Dropdown console functionality for st terminal in i3wm

st-dropdown

#!/bin/sh

pct_w="${PCT_W:-80}"   pct_h="${PCT_H:-80}"  # desired percent dimensions
pad_w="${PAD_W:-8}"    pad_h="${PAD_H:-4}"   # pixels of extra padding
chr_w="${CHR_W:-100}"  chr_h="${CHR_H:-35}"  # initial character dimensions

comment() {
  cat <<'END'
usage: st-dropdown [gap] [position]

Creates a floating st window. If the window already exists, toggles display.

Allowed positions are center (default), top, bottom, left and right.
The window size is determined by the env vars above and your screen size.

The gap specifies how many pixels (default 0) go between the window and screen
edges.

To use it, you need lines like below in your i3 config:

bindsym $mod+grave exec st-dropdown top
for_window [instance="^ST dropdown$"] \
  floating enable, sticky enable, move to scratchpad

END
}

script="$(basename "$0")"
title="$script"     # some applications can change the title
name="ST dropdown"  # ensure the name is unique
sec=0.1             # estimated time to start and register st

if ! >/dev/null 2>&1 command -v st i3-msg jq; then
  >&2 echo "$script requires st, i3-msg, and jq in \$PATH"
  exit 1
fi

get_id_and_dims() {
  # Store the X11 ID and dimensions of the current dropdown window,
  # or error if it's not in the tree.
  # shellcheck disable=2046
  set -- $(i3-msg -t get_tree | jq --raw-output \
    'first(.. | select(.window_properties?.instance == "'"$name"'")) |
    .window, (.rect | .x, .y, .width, .height)')
  [ -n "$1" ] || return 1

  id="$1" old_x="$2" old_y="$3" old_width="$4" old_height="$5"
}

resize() {
  # Get the dimensions of the output with the focused window and scale.
  # shellcheck disable=2046
  set -- $(i3-msg -t get_tree | jq --raw-output \
    'first(.nodes[] | select(.. | .focused? ) | .rect?) |
    .width, .height, .x, .y,
    .width * '"$pct_w"' / 100 + '"$pad_w"',
    .height * '"$pct_h"' / 100 + '"$pad_h")
  # Proceed with resize only if dimensions are available.
  [ -n "$1" ] && [ -n "$2" ] || return 1

  # Resize requires ints, but jq cannot round, cast to int, or do printf.
  read -r s_width s_height s_x s_y w_width w_height << READ
    $(printf '%d %d %d %d %.0f %.0f' "$1" "$2" "$3" "$4" "$5" "$6")
READ

  # Proceed with resize only if dimensions are different.
  [ "$w_width" = "$old_width" ] && [ "$w_height" = "$old_height" ] && return
  i3-msg -q "[id=$id] resize set $w_width $w_height"
}

toggle() {
  i3-msg -q "[id=$id] scratchpad show"
}

move() {
  # Proceed with move only if position is computable.
  [ -n "$s_width" ] && [ -n "$s_height" ] || return 1

  # Assign gap to the first arg if it's an integer.
  gap=0
  if [ -z "${1//[0-9]/}" ]; then
    gap=$1
    shift
  fi

  case $1 in
  center|'')
    x=$(((s_width - w_width) / 2)) y=$(((s_height - w_height) / 2)) ;;
  top)
    x=$(((s_width - w_width) / 2)) y=$gap ;;
  bottom)
    x=$(((s_width - w_width) / 2)) y=$((s_height - w_height - gap)) ;;
  left)
    x=$gap y=$(((s_height - w_height) / 2)) ;;
  right)
    x=$((s_width - w_width - gap)) y=$(((s_height - w_height) / 2)) ;;
  *)
    >&2 echo "Invalid window position: $1"
    exit 1
  esac

  x=$((x + s_x)) y=$((y + s_y))
  # Proceed with move only if position is different.
  [ "$old_x" -eq "$x" ] && [ "$old_y" -eq "$y" ] && return
  i3-msg -q "[id=$id] move position $x $y"
}

get_id_and_dims || {
  # If the window is not found, fork st and wait for i3 to register it.
  st -n "$name" -t "$title" -ig "${chr_w}x${chr_h}" &
  while true; do
    sleep $sec
    get_id_and_dims && break
    # Back off with increasing timeout.
    sec="$(jq --null-input $sec' * 2')"
  done
}

# Window must be off the scratchpad for moving to work, so toggle first.
resize
toggle
move "$@"