Move time code from old-panel into an applet

Removes the last of `old-panel`.

applets/cosmic-applet-time/src/deref_cell.rs

@@ -0,0 +1,31 @@
+use once_cell::unsync::OnceCell;
+
+/// Wrapper around `OnceCell` implementing `Deref`, and thus also panicking
+/// when not set (or set twice).
+///
+/// To be used in place of `gtk::TemplateChild`, but without xml.
+pub struct DerefCell<T>(OnceCell<T>);
+
+impl<T> DerefCell<T> {
+    #[track_caller]
+    pub fn set(&self, value: T) {
+        if self.0.set(value).is_err() {
+            panic!("Initialized twice");
+        }
+    }
+}
+
+impl<T> Default for DerefCell<T> {
+    fn default() -> Self {
+        Self(OnceCell::default())
+    }
+}
+
+impl<T> std::ops::Deref for DerefCell<T> {
+    type Target = T;
+
+    #[track_caller]
+    fn deref(&self) -> &T {
+        self.0.get().unwrap()
+    }
+}

applets/cosmic-applet-time/src/main.rs

@@ -0,0 +1,32 @@
+use gtk4::{glib, prelude::*};
+
+mod deref_cell;
+mod time_button;
+use time_button::TimeButton;
+
+fn main() {
+    gtk4::init().unwrap();
+
+    let provider = gtk4::CssProvider::new();
+    provider.load_from_data(include_bytes!("style.css"));
+    gtk4::StyleContext::add_provider_for_display(
+        &gtk4::gdk::Display::default().expect("Could not connect to a display."),
+        &provider,
+        gtk4::STYLE_PROVIDER_PRIORITY_APPLICATION,
+    );
+
+    let time_button = TimeButton::new();
+
+    gtk4::Window::builder()
+        .decorated(false)
+        .child(&time_button)
+        .resizable(false)
+        .width_request(1)
+        .height_request(1)
+        .css_classes(vec!["root_window".to_string()])
+        .build()
+        .show();
+
+    let main_loop = glib::MainLoop::new(None, false);
+    main_loop.run();
+}

applets/cosmic-applet-time/src/style.css

@@ -0,0 +1,33 @@
+.loading-overlay {
+	background-color: #2f2f2f;
+	opacity: 0.85;
+}
+
+image.panel_icon {
+    padding-left: 0px;
+    padding-right: 0px;
+    padding-top: 0px;
+    padding-bottom: 0px;
+}
+
+button.panel_icon {
+    border-radius: 12px;
+    transition: 100ms;
+    padding: 4px;
+    border-color: transparent;
+    background: transparent;
+    outline-color: transparent;
+}
+
+button.panel_icon:hover {
+    border-radius: 12px;
+    transition: 100ms;
+    padding: 4px;
+    border-color: rgba(255, 255, 255, 0.1);
+    outline-color: rgba(255, 255, 255, 0.1);
+    background: rgba(255, 255, 255, 0.1);
+}
+
+window.root_window {
+	background: transparent;
+}

applets/cosmic-applet-time/src/time_button.rs

@@ -0,0 +1,110 @@
+use cascade::cascade;
+use gtk4::{
+    glib::{self, clone},
+    pango,
+    prelude::*,
+    subclass::prelude::*,
+};
+
+use crate::deref_cell::DerefCell;
+
+#[derive(Default)]
+pub struct TimeButtonInner {
+    calendar: DerefCell<gtk4::Calendar>,
+    button: DerefCell<gtk4::MenuButton>,
+    label: DerefCell<gtk4::Label>,
+}
+
+#[glib::object_subclass]
+impl ObjectSubclass for TimeButtonInner {
+    const NAME: &'static str = "S76TimeButton";
+    type ParentType = gtk4::Widget;
+    type Type = TimeButton;
+
+    fn class_init(klass: &mut Self::Class) {
+        klass.set_layout_manager_type::<gtk4::BinLayout>();
+    }
+}
+
+impl ObjectImpl for TimeButtonInner {
+    fn constructed(&self, obj: &TimeButton) {
+        let calendar = cascade! {
+            gtk4::Calendar::new();
+        };
+
+        let label = cascade! {
+            gtk4::Label::new(None);
+            ..set_attributes(Some(&cascade! {
+                pango::AttrList::new();
+                ..insert(pango::AttrInt::new_weight(pango::Weight::Bold));
+            }));
+        };
+
+        let popover = cascade! {
+            gtk4::Popover::new();
+            ..set_child(Some(&cascade! {
+                gtk4::Box::new(gtk4::Orientation::Horizontal, 0);
+                ..append(&calendar);
+            }));
+            ..connect_show(clone!(@strong obj => move |_| obj.opening()));
+        };
+
+        let button = cascade! {
+            gtk4::MenuButton::new();
+            ..set_child(Some(&label));
+            ..set_has_frame(false);
+            ..set_parent(obj);
+            ..set_popover(Some(&popover));
+        };
+
+        self.calendar.set(calendar);
+        self.button.set(button);
+        self.label.set(label);
+
+        // TODO: better way to do this?
+        glib::timeout_add_seconds_local(
+            1,
+            clone!(@weak obj => @default-return glib::Continue(false), move || {
+                obj.update_time();
+                glib::Continue(true)
+            }),
+        );
+        obj.update_time();
+    }
+
+    fn dispose(&self, _obj: &TimeButton) {
+        self.button.unparent();
+    }
+}
+
+impl WidgetImpl for TimeButtonInner {}
+
+glib::wrapper! {
+    pub struct TimeButton(ObjectSubclass<TimeButtonInner>)
+        @extends gtk4::Widget;
+}
+
+impl TimeButton {
+    pub fn new() -> Self {
+        glib::Object::new::<Self>(&[]).unwrap()
+    }
+
+    fn inner(&self) -> &TimeButtonInner {
+        TimeButtonInner::from_instance(self)
+    }
+
+    fn opening(&self) {
+        let date = glib::DateTime::now(&glib::TimeZone::local()).unwrap();
+        self.inner().calendar.clear_marks();
+        self.inner().calendar.select_day(&date);
+    }
+
+    fn update_time(&self) {
+        // TODO: Locale-based formatting?
+        let time = chrono::Local::now();
+        self.inner()
+            .label
+            .set_label(&time.format("%b %-d %-I:%M %p").to_string());
+        // time.format("%B %-d %Y")
+    }
+}