconfig to override outline font by bitmap font.

our bitmap fonts will be released soon (in terms of GPL), I would like
to make a clear statement on how to use of the font in the realease
documents, therefore, your input on these two questions is highly
appreciated.

Qianqian