Copy 24-bit-color.sh from iTerm2.

tools/24-bit-color.sh

@@ -0,0 +1,113 @@
+#!/bin/bash
+#
+#   This file echoes four gradients with 24-bit color codes
+#   to the terminal to demonstrate their functionality.
+#   The foreground escape sequence is ^[38;2;<r>;<g>;<b>m
+#   The background escape sequence is ^[48;2;<r>;<g>;<b>m
+#   <r> <g> <b> range from 0 to 255 inclusive.
+#   The escape sequence ^[0m returns output to default
+
+#
+# From
+# https://github.com/gnachman/iTerm2/blob/master/tests/24-bit-color.sh
+# and presumably covered by
+# https://github.com/gnachman/iTerm2/blob/master/LICENSE
+#
+
+if which gseq >/dev/null
+then
+    SEQ=gseq
+else
+    SEQ=seq
+fi	
+SEPARATOR=';'
+
+setBackgroundColor()
+{
+    echo -en "\033[48${SEPARATOR}2${SEPARATOR}$1${SEPARATOR}$2${SEPARATOR}$3""m"
+}
+
+resetOutput()
+{
+    echo -en "\033[0m\n"
+}
+
+# Gives a color $1/255 % along HSV
+# Who knows what happens when $1 is outside 0-255
+# Echoes "$red $green $blue" where
+# $red $green and $blue are integers
+# ranging between 0 and 255 inclusive
+rainbowColor()
+{ 
+    let h=$1/43
+    let f=$1-43*$h
+    let t=$f*255/43
+    let q=255-t
+
+    if [ $h -eq 0 ]
+    then
+        echo "255 $t 0"
+    elif [ $h -eq 1 ]
+    then
+        echo "$q 255 0"
+    elif [ $h -eq 2 ]
+    then
+        echo "0 255 $t"
+    elif [ $h -eq 3 ]
+    then
+        echo "0 $q 255"
+    elif [ $h -eq 4 ]
+    then
+        echo "$t 0 255"
+    elif [ $h -eq 5 ]
+    then
+        echo "255 0 $q"
+    else
+        # execution should never reach here
+        echo "0 0 0"
+    fi
+}
+
+for i in `$SEQ 0 127`; do
+    setBackgroundColor $i 0 0
+    echo -en " "
+done
+resetOutput
+for i in `$SEQ 255 128`; do
+    setBackgroundColor $i 0 0
+    echo -en " "
+done
+resetOutput
+
+for i in `$SEQ 0 127`; do
+    setBackgroundColor 0 $i 0
+    echo -n " "
+done
+resetOutput
+for i in `$SEQ 255 128`; do
+    setBackgroundColor 0 $i 0
+    echo -n " "
+done
+resetOutput
+
+for i in `$SEQ 0 127`; do
+    setBackgroundColor 0 0 $i
+    echo -n " "
+done
+resetOutput
+for i in `$SEQ 255 128`; do
+    setBackgroundColor 0 0 $i
+    echo -n " "
+done
+resetOutput
+
+for i in `$SEQ 0 127`; do
+    setBackgroundColor `rainbowColor $i`
+    echo -n " "
+done
+resetOutput
+for i in `$SEQ 255 128`; do
+    setBackgroundColor `rainbowColor $i`
+    echo -n " "
+done
+resetOutput