gallery/noise: Initial commit

gallery/noise/config.sh

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+# Config for the 'noise' screensaver
+
+# Name of the screensaver (12 chars max)
+name="noise"
+# Tagline for the screensaver (40 chars max)
+tagline="Retro CRT static noise screensaver"
+description="Relive the analog static noise of the yester-years."
+authors=""
+license="MIT"
+settings=""

gallery/noise/noise.sh

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+#!/usr/bin/env bash
+# Replicate old-school CRT static noise
+
+# Handler for SIGINT (Ctrl‑C)
+_handle_cleanup_and_exit() {
+  # show the cursor again
+  tput cnorm       
+  tput sgr0
+  echo
+  clear
+  exit 0
+}
+
+# Handler for SIGWINCH (window resize)
+_handle_window_resize() {
+  width="$(tput cols)"
+  height="$(tput lines)"
+  clear
+}
+
+# Capture Ctrl‑C
+trap _handle_cleanup_and_exit SIGINT 
+# Capture SIGWINCH
+trap _handle_window_resize SIGWINCH
+
+# Get terminal dimensions
+width="${COLUMNS:-$(tput cols)}"
+height="${LINES:-$(tput lines)}"
+
+# For portability, we use these UTF codes
+block100="\xe2\x96\x88"  # u2588\0xe2 0x96 0x88 Solid Block 100%
+block75="\xe2\x96\x93"   # u2593\0xe2 0x96 0x93 Dark shade 75%
+block50="\xe2\x96\x92"   # u2592\0xe2 0x96 0x92 Half shade 50%
+block25="\xe2\x96\x91"   # u2591\0xe2 0x96 0x91 Light shade 25%
+block00=' '              # Literal space
+
+blocks=( "${block100}" "${block75}" "${block50}" "${block25}" "${block00}" )
+
+# Randomly select one of the color sets
+# This could be moved to an arg in the future
+# or split to a separate screensaver
+# This would allow desired behaviour to be selectable
+while true; do
+  rand="${RANDOM}"
+
+  # Require range [0, 32766] to evenly divide by 2
+  # Reject 32767 to avoid modulo bias
+  if (( rand < 32767 )); then
+    result=$(( rand % 2 ))
+    if (( result == 0 )); then
+      # Black, white, greys from 256 ANSI set
+      color_set=( 0 7 8 15 16 145 188 {231..255} )  
+    else
+      # Black, white, greys from 256 ANSI set, with RGBY thrown in
+      color_set=( 0 7 8 15 16 145 188 {231..255} 196 46 21 226 )
+    fi
+    break
+  fi
+  # If we're at this line, RANDOM hit 32767!
+done
+
+tput setab 0 # black background
+clear
+tput civis # no cursor
+
+# Initialise vars for batching
+buffer=""
+count=0
+batch_size=100
+
+while true; do
+  # Get random location and color
+  x=$(( ${SRANDOM:-$RANDOM} % width + 1 ))
+  y=$(( ${SRANDOM:-$RANDOM} % height + 1 ))
+  color_element=$(( ${SRANDOM:-$RANDOM} % ${#color_set[@]} ))
+  color_code="${color_set[color_element]}"
+  block_element=$(( ${SRANDOM:-$RANDOM} % ${#blocks[@]} ))
+  block=${blocks[block_element]}
+
+  # Build a buffer of changes to emit
+  buffer+="\e[${y};${x}H\e[38;5;${color_code}m${block}"
+  ((count++))
+
+  # Once the buffer size meets the threshold, dump it and start again
+  if (( count >= batch_size )); then
+    printf -- '%b' "${buffer}"
+    buffer=""
+    count=0
+  fi
+done
+