T16 review fixes: an unknown system zone stops instead of reading as UTC, the view window refits when data shrinks, the volume profile counts narrow and flat candles whole, Fibonacci labels stay in their pane, the DOM ladder shows its tick's decimals, the tape flashes on each new trade, typed numbers reach their owner before a press, and a smaller loss than expected reads as a beat

src/finance/calendars.rs

@@ -11,7 +11,11 @@ use crate::{
     forms::flag,
     tables::{Cell, Column, DataTable, Row},
     theme::{ActiveTheme, TextSize},
-    typography::{Ellipsis, format, tabular},
+    typography::{
+        Ellipsis,
+        format::{self, system_zone},
+        tabular,
+    },
 };
 
 /// An economic release: when, for which region, what, how much it moves markets from one to three, and its figure as it came, as forecast and as before.
@@ -31,7 +35,7 @@ pub struct Release {
 #[derive(IntoElement)]
 pub struct EconomicCalendar {
     releases: Vec<Release>,
-    zone: TimeZone,
+    zone: Option<TimeZone>,
 }
 
 impl EconomicCalendar {
@@ -45,18 +49,22 @@ impl EconomicCalendar {
         );
         Self {
             releases,
-            zone: TimeZone::system(),
+            zone: None,
         }
     }
 
     pub fn zone(mut self, zone: TimeZone) -> Self {
-        self.zone = zone;
+        self.zone = Some(zone);
         self
     }
 }
 
 impl RenderOnce for EconomicCalendar {
     fn render(mut self, _: &mut Window, cx: &mut App) -> impl IntoElement {
+        let zone = self
+            .zone
+            .clone()
+            .unwrap_or_else(|| system_zone("EconomicCalendar"));
         let theme = cx.theme();
         let colors = theme.colors.clone();
         self.releases.sort_by_key(|release| release.time);
@@ -68,7 +76,7 @@ impl RenderOnce for EconomicCalendar {
         let mut out: Vec<gpui::AnyElement> = Vec::new();
         let mut day: Option<Date> = None;
         for release in &self.releases {
-            let zoned = release.time.to_zoned(self.zone.clone());
+            let zoned = release.time.to_zoned(zone.clone());
             if day != Some(zoned.date()) {
                 day = Some(zoned.date());
                 out.push(
@@ -179,6 +187,11 @@ pub struct Earnings {
     pub reported: Option<f64>,
 }
 
+/// How far a report beat its estimate, as a share of the estimate's size: positive when better, whatever the sign.
+pub(crate) fn surprise(estimate: f64, reported: f64) -> f64 {
+    (reported - estimate) / estimate.abs()
+}
+
 /// Earnings by date: each company, when in the day it reports, what is expected, and once reported, how far it beat or missed.
 #[derive(IntoElement)]
 pub struct EarningsCalendar {
@@ -222,7 +235,7 @@ impl RenderOnce for EarningsCalendar {
                 );
                 let surprise = match earnings.reported {
                     Some(reported) if earnings.estimate != 0.0 => {
-                        let share = reported / earnings.estimate - 1.0;
+                        let share = surprise(earnings.estimate, reported);
                         Cell::Tag(
                             format::percent(share, 1, true).into(),
                             if share >= 0.0 {
@@ -270,7 +283,7 @@ type OnStory = Rc<dyn Fn(usize, &mut Window, &mut App)>;
 pub struct NewsFeed {
     id: ElementId,
     stories: Vec<Story>,
-    zone: TimeZone,
+    zone: Option<TimeZone>,
     on_open: Option<OnStory>,
 }
 
@@ -279,13 +292,13 @@ impl NewsFeed {
         Self {
             id: id.into(),
             stories: stories.into_iter().collect(),
-            zone: TimeZone::system(),
+            zone: None,
             on_open: None,
         }
     }
 
     pub fn zone(mut self, zone: TimeZone) -> Self {
-        self.zone = zone;
+        self.zone = Some(zone);
         self
     }
 
@@ -298,6 +311,7 @@ impl NewsFeed {
 
 impl RenderOnce for NewsFeed {
     fn render(self, _: &mut Window, cx: &mut App) -> impl IntoElement {
+        let zone = self.zone.clone().unwrap_or_else(|| system_zone("NewsFeed"));
         let theme = cx.theme();
         let colors = theme.colors.clone();
         let mut order: Vec<usize> = (0..self.stories.len()).collect();
@@ -315,7 +329,7 @@ impl RenderOnce for NewsFeed {
                 let open = self.on_open.clone();
                 let when = story
                     .time
-                    .to_zoned(self.zone.clone())
+                    .to_zoned(zone.clone())
                     .strftime("%b %-d, %H:%M")
                     .to_string();
                 div()
@@ -376,3 +390,14 @@ impl RenderOnce for NewsFeed {
             }))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::surprise;
+
+    #[test]
+    fn a_smaller_loss_than_expected_is_a_beat() {
+        assert_eq!(surprise(-1.0, -0.5), 0.5);
+        assert_eq!(surprise(2.0, 1.5), -0.25);
+    }
+}