Merge pull request #588 from Silvertree2010/fix/h851-min-secs-counter-ruler-shows-1-m

Fix Min:Secs showing 1 ms early at exact millisecond positions

crates/time/src/format.rs

@@ -43,7 +43,8 @@ impl TimeFormat {
 
 fn min_secs(s: Samples, sr: SampleRate) -> String {
     let neg = s < 0;
-    let ms_total = (sr.seconds(s.saturating_abs()) * 1000.0).floor() as i64;
+    // Integer maths: a float `seconds * 1000` lands just below exact millisecond positions.
+    let ms_total = i64::try_from(i128::from(s).abs() * 1000 / i128::from(sr.hz().max(1))).unwrap_or(i64::MAX);
     let mins = ms_total / 60_000;
     let secs = (ms_total / 1000) % 60;
     let ms = ms_total % 1000;

crates/time/tests/min_secs_exact_ms.rs

@@ -0,0 +1,36 @@
+//! Min:Secs shows exact millisecond positions exactly (no float-floor off-by-one).
+
+use soundcraft_time::{FrameRate, SampleRate, TempoMap, TimeFormat, format_position};
+
+fn min_secs(s: i64, sr: SampleRate) -> String {
+    format_position(s, TimeFormat::MinSecs, sr, &TempoMap::default(), FrameRate::default(), 0, 0)
+}
+
+fn expected(ms_total: i64) -> String {
+    format!("{}:{:02}.{:03}", ms_total / 60_000, (ms_total / 1000) % 60, ms_total % 1000)
+}
+
+#[test]
+fn known_positions_at_44100() {
+    assert_eq!(min_secs(88_641, SampleRate::HZ_44100), "0:02.010");
+    assert_eq!(min_secs(89_523, SampleRate::HZ_44100), "0:02.030");
+}
+
+#[test]
+fn negative_position_at_44100() {
+    assert_eq!(min_secs(-88_641, SampleRate::HZ_44100), "-0:02.010");
+}
+
+#[test]
+fn every_exact_millisecond_displays_exactly() {
+    for sr in [SampleRate::HZ_44100, SampleRate::HZ_48000] {
+        let hz = i64::from(sr.hz());
+        for ms in 0..=600_000_i64 {
+            if (ms * hz) % 1000 != 0 {
+                continue;
+            }
+            let s = ms * hz / 1000;
+            assert_eq!(min_secs(s, sr), expected(ms), "{hz} Hz, sample {s}");
+        }
+    }
+}