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### Taijitu ... the ultimate symbol of power

by zentara (Archbishop)
 on Mar 21, 2012 at 12:00 UTC ( #960766=poem: print w/replies, xml ) Need Help??

Sometimes a picture is better than 10,000 words. screenshot

P.S. If anyone knows how to rotate the entire Cairo surface, please show me. \$cr->rotate( PI/6 ); dosn't seem to work.

#!/usr/bin/perl use strict; use warnings; use Cairo; use constant { IMG_WIDTH => 480, IMG_HEIGHT => 480, PI => 3.1416 }; die "png backend not supported" unless (Cairo::HAS_PNG_FUNCTIONS); my \$png = "\$0.png"; my \$surf = Cairo::ImageSurface->create ('rgb24', IMG_WIDTH, IMG_HEIGHT +); my \$cr = Cairo::Context->create (\$surf); # to avoid a bit of angular confusion... :-) # arc angles are measured from 0 on the x-axis, and angles are # measured clockwise. So the usual 90 degree position is 3*PI/2. # There is a negative arc function, see the perldoc for Cairo. # In other words, the positive y axis is directed downward #left \$cr->arc (IMG_WIDTH/2, IMG_HEIGHT/2, IMG_WIDTH/2, 3*PI/2, PI/2); \$cr->set_source_rgb (1, 1, 1); \$cr->fill; #right \$cr->arc (IMG_WIDTH/2, IMG_HEIGHT/2, IMG_WIDTH/2, PI/2, 3*PI/2); \$cr->set_source_rgb (0, 0, 0); \$cr->fill; #top semicircle \$cr->arc (IMG_WIDTH/2, 3*IMG_HEIGHT/4, IMG_HEIGHT/4, 3*PI/2, PI/2); \$cr->set_source_rgb (0, 0, 0); \$cr->fill; #bottom semicircle \$cr->arc (IMG_WIDTH/2, IMG_HEIGHT/4, IMG_HEIGHT/4, PI/2 , 3*PI/2 ); \$cr->set_source_rgb (1, 1, 1); \$cr->fill; #encompassing boundary \$cr->arc (IMG_WIDTH/2, IMG_HEIGHT/2, IMG_WIDTH/2, 0, 2*PI); \$cr->set_source_rgb (1, 1, 1); \$cr->stroke; # opposite kernels # top \$cr->arc (IMG_WIDTH/2, IMG_HEIGHT/4, IMG_WIDTH/20, 0, 2*PI); \$cr->set_source_rgb (0, 0, 0); \$cr->fill; #bottom \$cr->arc (IMG_WIDTH/2, 3*IMG_HEIGHT/4, IMG_HEIGHT/20, 0, 2*PI); \$cr->set_source_rgb (1, 1, 1); \$cr->fill; \$surf->write_to_png (\$png); system ("display \$png"); # requires ImageMagick to be installed

I'm not really a human, but I play one on earth.
Old Perl Programmer Haiku ................... flash japh

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