#!/bin/sh # Usage: # $0 source-image-name output-image-name [ultimate-source [maxsize]] # # source-image-name can be as-is under img or autogenerated under img/a # Must be an acceptable primary image format. # # output-image-name target output filename # Must be under img/a/ or out/ and # must have a known alternate format suffix # # maxsize if present then the maximum allowed size for the alternate # If not supplied then a maximum will be computed # which is sufficiently smaller to be worthwhile. # # ultimate-source ultimate source image with original extension # Used to determine lossy or lossless handling. # If unset, source-image-name is used. # This will *remove* the output image target if the input does not exist. # This generates no output other than informational, on stderr. # This script will: # * do nothing (with no output image generated) # * leave an existing output image in place as up to date # * atomically create or replace the specified output image # * remove the output image if extant and the input not # # This may use/create flags under the .flags directory next to the output file. #echo "INFO: $0 $@" 1>&2 # Capture inputs. SRCIMGNAME=$1 OUTIMGNAME=$2 ULTIMATESRC=${3:-$1} MAXSIZE=$4 # Build an alternate format compact image on demand if needed and possible. # Any creation or update of the output image will be atomic. # Any created or updated output image will globally readable, user writable. # This may use a flag to cache a DONE or FAIL state. # Such flags will be ignored if this script is newer than the flag. # Such flags will be ignored if the rebuild flag is newer. # The output image must be within the autogen area. # The output image suffix determines the output format. # An unknown format will cause immedate return without making flags, etc. # The input image format must be an acceptable/known primary image format. # FOR NOW only PNG (.png) input is acceptable. # This can be used to build compact alternate images # * from autoscaled images while they are being built # * on demand from source hero and body images being used as-is # VARIABLES MATCHING FROM get_hero_img_inline. # TODO: they can be in future sourced from a common config file. # Until then, keep them in step. # # AUTOGEN cache locations. CACHEDIRAG=img/a # If the rebuild flags exists and is newer than any cached result flag, # unconditionally try to rebuild/refresh everything (carefully, under a lock). # Else return immediately on cached positive or negative results. # Assumes that a cached positive result is the most likely. # Should be touched after any substantive change to image selection/generation. REBUILDFLAG=$CACHEDIRAG/.rebuild.flag # Ceiling size (%) of alternate format image to use. MAXALTIMGPC=95 # Approximate uncompressed HTML overhead of an extra picture source tag. PICTURESOURCEOH=101 # ImageMagick seems not to work well as a wrapper on RPi with cwebp 0.5.2 # DHD20210802: use locally-built (cut-down) cwebp if available, not distro. CWEBP=cwebp if [ -x /usr/local/bin/cwebp ]; then CWEBP=/usr/local/bin/cwebp; fi # Input image validation. # Input image must be of acceptable primary type. case $SRCIMGNAME in *.png) ;; # Good! *.jpg) ;; # Good! *) echo "ERROR: input image type not acceptable" 1>&2 exit 1;; esac # Output image validation. # Output image must be of an acceptable alternative type. case $OUTIMGNAME in *.webp) ;; # Good! *.avif|*.jxl) #echo "INFO: output image type not yet available" 1>&2 exit 0;; # Not an error, just does nothing. *) echo "ERROR: output image type not acceptable" 1>&2 exit 1;; esac # # Output image path must be in the autogenerated image directory or out/. case $OUTIMGNAME in out/*) ;; # Good! $CACHEDIRAG/*) ;; # Good! *) echo "ERROR: output image path not acceptable: not under out/ nor $CACHEDIRAG" 1>&2 exit 1;; esac # If input image does not exist and output does, remove the output and stop. # Not an error. if [ ! -s "$SRCIMGNAME" -a -f "$OUTIMGNAME" ]; then rm -f "$OUTIMGNAME" echo "INFO: input image file missing or zero length, output removed." 1>&2 exit 0 fi # Mode selection. case $ULTIMATESRC in *.png) MODE=lossless;; # Good! *.jpg) MODE=lossy;; # Good! *) echo "ERROR: cannot determine processing mode from ultimate source name" 1>&2 exit 1;; esac # Create a maximum output size if not provided. if [ "" = "$MAXSIZE" ]; then srcsize="`wc -c < $SRCIMGNAME | awk '{print $1}'`" # Allow for the HTML overhead of a new source tag. # Then enforce a mimimum % saving. MAXSIZE="`expr \( $srcsize \* $MAXALTIMGPC \) / 100`" outsizelessoh="`expr $srcsize - $PICTURESOURCEOH`" if [ "$outsizelessoh" -lt "$MAXSIZE" ]; then MAXSIZE=$outsizelessoh fi #echo "INFO: computed MAXSIZE=$MAXSIZE from input size $srcsize" 1>&2 fi # Temporary output filename, parallel safe, removed on error exit. OUTTMPNAME=$OUTIMGNAME.$$.tmp trap "rm -f $OUTTMPNAME; exit 1" 1 2 15 # Handle lossless alternative formats first. if [ "lossless" = "$MODE" ]; then case $OUTIMGNAME in *.webp) $CWEBP -quiet -mt -q 100 -lossless -m 6 $SRCIMGNAME -o $OUTTMPNAME ;; *) echo "ERROR: output image type invalid" 1>&2; exit 1;; esac fi # LOSSLESS # Handle lossy. if [ "lossy" = "$MODE" ]; then case $OUTIMGNAME in *.webp) # Assume that cwebp does a reasonable job automatically. $CWEBP -quiet -mt -m 6 $SRCIMGNAME -o $OUTTMPNAME ;; *) echo "ERROR: output image type invalid" 1>&2; exit 1;; esac fi # LOSSLESS # Atomically move new file into place if: # * It exists and is non-zero length. # * It is different to something already there. # If no alternate was produced or was zero length or too large # then remove new tmp *and any extant result* are removed. # This is not an error. #if [ -s "$OUTTMPNAME" ]; then echo "INFO: MADE alternate `ls -l $OUTTMPNAME`" 1>&2; fi if [ ! -s "$OUTTMPNAME" ]; then echo "INFO: alternate not made or zero-length" 1>&2 rm -f $OUTTMPNAME $OUTIMGNAME exit 0 fi if [ "`wc -c < $OUTTMPNAME`" -gt "$MAXSIZE" ]; then #echo "INFO: alternate too large" 1>&2 rm -f $OUTTMPNAME $OUTIMGNAME exit 0 fi # Only move valid new alternate into place if different from any extant. # If there is an extant identical result in place, discard the new tmp. if [ -s "$OUTIMGNAME" ]; then if cmp -s $OUTTMPNAME $OUTIMGNAME; then echo "INFO: leaving alone unchanged alternate $OUTIMGNAME" 1>&2 rm -f $OUTTMPNAME exit 0 fi chmod u+w $OUTIMGNAME fi # Make new tmp globally readable. chmod a+r $OUTTMPNAME # Atomic move into place. mv -f $OUTTMPNAME $OUTIMGNAME echo "INFO: moved into place new alternate $OUTIMGNAME" 1>&2 # Clean up any residual temporary file and exit without error. rm -f $OUTTMPNAME exit 0 # Code from the future... if false; then # WEBP lossy if [ "webp" = "$fmt" ]; then # Attempt to build a temporary alternate # to move into place later. # TARGETPSNR includes a fudge factor from ImageMagick to WEBP. TARGETPSNR=`$COMPARE -metric PSNR $NOLOSSTMP ${imain} null: 2>&1 | awk '{print ($1 + 4.5)}'` #echo "INFO: TARGETPSNR $TARGETPSNR" | tee -a $AGHBINFO 1>&2 # If it is zero length or not enough smaller, zap it. # NOTE: always generate from the *lossless* version. $CWEBP -quiet -mt -psnr $TARGETPSNR -pass 10 -m 6 -af $NOLOSSTMP -o $itmp if [ ! -f "$itmp" ]; then continue; fi if [ ! -s "$itmp" ]; then rm -f "$itmp"; continue; fi imainsize="`wc -c < $imain | awk '{print $1}'`" itmpsize="`wc -c < $itmp | awk '{print $1}'`" # Allow for the HTML overhead of a new source tag. # Then enforce a mimimum % saving. maxtmpsize="`expr \( $imainsize \* $MAXALTIMGPC \) / 100`" #echo "INFO: imainsize=$imainsize maxtmpsize=$maxtmpsize itmpsize=$itmpsize" | tee -a $AGHBINFO 1>&2 if [ "$itmpsize" -gt "$maxtmpsize" ]; then rm -f "$itmp"; continue; fi echo "INFO: MADE smaller alternate $itmp $itmpsize cf $imainsize" | tee -a $AGHBINFO 1>&2 fi