Add whole-take time shifting

Ctrl+Shift+Left/Right move every note in the take by one grid cell, for
clips that landed off the beat.

Since the whole take moves together, notes cannot collide with each other;
the hazard is the item boundary. Notes pushed past either end stop sounding
but are not deleted, so the operation is reversible -- shifting back restores
them. The plain keys still refuse when that would happen and report the count,
because a clip that has silently lost its first bar is a bad thing to discover
later. Ctrl+Alt+Shift forces it and names the consequence.

Positions are converted through QN rather than offset in raw ticks, so shifts
stay musically correct across tempo changes.

MidiGrid_ShiftLeft.lua

@@ -0,0 +1,5 @@
+-- MIDI Grid: shift all notes one cell left, refusing if any would be lost
+local dir = ({ reaper.get_action_context() })[2]:match("@?(.*[\\/])")
+local G = dofile(dir .. "midigrid_lib.lua")
+if not G.isActive() then return end
+G.runShift(-1, false)

MidiGrid_ShiftLeftForce.lua

@@ -0,0 +1,5 @@
+-- MIDI Grid: shift all notes one cell left even if some leave the item
+local dir = ({ reaper.get_action_context() })[2]:match("@?(.*[\\/])")
+local G = dofile(dir .. "midigrid_lib.lua")
+if not G.isActive() then return end
+G.runShift(-1, true)

MidiGrid_ShiftRight.lua

@@ -0,0 +1,5 @@
+-- MIDI Grid: shift all notes one cell right, refusing if any would be lost
+local dir = ({ reaper.get_action_context() })[2]:match("@?(.*[\\/])")
+local G = dofile(dir .. "midigrid_lib.lua")
+if not G.isActive() then return end
+G.runShift(1, false)

MidiGrid_ShiftRightForce.lua

@@ -0,0 +1,5 @@
+-- MIDI Grid: shift all notes one cell right even if some leave the item
+local dir = ({ reaper.get_action_context() })[2]:match("@?(.*[\\/])")
+local G = dofile(dir .. "midigrid_lib.lua")
+if not G.isActive() then return end
+G.runShift(1, true)

README.md

@@ -72,6 +72,8 @@ actions by hand in Actions → Show action list. That always works.
 | `Left` / `Right` | Cursor back / forward one grid cell | OSARA previous / next chord |
 | `Up` / `Down` | Pitch up / down one scale degree | OSARA higher / lower note in chord |
 | `Enter` | Toggle note at cursor cell | Edit: Event properties |
+| `Ctrl+Shift+Left` / `Ctrl+Shift+Right` | Shift **all** notes one cell, refusing if any would leave the item | — |
+| `Ctrl+Alt+Shift+Left` / `Ctrl+Alt+Shift+Right` | Same, but shift anyway | — |
 | `L` / `Shift+L` | Lengthen / shorten note by one cell | Edit: Lengthen / shorten notes one grid unit |
 | `Alt+J` | Join a run of repeated notes into one | — |
 | `Alt+3` | Toggle diatonic triad on cursor pitch | — |
@@ -147,6 +149,27 @@ survive. They also need no mode: `L` behaves identically whether hold is on or
 off, so there is no state to set up beforehand and none to remember to turn
 off afterwards.
 
+## Shifting notes in time
+
+If a whole clip landed a couple of cells off the beat, `Ctrl+Shift+Left` and
+`Ctrl+Shift+Right` move **every note in the take** by one grid cell.
+
+Because the entire take moves together, notes can never collide with each
+other. What is at stake is the **item boundary**: notes pushed past either end
+stop sounding. They are *not* deleted — shifting back the other way brings
+them straight back — but a clip that has quietly lost its first bar is not
+something you want to discover two hours later.
+
+So the plain keys **refuse** the shift if any note would end up outside, and
+say how many: *"Not shifted left, 3 notes would fall outside the item. Add Alt
+to force."*
+
+Adding **Alt** (`Ctrl+Alt+Shift+Left` / `Right`) does it anyway, reporting the
+consequence: *"Shifted left, 3 notes now outside the item and silent."*
+
+Positions are converted through quarter-notes rather than offset in raw ticks,
+so a shift stays musically correct across tempo changes.
+
 ## Chords
 
 `Alt+3` stamps a **diatonic triad** on the cursor pitch; `Alt+7` a seventh

install.ps1

@@ -55,7 +55,11 @@ $actions = @(
     @('RSmidigrid_veldn',  32060, 'MIDI Grid: Velocity down',                   'MidiGrid_VelDown.lua'),
     @('RSmidigrid_longer', 32060, 'MIDI Grid: Lengthen note one cell',          'MidiGrid_Lengthen.lua'),
     @('RSmidigrid_shorter',32060, 'MIDI Grid: Shorten note one cell',           'MidiGrid_Shorten.lua'),
-    @('RSmidigrid_join',   32060, 'MIDI Grid: Join run of repeated notes',      'MidiGrid_Join.lua')
+    @('RSmidigrid_join',   32060, 'MIDI Grid: Join run of repeated notes',      'MidiGrid_Join.lua'),
+    @('RSmidigrid_shl',    32060, 'MIDI Grid: Shift all notes one cell left',   'MidiGrid_ShiftLeft.lua'),
+    @('RSmidigrid_shr',    32060, 'MIDI Grid: Shift all notes one cell right',  'MidiGrid_ShiftRight.lua'),
+    @('RSmidigrid_shlf',   32060, 'MIDI Grid: Shift all notes left (force)',    'MidiGrid_ShiftLeftForce.lua'),
+    @('RSmidigrid_shrf',   32060, 'MIDI Grid: Shift all notes right (force)',   'MidiGrid_ShiftRightForce.lua')
 )
 
 # flags, keycode, section, id
@@ -78,7 +82,11 @@ $keys = @(
     @(21, 32808, 32060, 'RSmidigrid_veldn'),
     @(1,  76,    32060, 'RSmidigrid_longer'),
     @(5,  76,    32060, 'RSmidigrid_shorter'),
-    @(17, 74,    32060, 'RSmidigrid_join')
+    @(17, 74,    32060, 'RSmidigrid_join'),
+    @(13, 32805, 32060, 'RSmidigrid_shl'),
+    @(13, 32807, 32060, 'RSmidigrid_shr'),
+    @(29, 32805, 32060, 'RSmidigrid_shlf'),
+    @(29, 32807, 32060, 'RSmidigrid_shrf')
 )
 
 $backup = "$kb.midigrid-backup"

midigrid_lib.lua

@@ -352,6 +352,83 @@ function M.toggleCell(take, pitch)
   return result, detail
 end
 
+---------------------------------------------------------------- time shift
+
+--[[
+  Move every note in the take by whole grid cells.
+
+  Because the entire take moves together, notes cannot collide with each
+  other -- the only thing at stake is the item's boundaries. Notes pushed
+  outside them are not deleted, they simply stop sounding, and shifting back
+  the other way restores them. The safe variant still refuses, because
+  silently silencing part of a clip is exactly the kind of thing you want to
+  be told about rather than discover later.
+
+  Positions are converted through QN rather than offset in ticks, so a shift
+  stays musically correct across tempo changes.
+
+  Returns moved, outside. moved is nil when the shift was refused.
+]]
+function M.shiftAllNotes(take, cells, force)
+  local _, notecnt = reaper.MIDI_CountEvts(take)
+  if notecnt == 0 then return 0, 0 end
+
+  local g = M.gridQN(take)
+  local item = reaper.GetMediaItemTake_Item(take)
+  local itemPos = reaper.GetMediaItemInfo_Value(item, "D_POSITION")
+  local itemLen = reaper.GetMediaItemInfo_Value(item, "D_LENGTH")
+  local loPPQ = reaper.MIDI_GetPPQPosFromProjTime(take, itemPos)
+  local hiPPQ = reaper.MIDI_GetPPQPosFromProjTime(take, itemPos + itemLen)
+
+  local moved, outside = {}, 0
+  for i = 0, notecnt - 1 do
+    local ok, _, _, s, e = reaper.MIDI_GetNote(take, i)
+    if ok then
+      local ns = reaper.MIDI_GetPPQPosFromProjQN(take,
+        reaper.MIDI_GetProjQNFromPPQPos(take, s) + cells * g)
+      local ne = reaper.MIDI_GetPPQPosFromProjQN(take,
+        reaper.MIDI_GetProjQNFromPPQPos(take, e) + cells * g)
+      moved[i] = { ns, ne }
+      if ns < loPPQ - SLACK or ne > hiPPQ + SLACK then outside = outside + 1 end
+    end
+  end
+
+  if outside > 0 and not force then return nil, outside end
+
+  reaper.Undo_BeginBlock2(0)
+  for i = 0, notecnt - 1 do
+    local np = moved[i]
+    if np then
+      reaper.MIDI_SetNote(take, i, nil, nil, np[1], np[2], nil, nil, nil, true)
+    end
+  end
+  reaper.MIDI_Sort(take)
+  reaper.Undo_EndBlock2(0, "MIDI Grid: shift notes", -1)
+
+  return notecnt, outside
+end
+
+-- Shared driver for the four shift actions: does the work and the speech.
+function M.runShift(cells, force)
+  local hwnd, take, err = M.editor()
+  if not take then M.say(err) return end
+
+  local moved, outside = M.shiftAllNotes(take, cells, force)
+  local dir = cells < 0 and "left" or "right"
+
+  if moved == nil then
+    M.say(("Not shifted %s, %d %s would fall outside the item. Add Alt to force.")
+      :format(dir, outside, outside == 1 and "note" or "notes"))
+  elseif moved == 0 then
+    M.say("No notes to shift")
+  elseif outside > 0 then
+    M.say(("Shifted %s, %d %s now outside the item and silent")
+      :format(dir, outside, outside == 1 and "note" or "notes"))
+  else
+    M.say(("Shifted %s, %d %s"):format(dir, moved, moved == 1 and "note" or "notes"))
+  end
+end
+
 --------------------------------------------------------------- note length
 
 --[[