Fix tempo-grid calculation: prevent duplicate events, enforce range

diff --git a/libs/ardour/tempo.cc b/libs/ardour/tempo.cc
index e24d21ef6bd6503687fed31b67931ef2dba26d56..77f7265717b6b0b27c21336ccd4a75c292150b60 100644 (file)
--- a/libs/ardour/tempo.cc
+++ b/libs/ardour/tempo.cc
@@ -4139,7 +4139,6 @@ TempoMap::get_grid (vector<TempoMap::BBTPoint>& points,
 {
        Glib::Threads::RWLock::ReaderLock lm (lock);
        int32_t cnt = ceil (beat_at_minute_locked (_metrics, minute_at_sample (lower)));
-       samplecnt_t pos = 0;
        /* although the map handles negative beats, bbt doesn't. */
        if (cnt < 0.0) {
                cnt = 0.0;
@@ -4149,13 +4148,18 @@ TempoMap::get_grid (vector<TempoMap::BBTPoint>& points,
                return;
        }
        if (bar_mod == 0) {
-               while (pos >= 0 && pos < upper) {
-                       pos = sample_at_minute (minute_at_beat_locked (_metrics, cnt));
+               while (true) {
+                       samplecnt_t pos = sample_at_minute (minute_at_beat_locked (_metrics, cnt));
+                       if (pos >= upper) {
+                               break;
+                       }
                        const MeterSection meter = meter_section_at_minute_locked (_metrics, minute_at_sample (pos));
                        const BBT_Time bbt = bbt_at_beat_locked (_metrics, cnt);
                        const double qn = pulse_at_beat_locked (_metrics, cnt) * 4.0;
 
-                       points.push_back (BBTPoint (meter, tempo_at_minute_locked (_metrics, minute_at_sample (pos)), pos, bbt.bars, bbt.beats, qn));
+                       if (pos >= lower) {
+                               points.push_back (BBTPoint (meter, tempo_at_minute_locked (_metrics, minute_at_sample (pos)), pos, bbt.bars, bbt.beats, qn));
+                       }
                        ++cnt;
                }
        } else {
@@ -4168,12 +4172,17 @@ TempoMap::get_grid (vector<TempoMap::BBTPoint>& points,
                        ++bbt.bars;
                }
 
-               while (pos >= 0 && pos < upper) {
-                       pos = sample_at_minute (minute_at_bbt_locked (_metrics, bbt));
+               while (true) {
+                       samplecnt_t pos = sample_at_minute (minute_at_bbt_locked (_metrics, bbt));
+                       if (pos >= upper) {
+                               break;
+                       }
                        const MeterSection meter = meter_section_at_minute_locked (_metrics, minute_at_sample (pos));
                        const double qn = pulse_at_bbt_locked (_metrics, bbt) * 4.0;
 
-                       points.push_back (BBTPoint (meter, tempo_at_minute_locked (_metrics, minute_at_sample (pos)), pos, bbt.bars, bbt.beats, qn));
+                       if (pos >= lower) {
+                               points.push_back (BBTPoint (meter, tempo_at_minute_locked (_metrics, minute_at_sample (pos)), pos, bbt.bars, bbt.beats, qn));
+                       }
                        bbt.bars += bar_mod;
                }
        }