Add a config flag to disable an output

resources/default-config.kdl

@@ -43,6 +43,9 @@ input {
 // The built-in laptop monitor is usually called "eDP-1".
 // Remember to uncommend the node by removing "/-"!
 /-output "eDP-1" {
+    // Uncomment this line to disable this output.
+    // off
+
     // Scale is a floating-point number, but at the moment only integer values work.
     scale 2.0
 

src/backend/tty.rs

@@ -431,6 +431,11 @@ impl Tty {
             .cloned()
             .unwrap_or_default();
 
+        if config.off {
+            debug!("output is disabled in the config");
+            return Ok(());
+        }
+
         let device = self
             .output_device
             .as_mut()

src/config.rs

@@ -120,6 +120,8 @@ pub struct Tablet {
 
 #[derive(knuffel::Decode, Debug, Clone, PartialEq)]
 pub struct Output {
+    #[knuffel(child)]
+    pub off: bool,
     #[knuffel(argument)]
     pub name: String,
     #[knuffel(child, unwrap(argument), default = 1.)]
@@ -133,6 +135,7 @@ pub struct Output {
 impl Default for Output {
     fn default() -> Self {
         Self {
+            off: false,
             name: String::new(),
             scale: 1.,
             position: None,
@@ -624,6 +627,7 @@ mod tests {
                     },
                 },
                 outputs: vec![Output {
+                    off: false,
                     name: "eDP-1".to_owned(),
                     scale: 2.,
                     position: Some(Position { x: 10, y: 20 }),