for i=1,math.floor(-dy) do
      Text.down(State)
    end
  end
end
function edit.text_input(State, t)
--?   print('text input', t)
  if State.search_term then
    State.search_term = State.search_term..t
    Text.search_next(State)
  else
    Text.text_input(State, t)
  end
  schedule_save(State)
end
function edit.keychord_press(State, chord, key)
  if State.selection1.line and
      -- printable character created using shift key => delete selection
      -- (we're not creating any ctrl-shift- or alt-shift- combinations using regular/printable keys)
      (not App.shift_down() or utf8.len(key) == 1) and

    Text.delete_selection(State, State.left, State.right)
  end
  if State.search_term then
    if chord == 'escape' then
      State.search_term = nil
      State.cursor1 = State.search_backup.cursor
      State.screen_top1 = State.search_backup.screen_top
      State.search_backup = nil
      Text.redraw_all(State)  -- if we're scrolling, reclaim all fragments to avoid memory leaks
    elseif chord == 'return' then
      State.search_term = nil
      State.search_backup = nil
    elseif chord == 'backspace' then
      local len = utf8.len(State.search_term)
      local byte_offset = Text.offset(State.search_term, len)
      State.search_term = string.sub(State.search_term, 1, byte_offset-1)
    elseif chord == 'down' then
      State.cursor1.pos = State.cursor1.pos+1
      Text.search_next(State)
    elseif chord == 'up' then
      Text.search_previous(State)
    end
    return
  elseif chord == 'C-f' then
    State.search_term = ''
    State.search_backup = {
      cursor={line=State.cursor1.line, pos=State.cursor1.pos},
      screen_top={line=State.screen_top1.line, pos=State.screen_top1.pos},
    }
  -- zoom
  elseif chord == 'C-=' then
    edit.update_font_settings(State, State.font_height+2)
    Text.redraw_all(State)
  elseif chord == 'C--' then
    if State.font_height > 2 then
      edit.update_font_settings(State, State.font_height-2)
      Text.redraw_all(State)
    end
  elseif chord == 'C-0' then
    edit.update_font_settings(State, 20)
    Text.redraw_all(State)
  -- undo
  elseif chord == 'C-z' then
    local event = undo_event(State)
    if event then
      local src = event.before
      State.screen_top1 = deepcopy(src.screen_top)
      State.cursor1 = deepcopy(src.cursor)
      State.selection1 = deepcopy(src.selection)
      patch(State.lines, event.after, event.before)
      patch_placeholders(State.line_cache, event.after, event.before)
      -- if we're scrolling, reclaim all fragments to avoid memory leaks
      Text.redraw_all(State)
      schedule_save(State)
    end
  elseif chord == 'C-y' then
    local event = redo_event(State)
    if event then
      local src = event.after
      State.screen_top1 = deepcopy(src.screen_top)
      State.cursor1 = deepcopy(src.cursor)
      State.selection1 = deepcopy(src.selection)
      patch(State.lines, event.before, event.after)
      -- if we're scrolling, reclaim all fragments to avoid memory leaks
      Text.redraw_all(State)
      schedule_save(State)
    end
  -- clipboard
  elseif chord == 'C-a' then
    State.selection1 = {line=1, pos=1}
    State.cursor1 = {line=#State.lines, pos=utf8.len(State.lines[#State.lines].data)+1}
  elseif chord == 'C-c' then
    local s = Text.selection(State)
    if s then
      App.set_clipboard(s)
    end
  elseif chord == 'C-x' then
    local s = Text.cut_selection(State, State.left, State.right)
    if s then
      App.set_clipboard(s)
    end
    schedule_save(State)
  elseif chord == 'C-v' then
    -- We don't have a good sense of when to scroll, so we'll be conservative
    -- and sometimes scroll when we didn't quite need to.
    local before_line = State.cursor1.line
    local before = snapshot(State, before_line)
    local clipboard_data = App.get_clipboard()
    for _,code in utf8.codes(clipboard_data) do
      local c = utf8.char(code)
      if c == '\n' then
        Text.insert_return(State)
      else
        Text.insert_at_cursor(State, c)
      end
    end
    if Text.cursor_out_of_screen(State) then
      Text.snap_cursor_to_bottom_of_screen(State, State.left, State.right)
    end
    schedule_save(State)
    record_undo_event(State, {before=before, after=snapshot(State, before_line, State.cursor1.line)})
  -- dispatch to text
  else
    Text.keychord_press(State, chord)
  end
end
function edit.key_release(State, key, scancode)
end
function edit.update_font_settings(State, font_height)
  State.font_height = font_height

  State.line_height = math.floor(font_height*1.3)
end
--== some methods for tests
-- Insulate tests from some key globals so I don't have to change the vast
-- majority of tests when they're modified for the real app.
Test_margin_left = 25
Test_margin_right = 0
function edit.initialize_test_state()
  -- if you change these values, tests will start failing
  return edit.initialize_state(
      15,  -- top margin
      Test_margin_left,
      App.screen.width - Test_margin_right,

      15)  -- line height
end
-- all text_input events are also keypresses
-- TODO: handle chords of multiple keys
function edit.run_after_text_input(State, t)
  edit.keychord_press(State, t)
  edit.text_input(State, t)
  edit.key_release(State, t)
  App.screen.contents = {}
  edit.update(State, 0)
  edit.draw(State)
end
-- not all keys are text_input

  App.screen.contents = {}
  edit.update(State, 0)
  edit.draw(State)
end
function edit.run_after_mouse_click(State, x,y, mouse_button)
  App.fake_mouse_press(x,y, mouse_button)
  edit.mouse_press(State, x,y, mouse_button)

  App.fake_mouse_release(x,y, mouse_button)
  edit.mouse_release(State, x,y, mouse_button)
  App.screen.contents = {}
  edit.update(State, 0)
  edit.draw(State)
end
function edit.run_after_mouse_press(State, x,y, mouse_button)
  App.fake_mouse_press(x,y, mouse_button)
  edit.mouse_press(State, x,y, mouse_button)
  App.screen.contents = {}
  edit.update(State, 0)
  edit.draw(State)
end
function edit.run_after_mouse_release(State, x,y, mouse_button)
  App.fake_mouse_release(x,y, mouse_button)
  edit.mouse_release(State, x,y, mouse_button)
  App.screen.contents = {}
  edit.update(State, 0)
  edit.draw(State)
end