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| -rw-r--r-- | colors.sh | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/colors.sh b/colors.sh new file mode 100644 index 0000000..e5322e1 --- /dev/null +++ b/colors.sh @@ -0,0 +1,98 @@ +#!/bin/bash +#https://gist.githubusercontent.com/HaleTom/89ffe32783f89f403bba96bd7bcd1263/raw/e50a28ec54188d2413518788de6c6367ffcea4f7/print256colours.sh + +# Tom Hale, 2016. MIT Licence. +# Print out 256 colours, with each number printed in its corresponding colour +# See http://askubuntu.com/questions/821157/print-a-256-color-test-pattern-in-the-terminal/821163#821163 + +set -eu # Fail on errors or undeclared variables + +printable_colours=256 + +# Return a colour that contrasts with the given colour +# Bash only does integer division, so keep it integral +function contrast_colour { + local r g b luminance + colour="$1" + + if (( colour < 16 )); then # Initial 16 ANSI colours + (( colour == 0 )) && printf "15" || printf "0" + return + fi + + # Greyscale # rgb_R = rgb_G = rgb_B = (number - 232) * 10 + 8 + if (( colour > 231 )); then # Greyscale ramp + (( colour < 244 )) && printf "15" || printf "0" + return + fi + + # All other colours: + # 6x6x6 colour cube = 16 + 36*R + 6*G + B # Where RGB are [0..5] + # See http://stackoverflow.com/a/27165165/5353461 + + # r=$(( (colour-16) / 36 )) + g=$(( ((colour-16) % 36) / 6 )) + # b=$(( (colour-16) % 6 )) + + # If luminance is bright, print number in black, white otherwise. + # Green contributes 587/1000 to human perceived luminance - ITU R-REC-BT.601 + (( g > 2)) && printf "0" || printf "15" + return + + # Uncomment the below for more precise luminance calculations + + # # Calculate percieved brightness + # # See https://www.w3.org/TR/AERT#color-contrast + # # and http://www.itu.int/rec/R-REC-BT.601 + # # Luminance is in range 0..5000 as each value is 0..5 + # luminance=$(( (r * 299) + (g * 587) + (b * 114) )) + # (( $luminance > 2500 )) && printf "0" || printf "15" +} + +# Print a coloured block with the number of that colour +function print_colour { + local colour="$1" contrast + contrast=$(contrast_colour "$1") + printf "\e[48;5;%sm" "$colour" # Start block of colour + printf "\e[38;5;%sm%3d" "$contrast" "$colour" # In contrast, print number + printf "\e[0m " # Reset colour +} + +# Starting at $1, print a run of $2 colours +function print_run { + local i + for (( i = "$1"; i < "$1" + "$2" && i < printable_colours; i++ )) do + print_colour "$i" + done + printf " " +} + +# Print blocks of colours +function print_blocks { + local start="$1" i + local end="$2" # inclusive + local block_cols="$3" + local block_rows="$4" + local blocks_per_line="$5" + local block_length=$((block_cols * block_rows)) + + # Print sets of blocks + for (( i = start; i <= end; i += (blocks_per_line-1) * block_length )) do + printf "\n" # Space before each set of blocks + # For each block row + for (( row = 0; row < block_rows; row++ )) do + # Print block columns for all blocks on the line + for (( block = 0; block < blocks_per_line; block++ )) do + print_run $(( i + (block * block_length) )) "$block_cols" + done + (( i += block_cols )) # Prepare to print the next row + printf "\n" + done + done +} + +print_run 0 16 # The first 16 colours are spread over the whole spectrum +printf "\n" +print_blocks 16 231 6 6 3 # 6x6x6 colour cube between 16 and 231 inclusive +print_blocks 232 255 12 2 1 # Not 50, but 24 Shades of Grey + |