90 lines
2.9 KiB
Perl
Executable File
90 lines
2.9 KiB
Perl
Executable File
#!/usr/bin/perl -w
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#
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# Convert PNG image to Spectrum format sprite image data
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#
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# Input image should be palettised 1-bit with no transparency
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#
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# Simon Owen <simon@simonowen.com>
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use Compress::Zlib;
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use Getopt::Std;
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# Allow -v option for verbose output
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getopts('v');
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# Strip path from input filename, and check
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$0 =~ s/.*\///;
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die "Usage: $0 <image> <sprite-width> [<sprite-height>]\n" unless @ARGV == 2 or @ARGV == 3;
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# Input image and output data file
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($file,$w,$h) = (@ARGV,$ARGV[1]); # height defaults to width if not provided
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die "Input image must be in PNG format\n" unless $file =~ /.png$/i;
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die "Sprite width should be 2-16 pixels\n" unless $w >= 2 && $w <= 16;
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die "Sprite height should be at least 1 pixel\n" unless $h > 0;
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# Slurp the entire PNG image
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open INPUT, "<$file" and binmode INPUT or die "$file: $!\n";
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read INPUT, $data='', -s $file;
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close INPUT;
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# Extract and check the image dimensions
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$data =~ /IHDR(.{8})/s;
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($iw,$ih) = unpack "N2", $1;
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die "Input image (${iw}x${ih}) must be an exact multiple of sprite size (${w}x${h})\n" if ($iw%$w) or ($ih%$h);
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# Extract and expand the compressed image data
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($data) = $data =~ /IDAT(.*).{8}IEND/s;
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$data = Compress::Zlib::uncompress($data);
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# Remove the type byte from the start of each line, leaving just 0+1 pixel values
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if (length($data) == (($iw+1)*$ih)) { # 8bpp?
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$data =~ s/.(.{$iw})/$1/sg;
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@data = map { $_&1 } unpack("C*", $data);
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} elsif (length($data) == (($iw/2+1)*$ih)) { # 4bpp?
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my $iw_2 = $iw/2;
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$data =~ s/.(.{$iw_2})/$1/sg;
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foreach (unpack("C*", $data)) {
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push @data, ($_>>4)&1, $_&1;
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}
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} else {
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die "Image data format is unsupported (size = ".@data." bytes)\n";
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}
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# Calculate rows+columns and the expected size of the output data
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($c,$r) = ($iw/$w,$ih/$h);
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$size = int(($w+7)/8)*$h*$r*$c;
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print "Input image ($file) = ${iw}x${ih}, sprite = ${w}x${h}\n" if $opt_v;
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foreach $y (0..$r-1)
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{
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foreach $x (0..$c-1)
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{
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foreach $l (0..$h-1) # line
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{
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# Calculate the offset of the required bit sequence
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my $o = ((($y*$h+$l)*$c) + $x) * $w;
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# Convert the individual bits to a binary string then a decimal value
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my $n = unpack("N", pack("B32", substr("0"x32 . join('', @data[$o..$o+$w-1]), -32)));
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# Pack into 1 or 2 bytes, with the bits left-aligned (MSB)
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$output .= pack(($w<=8)?"C":"n", $n << (8-($w & 7)));
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}
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}
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}
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# Sanity check the output data size
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die "Output data ", length($output), " is the wrong size! (should be $size)\n" unless length($output) == $size;
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# The output file is the input filename with a .bin extension instead of .png
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$file =~ s/png$/bin/i;
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open OUTPUT, ">$file" and binmode OUTPUT or die "$file: $!\n";
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# Determine the size of a single sprite, and strip blank sprites from the end of the data
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$ss = length($output) / ($r*$c);
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$output =~ s/(\0{$ss})*$//;
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print "Output data ($file) = ", length($output), " bytes = ", length($output)/$ss, " sprites\n" if $opt_v;
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print OUTPUT $output;
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close OUTPUT;
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