xss-lock: tentative to keep current gamma

This doesn't seem to work. It seems xrandr 1.5.0 doesn't set gamma
values correctly, but even xrandr 1.5.1 seems to have an issue setting
the appropriate gamma value from an existing value.

bin/xss-lock

@@ -20,22 +20,23 @@ case "$1" in
         ;;
     dim|notify)
         echo "notify: start"
-        pkill -STOP redshift
+        redshift=$(systemctl --user show \
+                             --property MainPID \
+                             --value redshift@$(systemd-escape -- "$DISPLAY").service)
+        [ x$redshift = x ] || kill -STOP $redshift
         current=$(xrandr --verbose | sed -n \
                                          -e 's/\([^ ]*\) connected .*/--output \1/p' \
                                          -e 's/\t*Gamma: *\([^ ]\)/--gamma \1/p' \
                                          -e 's/\t*Brightness: *\([^ ]\)/--brightness \1/p' | \
                       tr '\n' ' ')
-        trap "echo resume redshift; xrandr $current; pkill -CONT redshift" EXIT
+        trap "echo notify: restore brightness;
+              xrandr $current;
+              [ x$redshift = x ] || kill -CONT $redshift" EXIT
         trap 'kill %% 2> /dev/null; exit 0' HUP  # user activity
         trap 'sleep 0.2s; kill %% 2> /dev/null; exit 0' TERM # locker started
-        outputs=($(xrandr -q | sed -n 's/\([^ ]*\) connected .*/\1/p'))
         for i in $(seq 0.7 -0.01 0.1); do
-            for out in ${outputs[@]}; do
-                xrandr --output $out --brightness $i || \
-                    outputs=("${outputs[@]/$out}")
-            done
-            sleep 0.1
+            xrandr $(echo $current | sed "s/\(--brightness\) [^ ]*/\1 $i/g")
+            sleep 0.05
         done
         echo "notify: end"
         sleep infinity &