* clean up, add comments * skip out-of-bounds notes * replace assert() with dialogs * add simple icon
222 lines
7.1 KiB
Lua
222 lines
7.1 KiB
Lua
ardour {
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["type"] = "EditorAction",
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name = "Scala to MIDI Tuning",
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license = "MIT",
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author = "Ardour Team",
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description = [[Read scala (.scl) tuning from a file, generate MIDI tuning standard (MTS) messages and send them to a MIDI port]]
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}
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function factory () return function ()
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-- return table of all MIDI tracks, and all instrument plugins.
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--
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-- MidiTrack::write_immediate_event() injects MIDI events to the track's input
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-- PluginInsert::write_immediate_event() sends events directly to a plugin
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function midi_targets ()
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local rv = {}
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for r in Session:get_tracks():iter() do
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if not r:to_track():isnil() then
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local mtr = r:to_track():to_midi_track()
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if not mtr:isnil() then
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rv["Track: '" .. r:name() .. "'"] = mtr
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end
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end
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local i = 0;
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while true do
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local proc = r:nth_plugin (i)
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if proc:isnil () then break end
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local pi = proc:to_plugininsert ()
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if pi:is_instrument () then
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rv["Track: '" .. r:name() .. "' | Plugin: '" .. pi:name() .. "'"] = pi
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end
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i = i + 1
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end
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end
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return rv
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end
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function log2 (v)
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return math.log (v) / math.log (2)
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end
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-- calculate MIDI note-number and cent-offset for a given frequency
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function freq_to_mts (hz)
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local note = math.floor (12. * log2 (hz / 440) + 69.0)
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local freq = 440.0 * 2.0 ^ ((note - 69) / 12);
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assert (freq > note)
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local cent = 1200.0 * log2 (hz / freq)
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return note, cent
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end
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-- apply octave and cent offset to the given frequency
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function calc_freq (hz, cent, octave)
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return hz * 2 ^ ((cent + 1200 * octave) / 1200)
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end
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local dialog_options = {
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{ type = "file", key = "file", title = "Select .scl file" },
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{ type = "dropdown", key = "tx", title = "MIDI SysEx Target", values = midi_targets () }
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}
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local rv = LuaDialog.Dialog ("Select Scala File and MIDI Taget", dialog_options):run ()
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dialog_options = nil -- drop references (track, plugins, shared ptr)
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collectgarbage () -- and release the references immediately
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if not rv then return end -- user cancelled
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-- read the scl file
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local freqtbl = {}
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local ln = 0
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local expected_len = 0
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local f = io.open (rv["file"], "r")
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if not f then
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LuaDialog.Message ("Scala to MTS", "File Not Found", LuaDialog.MessageType.Error, LuaDialog.ButtonType.Close):run ()
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return
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end
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-- parse scala file and convert all intervals to cents
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-- http://www.huygens-fokker.org/scala/scl_format.html
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freqtbl[1] = 0.0 -- implicit
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for line in f:lines () do
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line = string.gsub (line, "%s", "") -- remove all whitespace
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if line:sub(0,1) == '!' then goto nextline end -- comment
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ln = ln + 1
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if ln < 2 then goto nextline end -- name
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if ln < 3 then
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expected_len = tonumber (line) -- number of notes on scale
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if expected_len < 1 or expected_len > 256 then break end -- invalid file
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goto nextline
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end
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local cents
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if string.find (line, ".", 1, true) then
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cents = tonumber (line)
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else
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local n, d = string.match(line, "(%d+)/(%d+)")
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if n then
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cents = 1200 * log2 (n / d)
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else
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local n = tonumber (line)
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cents = 1200 * log2 (n)
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end
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end
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--print ("SCL", ln - 2, cents)
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freqtbl[ln - 1] = cents
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::nextline::
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end
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f:close ()
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-- We need at least one interval.
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-- While legal in scl, single note scales are not useful here.
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if expected_len < 1 or expected_len + 2 ~= ln then
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LuaDialog.Message ("Scala to MTS", "Invalid or unusable scale file.", LuaDialog.MessageType.Error, LuaDialog.ButtonType.Close):run ()
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return
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end
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-- The last entry must be an octave to map it
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if freqtbl[expected_len + 1] ~= 1200 then
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LuaDialog.Message ("Scala to MTS", "The scale does not repeat after an octave.", LuaDialog.MessageType.Error, LuaDialog.ButtonType.Close):run ()
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return
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end
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assert (expected_len + 2 == ln)
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assert (expected_len > 0)
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assert (freqtbl[expected_len + 1] == 1200)
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-- TODO consider reading a .kbm file or make these configurable in the dialog
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-- http://www.huygens-fokker.org/scala/help.htm#mappings
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local ref_root = 60 -- middle C
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local ref_note = 69 -- A4
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local ref_freq = 440.0
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-- calculate frequency at ref_root
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local ref_base = ref_freq * 2.0 ^ ((ref_root - ref_note) / 12);
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-- prepare sending data
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local tx = rv["tx"] -- output port
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local parser = ARDOUR.RawMidiParser () -- construct a MIDI parser
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-- show progress dialog
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local pdialog = LuaDialog.ProgressWindow ("Scala to MIDI Tuning", true)
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pdialog:progress (0, "Tuning");
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-- iterate over all MIDI notes
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for nn = 0, 127 do
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if pdialog:canceled () then break end
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-- calculate the note relative to kbm's ref_root
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local delta = nn - ref_root
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local delta_octv = math.floor (delta / expected_len)
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local delta_note = delta % expected_len
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-- calculate the frequency of the note according to the scl
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local fq = calc_freq (ref_base, freqtbl [ delta_note + 1 ], delta_octv)
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-- and then convert this frequency to the MIDI note number (and cent offset)
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local base, cent = freq_to_mts (fq)
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-- MTS uses two MIDI bytes (2^14) for cents
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local cc = math.floor (163.83 * cent + 0.5) | 0
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local cent_lsb = (cc >> 7) & 127
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local cent_msb = cc & 127
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--print ("MIDI Note:", nn, "scale-note:", delta_note, "Octave:", delta_octv, "-> Freq:", fq, "= note:", base, "+", cent, "cents (", cc, ")")
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if (base < 0 or base > 127) then
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-- skip out of bounds MIDI notes
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goto continue
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end
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-- MIDI Tuning message
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-- http://www.microtonal-synthesis.com/MIDItuning.html
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local syx = string.char (
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0xf0, 0x7f, -- realtime sysex
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0x7f, -- target-id
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0x08, 0x02, -- tuning, note change request
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0x00, -- tuning program number 0 to 127 in hexadecimal
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0x01, -- number of notes to be changed
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nn, -- note number to be changed
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base, -- semitone (MIDI note number to retune to, unit is 100 cents)
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cent_msb, -- MSB of fractional part (1/128 semitone = 100/128 cents = .78125 cent units)
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cent_lsb, -- LSB of fractional part (1/16384 semitone = 100/16384 cents = .0061 cent units)
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0xf7
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)
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-- parse message to C/C++ uint8_t* array (Validate message correctness. This
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-- also returns C/C++ uint8_t* array for direct use with write_immediate_event.)
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for b = 1, 12 do
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if parser:process_byte (syx:byte (b)) then
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tx:write_immediate_event (parser:buffer_size (), parser:midi_buffer ())
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-- Slow things down a bit to ensure that no messages as lost.
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-- Physical MIDI is sent at 31.25kBaud.
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-- Every message is sent as 10bit message on the wire,
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-- so every MIDI byte needs 320usec.
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ARDOUR.LuaAPI.usleep (400 * parser:buffer_size ())
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end
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end
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-- show progress
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pdialog:progress (nn / 127, string.format ("Note %d freq: %.2f (%d + %d)", nn, fq, base, cc))
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if pdialog:canceled () then break end
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::continue::
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end
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-- hide modal progress dialog and destroy it
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pdialog:done ();
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end end
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-- simple icon
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function icon (params) return function (ctx, width, height, fg)
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ctx:set_source_rgba (ARDOUR.LuaAPI.color_to_rgba (fg))
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local txt = Cairo.PangoLayout (ctx, "ArdourMono ".. math.ceil(math.min (width, height) * .45) .. "px")
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txt:set_text ("SCL\nMTS")
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local tw, th = txt:get_pixel_size ()
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ctx:move_to (.5 * (width - tw), .5 * (height - th))
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txt:show_in_cairo_context (ctx)
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end end
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