Remove "seconds_since_midnight" from epi/eframe. Use chrono instead

chrono works both natively and on web.

Related: https://github.com/emilk/egui/issues/212

egui_demo_lib/src/apps/fractal_clock.rs

@@ -37,10 +37,10 @@ impl epi::App for FractalClock {
         "🕑 Fractal Clock"
     }
 
-    fn update(&mut self, ctx: &egui::CtxRef, frame: &mut epi::Frame<'_>) {
+    fn update(&mut self, ctx: &egui::CtxRef, _frame: &mut epi::Frame<'_>) {
         egui::CentralPanel::default()
             .frame(Frame::dark_canvas(&ctx.style()))
-            .show(ctx, |ui| self.ui(ui, frame.info().seconds_since_midnight));
+            .show(ctx, |ui| self.ui(ui, crate::seconds_since_midnight()));
     }
 }
 

egui_demo_lib/src/lib.rs

@@ -154,3 +154,19 @@ fn test_egui_zero_window_size() {
         assert!(clipped_meshes.is_empty(), "There should be nothing to show");
     }
 }
+
+// ----------------------------------------------------------------------------
+
+/// Time of day as seconds since midnight. Used for clock in demo app.
+pub(crate) fn seconds_since_midnight() -> Option<f64> {
+    #[cfg(feature = "chrono")]
+    {
+        use chrono::Timelike;
+        let time = chrono::Local::now().time();
+        let seconds_since_midnight =
+            time.num_seconds_from_midnight() as f64 + 1e-9 * (time.nanosecond() as f64);
+        Some(seconds_since_midnight)
+    }
+    #[cfg(not(feature = "chrono"))]
+    None
+}

egui_demo_lib/src/wrap_app.rs

@@ -133,7 +133,7 @@ impl WrapApp {
             ui.with_layout(egui::Layout::right_to_left(), |ui| {
                 if false {
                     // TODO: fix the overlap on small screens
-                    if let Some(seconds_since_midnight) = frame.info().seconds_since_midnight {
+                    if let Some(seconds_since_midnight) = crate::seconds_since_midnight() {
                         if clock_button(ui, seconds_since_midnight).clicked() {
                             self.selected_anchor = "clock".to_owned();
                             if frame.is_web() {