wip: support desktop portal color-scheme, and accent variables

src/theme/portal.rs

@@ -0,0 +1,77 @@
+use ashpd::desktop::settings::{ColorScheme, Contrast};
+use ashpd::desktop::Color;
+use iced::futures::{self, select, FutureExt, SinkExt, StreamExt};
+use iced_futures::subscription;
+
+#[derive(Debug, Clone)]
+pub enum Desktop {
+    Accent(Color),
+    ColorScheme(ColorScheme),
+    Contrast(Contrast),
+}
+
+pub fn desktop_settings() -> iced_futures::Subscription<Desktop> {
+    subscription::channel(std::any::TypeId::of::<Desktop>(), 10, |mut tx| {
+        async move {
+            let Ok(settings) = ashpd::desktop::settings::Settings::new().await else {
+                // wait forever
+                futures::future::pending::<()>().await;
+                unreachable!()
+            };
+            let mut color_scheme_stream = settings.receive_color_scheme_changed().await.ok();
+            let mut accent_stream = settings.receive_accent_color_changed().await.ok();
+            let mut contrast_stream = settings.receive_contrast_changed().await.ok();
+
+            loop {
+                let next_color_scheme = async {
+                    if let Some(s) = color_scheme_stream.as_mut() {
+                        return s.next().await;
+                    }
+                    futures::future::pending().await
+                };
+                let next_accent = async {
+                    if let Some(s) = accent_stream.as_mut() {
+                        // Item type is wrong in this version
+                        // updating requires updating to zbus 4
+                        return if s.next().await.is_some() {
+                            settings.accent_color().await.ok()
+                        } else {
+                            None
+                        };
+                    }
+                    futures::future::pending().await
+                };
+                let next_contrast = async {
+                    if let Some(s) = contrast_stream.as_mut() {
+                        return s.next().await;
+                    }
+                    futures::future::pending().await
+                };
+
+                select! {
+                    s = next_color_scheme.fuse() => {
+                        if let Some(s) = s {
+                            _ = tx.send(Desktop::ColorScheme(s)).await;
+                        } else {
+                            color_scheme_stream = None;
+                        }
+                    },
+                    a = next_accent.fuse() => {
+                        if let Some(a) = a {
+                            _ = tx.send(Desktop::Accent(a)).await;
+                        } else {
+                            accent_stream = None;
+                        }
+                    },
+                    c = next_contrast.fuse() => {
+                        if let Some(c) = c {
+                            _ = tx.send(Desktop::Contrast(c)).await;
+                        } else {
+                            contrast_stream = None;
+                        }
+                    }
+                };
+            }
+        }
+    })
+}