Add Automation List / Region envelope example script

share/scripts/s_region_envelope.lua

@@ -0,0 +1,34 @@
+ardour { ["type"] = "Snippet", name = "Evaluate Region Gain Curve" }
+-- see also "Set Region Gain Curve" snippet
+
+function factory () return function ()
+
+	local sel = Editor:get_selection ()
+
+	-- iterate over selected regions
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:RegionSelection
+	for r in sel.regions:regionlist ():iter () do
+
+		-- test if it's an audio region
+		local ar = r:to_audioregion ();
+		if ar:isnil () then
+			goto next
+		end
+
+		-- get region-gain-curve is-a
+		-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:AutomationList
+		local al = ar:envelope ()
+
+		-- evaluate at 3 seconds (interpolated value)
+		print ("Value at 3sec", al:eval(Temporal.timepos_t(Session:nominal_sample_rate () * 3)))
+
+		-- iterate over events in the Automation List
+		for ev in al:events():iter() do
+			-- each event is-a https://manual.ardour.org/lua-scripting/class_reference/#Evoral:ControlEvent
+			-- when is-a https://manual.ardour.org/lua-scripting/class_reference/#Temporal:timepos_t
+			print (ev.when, ev.value)
+		end
+
+		::next::
+	end
+end end