#!/bin/sh

PATH=${PWD%code*}code:$PATH

# Encode a (forged) PNG that has alpha channel using a palette

priforgepng -s 32 -d 3 grl glr rtl gbt | priweavepng - - - - |
  pripalpng - |
  pripnglsch |
  # Awkward way of checking if output contains both strings
  while read -r a
  do
    case $a in
      (IHDR*00000020000000200803000000) printf i;;
      (tRNS*) echo t;;
    esac
  done |
  grep -q '^it$'