June 2018 Update

Task/Bitmap-Read-an-image-through-a-pipe/Perl-6/bitmap-read-an-image-through-a-pipe.pl6

@@ -0,0 +1,33 @@
+class Pixel { has UInt ($.R, $.G, $.B) }
+class Bitmap {
+    has UInt ($.width, $.height);
+    has Pixel @.data;
+}
+
+role PPM {
+    method P6 returns Blob {
+	"P6\n{self.width} {self.height}\n255\n".encode('ascii')
+	~ Blob.new: flat map { .R, .G, .B }, self.data
+    }
+}
+
+sub getline ( $proc ) {
+    my $line = '#'; # skip comment when reading a .png
+    $line = $proc.out.get while $line.substr(0,1) eq '#';
+    $line;
+}
+
+my $filename = './camelia.png';
+
+my $proc = run 'convert', $filename, 'ppm:-', :enc('ISO-8859-1'), :out;
+
+my $type = getline($proc);
+my ($width, $height) = getline($proc).split: ' ';
+my $depth = getline($proc);
+
+my Bitmap $b = Bitmap.new( width => $width.Int, height => $height.Int) but PPM;
+
+$b.data = $proc.out.slurp.ords.rotor(3).map:
+  { Pixel.new(R => .[0], G => .[1], B => .[2]) };
+
+'./camelia.ppm'.IO.open(:bin, :w).write: $b.P6;