Add Lua example snippet to set region fades

share/scripts/s_set_region_fades.lua

@@ -0,0 +1,44 @@
+ardour { ["type"] = "Snippet", name = "Set Region Fades" }
+
+function factory () return function ()
+
+	-- ensure sure that fades are used and visible
+	-- (Session > Properties > Fades)
+	assert (Session:cfg():get_use_region_fades())
+	assert (Session:cfg():get_show_region_fades())
+
+	-- get Editor selection
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:Editor
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:Selection
+	local sel = Editor:get_selection ()
+	-- query the session's currane sample-rate
+	local sr = Session:nominal_sample_rate ()
+
+	-- iterate over Regions that part of the selection
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:RegionSelection
+	for r in sel.regions:regionlist ():iter () do
+		-- each of the items 'r' is-a
+		-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:Region
+
+		-- test if it is an audio region
+		local ar = r:to_audioregion ()
+		if ar:isnil () then goto next end
+
+		-- fade in/out for 500 msec, or half the region-length, whatever is shorter
+		local fadelen = .5 * sr
+		if fadelen > r:length () / 2 then
+			fadelen = r:length () / 2
+		end
+
+		-- https://manual.ardour.org/lua-scripting/class_reference/#ARDOUR.FadeShape
+		ar:set_fade_in_shape (ARDOUR.FadeShape.FadeConstantPower)
+		ar:set_fade_in_length (fadelen)
+		ar:set_fade_in_active (true)
+
+		ar:set_fade_out_shape (ARDOUR.FadeShape.FadeConstantPower)
+		ar:set_fade_out_length (fadelen)
+		ar:set_fade_out_active (true)
+
+		::next::
+	end
+end end