chetan · February 22, 2019 20:35 · Feb 22, 2019
diff --git a/convert.sh b/convert.sh
@@ -0,0 +1,86 @@
+#!/bin/bash
+
+# convert.sh
+# util for generating resized images at multiple common display resolutions
+
+
+SIZES="720 750 1080 1100 1440 1680 2880"
+EXTS="jpg JPG jpeg JPEG"
+
+print_res() {
+  for f in "$@"; do
+    echo "$f: $(file "$f" | grep -Eo '[0-9]+x[0-9]+' | tail -n 1)";
+  done
+}
+
+split_name() {
+  local f=$1
+  local e
+  filename=""
+  ext=""
+  for e in $EXTS; do
+    echo $f | egrep \."$e"\$ >/dev/null
+    if [[ $? -eq 0 ]]; then
+      filename=$(basename $f .$e)
+      ext="$e"
+      return
+    fi
+  done
+}
+
+resize() {
+  if [ $# -eq 0 ]; then
+    return
+  fi
+
+  local f=$1
+
+  if [ ! -f "$f" ]; then
+    echo "warning: $f not found"
+    return
+  fi
+
+  echo "* resizing $f ..."
+
+  split_name $f
+  if [[ -z "$filename" ]]; then
+    echo "error: unknown file ext for $f"
+    return
+  fi
+
+  # convert images
+  for size in $SIZES; do
+    echo "  - ${size}px"
+  	convert $f -resize "${size}x" -blur 0x2 "${filename}-${size}w-o.${ext}"
+    /usr/local/opt/mozjpeg/bin/cjpeg -outfile "${filename}-${size}w.${ext}" "${filename}-${size}w-o.${ext}"
+    rm -f "${filename}-${size}w-o.${ext}"
+  done
+
+  echo "  done"
+
+  # print srcset for html
+  local src
+  read -r -d '' src <<-EOF
+  srcset="$(for size in $SIZES; do
+    echo "        ${filename}-${size}w.${ext} ${size}w,";
+  done;)"
+EOF
+  echo "$src" | sed -E -e 's/" +/"/' | sed -E -e 's/,"$/"/'
+  echo
+
+  # print image-set for css
+  read -r -d '' src <<-EOF
+  image-set($(for size in $SIZES; do
+    echo "          url(\"${filename}-${size}w.${ext}\") 1x,";
+  done;))
+EOF
+  echo "$src" | sed -E -e 's/\( +/(/' | sed -E -e 's/,)$/)/'
+}
+
+if [ $# -eq 0 ]; then
+  echo "usage: $0 file.jpg [...]"
+fi
+
+for f in "$@"; do
+  resize "$1"
+done