midigrid/MidiGrid_ToggleMode.lua

-- MIDI Grid: toggle grid entry mode on/off
local dir = ({ reaper.get_action_context() })[2]:match("@?(.*[\\/])")
local G = dofile(dir .. "midigrid_lib.lua")

local now = not G.isActive()
G.set("active", now and 1 or 0)

if not now then
  -- Hand back the record arm/monitor state grid mode borrowed for preview.
  G.restoreRouting()
  G.say("Grid mode off")
  return
end

local hwnd, take, err = G.editor()
if not take then
  -- Mode is still armed; it simply has nothing to act on yet.
  G.say("Grid mode on, " .. err)
  return
end

-- Preview must sound through the instrument of the track being edited.
G.routePreview(take)

-- Park the pitch cursor on a scale tone so the very first up/down press
-- moves by a sensible degree rather than off a foreign note.
local p = G.getPitch(hwnd)
if not G.inScale(p) then
  local up = G.scaleStep(p, 1)
  if up then p = up ; G.setPitch(hwnd, p) end
end

local g = G.gridQN(take)
G.say(("Grid mode on, %s, grid %s, %s, %s, %s"):format(
  G.scaleName(),
  G.gridLabel(g),
  G.isHold() and "hold on" or "hold off",
  G.noteName(p),
  G.cellPosText(take)))