Add example selection-changed Lua script

share/scripts/_selection_change_callback.lua

@@ -0,0 +1,70 @@
+ardour {  ["type"] = "EditorHook", name = "On Editor Selection Change" }
+
+function signals ()
+	-- call script function when editor selection changes
+	return LuaSignal.Set():add ({[LuaSignal.SelectionChanged] = true})
+end
+
+-- output is printed to Window > Log
+
+function factory () return function ()
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:Selection
+	-- the Ardour Selection can include multiple items
+	-- (regions, tracks, ranges, markers, automation, midi-notes etc)
+	local sel = Editor:get_selection ()
+
+	--
+	-- At the point of writing the following data items are available
+	--
+
+	-- Track/Bus Selection
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:TrackSelection
+	for r in sel.tracks:routelist ():iter () do
+		-- each of the items is a
+		-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:Route
+		print ("Route:", r:name ())
+	end
+
+	-- Region selection
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:RegionSelection
+	for r in sel.regions:regionlist ():iter () do
+		-- each of the items is a
+		-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:Region
+		print ("Region:", r:name ())
+	end
+
+	-- Time Range selection, total span of all ranges (0, 0 if no time range is selected)
+	if sel.time:start_sample () < sel.time:end_sample () then
+		print ("Total Range:", sel.time:start_sample (), sel.time:end_sample ())
+	end
+
+	-- .. and the same in Temporal.timepos_t
+	if sel.time:start_time () < sel.time:end_time () then
+		print ("Total Range:", sel.time:start_time (), sel.time:end_time ())
+	end
+
+	-- Range selection, individual ranges.
+	for ar in sel.time:iter () do
+		-- each of the items is a
+		-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:TimelineRange
+		print ("Range:", ar.id, ar.start, ar._end)
+	end
+
+	-- Markers
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:MarkerSelection
+	for m in sel.markers:iter () do
+		-- each of the items is a
+		-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOURUI::ArdourMarker
+		print ("Marker:", m:name (), m:position(), m:_type())
+	end
+
+	----------------------------------------------------------
+	-- The total time extents of all selected regions and ranges
+	local ok, ext = Editor:get_selection_extents (Temporal.timepos_t(0), Temporal.timepos_t(0))
+	if ok then
+		print ("Selection Extents:", ext[1], ext[2])
+	else
+		print ("No region or range is selected")
+	end
+
+end end