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#! /usr/bin/perl
# This short script creates fixed look-up tables for xcftools
#
# This file was written by Henning Makholm <henning@makholm.net>
# It is hereby in the public domain.
#
# In jurisdictions that do not recognise grants of copyright to the
# public domain: I, the author and (presumably, in those jurisdictions)
# copyright holder, hereby permit anyone to distribute and use this code,
# in source code or binary form, with or without modifications. This
# permission is world-wide and irrevocable.
#
# Of course, I will not be liable for any errors or shortcomings in the
# code, since I give it away without asking any compenstations.
#
# If you use or distribute this code, I would appreciate receiving
# credit for writing it, in whichever way you find proper and customary.
use strict ; use warnings ;
sub shipsubarray (@) {
while( @_ > 1 && $_[$#_] == 0 ) {
pop @_ ;
}
my $last = pop @_ ;
print " {" ;
my $left = 75 ;
for my $d ( (map{ $_ . "," } @_), "$last}," ) {
if( length($d) > $left ) {
print "\n " ;
$left = 75 ;
}
print $d ;
$left -= length($d) ;
}
print "\n" ;
}
my $precompute_it = 1 ;
if( open CONFIGH, "<", "config.h" ) {
$precompute_it = 0 ;
while( <CONFIGH> ) {
if( /\#\s*define\s+PRECOMPUTED_SCALETABLE/ ) {
$precompute_it = 1 ;
last ;
}
}
close CONFIGH ;
}
print "/* Autogenerated by $0 */\n" ;
print "#include \"pixels.h\"\n" ;
print "#ifdef PRECOMPUTED_SCALETABLE\n" ;
if( $precompute_it ) {
print "const uint8_t scaletable[256][256] = {\n" ;
for my $p ( 0..255 ) {
shipsubarray( map { int(($p*$_+127)/255) } ( 0 .. 255 ) );
# This formula has the property that
# scaletable[p][q] + scaletable[255-p][q] == q
# for all uint8_t values of p and q.
# This is important in order that a partially transparent
# pixel does not change the color of the underlying pixel
# unless the two pixels have different colors.
}
print "};\n" ;
} else {
print "#error PRECOMPUTED_SCALETABLE was not defined at generation time\n";
}
print "#endif\n" ;
if(0) {
print "const uint8_t divtable[256][256] = {\n" ;
for my $p ( 0..255 ) {
shipsubarray( map { $_ >= $p ? 255 : int(0.5 + 255*$_/$p) }
( 0 .. 255 ) );
}
print "};\n" ;
}
print "const rgba graytable[256] = {\n" ;
for my $p ( 0..255 ) {
print " (rgba)$p << RED_SHIFT | (rgba)$p << GREEN_SHIFT | (rgba)$p << BLUE_SHIFT,\n" ;
}
print "};\n" ;
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