Use dotter

local/bin/lock

@@ -0,0 +1,10 @@
+#!/bin/sh
+for o in HDMI-A-2 DP-1 eDP-1; do
+	grim -o "$o" "/tmp/$o.png"
+    # check if the file exists
+    if [[ -f "/tmp/$o.png" ]]; then
+        corrupter "/tmp/$o.png" "/tmp/$o.png" &
+    fi
+done
+wait
+exec gtklock "$@"