Around 10 o'clock on Feb 26, Arun Sharma wrote:

> The general development direction in the XFree86 tree is towards client side 
>  fonts, although new efforts like ST are favoring server side font
>  handling.

Server side font handling for sophisticated layout requires a new X 
extension.  Client side fonts can be done with the existing core graphics 
primitives, although performance is quite a bit slower.  The Render 
extension permits many different client side implementations to share the 
same X extension; server side fonts require a new extension for each 
implmentation.

> One of the primary justifications for client side fonts is the slow pace of
> X server development and the difficulty of supporting legacy X servers

Performance is another important reason for client-side fonts.  We know 
what the network behaviour of that solution will be; server side layout
is an unproven technique with potentially large numbers of round trips 
required.

>  X protocol was designed at a time when the distinction between
>  characters and glyphs was not very important (hence the language
>  in the protocol and the man pages)

Not just 'not very important'; there was no distinction.  Character 
encodings were assumed to be the same as glyph encodings; the notion that 
text would come in an encoding that wasn't suitable for direct display 
had not been heard of yet.  As a result, the core protocol is incapable of 
supporting any kind of sophisticated character->glyph mapping.

The question is not whether the core text code can be used for 
sophisticated layout, the only question is what system should replace it.

Client side text has the advantage of a uniform mechanism and interface 
for all X servers; the extension provides a performance advantage, but 
text is more than usable even on legacy X servers.  On the local machine, 
I can draw some 13000 24 pixel anti-aliased glyphs per second and nearly 
90000 'aliased' glyphs per second.

Keith Packard        XFree86 Core Team        Compaq Cambridge Research Lab


_______________________________________________
Fonts mailing list
[EMAIL PROTECTED]
http://XFree86.Org/mailman/listinfo/fonts

Reply via email to