tools/24-bit-color.sh

   1 #!/bin/bash
   2 #
   3 #   This file echoes four gradients with 24-bit color codes
   4 #   to the terminal to demonstrate their functionality.
   5 #   The foreground escape sequence is ^[38;2;<r>;<g>;<b>m
   6 #   The background escape sequence is ^[48;2;<r>;<g>;<b>m
   7 #   <r> <g> <b> range from 0 to 255 inclusive.
   8 #   The escape sequence ^[0m returns output to default
   9
  10 #
  11 # From
  12 # https://github.com/gnachman/iTerm2/blob/master/tests/24-bit-color.sh
  13 # and presumably covered by
  14 # https://github.com/gnachman/iTerm2/blob/master/LICENSE
  15 #
  16
  17 SEQ1=
  18 if which gseq >/dev/null 2>&1; then
  19     SEQ1=gseq
  20 elif seq --version|grep -q GNU; then
  21     SEQ1=seq
  22 fi
  23 if [ -n "$SEQ1" ]; then
  24     # GNU seq requires a -ve increment if going backwards
  25     seq1()
  26     {
  27         if [ $1 -gt $2 ]; then
  28             $SEQ1 $1 -1 $2
  29         else
  30             $SEQ1 $1 $2
  31         fi
  32     }
  33     SEQ=seq1
  34 else
  35     SEQ=seq
  36 fi
  37 SEPARATOR=':'
  38
  39 setBackgroundColor()
  40 {
  41     echo -en "\033[48${SEPARATOR}2${SEPARATOR}$1${SEPARATOR}$2${SEPARATOR}$3""m"
  42 }
  43
  44 resetOutput()
  45 {
  46     echo -en "\033[0m\n"
  47 }
  48
  49 # Gives a color $1/255 % along HSV
  50 # Who knows what happens when $1 is outside 0-255
  51 # Echoes "$red $green $blue" where
  52 # $red $green and $blue are integers
  53 # ranging between 0 and 255 inclusive
  54 rainbowColor()
  55 {
  56     let h=$1/43
  57     let f=$1-43*$h
  58     let t=$f*255/43
  59     let q=255-t
  60
  61     if [ $h -eq 0 ]
  62     then
  63         echo "255 $t 0"
  64     elif [ $h -eq 1 ]
  65     then
  66         echo "$q 255 0"
  67     elif [ $h -eq 2 ]
  68     then
  69         echo "0 255 $t"
  70     elif [ $h -eq 3 ]
  71     then
  72         echo "0 $q 255"
  73     elif [ $h -eq 4 ]
  74     then
  75         echo "$t 0 255"
  76     elif [ $h -eq 5 ]
  77     then
  78         echo "255 0 $q"
  79     else
  80         # execution should never reach here
  81         echo "0 0 0"
  82     fi
  83 }
  84
  85 for i in `$SEQ 0 127`; do
  86     setBackgroundColor $i 0 0
  87     echo -en " "
  88 done
  89 resetOutput
  90 for i in `$SEQ 255 128`; do
  91     setBackgroundColor $i 0 0
  92     echo -en " "
  93 done
  94 resetOutput
  95
  96 for i in `$SEQ 0 127`; do
  97     setBackgroundColor 0 $i 0
  98     echo -n " "
  99 done
 100 resetOutput
 101 for i in `$SEQ 255 128`; do
 102     setBackgroundColor 0 $i 0
 103     echo -n " "
 104 done
 105 resetOutput
 106
 107 for i in `$SEQ 0 127`; do
 108     setBackgroundColor 0 0 $i
 109     echo -n " "
 110 done
 111 resetOutput
 112 for i in `$SEQ 255 128`; do
 113     setBackgroundColor 0 0 $i
 114     echo -n " "
 115 done
 116 resetOutput
 117
 118 for i in `$SEQ 0 127`; do
 119     setBackgroundColor `rainbowColor $i`
 120     echo -n " "
 121 done
 122 resetOutput
 123 for i in `$SEQ 255 128`; do
 124     setBackgroundColor `rainbowColor $i`
 125     echo -n " "
 126 done
 127 resetOutput