From c0704be3439d3db3c36308fb7c010641f2072ac5 Mon Sep 17 00:00:00 2001
From: Mitchell R <root@mitchellr.info>
Date: Sun, 10 May 2026 22:46:30 +0200
Subject: [PATCH] feat: DPMS fallback via wlr-randr for non-CEC desktop
 monitors

---
 kiosk/src/cec.rs | 104 +++++++++++++++++++++++++++++++++++------------
 kiosk/src/ui.rs  |   4 +-
 2 files changed, 80 insertions(+), 28 deletions(-)

diff --git a/kiosk/src/cec.rs b/kiosk/src/cec.rs
index 98ecf3e..f394f54 100644
--- a/kiosk/src/cec.rs
+++ b/kiosk/src/cec.rs
@@ -1,44 +1,49 @@
-//! CEC (HDMI Consumer Electronics Control) — manages display power state
-//! via `cec-ctl` subprocess. v4l-utils package provides cec-ctl on Pi5.
+//! Display power management — CEC for TVs, DPMS (wlr-randr/xset) for monitors.
 //!
-//! Commands:
-//!   - standby: tell TV to sleep
-//!   - image-view-on: wake TV
-//!   - is-active-source: query state
+//! Tries CEC first (works for HDMI TVs).
+//! Falls back to compositor-level output disable for desktop monitors that
+//! don't speak CEC.
 
 use std::process::Command;
 use tracing::{info, warn};
 
 const CEC_DEVICE: &str = "/dev/cec0";
 
-/// Send CEC standby (sleep) to all connected devices.
-pub fn standby() -> bool {
-    info!("cec: standby");
+/// Put the display to sleep — try CEC first, fall back to compositor DPMS.
+pub fn standby() {
+    info!("power: standby");
+    if !cec_standby() {
+        wlr_output_off();
+    }
+}
+
+/// Wake the display — try CEC first, fall back to compositor DPMS.
+pub fn wake() {
+    info!("power: wake");
+    if !cec_wake() {
+        wlr_output_on();
+    }
+}
+
+fn cec_standby() -> bool {
     run_cec(&["--standby", "--to", "0"])
 }
 
-/// Send CEC image-view-on (wake) to TV.
-pub fn wake() -> bool {
-    info!("cec: wake");
+fn cec_wake() -> bool {
     run_cec(&["--image-view-on", "--to", "0"])
 }
 
-/// Switch HDMI input on TV to this device.
-pub fn become_active_source() -> bool {
-    info!("cec: become active source");
-    run_cec(&["--active-source", "phys-addr=0.0.0.0"])
-}
-
 fn run_cec(args: &[&str]) -> bool {
-    match Command::new("cec-ctl")
-        .arg("-d")
-        .arg(CEC_DEVICE)
-        .args(args)
-        .output()
-    {
-        Ok(out) if out.status.success() => true,
+    if !std::path::Path::new(CEC_DEVICE).exists() {
+        return false;
+    }
+    match Command::new("cec-ctl").arg("-d").arg(CEC_DEVICE).args(args).output() {
+        Ok(out) if out.status.success() => {
+            info!("cec: ok");
+            true
+        }
         Ok(out) => {
-            warn!("cec-ctl failed: {}", String::from_utf8_lossy(&out.stderr));
+            warn!("cec failed: {}", String::from_utf8_lossy(&out.stderr));
             false
         }
         Err(e) => {
@@ -47,3 +52,50 @@ fn run_cec(args: &[&str]) -> bool {
         }
     }
 }
+
+/// Turn off all outputs via wlr-randr (Wayland compositors: labwc, wayfire, sway).
+fn wlr_output_off() {
+    // Get list of outputs
+    let outputs = list_outputs();
+    if outputs.is_empty() {
+        warn!("dpms: no outputs found");
+        return;
+    }
+    for output in outputs {
+        match Command::new("wlr-randr")
+            .args(["--output", &output, "--off"])
+            .output()
+        {
+            Ok(out) if out.status.success() => info!("dpms: {output} off"),
+            Ok(out) => warn!("dpms off {output} failed: {}", String::from_utf8_lossy(&out.stderr)),
+            Err(e) => warn!("wlr-randr unavailable: {e}"),
+        }
+    }
+}
+
+fn wlr_output_on() {
+    let outputs = list_outputs();
+    for output in outputs {
+        match Command::new("wlr-randr")
+            .args(["--output", &output, "--on"])
+            .output()
+        {
+            Ok(out) if out.status.success() => info!("dpms: {output} on"),
+            Ok(out) => warn!("dpms on {output} failed: {}", String::from_utf8_lossy(&out.stderr)),
+            Err(e) => warn!("wlr-randr unavailable: {e}"),
+        }
+    }
+}
+
+fn list_outputs() -> Vec<String> {
+    let out = match Command::new("wlr-randr").output() {
+        Ok(out) => out,
+        Err(_) => return Vec::new(),
+    };
+    let text = String::from_utf8_lossy(&out.stdout);
+    text.lines()
+        .filter(|l| !l.starts_with(' ') && !l.is_empty())
+        .map(|l| l.split_whitespace().next().unwrap_or("").to_string())
+        .filter(|s| !s.is_empty())
+        .collect()
+}
diff --git a/kiosk/src/ui.rs b/kiosk/src/ui.rs
index 485af6c..13c6eab 100644
--- a/kiosk/src/ui.rs
+++ b/kiosk/src/ui.rs
@@ -89,8 +89,8 @@ fn activate(app: &Application) {
                         let bundle = server::fetch_bundle(&server_for_reload, &key_for_reload);
                         let _ = tx_for_reload.send(WorkerMsg::RenderBundle(bundle));
                     }
-                    ServerMsg::Standby => { cec::standby(); }
-                    ServerMsg::Wake => { cec::wake(); }
+                    ServerMsg::Standby => cec::standby(),
+                    ServerMsg::Wake => cec::wake(),
                 }
             }
         });