Re: Canvas change in gnome 1.2 (helix)

[Nathan Hurst <njh hawthorn csse monash edu au>]

On Fri, 26 May 2000, Federico Mena Quintero wrote:

> >  Because of font brokenness.   I'm halfway through making a freetype based
> >  gnome-canvas-aa widget.  You've welcome to my partial code.  
> 
> Wow, this is awesome!  Where can we look at your code?

As I said in my last replay it is currently scattered across three
machines and so on.  I'm also working with freetype2, which recently
underwent slight changes so I need to retest with the new version.

More importantly, can we gather all the people who are interested in a new
font toolkit together so we find out what exists, and try and a) do it
properly, and b) minimised excess work.

> Just render the mask with Freetype and then composite it to the
> GnomeCanvasBuf by hand.  The libart code has an example of how to do
> fast pixel-by-pixel compositing of a solid color.  Please tell us if
> you need help with this.

That's what I do... but if someone else has a nice widget or whatever to
do this, I would rather work with that, as other people can then write
MMX/Altivec optimisations.  The data needs to be kept in case the letter
crosses a block boundary.

> Can Freetype give you horizontal spans of where the pixels for a
> rendered font are turned on?  We could then use horizontal lines to
> draw nice scaled fonts on the Gdk canvas.

Sort of.  I had a long chat with david turner over this:
http://www.csse.monash.edu.au/~njh/phd/dturner-freetype-log-3.txt

The biggest problem is antialiasing(there is an overhead issue at small
sizes too).  The libart method of delta + offset may work.  I've also
written bits of a library to do span list management(union, set
difference), but that only handles boolean spans, and linear spans aren't
closed under multiplication(equivalent to intersection).

> Having a Freetype-based text item would be awesome.  Thanks a *lot*
> for doing this work!

I'm only halfway, and the whole issue of font management needs to be
looked through too.  I'll chat with Owen and see what sort of interface he
wants for Pango.  My current interface is a list of glyphs, which I have a
crappy function to build from a c -string and a font.  We really want to
do embedded fonts and stuff at this stage too.

njh