Thesis: create low-res photos on-the-fly from existing photos

chertex.sh

@@ -84,8 +84,8 @@ if [ $# -eq 1 ]; then
    fi
 
 	#### Special treatment for thesis
-	# If $jobname is thesis, fetch some external assets
    if [[ ${PWD} ==  "/media/bay/taha/chepec/thesis" && $jobname == "thesis" ]]; then
+      # Fetch external assets by reading any assets.external files in assets/ tree
       echo "<thesis> -------------------------------"
       echo "<thesis> Getting external assets"
       echo "<thesis> -------------------------------"
@@ -108,9 +108,58 @@ if [ $# -eq 1 ]; then
             done < "$assets"
          fi
       done
+
+      # Create low-res photos on-the-fly from existing photos/
+      echo "<thesis> -------------------------------"
+      echo "<thesis> Create low-res photos tree"
+      echo "<thesis> -------------------------------"
+      # copy existing photos to assets/photos/.lowres/ path 
+      # to save time, rsync only if highres photo has more recent timestamp (otherwise, keep lowres photo without overwriting)
+      # Note: rsync usually looks at file timestamp and size, and if either has changed, copies the file (simplified explanation)
+      # in this case, I'd like rsync to only compare timestamps and disregard size 
+      # rsync can't do that. We need to use a different tool. See e.g.
+      # https://superuser.com/questions/260092/rsync-switch-to-only-compare-timestamps
+      # copy only the "large" photos that have file modtimes more recent than the last time this operation was run
+      photoslastrun="/media/bay/taha/chepec/thesis/assets/photos/.lowres/lastrun"
+      if [ ! -f "$photoslastrun" ]; then
+         # if, for some reason, the lastrun file does not exist
+         # copy over everything and then create the file
+         rsync -av /media/bay/taha/chepec/thesis/assets/photos/* /media/bay/taha/chepec/thesis/assets/photos/.lowres/ --exclude /media/bay/taha/chepec/thesis/assets/photos/.lowres/
+         touch "$photoslastrun"
+      fi
+      # cd and use --parents arg to preserve directory structure in .lowres target
+      cd /media/bay/taha/chepec/thesis/assets/photos
+      newphotos="$(find . -type f -cnewer $photoslastrun ! -path './.lowres/*')"
+      if [ -n "$newphotos" ]; then
+         for newphoto in $newphotos; do
+            cp --parents $newphoto .lowres/
+         done
+         # cd - also creates output (the current wd). Redirect to null suppresses the output.
+         cd - >/dev/null
+      fi
+      # in the low-res tree, find any photo larger than specific size (500kB)
+      largephotos="$(find /media/bay/taha/chepec/thesis/assets/photos/.lowres/ -size +500k)"
+      for largephotofilename in $largephotos; do
+         # for the next statement to work reliably, we should probably convert other formats to JPEG
+         # detect file extension, and based on it, convert to jpg using mogrify
+         largephotobase=$(basename -- "$largephotofilename") # just the filename (with extension, sans parents)
+         largephototype=${largephotobase#*.} # file extension only
+         largephotoname=${largephotofilename%.*} # path without extension
+         largephotobasename=${largephotobase%.*} # basename without extension
+         if [ ! "$largephototype" == "jpg" ] && [ ! "$largephototype" == "jpeg" ] && [ ! "$largephototype" == "JPG" ] && [ ! "$largephototype" == "JPEG" ]; then
+            echo "<thesis> Converting $largephotobase to JPG format"
+            mogrify -format jpg $largephotofilename
+            # remove the now unnecessary non-jpg file from .lowres/
+            rm "$largephotofilename"
+         fi
+         # convert photo in-place (overwrite) with new one roughly 300kb in size
+         # https://stackoverflow.com/questions/6917219/imagemagick-scale-jpeg-image-with-a-maximum-file-size
+         echo "<thesis> Shrinking $largephotobasename.jpg"
+         convert $largephotoname.jpg -define jpeg:extent=300kb $largephotoname.jpg
+      done
    fi
    # short delay to enable on-screen reading of previous echo
-	simpledelay.sh 1
+	simpledelay.sh 2
 
 
    ## Handle knitr or pgfSweave jobs (each requires separate treatment)