feat(time): formattable datetime strings with strftime

cosmic-applet-time/src/window.rs

@@ -43,6 +43,11 @@ use icu::{
 
 static AUTOSIZE_MAIN_ID: LazyLock<Id> = LazyLock::new(|| Id::new("autosize-main"));
 
+// Specifiers for strftime that indicate seconds. Subsecond precision isn't supported by the applet
+// so those specifiers aren't listed here. This list is non-exhaustive, and it's possible that %X
+// and other specifiers have to be added depending on locales.
+const STRFTIME_SECONDS: &[char] = &['S', 'T', '+', 's'];
+
 fn get_system_locale() -> Locale {
     for var in ["LC_TIME", "LC_ALL", "LANG"] {
         if let Ok(locale_str) = std::env::var(var) {
@@ -159,6 +164,16 @@ impl Window {
     }
 
     fn vertical_layout(&self) -> Element<'_, Message> {
+        let elements: Vec<Element<'_, Message>> = if !self.config.format_strftime.is_empty() {
+            // strftime formatter may override locale specific elements so it stands alone rather
+            // than using ICU to determine a format.
+            self.now
+                .format(&self.config.format_strftime)
+                .to_string()
+                .split_whitespace()
+                .map(|piece| self.core.applet.text(piece.to_owned()).into())
+                .collect()
+        } else {
             let mut elements = Vec::new();
             let date = self.now.naive_local();
             let datetime = self.create_datetime(&date);
@@ -199,6 +214,9 @@ impl Window {
                 elements.push(self.core.applet.text(p.to_owned()).into());
             }
 
+            elements
+        };
+
         let date_time_col = Column::with_children(elements)
             .align_x(Alignment::Center)
             .spacing(4);
@@ -216,6 +234,9 @@ impl Window {
     }
 
     fn horizontal_layout(&self) -> Element<'_, Message> {
+        let formatted_date = if !self.config.format_strftime.is_empty() {
+            self.now.format(&self.config.format_strftime).to_string()
+        } else {
             let datetime = self.create_datetime(&self.now);
             let mut prefs = DateTimeFormatterPreferences::from(self.locale.clone());
             prefs.hour_cycle = Some(if self.config.military_time {
@@ -224,7 +245,7 @@ impl Window {
                 HourCycle::H12
             });
 
-        let formatted_date = if self.config.show_date_in_top_panel {
+            if self.config.show_date_in_top_panel {
                 if self.config.show_weekday {
                     let mut fs = fieldsets::MDET::long();
                     if !self.config.show_seconds {
@@ -253,6 +274,7 @@ impl Window {
                     .unwrap()
                     .format(&datetime)
                     .to_string()
+            }
         };
 
         Element::from(
@@ -587,7 +609,20 @@ impl cosmic::Application for Window {
             Message::ConfigChanged(c) => {
                 // Don't interrupt the tick subscription unless necessary
                 self.show_seconds_tx.send_if_modified(|show_seconds| {
-                    if *show_seconds == c.show_seconds {
+                    if !c.format_strftime.is_empty() {
+                        if c.format_strftime.split('%').any(|s| {
+                            STRFTIME_SECONDS.contains(&s.chars().next().unwrap_or_default())
+                        }) && !*show_seconds
+                        {
+                            // The strftime formatter contains a seconds specifier. Force enable
+                            // ticking per seconds internally regardless of the user setting.
+                            // This does not change the user's setting. It's invisible to the user.
+                            *show_seconds = true;
+                            true
+                        } else {
+                            false
+                        }
+                    } else if *show_seconds == c.show_seconds {
                         false
                     } else {
                         *show_seconds = c.show_seconds;

cosmic-applets-config/src/time.rs

@@ -11,6 +11,8 @@ pub struct TimeAppletConfig {
     pub first_day_of_week: u8,
     pub show_date_in_top_panel: bool,
     pub show_weekday: bool,
+    #[serde(default, skip_serializing_if = "str::is_empty")]
+    pub format_strftime: String,
 }
 
 impl Default for TimeAppletConfig {
@@ -21,6 +23,7 @@ impl Default for TimeAppletConfig {
             first_day_of_week: 6,
             show_date_in_top_panel: true,
             show_weekday: false,
+            format_strftime: Default::default(),
         }
     }
 }