battery: More work on brightness handling

applets/cosmic-applet-power-battery/src/backlight.rs

@@ -1,3 +1,6 @@
+// TODO: use udev to monitor for brightness changes?
+// How should key bindings be handled? Need something like gnome-settings-daemon?
+
 use std::{
     fs::{self, File},
     io::{self, Read},
@@ -5,17 +8,33 @@ use std::{
     str::FromStr,
 };
 
+#[zbus::dbus_proxy(
+    default_service = "org.freedesktop.login1",
+    interface = "org.freedesktop.login1.Session"
+)]
+trait LogindSession {
+    fn set_brightness(&self, subsystem: &str, name: &str, brightness: u32) -> zbus::Result<()>;
+}
+
 struct Backlight(PathBuf);
 
 impl Backlight {
-    fn brightness(&self) -> Option<i64> {
+    fn brightness(&self) -> Option<u32> {
         self.prop("brightness")
     }
 
-    fn max_brightness(&self) -> Option<i64> {
+    fn max_brightness(&self) -> Option<u32> {
         self.prop("max_brightness")
     }
 
+    async fn set_brightness(
+        &self,
+        session: &LogindSessionProxy<'_>,
+        value: u32,
+    ) -> zbus::Result<()> {
+        session.set_brightness("backlight", "", value).await // XXX
+    }
+
     fn prop<T: FromStr>(&self, name: &str) -> Option<T> {
         let mut file = File::open(&self.0.join(name)).ok()?;
         let mut s = String::new();
@@ -39,3 +58,5 @@ fn backlight() -> io::Result<Option<Backlight>> {
     }
     Ok(best_backlight)
 }
+
+// TODO: keyboard backlight

applets/cosmic-applet-power-battery/src/main.rs

@@ -1,7 +1,7 @@
 use futures::prelude::*;
 use gtk4::{glib, prelude::*};
 use relm4::{ComponentParts, ComponentSender, RelmApp, SimpleComponent, WidgetPlus};
-use std::time::Duration;
+use std::{process::Command, time::Duration};
 
 mod backlight;
 mod upower;
@@ -164,6 +164,11 @@ impl SimpleComponent for AppModel {
 
                         gtk4::Button {
                             set_label: "Power Settings...",
+                            connect_clicked => move |_| {
+                                // XXX open subpanel
+                                let _ = Command::new("cosmic-settings").spawn();
+                                // TODO hide
+                            }
                         }
                     }
                 }