#!/bin/sh

#

# Copyright (c) 2013 John Cunningham Bowler

#

# Last changed in libpng 1.6.0 [February 14, 2013]

#

# This code is released under the libpng license.

# For conditions of distribution and use, see the disclaimer

# and license in png.h

#

# Generate a set of PNG test images.  The images are generated in a

# sub-directory called 'tests' by default, however a command line argument will

# change that name.  The generation requires a built version of makepng in the

# current directory.

#

usage(){

   exec >&2

   echo "$0 [<directory>]"</directory>

   echo '  Generate a set of PNG test files in "directory" ("tests" by default)'

   exit 1

}

mp="$PWD/makepng"

test -x "$mp" || {

   exec >&2

   echo "$0: the 'makepng' program must exist"

   echo "  in the directory within which this program:"

   echo "    $mp"

   echo "  is executed"

   usage

}

# Just one argument: the directory

testdir="tests"

test $# -gt 1 && {

   testdir="$1"

   shift

}

test $# -eq 0 || usage

# Take care not to clobber something

if test -e "$testdir"

then

   test -d "$testdir" || usage

else

   # mkdir -p isn't portable, so do the following

   mkdir "$testdir" 2>/dev/null || mkdir -p "$testdir" || usage

fi

# This fails in a very satisfactory way if it's not accessible

cd "$testdir"

:>"test$$.png" || {

   exec >&2

   echo "$testdir: directory not writable"

   usage

}

rm "test$$.png" || {

   exec >&2

   echo "$testdir: you have create but not write privileges here."

   echo "  This is unexpected.  You have a spurion; "'"'"test$$.png"'"'"."

   echo "  You need to remove this yourself.  Try a different directory."

   exit 1

}

# Now call makepng ($mp) to create every file we can think of with a

# reasonable name

doit(){

   for gamma in "" --sRGB --linear --1.8

   do

      case "$gamma" in

         "")

            gname=;;

         --sRGB)

            gname="-srgb";;

         --linear)

            gname="-lin";;

         --1.8)

            gname="-18";;

         *)

            gname="-$gamma";;

      esac

      "$mp" $gamma "$1" "$2" "test-$1-$2$gname.png"

   done

}

#

for ct in gray palette

do

   for bd in 1 2 4 8

   do

      doit "$ct" "$bd"

   done

done

#

doit "gray" "16"

#

for ct in gray-alpha rgb rgb-alpha

do

   for bd in 8 16

   do

      doit "$ct" "$bd"

   done

done