From 16fb9fc2233f3a3c0b61aee034da4c49979e30c2 Mon Sep 17 00:00:00 2001
From: Mischa POSLAWSKY <perl@shiar.org>
Date: Mon, 2 Nov 2015 05:48:59 +0100
Subject: [PATCH] termcol: ?img option to draw one image with each palette
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Manipulate source PNG file at data/indi.png to use palette colours in order
to compare look of an EGA game for each.  Quickly implemented by overwriting
data at certain positions, which will break with unexpected data.

Inline encoding increases page size by 6⋅5kB ≈ 30kB.
---
 termcol.plp | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/termcol.plp b/termcol.plp
index 0b3d236..04157ef 100644
--- a/termcol.plp
+++ b/termcol.plp
@@ -14,6 +14,8 @@ Html({
 	stylesheet => [qw'light dark'],
 });
 
+my $imgfile = exists $get{img} && 'indi.png';
+
 my @termlist;
 push @termlist, split /\W+/, $ENV{PATH_INFO} || 'default';
 
@@ -42,6 +44,7 @@ print
 
 <div class="section">
 <:
+use 5.010;
 use Shiar_Sheet::Colour '1.03';
 use List::Util qw( min max );
 
@@ -69,6 +72,28 @@ sub colcell {
 	return "$out\n";
 }
 
+sub img_egapal {
+	my ($palette) = @_;
+	return eval {
+		require MIME::Base64;
+		require Digest::CRC;
+
+		local $/;
+		open my $img, '<:bytes', "data/$imgfile" or die "$!\n";
+		my $imgdata = readline $img;
+
+		my $offset = 0x29 - 4;
+		my $len = 16 * 3;
+		my $chunklen = $len + 4;
+		substr($imgdata, $offset+4, $len) = pack 'H*', join '', @{$palette};
+		my ($p, $crc) = unpack "x${offset}a${chunklen}N", $imgdata;
+		substr($imgdata, $offset+4+$len, 4) = pack 'N', Digest::CRC::crc32($p);
+
+		return sprintf '<img src="data:image/png;base64,%s">',
+			MIME::Base64::encode_base64($imgdata);
+	} || $@;
+}
+
 for my $term (@termlist) {
 	my $info = $palettes->{$term};
 	ref $info eq 'HASH' or next;
@@ -104,6 +129,8 @@ for my $term (@termlist) {
 			$name = [ $name, ['#333'] ] if $term eq 'xkcd';
 			print '<tr>', colcell($name, $rgb);
 		}
+
+		print '<tr><td>', img_egapal(\@{$colours}) if $imgfile;
 		print "</table>\n\n";
 	}
 }
@@ -168,10 +195,17 @@ sub coltable_hsv {
 		my $colbreak = scalar map { @$_ } @colmap;  # same width as hue rows
 		for my $num (sort { $greymap{$a} <=> $greymap{$b} } keys %greymap) {
 			$out .= '<tr>' unless $col++ % $colbreak;
-			$out .= colcell($num, ($greymap{$num}) x 3);
+			$out .= colcell($num, ($greymap{$num}));
 		}
 	}
 
+	if ($imgfile) {
+		my @palette = map { [ @{$_}[1 .. 3] ] } map {@$_} map {@$_} @colmap;
+		my $imgdata = img_egapal(\@palette);
+		my $tablespan = scalar map { @$_ } @colmap;
+		$out .= "<tr><td colspan=$tablespan>$imgdata";
+	}
+
 	return $out;
 }
 
-- 
2.30.0