experiment: new edit namespace

Still lots to do, but the eventual hope is that this will make this
project's code easier to reuse from other LÖVE projects.

One gotcha: even as we start putting code more aggressively into nested
tables, tests must remain at the top-level. Otherwise they won't run.

3 files changed, 463 insertions, 416 deletions

diff --git a/Manual_tests.md b/Manual_tests.md
index 690ccd9..8c2dd30 100644
--- a/Manual_tests.md
+++ b/Manual_tests.md
@@ -24,6 +24,10 @@ Lua is dynamically typed. Tests can't patch over lack of type-checking.
 * Like any high-level language, it's easy to accidentally alias two non-scalar
   variables. I wish there was a way to require copy when assigning.
 
+* My test harness automatically runs `test_*` methods -- but only at the
+  top-level. I wish there was a way to raise warnings if someone defines such
+  a function inside a dict somewhere.
+
 ### Todo list
 
 * Initializing settings:
diff --git a/edit.lua b/edit.lua
new file mode 100644
index 0000000..8ecbf24
--- /dev/null
+++ b/edit.lua
@@ -0,0 +1,446 @@
+utf8 = require 'utf8'
+
+require 'file'
+require 'button'
+require 'text'
+require 'drawing'
+require 'geom'
+require 'help'
+require 'icons'
+
+edit = {}
+
+-- run in both tests and a real run
+function edit.initialize_globals()
+-- a line is either text or a drawing
+-- a text is a table with:
+--    mode = 'text',
+--    string data,
+--    startpos, the index of data the line starts rendering from (if currently on screen), can only be >1 for topmost line on screen
+--    starty, the y coord in pixels
+--    some cached data that's blown away and recomputed when data changes:
+--      fragments: snippets of rendered love.graphics.Text, guaranteed to not wrap
+--      screen_line_starting_pos: optional array of grapheme indices if it wraps over more than one screen line
+-- a drawing is a table with:
+--    mode = 'drawing'
+--    a (y) coord in pixels (updated while painting screen),
+--    a (h)eight,
+--    an array of points, and
+--    an array of shapes
+-- a shape is a table containing:
+--    a mode
+--    an array points for mode 'freehand' (raw x,y coords; freehand drawings don't pollute the points array of a drawing)
+--    an array vertices for mode 'polygon', 'rectangle', 'square'
+--    p1, p2 for mode 'line'
+--    center, radius for mode 'circle'
+--    center, radius, start_angle, end_angle for mode 'arc'
+-- Unless otherwise specified, coord fields are normalized; a drawing is always 256 units wide
+-- The field names are carefully chosen so that switching modes in midstream
+-- remembers previously entered points where that makes sense.
+Lines = {{mode='text', data=''}}
+
+-- Lines can be too long to fit on screen, in which case they _wrap_ into
+-- multiple _screen lines_.
+--
+-- Therefore, any potential location for the cursor can be described in two ways:
+-- * schema 1: As a combination of line index and position within a line (in utf8 codepoint units)
+-- * schema 2: As a combination of line index, screen line index within the line, and a position within the screen line.
+--
+-- Most of the time we'll only persist positions in schema 1, translating to
+-- schema 2 when that's convenient.
+--
+-- Make sure these coordinates are never aliased, so that changing one causes
+-- action at a distance.
+Screen_top1 = {line=1, pos=1}  -- position of start of screen line at top of screen
+Cursor1 = {line=1, pos=1}  -- position of cursor
+Screen_bottom1 = {line=1, pos=1}  -- position of start of screen line at bottom of screen
+
+Selection1 = {}
+Old_cursor1, Old_selection1, Mousepress_shift = nil  -- some extra state to compute selection between mouse press and release
+Recent_mouse = {}  -- when selecting text, avoid recomputing some state on every single frame
+
+Cursor_x, Cursor_y = 0, 0  -- in pixels
+
+Current_drawing_mode = 'line'
+Previous_drawing_mode = nil
+
+-- values for tests
+Font_height = 14
+Line_height = 15
+-- widest possible character width
+Em = App.newText(love.graphics.getFont(), 'm')
+
+Margin_top = 15
+Margin_left = 25
+Margin_right = 25
+Margin_width = Margin_left + Margin_right
+
+Drawing_padding_top = 10
+Drawing_padding_bottom = 10
+Drawing_padding_height = Drawing_padding_top + Drawing_padding_bottom
+
+Filename = love.filesystem.getUserDirectory()..'/lines.txt'
+Next_save = nil
+
+-- undo
+History = {}
+Next_history = 1
+
+-- search
+Search_term = nil
+Search_text = nil
+Search_backup = nil  -- stuff to restore when cancelling search
+
+-- resize
+Last_resize_time = nil
+
+-- blinking cursor
+Cursor_time = 0
+
+end  -- App.initialize_globals
+
+function edit.draw()
+  Button_handlers = {}
+
+  love.graphics.setColor(0, 0, 0)
+--?   print(Screen_top1.line, Screen_top1.pos, Cursor1.line, Cursor1.pos)
+  assert(Text.le1(Screen_top1, Cursor1))
+  Cursor_y = -1
+  local y = Margin_top
+--?   print('== draw')
+  for line_index = Screen_top1.line,#Lines do
+    local line = Lines[line_index]
+--?     print('draw:', y, line_index, line)
+    if y + Line_height > App.screen.height then break end
+    Screen_bottom1.line = line_index
+    if line.mode == 'text' and line.data == '' then
+      line.starty = y
+      line.startpos = 1
+      -- insert new drawing
+      button('draw', {x=4,y=y+4, w=12,h=12, color={1,1,0},
+        icon = icon.insert_drawing,
+        onpress1 = function()
+                     Drawing.before = snapshot(line_index-1, line_index)
+                     table.insert(Lines, line_index, {mode='drawing', y=y, h=256/2, points={}, shapes={}, pending={}})
+                     if Cursor1.line >= line_index then
+                       Cursor1.line = Cursor1.line+1
+                     end
+                     schedule_save()
+                     record_undo_event({before=Drawing.before, after=snapshot(line_index-1, line_index+1)})
+                   end
+      })
+      if Search_term == nil then
+        if line_index == Cursor1.line then
+          Text.draw_cursor(Margin_left, y)
+        end
+      end
+      Screen_bottom1.pos = Screen_top1.pos
+      y = y + Line_height
+    elseif line.mode == 'drawing' then
+      y = y+Drawing_padding_top
+      line.y = y
+      Drawing.draw(line)
+      y = y + Drawing.pixels(line.h) + Drawing_padding_bottom
+    else
+      line.starty = y
+      line.startpos = 1
+      if line_index == Screen_top1.line then
+        line.startpos = Screen_top1.pos
+      end
+--?       print('text.draw', y, line_index)
+      y, Screen_bottom1.pos = Text.draw(line, line_index, line.starty, Margin_left, App.screen.width-Margin_right)
+      y = y + Line_height
+--?       print('=> y', y)
+    end
+  end
+  if Cursor_y == -1 then
+    Cursor_y = App.screen.height
+  end
+--?   print('screen bottom: '..tostring(Screen_bottom1.pos)..' in '..tostring(Lines[Screen_bottom1.line].data))
+  if Search_term then
+    Text.draw_search_bar()
+  end
+end
+
+function edit.update(dt)
+  Cursor_time = Cursor_time + dt
+  -- some hysteresis while resizing
+  if Last_resize_time then
+    if App.getTime() - Last_resize_time < 0.1 then
+      return
+    else
+      Last_resize_time = nil
+    end
+  end
+  Drawing.update(dt)
+  if Next_save and Next_save < App.getTime() then
+    save_to_disk(Lines, Filename)
+    Next_save = nil
+  end
+end
+
+function schedule_save()
+  if Next_save == nil then
+    Next_save = App.getTime() + 3  -- short enough that you're likely to still remember what you did
+  end
+end
+
+function edit.quit()
+  -- make sure to save before quitting
+  if Next_save then
+    save_to_disk(Lines, Filename)
+  end
+end
+
+function edit.mouse_pressed(x,y, mouse_button)
+  if Search_term then return end
+  -- ensure cursor is visible immediately after it moves
+  Cursor_time = 0
+--?   print('press', Selection1.line, Selection1.pos)
+  propagate_to_button_handlers(x,y, mouse_button)
+
+  for line_index,line in ipairs(Lines) do
+    if line.mode == 'text' then
+      if Text.in_line(line, x,y, Margin_left, App.screen.width-Margin_right) then
+        -- delicate dance between cursor, selection and old cursor/selection
+        -- scenarios:
+        --  regular press+release: sets cursor, clears selection
+        --  shift press+release:
+        --    sets selection to old cursor if not set otherwise leaves it untouched
+        --    sets cursor
+        --  press and hold to start a selection: sets selection on press, cursor on release
+        --  press and hold, then press shift: ignore shift
+        --    i.e. mousereleased should never look at shift state
+        Old_cursor1 = Cursor1
+        Old_selection1 = Selection1
+        Mousepress_shift = App.shift_down()
+        Selection1 = {
+            line=line_index,
+            pos=Text.to_pos_on_line(line, x, y, Margin_left, App.screen.width-Margin_right),
+        }
+--?         print('selection', Selection1.line, Selection1.pos)
+        break
+      end
+    elseif line.mode == 'drawing' then
+      if Drawing.in_drawing(line, x, y) then
+        Lines.current_drawing_index = line_index
+        Lines.current_drawing = line
+        Drawing.before = snapshot(line_index)
+        Drawing.mouse_pressed(line, x,y, mouse_button)
+        break
+      end
+    end
+  end
+end
+
+function edit.mouse_released(x,y, mouse_button)
+  if Search_term then return end
+--?   print('release')
+  -- ensure cursor is visible immediately after it moves
+  Cursor_time = 0
+  if Lines.current_drawing then
+    Drawing.mouse_released(x,y, mouse_button)
+    schedule_save()
+    if Drawing.before then
+      record_undo_event({before=Drawing.before, after=snapshot(Lines.current_drawing_index)})
+      Drawing.before = nil
+    end
+  else
+    for line_index,line in ipairs(Lines) do
+      if line.mode == 'text' then
+        if Text.in_line(line, x,y, Margin_left, App.screen.width-Margin_right) then
+--?           print('reset selection')
+          Cursor1 = {
+              line=line_index,
+              pos=Text.to_pos_on_line(line, x, y, Margin_left, App.screen.width-Margin_right),
+          }
+--?           print('cursor', Cursor1.line, Cursor1.pos)
+          if Mousepress_shift then
+            if Old_selection1.line == nil then
+              Selection1 = Old_cursor1
+            else
+              Selection1 = Old_selection1
+            end
+          end
+          Old_cursor1, Old_selection1, Mousepress_shift = nil
+          if eq(Cursor1, Selection1) then
+            Selection1 = {}
+          end
+          break
+        end
+      end
+    end
+--?     print('selection:', Selection1.line, Selection1.pos)
+  end
+end
+
+function edit.textinput(t)
+  -- ensure cursor is visible immediately after it moves
+  Cursor_time = 0
+  for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
+  if Search_term then
+    Search_term = Search_term..t
+    Search_text = nil
+    Text.search_next()
+  elseif Current_drawing_mode == 'name' then
+    local before = snapshot(Lines.current_drawing_index)
+    local drawing = Lines.current_drawing
+    local p = drawing.points[drawing.pending.target_point]
+    p.name = p.name..t
+    record_undo_event({before=before, after=snapshot(Lines.current_drawing_index)})
+  else
+    Text.textinput(t)
+  end
+  schedule_save()
+end
+
+function edit.keychord_pressed(chord, key)
+  -- ensure cursor is visible immediately after it moves
+  Cursor_time = 0
+  if Selection1.line and
+      not Lines.current_drawing 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
+      chord ~= 'C-c' and chord ~= 'C-x' and chord ~= 'backspace' and backspace ~= 'delete' and not App.is_cursor_movement(chord) then
+    Text.delete_selection(Margin_left, App.screen.width-Margin_right)
+  end
+  if Search_term then
+    if chord == 'escape' then
+      Search_term = nil
+      Search_text = nil
+      Cursor1 = Search_backup.cursor
+      Screen_top1 = Search_backup.screen_top
+      Search_backup = nil
+      Text.redraw_all()  -- if we're scrolling, reclaim all fragments to avoid memory leaks
+    elseif chord == 'return' then
+      Search_term = nil
+      Search_text = nil
+      Search_backup = nil
+    elseif chord == 'backspace' then
+      local len = utf8.len(Search_term)
+      local byte_offset = Text.offset(Search_term, len)
+      Search_term = string.sub(Search_term, 1, byte_offset-1)
+      Search_text = nil
+    elseif chord == 'down' then
+      Cursor1.pos = Cursor1.pos+1
+      Text.search_next()
+    elseif chord == 'up' then
+      Text.search_previous()
+    end
+    return
+  elseif chord == 'C-f' then
+    Search_term = ''
+    Search_backup = {cursor={line=Cursor1.line, pos=Cursor1.pos}, screen_top={line=Screen_top1.line, pos=Screen_top1.pos}}
+    assert(Search_text == nil)
+  elseif chord == 'C-=' then
+    initialize_font_settings(Font_height+2)
+    Text.redraw_all()
+  elseif chord == 'C--' then
+    initialize_font_settings(Font_height-2)
+    Text.redraw_all()
+  elseif chord == 'C-0' then
+    initialize_font_settings(20)
+    Text.redraw_all()
+  elseif chord == 'C-z' then
+    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
+    local event = undo_event()
+    if event then
+      local src = event.before
+      Screen_top1 = deepcopy(src.screen_top)
+      Cursor1 = deepcopy(src.cursor)
+      Selection1 = deepcopy(src.selection)
+      patch(Lines, event.after, event.before)
+      Text.redraw_all()  -- if we're scrolling, reclaim all fragments to avoid memory leaks
+      schedule_save()
+    end
+  elseif chord == 'C-y' then
+    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
+    local event = redo_event()
+    if event then
+      local src = event.after
+      Screen_top1 = deepcopy(src.screen_top)
+      Cursor1 = deepcopy(src.cursor)
+      Selection1 = deepcopy(src.selection)
+      patch(Lines, event.before, event.after)
+      Text.redraw_all()  -- if we're scrolling, reclaim all fragments to avoid memory leaks
+      schedule_save()
+    end
+  -- clipboard
+  elseif chord == 'C-c' then
+    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
+    local s = Text.selection()
+    if s then
+      App.setClipboardText(s)
+    end
+  elseif chord == 'C-x' then
+    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
+    local s = Text.cut_selection(Margin_left, App.screen.width-Margin_right)
+    if s then
+      App.setClipboardText(s)
+    end
+    schedule_save()
+  elseif chord == 'C-v' then
+    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
+    -- 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 = Cursor1.line
+    local before = snapshot(before_line)
+    local clipboard_data = App.getClipboardText()
+    for _,code in utf8.codes(clipboard_data) do
+      local c = utf8.char(code)
+      if c == '\n' then
+        Text.insert_return()
+      else
+        Text.insert_at_cursor(c)
+      end
+    end
+    if Text.cursor_past_screen_bottom() then
+      Text.snap_cursor_to_bottom_of_screen(Margin_left, App.screen.height-Margin_right)
+    end
+    schedule_save()
+    record_undo_event({before=before, after=snapshot(before_line, Cursor1.line)})
+  -- dispatch to drawing or text
+  elseif App.mouse_down(1) or chord:sub(1,2) == 'C-' then
+    -- DON'T reset line.y here
+    local drawing_index, drawing = Drawing.current_drawing()
+    if drawing_index then
+      local before = snapshot(drawing_index)
+      Drawing.keychord_pressed(chord)
+      record_undo_event({before=before, after=snapshot(drawing_index)})
+      schedule_save()
+    end
+  elseif chord == 'escape' and not App.mouse_down(1) then
+    for _,line in ipairs(Lines) do
+      if line.mode == 'drawing' then
+        line.show_help = false
+      end
+    end
+  elseif Current_drawing_mode == 'name' then
+    if chord == 'return' then
+      Current_drawing_mode = Previous_drawing_mode
+      Previous_drawing_mode = nil
+    else
+      local before = snapshot(Lines.current_drawing_index)
+      local drawing = Lines.current_drawing
+      local p = drawing.points[drawing.pending.target_point]
+      if chord == 'escape' then
+        p.name = nil
+        record_undo_event({before=before, after=snapshot(Lines.current_drawing_index)})
+      elseif chord == 'backspace' then
+        local len = utf8.len(p.name)
+        local byte_offset = Text.offset(p.name, len-1)
+        if len == 1 then byte_offset = 0 end
+        p.name = string.sub(p.name, 1, byte_offset)
+        record_undo_event({before=before, after=snapshot(Lines.current_drawing_index)})
+      end
+    end
+    schedule_save()
+  else
+    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
+    Text.keychord_pressed(chord)
+  end
+end
+
+function edit.key_released(key, scancode)
+end
diff --git a/main.lua b/main.lua
index 72b6834..6a4e30c 100644
--- a/main.lua
+++ b/main.lua
@@ -2,106 +2,17 @@ utf8 = require 'utf8'
 
 require 'app'
 require 'test'
-
 require 'keychord'
-require 'file'
-require 'button'
-require 'text'
-require 'drawing'
-require 'geom'
-require 'help'
-require 'icons'
 
 require 'main_tests'
 
+-- delegate most business logic to a layer that can be reused by other projects
+require 'edit'
+
 -- called both in tests and real run
 function App.initialize_globals()
--- a line is either text or a drawing
--- a text is a table with:
---    mode = 'text',
---    string data,
---    startpos, the index of data the line starts rendering from (if currently on screen), can only be >1 for topmost line on screen
---    starty, the y coord in pixels
---    some cached data that's blown away and recomputed when data changes:
---      fragments: snippets of rendered love.graphics.Text, guaranteed to not wrap
---      screen_line_starting_pos: optional array of grapheme indices if it wraps over more than one screen line
--- a drawing is a table with:
---    mode = 'drawing'
---    a (y) coord in pixels (updated while painting screen),
---    a (h)eight,
---    an array of points, and
---    an array of shapes
--- a shape is a table containing:
---    a mode
---    an array points for mode 'freehand' (raw x,y coords; freehand drawings don't pollute the points array of a drawing)
---    an array vertices for mode 'polygon', 'rectangle', 'square'
---    p1, p2 for mode 'line'
---    center, radius for mode 'circle'
---    center, radius, start_angle, end_angle for mode 'arc'
--- Unless otherwise specified, coord fields are normalized; a drawing is always 256 units wide
--- The field names are carefully chosen so that switching modes in midstream
--- remembers previously entered points where that makes sense.
-Lines = {{mode='text', data=''}}
-
--- Lines can be too long to fit on screen, in which case they _wrap_ into
--- multiple _screen lines_.
---
--- Therefore, any potential location for the cursor can be described in two ways:
--- * schema 1: As a combination of line index and position within a line (in utf8 codepoint units)
--- * schema 2: As a combination of line index, screen line index within the line, and a position within the screen line.
---
--- Most of the time we'll only persist positions in schema 1, translating to
--- schema 2 when that's convenient.
---
--- Make sure these coordinates are never aliased, so that changing one causes
--- action at a distance.
-Screen_top1 = {line=1, pos=1}  -- position of start of screen line at top of screen
-Cursor1 = {line=1, pos=1}  -- position of cursor
-Screen_bottom1 = {line=1, pos=1}  -- position of start of screen line at bottom of screen
-
-Selection1 = {}
-Old_cursor1, Old_selection1, Mousepress_shift = nil  -- some extra state to compute selection between mouse press and release
-Recent_mouse = {}  -- when selecting text, avoid recomputing some state on every single frame
-
-Cursor_x, Cursor_y = 0, 0  -- in pixels
-
-Current_drawing_mode = 'line'
-Previous_drawing_mode = nil
-
--- values for tests
-Font_height = 14
-Line_height = 15
--- widest possible character width
-Em = App.newText(love.graphics.getFont(), 'm')
-
-Margin_top = 15
-Margin_left = 25
-Margin_right = 25
-Margin_width = Margin_left + Margin_right
-
-Drawing_padding_top = 10
-Drawing_padding_bottom = 10
-Drawing_padding_height = Drawing_padding_top + Drawing_padding_bottom
-
-Filename = love.filesystem.getUserDirectory()..'/lines.txt'
-Next_save = nil
-
--- undo
-History = {}
-Next_history = 1
-
--- search
-Search_term = nil
-Search_text = nil
-Search_backup = nil  -- stuff to restore when cancelling search
-
--- resize
-Last_resize_time = nil
-
--- blinking cursor
-Cursor_time = 0
-
-end  -- App.initialize_globals
+  return edit.initialize_globals()
+end
 
 -- called only for real run
 function App.initialize(arg)
@@ -225,96 +136,15 @@ function App.filedropped(file)
 end
 
 function App.draw()
-  Button_handlers = {}
-
-  love.graphics.setColor(0, 0, 0)
---?   print(Screen_top1.line, Screen_top1.pos, Cursor1.line, Cursor1.pos)
-  assert(Text.le1(Screen_top1, Cursor1))
-  Cursor_y = -1
-  local y = Margin_top
---?   print('== draw')
-  for line_index = Screen_top1.line,#Lines do
-    local line = Lines[line_index]
---?     print('draw:', y, line_index, line)
-    if y + Line_height > App.screen.height then break end
-    Screen_bottom1.line = line_index
-    if line.mode == 'text' and line.data == '' then
-      line.starty = y
-      line.startpos = 1
-      -- insert new drawing
-      button('draw', {x=4,y=y+4, w=12,h=12, color={1,1,0},
-        icon = icon.insert_drawing,
-        onpress1 = function()
-                     Drawing.before = snapshot(line_index-1, line_index)
-                     table.insert(Lines, line_index, {mode='drawing', y=y, h=256/2, points={}, shapes={}, pending={}})
-                     if Cursor1.line >= line_index then
-                       Cursor1.line = Cursor1.line+1
-                     end
-                     schedule_save()
-                     record_undo_event({before=Drawing.before, after=snapshot(line_index-1, line_index+1)})
-                   end
-      })
-      if Search_term == nil then
-        if line_index == Cursor1.line then
-          Text.draw_cursor(Margin_left, y)
-        end
-      end
-      Screen_bottom1.pos = Screen_top1.pos
-      y = y + Line_height
-    elseif line.mode == 'drawing' then
-      y = y+Drawing_padding_top
-      line.y = y
-      Drawing.draw(line)
-      y = y + Drawing.pixels(line.h) + Drawing_padding_bottom
-    else
-      line.starty = y
-      line.startpos = 1
-      if line_index == Screen_top1.line then
-        line.startpos = Screen_top1.pos
-      end
---?       print('text.draw', y, line_index)
-      y, Screen_bottom1.pos = Text.draw(line, line_index, line.starty, Margin_left, App.screen.width-Margin_right)
-      y = y + Line_height
---?       print('=> y', y)
-    end
-  end
-  if Cursor_y == -1 then
-    Cursor_y = App.screen.height
-  end
---?   print('screen bottom: '..tostring(Screen_bottom1.pos)..' in '..tostring(Lines[Screen_bottom1.line].data))
-  if Search_term then
-    Text.draw_search_bar()
-  end
+  edit.draw()
 end
 
 function App.update(dt)
-  Cursor_time = Cursor_time + dt
-  -- some hysteresis while resizing
-  if Last_resize_time then
-    if App.getTime() - Last_resize_time < 0.1 then
-      return
-    else
-      Last_resize_time = nil
-    end
-  end
-  Drawing.update(dt)
-  if Next_save and Next_save < App.getTime() then
-    save_to_disk(Lines, Filename)
-    Next_save = nil
-  end
-end
-
-function schedule_save()
-  if Next_save == nil then
-    Next_save = App.getTime() + 3  -- short enough that you're likely to still remember what you did
-  end
+  edit.update(dt)
 end
 
 function love.quit()
-  -- make sure to save before quitting
-  if Next_save then
-    save_to_disk(Lines, Filename)
-  end
+  edit.quit()
   -- save some important settings
   local x,y,displayindex = love.window.getPosition()
   local filename = Filename
@@ -331,254 +161,21 @@ function love.quit()
 end
 
 function App.mousepressed(x,y, mouse_button)
-  if Search_term then return end
-  -- ensure cursor is visible immediately after it moves
-  Cursor_time = 0
---?   print('press', Selection1.line, Selection1.pos)
-  propagate_to_button_handlers(x,y, mouse_button)
-
-  for line_index,line in ipairs(Lines) do
-    if line.mode == 'text' then
-      if Text.in_line(line, x,y, Margin_left, App.screen.width-Margin_right) then
-        -- delicate dance between cursor, selection and old cursor/selection
-        -- scenarios:
-        --  regular press+release: sets cursor, clears selection
-        --  shift press+release:
-        --    sets selection to old cursor if not set otherwise leaves it untouched
-        --    sets cursor
-        --  press and hold to start a selection: sets selection on press, cursor on release
-        --  press and hold, then press shift: ignore shift
-        --    i.e. mousereleased should never look at shift state
-        Old_cursor1 = Cursor1
-        Old_selection1 = Selection1
-        Mousepress_shift = App.shift_down()
-        Selection1 = {
-            line=line_index,
-            pos=Text.to_pos_on_line(line, x, y, Margin_left, App.screen.width-Margin_right),
-        }
---?         print('selection', Selection1.line, Selection1.pos)
-        break
-      end
-    elseif line.mode == 'drawing' then
-      if Drawing.in_drawing(line, x, y) then
-        Lines.current_drawing_index = line_index
-        Lines.current_drawing = line
-        Drawing.before = snapshot(line_index)
-        Drawing.mouse_pressed(line, x,y, mouse_button)
-        break
-      end
-    end
-  end
+  return edit.mouse_pressed(x,y, mouse_button)
 end
 
 function App.mousereleased(x,y, mouse_button)
-  if Search_term then return end
---?   print('release')
-  -- ensure cursor is visible immediately after it moves
-  Cursor_time = 0
-  if Lines.current_drawing then
-    Drawing.mouse_released(x,y, mouse_button)
-    schedule_save()
-    if Drawing.before then
-      record_undo_event({before=Drawing.before, after=snapshot(Lines.current_drawing_index)})
-      Drawing.before = nil
-    end
-  else
-    for line_index,line in ipairs(Lines) do
-      if line.mode == 'text' then
-        if Text.in_line(line, x,y, Margin_left, App.screen.width-Margin_right) then
---?           print('reset selection')
-          Cursor1 = {
-              line=line_index,
-              pos=Text.to_pos_on_line(line, x, y, Margin_left, App.screen.width-Margin_right),
-          }
---?           print('cursor', Cursor1.line, Cursor1.pos)
-          if Mousepress_shift then
-            if Old_selection1.line == nil then
-              Selection1 = Old_cursor1
-            else
-              Selection1 = Old_selection1
-            end
-          end
-          Old_cursor1, Old_selection1, Mousepress_shift = nil
-          if eq(Cursor1, Selection1) then
-            Selection1 = {}
-          end
-          break
-        end
-      end
-    end
---?     print('selection:', Selection1.line, Selection1.pos)
-  end
+  return edit.mouse_released(x,y, mouse_button)
 end
 
 function App.textinput(t)
-  -- ensure cursor is visible immediately after it moves
-  Cursor_time = 0
-  for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
-  if Search_term then
-    Search_term = Search_term..t
-    Search_text = nil
-    Text.search_next()
-  elseif Current_drawing_mode == 'name' then
-    local before = snapshot(Lines.current_drawing_index)
-    local drawing = Lines.current_drawing
-    local p = drawing.points[drawing.pending.target_point]
-    p.name = p.name..t
-    record_undo_event({before=before, after=snapshot(Lines.current_drawing_index)})
-  else
-    Text.textinput(t)
-  end
-  schedule_save()
+  return edit.textinput(t)
 end
 
 function App.keychord_pressed(chord, key)
-  -- ensure cursor is visible immediately after it moves
-  Cursor_time = 0
-  if Selection1.line and
-      not Lines.current_drawing 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
-      chord ~= 'C-c' and chord ~= 'C-x' and chord ~= 'backspace' and backspace ~= 'delete' and not App.is_cursor_movement(chord) then
-    Text.delete_selection(Margin_left, App.screen.width-Margin_right)
-  end
-  if Search_term then
-    if chord == 'escape' then
-      Search_term = nil
-      Search_text = nil
-      Cursor1 = Search_backup.cursor
-      Screen_top1 = Search_backup.screen_top
-      Search_backup = nil
-      Text.redraw_all()  -- if we're scrolling, reclaim all fragments to avoid memory leaks
-    elseif chord == 'return' then
-      Search_term = nil
-      Search_text = nil
-      Search_backup = nil
-    elseif chord == 'backspace' then
-      local len = utf8.len(Search_term)
-      local byte_offset = Text.offset(Search_term, len)
-      Search_term = string.sub(Search_term, 1, byte_offset-1)
-      Search_text = nil
-    elseif chord == 'down' then
-      Cursor1.pos = Cursor1.pos+1
-      Text.search_next()
-    elseif chord == 'up' then
-      Text.search_previous()
-    end
-    return
-  elseif chord == 'C-f' then
-    Search_term = ''
-    Search_backup = {cursor={line=Cursor1.line, pos=Cursor1.pos}, screen_top={line=Screen_top1.line, pos=Screen_top1.pos}}
-    assert(Search_text == nil)
-  elseif chord == 'C-=' then
-    initialize_font_settings(Font_height+2)
-    Text.redraw_all()
-  elseif chord == 'C--' then
-    initialize_font_settings(Font_height-2)
-    Text.redraw_all()
-  elseif chord == 'C-0' then
-    initialize_font_settings(20)
-    Text.redraw_all()
-  elseif chord == 'C-z' then
-    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
-    local event = undo_event()
-    if event then
-      local src = event.before
-      Screen_top1 = deepcopy(src.screen_top)
-      Cursor1 = deepcopy(src.cursor)
-      Selection1 = deepcopy(src.selection)
-      patch(Lines, event.after, event.before)
-      Text.redraw_all()  -- if we're scrolling, reclaim all fragments to avoid memory leaks
-      schedule_save()
-    end
-  elseif chord == 'C-y' then
-    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
-    local event = redo_event()
-    if event then
-      local src = event.after
-      Screen_top1 = deepcopy(src.screen_top)
-      Cursor1 = deepcopy(src.cursor)
-      Selection1 = deepcopy(src.selection)
-      patch(Lines, event.before, event.after)
-      Text.redraw_all()  -- if we're scrolling, reclaim all fragments to avoid memory leaks
-      schedule_save()
-    end
-  -- clipboard
-  elseif chord == 'C-c' then
-    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
-    local s = Text.selection()
-    if s then
-      App.setClipboardText(s)
-    end
-  elseif chord == 'C-x' then
-    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
-    local s = Text.cut_selection(Margin_left, App.screen.width-Margin_right)
-    if s then
-      App.setClipboardText(s)
-    end
-    schedule_save()
-  elseif chord == 'C-v' then
-    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
-    -- 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 = Cursor1.line
-    local before = snapshot(before_line)
-    local clipboard_data = App.getClipboardText()
-    for _,code in utf8.codes(clipboard_data) do
-      local c = utf8.char(code)
-      if c == '\n' then
-        Text.insert_return()
-      else
-        Text.insert_at_cursor(c)
-      end
-    end
-    if Text.cursor_past_screen_bottom() then
-      Text.snap_cursor_to_bottom_of_screen(Margin_left, App.screen.height-Margin_right)
-    end
-    schedule_save()
-    record_undo_event({before=before, after=snapshot(before_line, Cursor1.line)})
-  -- dispatch to drawing or text
-  elseif App.mouse_down(1) or chord:sub(1,2) == 'C-' then
-    -- DON'T reset line.y here
-    local drawing_index, drawing = Drawing.current_drawing()
-    if drawing_index then
-      local before = snapshot(drawing_index)
-      Drawing.keychord_pressed(chord)
-      record_undo_event({before=before, after=snapshot(drawing_index)})
-      schedule_save()
-    end
-  elseif chord == 'escape' and not App.mouse_down(1) then
-    for _,line in ipairs(Lines) do
-      if line.mode == 'drawing' then
-        line.show_help = false
-      end
-    end
-  elseif Current_drawing_mode == 'name' then
-    if chord == 'return' then
-      Current_drawing_mode = Previous_drawing_mode
-      Previous_drawing_mode = nil
-    else
-      local before = snapshot(Lines.current_drawing_index)
-      local drawing = Lines.current_drawing
-      local p = drawing.points[drawing.pending.target_point]
-      if chord == 'escape' then
-        p.name = nil
-        record_undo_event({before=before, after=snapshot(Lines.current_drawing_index)})
-      elseif chord == 'backspace' then
-        local len = utf8.len(p.name)
-        local byte_offset = Text.offset(p.name, len-1)
-        if len == 1 then byte_offset = 0 end
-        p.name = string.sub(p.name, 1, byte_offset)
-        record_undo_event({before=before, after=snapshot(Lines.current_drawing_index)})
-      end
-    end
-    schedule_save()
-  else
-    for _,line in ipairs(Lines) do line.y = nil end  -- just in case we scroll
-    Text.keychord_pressed(chord)
-  end
+  return edit.keychord_pressed(chord, key)
 end
 
 function App.keyreleased(key, scancode)
+  return edit.key_released(key, scancode)
 end