rework brightness-notify to properly calculate using percentages

.local/bin/brightness-notify

@@ -1,32 +1,33 @@
 #!/bin/sh
-
-calc() {
-	awk "BEGIN {print int($*)}"
-}
-
 msgTag="brightness" # Arbitrary but unique message tag
-oldbrightness="$(cat /sys/class/backlight/*/brightness)"
-newbrightness="$(calc "$oldbrightness + $1 * 2.55")"
-percentage=$(calc "$newbrightness * .39215686274509803921")
 highlight="#7aa2f7"
 
-if [ "$percentage" -gt "100" ]; then
+round() {
+	awk "BEGIN {printf \"%.0f\", $*}"
+}
+
+oldbrightness="$(cat /sys/class/backlight/*/brightness)"
+oldpercent="$(round "$oldbrightness * (100/255)")"
+newpercent="$(round "$oldpercent + $1")"
+newbrightness="$(round "$newpercent * (255/100)")"
+
+if [ "$newpercent" -gt "100" ]; then
 	icon="gpm-brightness-lcd"
-    percentage=100
+	newpercent=100
-    newbrightness=255
+	newbrightness=255
-elif [ "$percentage" -gt "50" ]; then
+elif [ "$newpercent" -gt "50" ]; then
 	icon="gpm-brightness-lcd"
-elif [ "$percentage" -gt "0" ]; then
+elif [ "$newpercent" -gt "0" ]; then
 	icon="gpm-brightness-lcd-disabled"
 else
 	icon="gpm-brightness-lcd-disabled"
-    percentage=0
+	newpercent=0
-    newbrightness=0
+	newbrightness=0
 fi
 
-echo $newbrightness | tee /sys/class/backlight/*/brightness
+round $newbrightness | tee /sys/class/backlight/*/brightness
 
-notify-send -a "changeBrightness" -i "$icon" -u low "Brightness: ${percentage}%" \
+notify-send -a "changeBrightness" -i "$icon" -u low "Brightness: ${newpercent}%" \
 	-h string:x-dunst-stack-tag:$msgTag \
-	-h int:value:$percentage \
+	-h int:value:$newpercent \
 	-h string:hlcolor:$highlight