[pure refactor] Fix viewport to timepanel dependency (#2256)

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### What

Follow up to
* #2251

Improves out dependency graph around re_viewer a little bit!

```
cargo install cargo-depgraph
cargo depgraph --all-deps --workspace-only --all-features --dedup-transitive-deps | dot -Tpng > rerun-dependency-graph.png
```

![image](https://github.com/rerun-io/rerun/assets/1220815/2c6e4098-efc8-45ec-a44f-98a488d497fa)




### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)

<!-- This line will get updated when the PR build summary job finishes.
-->
PR Build Summary: https://build.rerun.io/pr/2256

crates/re_format/src/lib.rs

@@ -1,6 +1,9 @@
 //! Miscellaneous tools to format and parse numbers, durations, etc.
 
 pub mod arrow;
+mod time;
+
+pub use time::next_grid_tick_magnitude_ns;
 
 // --- Numbers ---
 

crates/re_format/src/time.rs

@@ -0,0 +1,20 @@
+/// When showing grid-lines representing time.
+///
+/// Given some spacing (e.g. 10s), return the next spacing (60s).
+pub fn next_grid_tick_magnitude_ns(spacing_ns: i64) -> i64 {
+    if spacing_ns <= 1_000_000_000 {
+        spacing_ns * 10 // up to 10 second ticks
+    } else if spacing_ns == 10_000_000_000 {
+        spacing_ns * 6 // to the whole minute
+    } else if spacing_ns == 60_000_000_000 {
+        spacing_ns * 10 // to ten minutes
+    } else if spacing_ns == 600_000_000_000 {
+        spacing_ns * 6 // to an hour
+    } else if spacing_ns == 60 * 60 * 1_000_000_000 {
+        spacing_ns * 12 // to 12 h
+    } else if spacing_ns == 12 * 60 * 60 * 1_000_000_000 {
+        spacing_ns * 2 // to a day
+    } else {
+        spacing_ns.checked_mul(10).unwrap_or(spacing_ns) // multiple of ten days
+    }
+}

crates/re_log_types/src/time.rs

@@ -99,6 +99,53 @@ impl Time {
         }
     }
 
+    /// Useful when showing dates/times on a timeline
+    /// and you want it compact.
+    ///
+    /// Shows dates when zoomed out, shows times when zoomed in,
+    /// shows relative millisecond when really zoomed in.
+    pub fn format_time_compact(&self) -> String {
+        let ns = self.nanos_since_epoch();
+        let relative_ns = ns % 1_000_000_000;
+        let is_whole_second = relative_ns == 0;
+        if is_whole_second {
+            if let Some(datetime) = self.to_datetime() {
+                let is_whole_minute = ns % 60_000_000_000 == 0;
+                let time_format = if self.is_exactly_midnight() {
+                    "[year]-[month]-[day]Z"
+                } else if is_whole_minute {
+                    "[hour]:[minute]Z"
+                } else {
+                    "[hour]:[minute]:[second]Z"
+                };
+                let parsed_format = time::format_description::parse(time_format).unwrap();
+                return datetime.format(&parsed_format).unwrap();
+            }
+
+            crate::Duration::from_nanos(ns).to_string()
+        } else {
+            // We are in the sub-second resolution.
+            // Showing the full time (HH:MM:SS.XXX or 3h 2m 6s …) becomes too long,
+            // so instead we switch to showing the time as milliseconds since the last whole second:
+            let ms = relative_ns as f64 * 1e-6;
+            if relative_ns % 1_000_000 == 0 {
+                format!("{ms:+.0} ms")
+            } else if relative_ns % 100_000 == 0 {
+                format!("{ms:+.1} ms")
+            } else if relative_ns % 10_000 == 0 {
+                format!("{ms:+.2} ms")
+            } else if relative_ns % 1_000 == 0 {
+                format!("{ms:+.3} ms")
+            } else if relative_ns % 100 == 0 {
+                format!("{ms:+.4} ms")
+            } else if relative_ns % 10 == 0 {
+                format!("{ms:+.5} ms")
+            } else {
+                format!("{ms:+.6} ms")
+            }
+        }
+    }
+
     #[inline]
     pub fn lerp(range: RangeInclusive<Time>, t: f32) -> Time {
         let (min, max) = (range.start().0, range.end().0);

crates/re_time_panel/Cargo.toml

@@ -19,14 +19,14 @@ all-features = true
 re_arrow_store.workspace = true
 re_data_store.workspace = true
 re_data_ui.workspace = true
+re_format.workspace = true
 re_log_types.workspace = true
 re_ui.workspace = true
 re_viewer_context.workspace = true
 
 egui.workspace = true
 itertools.workspace = true
 serde = "1.0"
-time.workspace = true
 vec1 = "1.8"
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]

crates/re_time_panel/src/lib.rs

@@ -4,15 +4,12 @@
 //! as well as all necessary ui elements that make it up.
 
 mod data_density_graph;
-mod format_time; // TODO(andreas): Move to re_format
 mod paint_ticks;
 mod time_axis;
 mod time_control_ui;
 mod time_ranges_ui;
 mod time_selection_ui;
 
-pub use format_time::{format_time_compact, next_grid_tick_magnitude_ns};
-
 use std::ops::RangeInclusive;
 
 use egui::{pos2, Color32, CursorIcon, NumExt, PointerButton, Rect, Shape, Vec2};
@@ -328,6 +325,7 @@ impl TimePanel {
         time_marker_ui(
             &self.time_ranges_ui,
             &mut ctx.rec_cfg.time_ctrl,
+            ctx.re_ui,
             ui,
             &time_area_painter,
             &timeline_rect,
@@ -627,6 +625,7 @@ fn collapsed_time_marker_and_time(ui: &mut egui::Ui, ctx: &mut ViewerContext<'_>
             time_marker_ui(
                 &time_ranges_ui,
                 &mut ctx.rec_cfg.time_ctrl,
+                ctx.re_ui,
                 ui,
                 &painter,
                 &time_range_rect,
@@ -987,6 +986,7 @@ fn interact_with_streams_rect(
 fn time_marker_ui(
     time_ranges_ui: &TimeRangesUi,
     time_ctrl: &mut TimeControl,
+    re_ui: &re_ui::ReUi,
     ui: &mut egui::Ui,
     time_area_painter: &egui::Painter,
     timeline_rect: &Rect,
@@ -1033,7 +1033,7 @@ fn time_marker_ui(
                 } else {
                     ui.visuals().widgets.inactive.fg_stroke
                 };
-                paint_time_cursor(
+                re_ui.paint_time_cursor(
                     time_area_painter,
                     x,
                     timeline_rect.top()..=ui.max_rect().bottom(),
@@ -1077,34 +1077,6 @@ fn time_marker_ui(
     }
 }
 
-pub fn paint_time_cursor(
-    painter: &egui::Painter,
-    x: f32,
-    y: RangeInclusive<f32>,
-    stroke: egui::Stroke,
-) {
-    let y_min = *y.start();
-    let y_max = *y.end();
-
-    let stroke = egui::Stroke {
-        width: 1.5 * stroke.width,
-        color: stroke.color,
-    };
-
-    let w = 10.0;
-    let triangle = vec![
-        pos2(x - 0.5 * w, y_min), // left top
-        pos2(x + 0.5 * w, y_min), // right top
-        pos2(x, y_min + w),       // bottom
-    ];
-    painter.add(egui::Shape::convex_polygon(
-        triangle,
-        stroke.color,
-        egui::Stroke::NONE,
-    ));
-    painter.vline(x, (y_min + w)..=y_max, stroke);
-}
-
 // ---------------------------------------------------------------------------
 
 /// Profiling macro for feature "puffin"

crates/re_time_panel/src/paint_ticks.rs

@@ -2,10 +2,9 @@ use std::ops::RangeInclusive;
 
 use egui::{lerp, pos2, remap_clamp, Align2, Color32, Rect, Rgba, Shape, Stroke};
 
+use re_format::next_grid_tick_magnitude_ns;
 use re_log_types::{Time, TimeRangeF, TimeReal, TimeType};
 
-use crate::format_time::{format_time_compact, next_grid_tick_magnitude_ns};
-
 use super::time_ranges_ui::TimeRangesUi;
 
 pub fn paint_time_ranges_and_ticks(
@@ -69,7 +68,7 @@ fn paint_time_range_ticks(
                 &ui.clip_rect(),
                 time_range, // ns
                 next_grid_tick_magnitude_ns,
-                |ns| format_time_compact(Time::from_ns_since_epoch(ns)),
+                |ns| Time::from_ns_since_epoch(ns).format_time_compact(),
             )
         }
         TimeType::Sequence => {

crates/re_ui/src/lib.rs

@@ -46,7 +46,7 @@ pub struct TopBarStyle {
 
 // ----------------------------------------------------------------------------
 
-use std::sync::Arc;
+use std::{ops::RangeInclusive, sync::Arc};
 
 use parking_lot::Mutex;
 
@@ -626,6 +626,37 @@ impl ReUi {
         style.background = self.egui_ctx.style().visuals.widgets.noninteractive.bg_fill;
         style
     }
+
+    /// Paints a time cursor for indicating the time on a time axis along x.
+    #[allow(clippy::unused_self)]
+    pub fn paint_time_cursor(
+        &self,
+        painter: &egui::Painter,
+        x: f32,
+        y: RangeInclusive<f32>,
+        stroke: egui::Stroke,
+    ) {
+        let y_min = *y.start();
+        let y_max = *y.end();
+
+        let stroke = egui::Stroke {
+            width: 1.5 * stroke.width,
+            color: stroke.color,
+        };
+
+        let w = 10.0;
+        let triangle = vec![
+            pos2(x - 0.5 * w, y_min), // left top
+            pos2(x + 0.5 * w, y_min), // right top
+            pos2(x, y_min + w),       // bottom
+        ];
+        painter.add(egui::Shape::convex_polygon(
+            triangle,
+            stroke.color,
+            egui::Stroke::NONE,
+        ));
+        painter.vline(x, (y_min + w)..=y_max, stroke);
+    }
 }
 
 // ----------------------------------------------------------------------------

crates/re_viewport/Cargo.toml

@@ -31,7 +31,6 @@ re_renderer = { workspace = true, default-features = false, features = [
   "serde",
 ] }
 re_tensor_ops.workspace = true
-re_time_panel.workspace = true # TODO(andreas): Unfortunate dependency, caused by `next_grid_tick_magnitude_ns`
 re_ui.workspace = true
 re_viewer_context.workspace = true
 

crates/re_viewport/src/view_time_series/ui.rs

@@ -4,7 +4,7 @@ use egui::{
 };
 
 use re_arrow_store::TimeType;
-use re_time_panel::next_grid_tick_magnitude_ns;
+use re_format::next_grid_tick_magnitude_ns;
 use re_viewer_context::ViewerContext;
 
 use super::SceneTimeSeries;
@@ -179,7 +179,8 @@ pub(crate) fn view_time_series(
         } else {
             ui.visuals().widgets.inactive.fg_stroke
         };
-        re_time_panel::paint_time_cursor(ui.painter(), time_x, response.rect.y_range(), stroke);
+        ctx.re_ui
+            .paint_time_cursor(ui.painter(), time_x, response.rect.y_range(), stroke);
     }
 
     response
@@ -188,7 +189,7 @@ pub(crate) fn view_time_series(
 fn format_time(time_type: TimeType, time_int: i64) -> String {
     if time_type == TimeType::Time {
         let time = re_log_types::Time::from_ns_since_epoch(time_int);
-        re_time_panel::format_time_compact(time)
+        time.format_time_compact()
     } else {
         time_type.format(re_log_types::TimeInt::from(time_int))
     }