The benefits of the new TextLine system

[Lars Clausen <lars raeder dk>]

Hans was asking about the TextLine layer I have been working on.  This
should put any doubts to rest (quite apart from the more stable widths):
I now have an implementation of the Text object that uses TextLine
internally.  As a test, I took the render-test diagram from samples,
zoomed it to 110%, then selected all objects and moved them around,
outputting the total time each rendering took.

With old-style rendering*:

Rendering took 733759 micros
Rendering took 737350 micros
Rendering took 725555 micros
Rendering took 734911 micros

Average of 732894 micros.

With TextLine-integrated rendering:

Rendering took 10876 micros
Rendering took 17610 micros
Rendering took 16255 micros
Rendering took 15894 micros

Average of 15159 micros.

A speed-up of a factor about 50 is worth an extra layer in the rendering
system (though the underlying draw_string layer can be considered
deprecated now).

I would like to get this further integrated in the objects, so that
those who currently call draw_string directly instead holds TextLine
objects.  But I think this speedup, along with the VDX implementation,
warrants a new release, so I'll start gearing up for that instead.  With
luck and some help, it should be out before Christmas.

-Lars

*) Actually, this "old-style" still uses TextLine as a temporary
structure.  The 0.95.1 version takes somewhere around 3 seconds per
render.