Add Lua script snippet to query/modify tempo-map

share/scripts/s_tempo_map.lua

@@ -0,0 +1,25 @@
+ardour { ["type"] = "Snippet", name = "tempo map examples" }
+
+function factory () return function ()
+
+	-- query BPM at 00:00:10:00
+	local tp = Temporal.timepos_t.from_superclock (Temporal.superclock_ticks_per_second * Session:nominal_sample_rate () * 10)
+	local tm = Temporal.TempoMap.use ()
+	print (tm:tempo_at (tp):quarter_notes_per_minute ())
+
+	-- set initial tempo to 140, ramp to 120 over the first 4/4 bar, then continue at BPM 80
+	Temporal.TempoMap.fetch_writable ()
+	local tm = Temporal.TempoMap.use ()
+	tm:set_tempo (Temporal.Tempo (140, 120, 4), Temporal.timepos_t ())
+	tm:set_tempo (Temporal.Tempo (80, 80, 4), Temporal.timepos_t.from_ticks (Temporal.ticks_per_beat * 4))
+	Temporal.TempoMap.update (tm)
+	tm = nil
+
+	-- Abort Edit example
+	-- after every call to Temporal.TempoMap.fetch_writable ()
+	-- there must be a matching call to
+	-- Temporal.TempoMap.update() or Temporal.TempoMap.abort_update()
+	Temporal.TempoMap.fetch_writable()
+	Temporal.TempoMap.abort_update()
+
+end end