use strict;
use warnings;

my $text =<<"__TEXT__";
This is a sample text going from red to blue, from 10 to 20 points in size and with 5 points random variation.
__TEXT__



print decorate( $text, [255,0,0], [0,0,255], 10, 20, 5); 


sub decorate {
	my ($str, $cl, $cr, $szl, $szr, $randomsize) = @_;
	my $s;
	my $lenStr = length( $str );

	for ( my $i = 0; $i < $lenStr; $i++) {
		my $c = substr($str, $i, 1);
		
		if ($c eq ' ') {
			$s .= "&nbsp;\n";
		} else {
			my $red = interpolate( $cl->[0], $cr->[0], $lenStr, $i, 0 );
			my $grn = interpolate( $cl->[1], $cr->[1], $lenStr, $i, 0 );
			my $blu = interpolate( $cl->[2], $cr->[2], $lenStr, $i, 0 );
			my $siz = interpolate( $szl,   $szr,   $lenStr, $i, $randomsize );
			
			$s .= sprintf("<span style=\"font-size: %dpt; color: #%02x%02x%02x\">$c</span>", 
		                 $siz, $red, $grn, $blu, $c);		
		}
		
	}

	return $s;
}

sub interpolate {
	my ($from, $to, $nSteps, $thisStep, $randomShift) = @_;
	
	my $realStep = $thisStep - $randomShift + rand($randomShift*2);
	
	my $val = $from + (($to-$from)/$nSteps) * $realStep;
	
	if ( $val < min($from,$to) ) { $val = min($from, $to) };
	if ( $val > max($from,$to) ) { $val = max($from, $to) };
	
	return $val;
}

sub min() {
	my ($a, $b) = @_;
	return ($a < $b) ? $a : $b;
}

sub max() {
	my ($a, $b) = @_;
	return ($a > $b) ? $a : $b;
}