chbg: to shrink image when too large (i.e. bigger than 3840x2160).

- images too large may cause lagging, especially gtklock.

bin/chbg

@@ -3,10 +3,20 @@
 [ -z "$1" ] && { echo "Usage: $0 <image-file>"; exit 1; }
 
 WP_DIR="$HOME/.local/share"
+finput=$1
 
-echo -n "making blurred version... "
+fw=$(magick identify -format "%w\n" $1)
+fh=$(magick identify -format "%h\n" $1)
+if [[ $((fw)) > 3840 && $((fh)) > 2160 ]]
+then
+	finput="/tmp/${finput##*/}"
+	echo "WARNING: image too large, resizing ..."
+	magick $1 -resize "3840x2160^" $finput
+fi
+
+echo -n "making blurred version of $finput ... "
 mkdir -p $WP_DIR
-cp $1 $WP_DIR/.wallpaper
+cp $finput $WP_DIR/.wallpaper
 magick $WP_DIR/.wallpaper -filter Gaussian -blur 0x30 $WP_DIR/.wallpaper_blur
 echo "Done."