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Syntactic Confectionery Delight

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( #3333=superdoc: print w/replies, xml ) Need Help??
OK, I've tidied up my first draft and added a little Tk testing toy. The contrasting colours returned tend toward the lighter but the hash is easily tweaked.
#! perl use strict; use warnings; use Tk; my $title = "colour contrast"; my $mw = new MainWindow( -title => $title ); my $fr = $mw->Frame()->pack; for ( 1 .. 5 ) { my $b = $fr->Button( -text => "Colour $_", )->pack; $b->configure( -command => [ \&pick_n_mix, $b ] ); } MainLoop(); sub pick_n_mix { my ($btn) = @_; my $old = $btn->cget( -bg ); my $col = $mw->chooseColor( -title => "Choose a nice colour...", -initialcolor => $old ); return unless $col; $btn->configure( -bg => $col, -activebackground => $col ); # Choose some contrasting colours... my $fg = contrast_colour($col); $btn->configure( -bg => $col, -activebackground => $col, -fg => $fg, -activeforeground => $fg ); } # given a colour in the form "#ff00ff" i.e. hex rrggbb, return a # contrasting colour sub contrast_colour { my $col = shift; # Need rgb values for colour... if ( not $col =~ /^#(\w\w)(\w\w)(\w\w)$/ ) { warn "failed to convert colour '$col' to rgb components\n"; return; } my ( $r, $g, $b ) = map hex, ( $1, $2, $3 ); # Use a hash of contrasting values for the "websafe pallette" # with emphasis on lighter colours... my %opp = qw(00 FF 33 FF 66 FF 99 FF CC 00 FF 00 ); # Round each value down to a multiple of hex 33 (i.e. 51)... map { $_ = int( $_ / 51 ) * 51 } ( $r, $g, $b ); # Replace each value with a contrasting value from the hash... map { $_ = $opp{ sprintf "%02X", $_ } } ( $r, $g, $b ); return "#$r$g$b"; }

In reply to Re: Contrasting Colours by Anonymous Monk
in thread Contrasting Colours by msemtd

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