Re: Going over bugs before release...

[Ethan M. <merritt@u.washington.edu>]

On Monday 23 February 2004 05:48 am, Dave Denholm wrote:
> > With the patch applied there is no problem with colors, but any
> > x11 plot containing rotated text is refreshed very much slower.
> > This is in particular noticeable when you resize the plot window.
> > But speeding up window resizing is certainly not release-critical,
> > so we can address it later.
>
> what's the change, and why does it cause a slowdown ?

The previous code assumed that text/background pixel area could
be represented by a 1-bit deep array.  The array was rotated, and
then the entire rotated array was ORer back onto the original image
in one (relatively fast) operation.  The problem is that ORing the
background color is only harmless if it is represented by all zeros.
If it is anything else then the OR operation perturbs the existing
colors.

The new code explicitly tests for pixels in the rotated text box that
are non-background, and substitutes them back into the original
image one by one.  That is relatively slow.

-- 
Ethan A Merritt       merritt@u.washington.edu
Biomolecular Structure Center    (206)543-1421
Mailstop 357742
University of Washington, Seattle, WA 98195