anigif

#!/usr/bin/env bash
usage ()
{
    usage="Usage: $0 [-rotate <90>] [-yoyo <1|0>] [-size <'[300x300]'>] [-out <\$(date +%s).gif>] [-preview <ql>] <image.jpg>|<image.jpg,...>

    -rotate <90> specifies degree of rotation (default 90)
    -yoyo <1|0> should gif reverse frames to provide back-and-forth (yoyo) effect (default true)
    -size <'[300x300]'> size of bounding box for frames to fit in (default 300x300)
    -out <output.gif> name of output file (default unix_epoch_timestamp.gif)
    -preview <cmd> command to execute to view output .gif

    Input file(s) can be a single image file, in which case all files within a second +/- its timestamp will be used as input files. Or you can give a list of input files that will be considered individually to be the frames of the output file.
    "
    printf %s\\n "$usage"
    exit
}

err(){
    printf >&2 '[ERROR] %s\n' "$*"
    exit 1
}

ql ()
{
        out=$(qlmanage -p "$@" 2>&1) || echo "$out"
}

command -v convert &>/dev/null || err "You must have the ''convert'' tool from ImageMagick in your PATH."

(($#)) || usage

# base comma d to which we append aadditional arguments
cmd=(convert -loop 0)
# default to 90º rotation by default
rotate=90
# default to going backwards at the end of the video
yoyo=1
# default to re-sizing on read to fit in a 300x300 box
size='[300x300]'
# should we preview (open) the .gif after generating it?
preview=ql
# (default outfile set after option processing)
outfile=

while :; do
    case $1 in
        -h)
            usage
            ;;
        -rotate)
            rotate=$2
            shift
            ;;
        -yoyo)
            yoyo=1
            ;;
        -out)
            outfile=$2
            shift
            ;;
        -size)
            size=$2
            shift
            ;;
        -preview)
            preview=$2
            shift
            ;;
        *)
            break
    esac
    shift
done

cmd+=( -rotate "$rotate" )

# default outfile is current timestamp in seconds to try to prevent chaos and overwrites
[[ $outfile ]] || outfile=$(date +%s).gif
[[ -e $outfile ]] && err "Outfile $outfile already exists"

frames=();

if (($# == 1)); then
    infile=$1;
    [[ -f $infile ]] || err "Infile should be a single, existing image file ('$infile' is not a file)"

    ttime=$(stat -t %s -f %m "$infile");

    for f in "${infile%/*}"/* ;
    do
        ctime=$(stat -t %s -f %m "$f");
        if (( ctime >= ttime-1 && ctime <=ttime+1 )); then
            frames+=( "${f}${size}" );
        fi;
    done;
else
    for f; do
        [[ -f $f ]] || err "Infile '$infile' does not exist"
        frames+=( "${f}${size}" );
    done
fi

if ((yoyo)); then
    for ((i=${#frames[@]};i>0;)); do
        frames+=( "${frames[--i]}" )
    done
fi 

# printf "%q " "${cmd[@]}" "${frames[@]}" "$outfile"; printf \\n
"${cmd[@]}" "${frames[@]}" "$outfile";
[[ $preview ]] && eval "$preview" "$outfile"