makemywall: new interface

We support new ways of reading files that we want to modify/generate:

% ./makemywall 1920 1080 myfile1.png myfile2.png
% ./makemywall 1920 1080 < mylist.txt
% find . -type f -name '*.png' | ./makemywall 1080 1920

makemywall

 
 usage() { 
   cat << EOH
-Usage:   $0 [-s] <source file> <width> <height> : creates a wallpaper
-            -s : use a "safer" and slower method to get the background color
-         $0 -h : displays this help message
-Example: $0 coolimage.png 1920 1080
+Generate wallpapers to a specified size, given a base picture
+
+$0 [-vs] width height [picture [picture [...]]]
+$0 -h
+
+-h : displays this help message
+-s : use a "safer" and slower method to get the background color
+-v : be verbose (set -x)
+
+Example: $0 1920 1080 coolimage.png
+
+The following syntax also works:
+find . -type f -name '*.png' | $0 1080 1920
 EOH
   exit ${1:-0}
 }
   echo "$1" && exit "${2:-1}"
 }
 
-if [ "$1" = "-h" ]; then
-  usage
-fi
+while getopts ":hvs" _opt; do
+  case "$_opt" in
+    h) usage       ;;
+    s) _slow=1     ;;
+    v) set -x      ;;
+    *) usage 1 >&2 ;;
+  esac
+done
+
+shift $((OPTIND-1))
 
-if [ "$1" = "-s" ]; then
+if [ -n "$_slow" ]; then
   getbg() {
     # We get all hexa codes of all pixels in the picture, and pick the most
     # frequent one... which should be the background color?
     convert "$1" -format %c +dither -depth 5  histogram:info: |
       sort -nr | head -1 | grep -Eo '#[A-F0-9]{6}'
   }
-  shift
 else
   getbg() {
     # We get the color of the top-left pixel.
   }
 fi
 
-if [  $# -ne 3 ]; then 
+# We require width & height
+# TODO: maybe auto-detect? seems tricky with dual screen
+if [ $# -lt 2 ]; then
   usage 1 >&2
 fi
+width="$1"
+height="$2"
+shift 2
 
-[ -r "$1" ] || die "File $1 is not readable!"
-inpfile="$1"
-outfile="$(basename "$inpfile")"
-width="$2"
-height="$3"
-bgcolor="$(getbg "$inpfile")"
+{ if [ -z "$1" ]; then
+  # No arguments, we read stdin
+  cat -
+else
+  for _file in "$@"; do
+    printf "%s\n" "$_file"
+  done
+fi } |
+while IFS= read -r inpfile; do
+  outfile="$(basename "$inpfile")"
+  bgcolor="$(getbg "$inpfile")"
 
-# We use the `-resize ..x..\>` syntax to only shrink pictures. Enlarging is
-# asking for trouble (artifacting, etc.)
-convert "$inpfile" -gravity center -resize "${width}x${height}>" \
-  -background "$bgcolor" -extent "${width}x${height}" \
-  "${outfile%.*}-${width}x${height}.${outfile##*.}"
+  # We use the `-resize ..x..\>` syntax to only shrink pictures. Enlarging is
+  # asking for trouble (artifacting, etc.)
+  convert "$inpfile" -gravity center -resize "${width}x${height}>" \
+    -background "$bgcolor" -extent "${width}x${height}" \
+    "${outfile%.*}-${width}x${height}.${outfile##*.}"
+done