#!/bin/sh
# constantinople - quick'n'dirty byzanz(1)-like screencast tool

[ "$1" = -w ] && shift || XWINOPTS=-root

[ -z "$1" ] && echo >&2 Usage: $0 [-w] output && exit 1

OPTS=$(xwininfo $XWINOPTS | awk '
  /Absolute upper-left X:/ { x = $4 }
  /Absolute upper-left Y:/ { y = $4 }
  /Width:/ { w = $2 }
  /Height:/ { h = $2 }
  END { print "-s " w "x" h " -i '$DISPLAY'+" x "," y }'
)

set -ex
ffmpeg -f x11grab -r 30 $OPTS -vcodec libx264 -preset ultrafast -crf 0 -threads 0 -y "$1.mkv"
ffmpeg -y -i "$1.mkv" -r 2 -pix_fmt rgb24 "$1.gif"
convert "$1.gif" -fuzz 8% -layers Optimize "$1.gif-"
mv "$1.gif-" "$1.gif"