Add receive_color_scheme_changed_with_init (#153)

* Revert "Cargo fmt"

This reverts commit 1441894.

* Revert "Remove unused"

This reverts commit a1c538d.

* Revert "Remove receive_color_scheme_changed_with_init"

This reverts commit 4ba6336.

* Simplify receive color scheme

src/desktop/settings.rs

@@ -27,9 +27,10 @@
 //! }
 //! ```
 
+use std::future::ready;
 use std::{collections::HashMap, convert::TryFrom, fmt::Debug};
 
-use futures_util::Stream;
+use futures_util::{Stream, StreamExt};
 use serde::{Deserialize, Serialize};
 use zbus::zvariant::{OwnedValue, Type, Value};
 
@@ -186,6 +187,20 @@ impl<'a> Settings<'a> {
             .await
     }
 
+    /// Listen to changes of the system's preferred color scheme
+    pub async fn receive_color_scheme_changed(
+        &self,
+    ) -> Result<impl Stream<Item = ColorScheme>, Error> {
+        Ok(self
+            .0
+            .signal_with_args::<Setting>(
+                "SettingChanged",
+                &[(0, APPEARANCE_NAMESPACE), (1, COLOR_SCHEME_KEY)],
+            )
+            .await?
+            .filter_map(|x| ready(ColorScheme::try_from(x).ok())))
+    }
+
     /// Signal emitted when a setting changes.
     ///
     /// # Specifications

src/proxy.rs

@@ -157,6 +157,31 @@ impl<'a> Proxy<'a> {
             .map_err(From::from)
     }
 
+    pub(crate) async fn signal_with_args<I>(
+        &self,
+        name: &'static str,
+        args: &[(u8, &str)],
+    ) -> Result<impl Stream<Item = I>, Error>
+    where
+        I: for<'de> Deserialize<'de> + Type + Debug,
+    {
+        Ok(self
+            .0
+            .receive_signal_with_args(name, args)
+            .await?
+            .filter_map({
+                #[cfg(not(feature = "tracing"))]
+                {
+                    move |msg| ready(msg.body().ok())
+                }
+                #[cfg(feature = "tracing")]
+                {
+                    let ifc = self.interface().to_owned();
+                    move |msg| ready(trace_body(name, &ifc, msg))
+                }
+            }))
+    }
+
     pub(crate) async fn signal<I>(&self, name: &'static str) -> Result<impl Stream<Item = I>, Error>
     where
         I: for<'de> Deserialize<'de> + Type + Debug,