#!/bin/bash
#
#  slideshow_next  image
#
# This program will do a animated transition to the single image given.
#
# If no "animate" is running, one will be started.
#
# This program assumes an image is currently being displayed by the IM
# "animate" command. The image currently displayed is stored in the
# file "last_image" in the current directory.
#
# The point is that it does not need to know all future animation sequences
# that will be displayed, to control a animation.
#
# Note that all images given should be all the same size!
#
####
#
# Anthony Thyssen   2008
#

#DEBUG=true
last_image_file=last_image    # make this $HOME/.last_image  ???
next_image=`realpath "$1"`

prev_image="$next_image"
if [ -s "$last_image_file" ]; then
  prev_image=`cat last_image | tr -d '\012'`
fi

# I use a temporary file so that I can background the "animate" command
umask 77
temp=`mktemp "${TMPDIR:-/tmp}/slideshow.XXXXXXXXXX.miff"` ||
  { echo >&2 "$PROGNAME: Unable to create temporary file"; exit 10;}
trap 'rm -f "$temp"' 0
trap "exit 2" 1 2 3 15

[ "$DEBUG" ] &&
 echo "morphing `basename $prev_image` to `basename $next_image`"

# Do you complex image transition here
# The last delay is minimum display time
# The extra frame is to prevent a 'flash' of the first frame
# just before the 'static' display is set.
convert -delay 20 "$prev_image" "$next_image" -morph 10 \
        \( +clone -set delay 300 \) +swap +delete \
        \( +clone -set delay 0 \) -loop 0 $temp

[ "$DEBUG" ] &&
 echo "animating transition"

# feed transition to the animation
animate -remote ephemeral:$temp &

# wait for 'ephemeral:' file to have been read
while [ -f $temp ]; do sleep .1; done

# Wait for transition time period to complete.
# Must be longer than transition time shorter than overall time.
# The transition animate must not reach the final frame or a flash
# of the first (original image) frame will become visible!
sleep 5

[ "$DEBUG" ] &&
 echo "setting static display"

# replace the transition image with a loop of the new image
animate -delay 100 -remote "$next_image" &

echo -n $next_image > last_image