=head1 NAME

draw.pod - overview of planned drawing changes

=head1 SYNOPSIS

  fix the processing done by the current combine modes
  combine modes for most drawing operations
  thick lines

=head1 combine mode fixes

Currently:

=over

=item *

the calculations are just wrong

=item *

they don't handle adapting to the target channel count

=back

To do:

=over

=item *

add a render function that calls the fill function then applies it to
the target based on the combine mode.

=item *

modify fill functions to always produce RGBA

=item *

have the combine mode functions just generate the color, the render
function can then alpha adjust it and apply it to the target

=back

=head1 combine modes for drawing functions

=over

=item *

write versions of each function that take a combine mode

=back

=head1 thick lines

Two possible approaches:

=over

=item *

given a polyline, generate a polygon for the entire shape - more
complex, overlap problems

=item *

given a polyline, generate polygons for each segment, draw to a work
image and use that to compose the fill - possible problems joining the
segments

=back