From f1886391c56e530bb1bb362a450aa9ab6cb8485c Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Thu, 1 Jun 2023 12:20:34 -0700
Subject: [PATCH 01/11] some temporary logging to catch a bug

The bug has been spotted twice:

1. In snap.love, I selected text in one node, then another, and hit:
  Error: text.lua:789: attempt to compare nil with number
  stack traceback:
    text.lua:789: in function 'lt1'
    select.lua:19: in function 'clip_selection'
    text.lua:32: in function 'draw'
    edit.lua:117: in function 'draw'
    [string "REPL"]:21: in function 'draw'
    main.lua:152: in function 'draw'
    app.lua:102: in function <app.lua:84>
    [C]: in function 'xpcall'
    app.lua:112: in function <app.lua:111>
    [C]: in function 'xpcall'

  Couldn't reproduce.

2. In text.love, inscript selected all text in a small buffer and then
   clicked outside the text. And got:

  Error: text.lua:784: attempt to compare nil with number
  Traceback
    [love "callbacks.lua"]:228: in function 'handler'
    text.lua:784: in function 'lt1'
    select.lua:19: in function 'clip_selection'
    text.lua:27: in function 'draw'
    edit.lua:117: in function 'draw'
    run.lua:136: in function 'draw'
    main.lua:148: in function 'draw'
    app.lua:42: in function <app.lua:22>
    [C]: in function 'xpcall'

  This is reproducible, and also across forks.
---
 edit.lua   | 14 ++++++++------
 run.lua    |  5 +++++
 select.lua |  4 ++++
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/edit.lua b/edit.lua
index 0f5bef5..7140997 100644
--- a/edit.lua
+++ b/edit.lua
@@ -223,7 +223,7 @@ end
 
 function edit.mouse_press(State, x,y, mouse_button)
   if State.search_term then return end
---?   print('press', State.cursor1.line)
+  print_and_log(('edit.mouse_press: cursor at %d,%d').format(State.cursor1.line, State.cursor1.pos))
   if mouse_press_consumed_by_any_button_handler(State, x,y, mouse_button) then
     -- press on a button and it returned 'true' to short-circuit
     return
@@ -241,6 +241,7 @@ function edit.mouse_press(State, x,y, mouse_button)
         --  press and hold to start a selection: sets selection on press, cursor on release
         --  press and hold, then press shift: ignore shift
         --    i.e. mouse_release should never look at shift state
+        print_and_log(('edit.mouse_press: in line %d').format(line_index))
         State.old_cursor1 = State.cursor1
         State.old_selection1 = State.selection1
         State.mousepress_shift = App.shift_down()
@@ -248,7 +249,7 @@ function edit.mouse_press(State, x,y, mouse_button)
             line=line_index,
             pos=Text.to_pos_on_line(State, line_index, x, y),
         }
---?         print('selection', State.selection1.line, State.selection1.pos)
+        print_and_log(('edit.mouse_press: selection now %d,%d').format(State.selection1.line, State.selection1.pos))
         break
       end
     elseif line.mode == 'drawing' then
@@ -266,7 +267,7 @@ end
 
 function edit.mouse_release(State, x,y, mouse_button)
   if State.search_term then return end
---?   print('release', State.cursor1.line)
+  print_and_log(('edit.mouse_release: cursor at %d,%d').format(State.cursor1.line, State.cursor1.pos))
   if State.lines.current_drawing then
     Drawing.mouse_release(State, x,y, mouse_button)
     schedule_save(State)
@@ -275,15 +276,16 @@ function edit.mouse_release(State, x,y, mouse_button)
       Drawing.before = nil
     end
   else
+    print_and_log('edit.mouse_release: no current drawing')
     for line_index,line in ipairs(State.lines) do
       if line.mode == 'text' then
         if Text.in_line(State, line_index, x,y) then
---?           print('reset selection')
+          print_and_log(('edit.mouse_release: in line %d').format(line_index))
           State.cursor1 = {
               line=line_index,
               pos=Text.to_pos_on_line(State, line_index, x, y),
           }
---?           print('cursor', State.cursor1.line, State.cursor1.pos)
+          print_and_log(('edit.mouse_release: cursor now %d,%d').format(State.cursor1.line, State.cursor1.pos))
           if State.mousepress_shift then
             if State.old_selection1.line == nil then
               State.selection1 = State.old_cursor1
@@ -299,7 +301,7 @@ function edit.mouse_release(State, x,y, mouse_button)
         end
       end
     end
---?     print('selection:', State.selection1.line, State.selection1.pos)
+    print_and_log(('edit.mouse_release: finally selection %s,%s cursor %d,%d').format(tostring(State.selection1.line), tostring(State.selection1.pos), State.cursor1.line, State.cursor1.pos))
   end
 end
 
diff --git a/run.lua b/run.lua
index d029bed..5f35a0b 100644
--- a/run.lua
+++ b/run.lua
@@ -48,6 +48,11 @@ function run.initialize(arg)
   end
 end
 
+function print_and_log(s)
+  print(s)
+  log(3, s)
+end
+
 function run.load_settings()
   love.graphics.setFont(love.graphics.newFont(Settings.font_height))
   -- determine default dimensions and flags
diff --git a/select.lua b/select.lua
index efb6909..094cca9 100644
--- a/select.lua
+++ b/select.lua
@@ -8,13 +8,17 @@
 -- Result: positions spos,epos between apos,bpos.
 function Text.clip_selection(State, line_index, apos, bpos)
   if State.selection1.line == nil then return nil,nil end
+  print_and_log('text.clip_selection')
   -- min,max = sorted(State.selection1,State.cursor1)
   local minl,minp = State.selection1.line,State.selection1.pos
+  print_and_log(('text.clip_selection: one end from selection: %d,%d'):format(minl,minp))
   local maxl,maxp
   if App.mouse_down(1) then
     maxl,maxp = Text.mouse_pos(State)
+    print_and_log(('text.clip_selection: other end from mouse: %d,%d'):format(maxl,maxp))
   else
     maxl,maxp = State.cursor1.line,State.cursor1.pos
+    print_and_log(('text.clip_selection: other end from cursor: %d,%d'):format(maxl,maxp))
   end
   if Text.lt1({line=maxl, pos=maxp},
               {line=minl, pos=minp}) then

From 3e848efb081797d2341254dbdfdcccc307cf5170 Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Thu, 1 Jun 2023 12:33:22 -0700
Subject: [PATCH 02/11] ah, I see the problem

Text.mouse_pos can sometimes set recent_mouse.time but not
recent_mouse.x/y. I'd assumed x/y is never nil in those situations, but
that's violated. It's most easily seen when typing C-a and then
clicking.
---
 edit.lua   | 14 +++++++-------
 select.lua |  7 +------
 2 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/edit.lua b/edit.lua
index 7140997..f9eb076 100644
--- a/edit.lua
+++ b/edit.lua
@@ -223,7 +223,7 @@ end
 
 function edit.mouse_press(State, x,y, mouse_button)
   if State.search_term then return end
-  print_and_log(('edit.mouse_press: cursor at %d,%d').format(State.cursor1.line, State.cursor1.pos))
+  print_and_log(('edit.mouse_press: cursor at %d,%d'):format(State.cursor1.line, State.cursor1.pos))
   if mouse_press_consumed_by_any_button_handler(State, x,y, mouse_button) then
     -- press on a button and it returned 'true' to short-circuit
     return
@@ -241,7 +241,7 @@ function edit.mouse_press(State, x,y, mouse_button)
         --  press and hold to start a selection: sets selection on press, cursor on release
         --  press and hold, then press shift: ignore shift
         --    i.e. mouse_release should never look at shift state
-        print_and_log(('edit.mouse_press: in line %d').format(line_index))
+        print_and_log(('edit.mouse_press: in line %d'):format(line_index))
         State.old_cursor1 = State.cursor1
         State.old_selection1 = State.selection1
         State.mousepress_shift = App.shift_down()
@@ -249,7 +249,7 @@ function edit.mouse_press(State, x,y, mouse_button)
             line=line_index,
             pos=Text.to_pos_on_line(State, line_index, x, y),
         }
-        print_and_log(('edit.mouse_press: selection now %d,%d').format(State.selection1.line, State.selection1.pos))
+        print_and_log(('edit.mouse_press: selection now %d,%d'):format(State.selection1.line, State.selection1.pos))
         break
       end
     elseif line.mode == 'drawing' then
@@ -267,7 +267,7 @@ end
 
 function edit.mouse_release(State, x,y, mouse_button)
   if State.search_term then return end
-  print_and_log(('edit.mouse_release: cursor at %d,%d').format(State.cursor1.line, State.cursor1.pos))
+  print_and_log(('edit.mouse_release: cursor at %d,%d'):format(State.cursor1.line, State.cursor1.pos))
   if State.lines.current_drawing then
     Drawing.mouse_release(State, x,y, mouse_button)
     schedule_save(State)
@@ -280,12 +280,12 @@ function edit.mouse_release(State, x,y, mouse_button)
     for line_index,line in ipairs(State.lines) do
       if line.mode == 'text' then
         if Text.in_line(State, line_index, x,y) then
-          print_and_log(('edit.mouse_release: in line %d').format(line_index))
+          print_and_log(('edit.mouse_release: in line %d'):format(line_index))
           State.cursor1 = {
               line=line_index,
               pos=Text.to_pos_on_line(State, line_index, x, y),
           }
-          print_and_log(('edit.mouse_release: cursor now %d,%d').format(State.cursor1.line, State.cursor1.pos))
+          print_and_log(('edit.mouse_release: cursor now %d,%d'):format(State.cursor1.line, State.cursor1.pos))
           if State.mousepress_shift then
             if State.old_selection1.line == nil then
               State.selection1 = State.old_cursor1
@@ -301,7 +301,7 @@ function edit.mouse_release(State, x,y, mouse_button)
         end
       end
     end
-    print_and_log(('edit.mouse_release: finally selection %s,%s cursor %d,%d').format(tostring(State.selection1.line), tostring(State.selection1.pos), State.cursor1.line, State.cursor1.pos))
+    print_and_log(('edit.mouse_release: finally selection %s,%s cursor %d,%d'):format(tostring(State.selection1.line), tostring(State.selection1.pos), State.cursor1.line, State.cursor1.pos))
   end
 end
 
diff --git a/select.lua b/select.lua
index 094cca9..3b36b52 100644
--- a/select.lua
+++ b/select.lua
@@ -8,17 +8,13 @@
 -- Result: positions spos,epos between apos,bpos.
 function Text.clip_selection(State, line_index, apos, bpos)
   if State.selection1.line == nil then return nil,nil end
-  print_and_log('text.clip_selection')
   -- min,max = sorted(State.selection1,State.cursor1)
   local minl,minp = State.selection1.line,State.selection1.pos
-  print_and_log(('text.clip_selection: one end from selection: %d,%d'):format(minl,minp))
   local maxl,maxp
   if App.mouse_down(1) then
     maxl,maxp = Text.mouse_pos(State)
-    print_and_log(('text.clip_selection: other end from mouse: %d,%d'):format(maxl,maxp))
   else
     maxl,maxp = State.cursor1.line,State.cursor1.pos
-    print_and_log(('text.clip_selection: other end from cursor: %d,%d'):format(maxl,maxp))
   end
   if Text.lt1({line=maxl, pos=maxp},
               {line=minl, pos=minp}) then
@@ -33,7 +29,6 @@ function Text.clip_selection(State, line_index, apos, bpos)
   -- compare bounds more carefully (start inclusive, end exclusive)
   local a_ge = Text.le1({line=minl, pos=minp}, {line=line_index, pos=apos})
   local b_lt = Text.lt1({line=line_index, pos=bpos}, {line=maxl, pos=maxp})
---?   print(minl,line_index,maxl, '--', minp,apos,bpos,maxp, '--', a_ge,b_lt)
   if a_ge and b_lt then
     -- fully contained
     return apos,bpos
@@ -64,7 +59,6 @@ function Text.draw_highlight(State, line, x,y, pos, lo,hi)
       local before = line.data:sub(pos_offset, lo_offset-1)
       lo_px = App.width(before)
     end
---?     print(lo,pos,hi, '--', lo_offset,pos_offset,hi_offset, '--', lo_px)
     local s = line.data:sub(lo_offset, hi_offset-1)
     App.color(Highlight_color)
     love.graphics.rectangle('fill', x+lo_px,y, App.width(s),State.line_height)
@@ -77,6 +71,7 @@ end
 function Text.mouse_pos(State)
   local time = love.timer.getTime()
   if State.recent_mouse.time and State.recent_mouse.time > time-0.1 then
+    print_and_log(('text.mouse_pos: returning recent value %d,%d'):format(State.recent_mouse.line, State.recent_mouse.pos))
     return State.recent_mouse.line, State.recent_mouse.pos
   end
   State.recent_mouse.time = time

From 9b3fa33f5bdd1237c2ea13e40c8aae9e837dd54f Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Thu, 1 Jun 2023 12:57:47 -0700
Subject: [PATCH 03/11] idea: set recent_mouse on mouse events

This helps, but doesn't address the C-a case. As it stands, literally my
first click of the mouse might need access to recent_mouse.line/pos
---
 edit.lua   | 3 ++-
 select.lua | 5 ++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/edit.lua b/edit.lua
index f9eb076..82d9542 100644
--- a/edit.lua
+++ b/edit.lua
@@ -249,7 +249,7 @@ function edit.mouse_press(State, x,y, mouse_button)
             line=line_index,
             pos=Text.to_pos_on_line(State, line_index, x, y),
         }
-        print_and_log(('edit.mouse_press: selection now %d,%d'):format(State.selection1.line, State.selection1.pos))
+        State.recent_mouse = {time=Current_time, line=State.selection1.line, pos=State.selection1.pos}
         break
       end
     elseif line.mode == 'drawing' then
@@ -286,6 +286,7 @@ function edit.mouse_release(State, x,y, mouse_button)
               pos=Text.to_pos_on_line(State, line_index, x, y),
           }
           print_and_log(('edit.mouse_release: cursor now %d,%d'):format(State.cursor1.line, State.cursor1.pos))
+          State.recent_mouse = {time=Current_time, line=State.cursor1.line, pos=State.cursor1.pos}
           if State.mousepress_shift then
             if State.old_selection1.line == nil then
               State.selection1 = State.old_cursor1
diff --git a/select.lua b/select.lua
index 3b36b52..d0509ef 100644
--- a/select.lua
+++ b/select.lua
@@ -69,12 +69,11 @@ end
 
 -- inefficient for some reason, so don't do it on every frame
 function Text.mouse_pos(State)
-  local time = love.timer.getTime()
-  if State.recent_mouse.time and State.recent_mouse.time > time-0.1 then
+  if State.recent_mouse.time and State.recent_mouse.time > Current_time-0.1 then
     print_and_log(('text.mouse_pos: returning recent value %d,%d'):format(State.recent_mouse.line, State.recent_mouse.pos))
     return State.recent_mouse.line, State.recent_mouse.pos
   end
-  State.recent_mouse.time = time
+  State.recent_mouse.time = Current_time
   local line,pos = Text.to_pos(State, App.mouse_x(), App.mouse_y())
   if line then
     State.recent_mouse.line = line

From 9b27a4d816bbfc23f122698e65f660d89c7664e4 Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Thu, 1 Jun 2023 21:59:09 -0700
Subject: [PATCH 04/11] failing test now looks realistic

---
 text_tests.lua | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/text_tests.lua b/text_tests.lua
index 8b646a4..bd449ac 100644
--- a/text_tests.lua
+++ b/text_tests.lua
@@ -882,6 +882,52 @@ function test_select_text_repeatedly_using_mouse_and_shift()
   check_eq(Editor_state.cursor1.pos, 2, 'cursor:pos')
 end
 
+function test_select_all_text()
+  -- display a single line of text
+  App.screen.init{width=75, height=80}
+  Editor_state = edit.initialize_test_state()
+  Editor_state.lines = load_array{'abc def'}
+  Text.redraw_all(Editor_state)
+  Editor_state.cursor1 = {line=1, pos=1}
+  Editor_state.screen_top1 = {line=1, pos=1}
+  Editor_state.screen_bottom1 = {}
+  edit.draw(Editor_state)
+  -- select all
+  App.fake_key_press('lctrl')
+  edit.run_after_keychord(Editor_state, 'C-a')
+  App.fake_key_release('lctrl')
+  edit.key_release(Editor_state, 'lctrl')
+  -- selection
+  check_eq(Editor_state.selection1.line, 1, 'selection:line')
+  check_eq(Editor_state.selection1.pos, 1, 'selection:pos')
+  check_eq(Editor_state.cursor1.line, 1, 'cursor:line')
+  check_eq(Editor_state.cursor1.pos, 8, 'cursor:pos')
+end
+
+function test_select_all_text_then_mouse_press_outside_text()
+  -- display a single line of text
+  App.screen.init{width=75, height=80}
+  Editor_state = edit.initialize_test_state()
+  Editor_state.lines = load_array{'abc def'}
+  Text.redraw_all(Editor_state)
+  Editor_state.cursor1 = {line=1, pos=1}
+  Editor_state.screen_top1 = {line=1, pos=1}
+  Editor_state.screen_bottom1 = {}
+  edit.draw(Editor_state)
+  -- select all
+  App.fake_key_press('lctrl')
+  edit.run_after_keychord(Editor_state, 'C-a')
+  App.fake_key_release('lctrl')
+  edit.key_release(Editor_state, 'lctrl')
+  -- selection
+  check_eq(Editor_state.selection1.line, 1, 'selection:line')
+  check_eq(Editor_state.selection1.pos, 1, 'selection:pos')
+  check_eq(Editor_state.cursor1.line, 1, 'cursor:line')
+  check_eq(Editor_state.cursor1.pos, 8, 'cursor:pos')
+  -- part of a mouse click outside the selected line
+  edit.run_after_mouse_press(Editor_state, 45, Margin_top + Editor_state.line_height + 10, --[[mouse button]] 1)
+end
+
 function test_cut_without_selection()
   -- display a few lines
   App.screen.init{width=Editor_state.left+30, height=60}

From cdef37c4191e48228d1ea83eb590e1f3109e3c8b Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Thu, 1 Jun 2023 22:12:12 -0700
Subject: [PATCH 05/11] get rid of recent_mouse

It's a hack:
  - if you start selecting from below final line the start of the
    selection is the most recent click even if it was forever ago
  - (the crash we're currently fixing) if you start up and immediately
    select all then click below final line => crash. recent_mouse was
    never set.
  - getting rid of it breaks no tests (except the crash we're currently
    fixing)
---
 edit.lua       |  4 ----
 select.lua     | 11 +----------
 text_tests.lua | 46 +++++++++++++++++++++++-----------------------
 3 files changed, 24 insertions(+), 37 deletions(-)

diff --git a/edit.lua b/edit.lua
index 82d9542..3e92a54 100644
--- a/edit.lua
+++ b/edit.lua
@@ -75,8 +75,6 @@ function edit.initialize_state(top, left, right, font_height, line_height)  -- c
     old_cursor1 = nil,
     old_selection1 = nil,
     mousepress_shift = nil,
-    -- when selecting text, avoid recomputing some state on every single frame
-    recent_mouse = {},
 
     -- cursor coordinates in pixels
     cursor_x = 0,
@@ -249,7 +247,6 @@ function edit.mouse_press(State, x,y, mouse_button)
             line=line_index,
             pos=Text.to_pos_on_line(State, line_index, x, y),
         }
-        State.recent_mouse = {time=Current_time, line=State.selection1.line, pos=State.selection1.pos}
         break
       end
     elseif line.mode == 'drawing' then
@@ -286,7 +283,6 @@ function edit.mouse_release(State, x,y, mouse_button)
               pos=Text.to_pos_on_line(State, line_index, x, y),
           }
           print_and_log(('edit.mouse_release: cursor now %d,%d'):format(State.cursor1.line, State.cursor1.pos))
-          State.recent_mouse = {time=Current_time, line=State.cursor1.line, pos=State.cursor1.pos}
           if State.mousepress_shift then
             if State.old_selection1.line == nil then
               State.selection1 = State.old_cursor1
diff --git a/select.lua b/select.lua
index d0509ef..dbd551b 100644
--- a/select.lua
+++ b/select.lua
@@ -69,17 +69,8 @@ end
 
 -- inefficient for some reason, so don't do it on every frame
 function Text.mouse_pos(State)
-  if State.recent_mouse.time and State.recent_mouse.time > Current_time-0.1 then
-    print_and_log(('text.mouse_pos: returning recent value %d,%d'):format(State.recent_mouse.line, State.recent_mouse.pos))
-    return State.recent_mouse.line, State.recent_mouse.pos
-  end
-  State.recent_mouse.time = Current_time
   local line,pos = Text.to_pos(State, App.mouse_x(), App.mouse_y())
-  if line then
-    State.recent_mouse.line = line
-    State.recent_mouse.pos = pos
-  end
-  return State.recent_mouse.line, State.recent_mouse.pos
+  return line, pos
 end
 
 function Text.to_pos(State, x,y)
diff --git a/text_tests.lua b/text_tests.lua
index bd449ac..eec3098 100644
--- a/text_tests.lua
+++ b/text_tests.lua
@@ -904,29 +904,29 @@ function test_select_all_text()
   check_eq(Editor_state.cursor1.pos, 8, 'cursor:pos')
 end
 
-function test_select_all_text_then_mouse_press_outside_text()
-  -- display a single line of text
-  App.screen.init{width=75, height=80}
-  Editor_state = edit.initialize_test_state()
-  Editor_state.lines = load_array{'abc def'}
-  Text.redraw_all(Editor_state)
-  Editor_state.cursor1 = {line=1, pos=1}
-  Editor_state.screen_top1 = {line=1, pos=1}
-  Editor_state.screen_bottom1 = {}
-  edit.draw(Editor_state)
-  -- select all
-  App.fake_key_press('lctrl')
-  edit.run_after_keychord(Editor_state, 'C-a')
-  App.fake_key_release('lctrl')
-  edit.key_release(Editor_state, 'lctrl')
-  -- selection
-  check_eq(Editor_state.selection1.line, 1, 'selection:line')
-  check_eq(Editor_state.selection1.pos, 1, 'selection:pos')
-  check_eq(Editor_state.cursor1.line, 1, 'cursor:line')
-  check_eq(Editor_state.cursor1.pos, 8, 'cursor:pos')
-  -- part of a mouse click outside the selected line
-  edit.run_after_mouse_press(Editor_state, 45, Margin_top + Editor_state.line_height + 10, --[[mouse button]] 1)
-end
+--? function test_select_all_text_then_mouse_press_outside_text()
+--?   -- display a single line of text
+--?   App.screen.init{width=75, height=80}
+--?   Editor_state = edit.initialize_test_state()
+--?   Editor_state.lines = load_array{'abc def'}
+--?   Text.redraw_all(Editor_state)
+--?   Editor_state.cursor1 = {line=1, pos=1}
+--?   Editor_state.screen_top1 = {line=1, pos=1}
+--?   Editor_state.screen_bottom1 = {}
+--?   edit.draw(Editor_state)
+--?   -- select all
+--?   App.fake_key_press('lctrl')
+--?   edit.run_after_keychord(Editor_state, 'C-a')
+--?   App.fake_key_release('lctrl')
+--?   edit.key_release(Editor_state, 'lctrl')
+--?   -- selection
+--?   check_eq(Editor_state.selection1.line, 1, 'selection:line')
+--?   check_eq(Editor_state.selection1.pos, 1, 'selection:pos')
+--?   check_eq(Editor_state.cursor1.line, 1, 'cursor:line')
+--?   check_eq(Editor_state.cursor1.pos, 8, 'cursor:pos')
+--?   -- part of a mouse click outside the selected line
+--?   edit.run_after_mouse_press(Editor_state, 45, Margin_top + Editor_state.line_height + 10, --[[mouse button]] 1)
+--? end
 
 function test_cut_without_selection()
   -- display a few lines

From e0462ea2d866588522501875840af464b75b4ece Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Fri, 2 Jun 2023 07:43:20 -0700
Subject: [PATCH 06/11] save the list of tests in repo

---
 text_tests | 113 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 text_tests

diff --git a/text_tests b/text_tests
new file mode 100644
index 0000000..b14f634
--- /dev/null
+++ b/text_tests
@@ -0,0 +1,113 @@
+== Summary of tests for the text editor
+
+This doesn't include all tests and might not change between forks, but it's
+intended to be the "timeless core" of a text editor widget that shouldn't
+change across forks.
+
+# basic
+initial state
+draw text
+draw wrapping text
+draw word wrapping text
+draw text wrapping within word
+draw wrapping text containing non ascii
+
+# mouse
+click moves cursor
+click to left of line
+click takes margins into account
+click on empty line
+click on wrapping line
+click on wrapping line takes margins into account
+click on wrapping line
+click on wrapping line rendered from partway at top of screen
+click past end of wrapping line
+click past end of wrapping line containing non ascii
+click past end of word wrapping line
+
+# cursor movement
+move left
+  move left to previous line
+move right
+  move right to next line
+
+move to start of word
+  move to start of previous word
+  move to start of word on previous line
+move past end of word
+  move past end of word on next line
+skip to previous word
+  skip past tab to previous word
+  skip multiple spaces to previous word
+skip to next word
+  skip past tab to next word
+  skip multiple spaces to next word
+
+# mutating text
+insert first character
+edit wrapping text
+insert newline
+insert newline at start of line
+insert from clipboard
+backspace from start of final line
+backspace past line boundary
+backspace over selection
+backspace over selection reverse
+backspace over multiple lines
+backspace to end of line
+backspace to start of line
+
+# scroll
+pagedown
+pagedown often shows start of wrapping line
+pagedown can start from middle of long wrapping line
+pagedown never moves up
+down arrow moves cursor
+down arrow scrolls down by one line
+down arrow scrolls down by one screen line
+down arrow scrolls down by one screen line after splitting within word
+pagedown followed by down arrow does not scroll screen up
+up arrow moves cursor
+up arrow scrolls up by one line
+up arrow scrolls up by one screen line
+up arrow scrolls up to final screen line
+up arrow scrolls up to empty line
+pageup
+pageup scrolls up by screen line
+pageup scrolls up from middle screen line
+enter on bottom line scrolls down
+enter on final line avoids scrolling down when not at bottom
+inserting text on final line avoids scrolling down when not at bottom
+typing on bottom line scrolls down
+left arrow scrolls up in wrapped line
+right arrow scrolls down in wrapped line
+home scrolls up in wrapped line
+end scrolls down in wrapped line
+position cursor on recently edited wrapping line
+backspace can scroll up
+backspace can scroll up screen line
+
+# selection
+select text using shift and cursor movement operations
+select text using mouse
+select text using mouse and shift
+select text repeatedly using mouse and shift
+cursor movement without shift resets selection
+edit deletes selection
+edit with shift key deletes selection
+deleting selection may scroll
+copy does not reset selection
+cut
+cut without selection
+paste replaces selection
+
+# search
+search
+search upwards
+search wrap
+search wrap upwards
+
+# undo
+undo insert text
+undo delete text
+undo restores selection

From 541519a9986fe5c85d6b03fc8cf993ba8e950b0c Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Fri, 2 Jun 2023 07:46:45 -0700
Subject: [PATCH 07/11] desired behavior now looks good

---
 text_tests | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/text_tests b/text_tests
index b14f634..d571368 100644
--- a/text_tests
+++ b/text_tests
@@ -90,9 +90,14 @@ backspace can scroll up screen line
 # selection
 select text using shift and cursor movement operations
 select text using mouse
+  clicking to left of a line = start of line
+  clicking to right of a line = end of line
+  clicking above topmost line = top of screen
+  clicking below bottom-most line = bottom of screen
 select text using mouse and shift
 select text repeatedly using mouse and shift
 cursor movement without shift resets selection
+mouse click without shift resets selection
 edit deletes selection
 edit with shift key deletes selection
 deleting selection may scroll

From 3114176ebd5b9895b5f67c759a2a705f673a4ac0 Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Sat, 3 Jun 2023 10:36:05 -0700
Subject: [PATCH 08/11] change how we handle clicks above top margin

---
 app.lua        |  1 +
 edit.lua       | 11 +++++++++++
 select.lua     |  3 +++
 text_tests.lua | 43 +++++++++++++++++++------------------------
 4 files changed, 34 insertions(+), 24 deletions(-)

diff --git a/app.lua b/app.lua
index 1d4a72b..584b17b 100644
--- a/app.lua
+++ b/app.lua
@@ -361,6 +361,7 @@ function App.run_tests()
   for _,name in ipairs(sorted_names) do
     App.initialize_for_test()
 --?     print('=== '..name)
+--?     _G[name]()
     xpcall(_G[name], function(err) prepend_debug_info_to_test_failure(name, err) end)
   end
   -- clean up all test methods
diff --git a/edit.lua b/edit.lua
index 3e92a54..ddd17c1 100644
--- a/edit.lua
+++ b/edit.lua
@@ -227,6 +227,17 @@ function edit.mouse_press(State, x,y, mouse_button)
     return
   end
 
+  if y < State.top then
+    State.old_cursor1 = State.cursor1
+    State.old_selection1 = State.selection1
+    State.mousepress_shift = App.shift_down()
+    State.selection1 = {
+        line=1,
+        pos=1,
+    }
+    return
+  end
+
   for line_index,line in ipairs(State.lines) do
     if line.mode == 'text' then
       if Text.in_line(State, line_index, x,y) then
diff --git a/select.lua b/select.lua
index dbd551b..c2fe7ad 100644
--- a/select.lua
+++ b/select.lua
@@ -74,6 +74,9 @@ function Text.mouse_pos(State)
 end
 
 function Text.to_pos(State, x,y)
+  if y < State.line_cache[State.screen_top1.line].starty then
+    return State.screen_top1.line, State.screen_top1.pos
+  end
   for line_index,line in ipairs(State.lines) do
     if line.mode == 'text' then
       if Text.in_line(State, line_index, x,y) then
diff --git a/text_tests.lua b/text_tests.lua
index eec3098..d5368a8 100644
--- a/text_tests.lua
+++ b/text_tests.lua
@@ -1,4 +1,6 @@
 -- major tests for text editing flows
+-- Arguably this should be called edit_tests.lua,
+-- but that would mess up the git blame at this point.
 
 function test_initial_state()
   App.screen.init{width=120, height=60}
@@ -828,6 +830,23 @@ function test_select_text_using_mouse()
   check_eq(Editor_state.cursor1.pos, 4, 'cursor:pos')
 end
 
+function test_select_text_using_mouse_starting_above_text()
+  App.screen.init{width=50, height=60}
+  Editor_state = edit.initialize_test_state()
+  Editor_state.lines = load_array{'abc', 'def', 'xyz'}
+  Text.redraw_all(Editor_state)
+  Editor_state.cursor1 = {line=1, pos=1}
+  Editor_state.screen_top1 = {line=1, pos=1}
+  Editor_state.screen_bottom1 = {}
+  Editor_state.selection1 = {}
+  edit.draw(Editor_state)  -- populate line_cache.starty for each line Editor_state.line_cache
+  -- press mouse above first line of text
+  edit.run_after_mouse_press(Editor_state, Editor_state.left+8,5, 1)
+  check(Editor_state.selection1.line ~= nil, 'selection:line-not-nil')
+  check_eq(Editor_state.selection1.line, 1, 'selection:line')
+  check_eq(Editor_state.selection1.pos, 1, 'selection:pos')
+end
+
 function test_select_text_using_mouse_and_shift()
   App.screen.init{width=50, height=60}
   Editor_state = edit.initialize_test_state()
@@ -904,30 +923,6 @@ function test_select_all_text()
   check_eq(Editor_state.cursor1.pos, 8, 'cursor:pos')
 end
 
---? function test_select_all_text_then_mouse_press_outside_text()
---?   -- display a single line of text
---?   App.screen.init{width=75, height=80}
---?   Editor_state = edit.initialize_test_state()
---?   Editor_state.lines = load_array{'abc def'}
---?   Text.redraw_all(Editor_state)
---?   Editor_state.cursor1 = {line=1, pos=1}
---?   Editor_state.screen_top1 = {line=1, pos=1}
---?   Editor_state.screen_bottom1 = {}
---?   edit.draw(Editor_state)
---?   -- select all
---?   App.fake_key_press('lctrl')
---?   edit.run_after_keychord(Editor_state, 'C-a')
---?   App.fake_key_release('lctrl')
---?   edit.key_release(Editor_state, 'lctrl')
---?   -- selection
---?   check_eq(Editor_state.selection1.line, 1, 'selection:line')
---?   check_eq(Editor_state.selection1.pos, 1, 'selection:pos')
---?   check_eq(Editor_state.cursor1.line, 1, 'cursor:line')
---?   check_eq(Editor_state.cursor1.pos, 8, 'cursor:pos')
---?   -- part of a mouse click outside the selected line
---?   edit.run_after_mouse_press(Editor_state, 45, Margin_top + Editor_state.line_height + 10, --[[mouse button]] 1)
---? end
-
 function test_cut_without_selection()
   -- display a few lines
   App.screen.init{width=Editor_state.left+30, height=60}

From cf0ba7c15431221e90f6aee87ea5b69ef0b18ea4 Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Sat, 3 Jun 2023 10:43:20 -0700
Subject: [PATCH 09/11] handle wrapping lines

---
 edit.lua       |  4 ++--
 text_tests.lua | 17 +++++++++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/edit.lua b/edit.lua
index ddd17c1..5918165 100644
--- a/edit.lua
+++ b/edit.lua
@@ -232,8 +232,8 @@ function edit.mouse_press(State, x,y, mouse_button)
     State.old_selection1 = State.selection1
     State.mousepress_shift = App.shift_down()
     State.selection1 = {
-        line=1,
-        pos=1,
+        line=State.screen_top1.line,
+        pos=State.screen_top1.pos,
     }
     return
   end
diff --git a/text_tests.lua b/text_tests.lua
index d5368a8..a01ad3e 100644
--- a/text_tests.lua
+++ b/text_tests.lua
@@ -847,6 +847,23 @@ function test_select_text_using_mouse_starting_above_text()
   check_eq(Editor_state.selection1.pos, 1, 'selection:pos')
 end
 
+function test_select_text_using_mouse_starting_above_text_wrapping_line()
+  -- first screen line starts in the middle of a line
+  App.screen.init{width=50, height=60}
+  Editor_state = edit.initialize_test_state()
+  Editor_state.lines = load_array{'abc', 'defgh', 'xyz'}
+  Text.redraw_all(Editor_state)
+  Editor_state.cursor1 = {line=2, pos=5}
+  Editor_state.screen_top1 = {line=2, pos=3}
+  Editor_state.screen_bottom1 = {}
+  -- press mouse above first line of text
+  edit.run_after_mouse_press(Editor_state, Editor_state.left+8,5, 1)
+  -- selection is at screen top
+  check(Editor_state.selection1.line ~= nil, 'selection:line-not-nil')
+  check_eq(Editor_state.selection1.line, 2, 'selection:line')
+  check_eq(Editor_state.selection1.pos, 3, 'selection:pos')
+end
+
 function test_select_text_using_mouse_and_shift()
   App.screen.init{width=50, height=60}
   Editor_state = edit.initialize_test_state()

From 9656e137742eb442e9ce013dd3f25cf6df8c9fad Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Sun, 4 Jun 2023 12:20:24 -0700
Subject: [PATCH 10/11] bugfix: inscript's bug

To fix this I have to first stop incrementally updating screen_bottom1
in the middle of a frame. Now it always has a good value from the end of
a frame.

I'm also running into some limitations in the test I'd ideally like to
write (that are documented in a comment), but I still get some sort of
automated test for this bugfix.
---
 edit.lua       | 31 +++++++++++++++++++++----------
 select.lua     |  8 ++------
 text.lua       | 15 +++++++++++++++
 text_tests.lua | 27 +++++++++++++++++++++++++++
 4 files changed, 65 insertions(+), 16 deletions(-)

diff --git a/edit.lua b/edit.lua
index 5918165..f436f36 100644
--- a/edit.lua
+++ b/edit.lua
@@ -152,12 +152,13 @@ function edit.draw(State)
   State.cursor_x = nil
   State.cursor_y = nil
   local y = State.top
+  local screen_bottom1 = {line=nil, pos=nil}
 --?   print('== draw')
   for line_index = State.screen_top1.line,#State.lines do
     local line = State.lines[line_index]
 --?     print('draw:', y, line_index, line)
     if y + State.line_height > App.screen.height then break end
-    State.screen_bottom1 = {line=line_index, pos=nil}
+    screen_bottom1.line = line_index
     if line.mode == 'text' then
 --?       print('text.draw', y, line_index)
       local startpos = 1
@@ -180,7 +181,7 @@ function edit.draw(State)
                      end,
         })
       end
-      y, State.screen_bottom1.pos = Text.draw(State, line_index, y, startpos)
+      y, screen_bottom1.pos = Text.draw(State, line_index, y, startpos)
 --?       print('=> y', y)
     elseif line.mode == 'drawing' then
       y = y+Drawing_padding_top
@@ -191,6 +192,7 @@ function edit.draw(State)
       assert(false)
     end
   end
+  State.screen_bottom1 = screen_bottom1
   if State.search_term then
     Text.draw_search_bar(State)
   end
@@ -221,7 +223,7 @@ end
 
 function edit.mouse_press(State, x,y, mouse_button)
   if State.search_term then return end
-  print_and_log(('edit.mouse_press: cursor at %d,%d'):format(State.cursor1.line, State.cursor1.pos))
+--?   print_and_log(('edit.mouse_press: cursor at %d,%d'):format(State.cursor1.line, State.cursor1.pos))
   if mouse_press_consumed_by_any_button_handler(State, x,y, mouse_button) then
     -- press on a button and it returned 'true' to short-circuit
     return
@@ -258,7 +260,7 @@ function edit.mouse_press(State, x,y, mouse_button)
             line=line_index,
             pos=Text.to_pos_on_line(State, line_index, x, y),
         }
-        break
+        return
       end
     elseif line.mode == 'drawing' then
       local line_cache = State.line_cache[line_index]
@@ -267,15 +269,24 @@ function edit.mouse_press(State, x,y, mouse_button)
         State.lines.current_drawing = line
         Drawing.before = snapshot(State, line_index)
         Drawing.mouse_press(State, line_index, x,y, mouse_button)
-        break
+        return
       end
     end
   end
+
+  -- still here? click is below all screen lines
+  State.old_cursor1 = State.cursor1
+  State.old_selection1 = State.selection1
+  State.mousepress_shift = App.shift_down()
+  State.selection1 = {
+      line=State.screen_bottom1.line,
+      pos=Text.pos_at_end_of_screen_line(State, State.screen_bottom1),
+  }
 end
 
 function edit.mouse_release(State, x,y, mouse_button)
   if State.search_term then return end
-  print_and_log(('edit.mouse_release: cursor at %d,%d'):format(State.cursor1.line, State.cursor1.pos))
+--?   print_and_log(('edit.mouse_release: cursor at %d,%d'):format(State.cursor1.line, State.cursor1.pos))
   if State.lines.current_drawing then
     Drawing.mouse_release(State, x,y, mouse_button)
     schedule_save(State)
@@ -284,16 +295,16 @@ function edit.mouse_release(State, x,y, mouse_button)
       Drawing.before = nil
     end
   else
-    print_and_log('edit.mouse_release: no current drawing')
+--?     print_and_log('edit.mouse_release: no current drawing')
     for line_index,line in ipairs(State.lines) do
       if line.mode == 'text' then
         if Text.in_line(State, line_index, x,y) then
-          print_and_log(('edit.mouse_release: in line %d'):format(line_index))
+--?           print_and_log(('edit.mouse_release: in line %d'):format(line_index))
           State.cursor1 = {
               line=line_index,
               pos=Text.to_pos_on_line(State, line_index, x, y),
           }
-          print_and_log(('edit.mouse_release: cursor now %d,%d'):format(State.cursor1.line, State.cursor1.pos))
+--?           print_and_log(('edit.mouse_release: cursor now %d,%d'):format(State.cursor1.line, State.cursor1.pos))
           if State.mousepress_shift then
             if State.old_selection1.line == nil then
               State.selection1 = State.old_cursor1
@@ -309,7 +320,7 @@ function edit.mouse_release(State, x,y, mouse_button)
         end
       end
     end
-    print_and_log(('edit.mouse_release: finally selection %s,%s cursor %d,%d'):format(tostring(State.selection1.line), tostring(State.selection1.pos), State.cursor1.line, State.cursor1.pos))
+--?     print_and_log(('edit.mouse_release: finally selection %s,%s cursor %d,%d'):format(tostring(State.selection1.line), tostring(State.selection1.pos), State.cursor1.line, State.cursor1.pos))
   end
 end
 
diff --git a/select.lua b/select.lua
index c2fe7ad..9b2a278 100644
--- a/select.lua
+++ b/select.lua
@@ -67,13 +67,8 @@ function Text.draw_highlight(State, line, x,y, pos, lo,hi)
   end
 end
 
--- inefficient for some reason, so don't do it on every frame
 function Text.mouse_pos(State)
-  local line,pos = Text.to_pos(State, App.mouse_x(), App.mouse_y())
-  return line, pos
-end
-
-function Text.to_pos(State, x,y)
+  local x,y = App.mouse_x(), App.mouse_y()
   if y < State.line_cache[State.screen_top1.line].starty then
     return State.screen_top1.line, State.screen_top1.pos
   end
@@ -84,6 +79,7 @@ function Text.to_pos(State, x,y)
       end
     end
   end
+  return State.screen_bottom1.line, Text.pos_at_end_of_screen_line(State, State.screen_bottom1)
 end
 
 function Text.cut_selection(State)
diff --git a/text.lua b/text.lua
index b6389e4..d89fb63 100644
--- a/text.lua
+++ b/text.lua
@@ -591,6 +591,7 @@ function Text.right_without_scroll(State)
   end
 end
 
+-- result: pos, index of screen line
 function Text.pos_at_start_of_screen_line(State, loc1)
   Text.populate_screen_line_starting_pos(State, loc1.line)
   local line_cache = State.line_cache[loc1.line]
@@ -603,6 +604,20 @@ function Text.pos_at_start_of_screen_line(State, loc1)
   assert(false)
 end
 
+function Text.pos_at_end_of_screen_line(State, loc1)
+  Text.populate_screen_line_starting_pos(State, loc1.line)
+  local line_cache = State.line_cache[loc1.line]
+  local most_recent_final_pos = utf8.len(State.lines[loc1.line].data)+1
+  for i=#line_cache.screen_line_starting_pos,1,-1 do
+    local spos = line_cache.screen_line_starting_pos[i]
+    if spos <= loc1.pos then
+      return most_recent_final_pos
+    end
+    most_recent_final_pos = spos-1
+  end
+  assert(false)
+end
+
 function Text.cursor_at_final_screen_line(State)
   Text.populate_screen_line_starting_pos(State, State.cursor1.line)
   local screen_lines = State.line_cache[State.cursor1.line].screen_line_starting_pos
diff --git a/text_tests.lua b/text_tests.lua
index a01ad3e..21a085a 100644
--- a/text_tests.lua
+++ b/text_tests.lua
@@ -864,6 +864,33 @@ function test_select_text_using_mouse_starting_above_text_wrapping_line()
   check_eq(Editor_state.selection1.pos, 3, 'selection:pos')
 end
 
+function test_select_text_using_mouse_starting_below_text()
+  -- I'd like to test what happens when a mouse click is below some page of
+  -- text, potentially even in the middle of a line.
+  -- However, it's brittle to set up a text line boundary just right.
+  -- So I'm going to just check things below the bottom of the final line of
+  -- text when it's in the middle of the screen.
+  -- final screen line ends in the middle of screen
+  App.screen.init{width=50, height=60}
+  Editor_state = edit.initialize_test_state()
+  Editor_state.lines = load_array{'abcde'}
+  Text.redraw_all(Editor_state)
+  Editor_state.cursor1 = {line=1, pos=1}
+  Editor_state.screen_top1 = {line=1, pos=1}
+  Editor_state.screen_bottom1 = {}
+  edit.draw(Editor_state)
+  local y = Editor_state.top
+  App.screen.check(y, 'ab', 'baseline:screen:1')
+  y = y + Editor_state.line_height
+  App.screen.check(y, 'cde', 'baseline:screen:2')
+  -- press mouse above first line of text
+  edit.run_after_mouse_press(Editor_state, 5,App.screen.height-5, 1)
+  -- selection is past bottom-most text in screen
+  check(Editor_state.selection1.line ~= nil, 'selection:line-not-nil')
+  check_eq(Editor_state.selection1.line, 1, 'selection:line')
+  check_eq(Editor_state.selection1.pos, 6, 'selection:pos')
+end
+
 function test_select_text_using_mouse_and_shift()
   App.screen.init{width=50, height=60}
   Editor_state = edit.initialize_test_state()

From 637e28f300def4172459dd1d6fdf6efd53200ea8 Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Sun, 4 Jun 2023 12:33:23 -0700
Subject: [PATCH 11/11] port inscript's bugfix to source editor

---
 edit.lua              |  2 +-
 source.lua            |  5 +++
 source_edit.lua       | 45 +++++++++++++++++------
 source_select.lua     | 22 ++---------
 source_text.lua       | 15 ++++++++
 source_text_tests.lua | 85 +++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 143 insertions(+), 31 deletions(-)

diff --git a/edit.lua b/edit.lua
index f436f36..e1a7fd5 100644
--- a/edit.lua
+++ b/edit.lua
@@ -252,7 +252,7 @@ function edit.mouse_press(State, x,y, mouse_button)
         --  press and hold to start a selection: sets selection on press, cursor on release
         --  press and hold, then press shift: ignore shift
         --    i.e. mouse_release should never look at shift state
-        print_and_log(('edit.mouse_press: in line %d'):format(line_index))
+--?         print_and_log(('edit.mouse_press: in line %d'):format(line_index))
         State.old_cursor1 = State.cursor1
         State.old_selection1 = State.selection1
         State.mousepress_shift = App.shift_down()
diff --git a/source.lua b/source.lua
index cab4512..b4489e1 100644
--- a/source.lua
+++ b/source.lua
@@ -113,6 +113,11 @@ function source.initialize_edit_side()
   end
 end
 
+function print_and_log(s)
+  print(s)
+  log(3, s)
+end
+
 function source.load_settings()
   local settings = Settings.source
   love.graphics.setFont(love.graphics.newFont(settings.font_height))
diff --git a/source_edit.lua b/source_edit.lua
index 58b1ccc..565b989 100644
--- a/source_edit.lua
+++ b/source_edit.lua
@@ -76,8 +76,6 @@ function edit.initialize_state(top, left, right, font_height, line_height)  -- c
     old_cursor1 = nil,
     old_selection1 = nil,
     mousepress_shift = nil,
-    -- when selecting text, avoid recomputing some state on every single frame
-    recent_mouse = {},
 
     -- cursor coordinates in pixels
     cursor_x = 0,
@@ -155,12 +153,13 @@ function edit.draw(State, hide_cursor)
   State.cursor_x = nil
   State.cursor_y = nil
   local y = State.top
+  local screen_bottom1 = {line=nil, pos=nil}
 --?   print('== draw')
   for line_index = State.screen_top1.line,#State.lines do
     local line = State.lines[line_index]
 --?     print('draw:', y, line_index, line)
     if y + State.line_height > App.screen.height then break end
-    State.screen_bottom1 = {line=line_index, pos=nil}
+    screen_bottom1.line = line_index
     if line.mode == 'text' then
 --?       print('text.draw', y, line_index)
       local startpos = 1
@@ -183,7 +182,7 @@ function edit.draw(State, hide_cursor)
                      end,
         })
       end
-      y, State.screen_bottom1.pos = Text.draw(State, line_index, y, startpos, hide_cursor)
+      y, screen_bottom1.pos = Text.draw(State, line_index, y, startpos, hide_cursor)
 --?       print('=> y', y)
     elseif line.mode == 'drawing' then
       y = y+Drawing_padding_top
@@ -194,6 +193,7 @@ function edit.draw(State, hide_cursor)
       assert(false)
     end
   end
+  State.screen_bottom1 = screen_bottom1
   if State.search_term then
     Text.draw_search_bar(State)
   end
@@ -224,12 +224,23 @@ end
 
 function edit.mouse_press(State, x,y, mouse_button)
   if State.search_term then return end
---?   print('press', State.cursor1.line)
+--?   print_and_log(('edit.mouse_press: cursor at %d,%d'):format(State.cursor1.line, State.cursor1.pos))
   if mouse_press_consumed_by_any_button_handler(State, x,y, mouse_button) then
     -- press on a button and it returned 'true' to short-circuit
     return
   end
 
+  if y < State.top then
+    State.old_cursor1 = State.cursor1
+    State.old_selection1 = State.selection1
+    State.mousepress_shift = App.shift_down()
+    State.selection1 = {
+        line=State.screen_top1.line,
+        pos=State.screen_top1.pos,
+    }
+    return
+  end
+
   for line_index,line in ipairs(State.lines) do
     if line.mode == 'text' then
       if Text.in_line(State, line_index, x,y) then
@@ -242,6 +253,7 @@ function edit.mouse_press(State, x,y, mouse_button)
         --  press and hold to start a selection: sets selection on press, cursor on release
         --  press and hold, then press shift: ignore shift
         --    i.e. mouse_release should never look at shift state
+--?         print_and_log(('edit.mouse_press: in line %d'):format(line_index))
         State.old_cursor1 = State.cursor1
         State.old_selection1 = State.selection1
         State.mousepress_shift = App.shift_down()
@@ -249,8 +261,7 @@ function edit.mouse_press(State, x,y, mouse_button)
             line=line_index,
             pos=Text.to_pos_on_line(State, line_index, x, y),
         }
---?         print('selection', State.selection1.line, State.selection1.pos)
-        break
+        return
       end
     elseif line.mode == 'drawing' then
       local line_cache = State.line_cache[line_index]
@@ -259,15 +270,24 @@ function edit.mouse_press(State, x,y, mouse_button)
         State.lines.current_drawing = line
         Drawing.before = snapshot(State, line_index)
         Drawing.mouse_press(State, line_index, x,y, mouse_button)
-        break
+        return
       end
     end
   end
+
+  -- still here? click is below all screen lines
+  State.old_cursor1 = State.cursor1
+  State.old_selection1 = State.selection1
+  State.mousepress_shift = App.shift_down()
+  State.selection1 = {
+      line=State.screen_bottom1.line,
+      pos=Text.pos_at_end_of_screen_line(State, State.screen_bottom1),
+  }
 end
 
 function edit.mouse_release(State, x,y, mouse_button)
   if State.search_term then return end
---?   print('release', State.cursor1.line)
+--?   print_and_log(('edit.mouse_release: cursor at %d,%d'):format(State.cursor1.line, State.cursor1.pos))
   if State.lines.current_drawing then
     Drawing.mouse_release(State, x,y, mouse_button)
     schedule_save(State)
@@ -276,15 +296,16 @@ function edit.mouse_release(State, x,y, mouse_button)
       Drawing.before = nil
     end
   else
+--?     print_and_log('edit.mouse_release: no current drawing')
     for line_index,line in ipairs(State.lines) do
       if line.mode == 'text' then
         if Text.in_line(State, line_index, x,y) then
---?           print('reset selection')
+--?           print_and_log(('edit.mouse_release: in line %d'):format(line_index))
           State.cursor1 = {
               line=line_index,
               pos=Text.to_pos_on_line(State, line_index, x, y),
           }
---?           print('cursor', State.cursor1.line, State.cursor1.pos)
+--?           print_and_log(('edit.mouse_release: cursor now %d,%d'):format(State.cursor1.line, State.cursor1.pos))
           if State.mousepress_shift then
             if State.old_selection1.line == nil then
               State.selection1 = State.old_cursor1
@@ -300,7 +321,7 @@ function edit.mouse_release(State, x,y, mouse_button)
         end
       end
     end
---?     print('selection:', State.selection1.line, State.selection1.pos)
+--?     print_and_log(('edit.mouse_release: finally selection %s,%s cursor %d,%d'):format(tostring(State.selection1.line), tostring(State.selection1.pos), State.cursor1.line, State.cursor1.pos))
   end
 end
 
diff --git a/source_select.lua b/source_select.lua
index 2298513..9b2a278 100644
--- a/source_select.lua
+++ b/source_select.lua
@@ -1,6 +1,4 @@
 -- helpers for selecting portions of text
--- To keep things simple, we'll ignore the B side when selections start on the
--- A side, and stick to within a single B side selections start in.
 
 -- Return any intersection of the region from State.selection1 to State.cursor1 (or
 -- current mouse, if mouse is pressed; or recent mouse if mouse is pressed and
@@ -31,7 +29,6 @@ function Text.clip_selection(State, line_index, apos, bpos)
   -- compare bounds more carefully (start inclusive, end exclusive)
   local a_ge = Text.le1({line=minl, pos=minp}, {line=line_index, pos=apos})
   local b_lt = Text.lt1({line=line_index, pos=bpos}, {line=maxl, pos=maxp})
---?   print(minl,line_index,maxl, '--', minp,apos,bpos,maxp, '--', a_ge,b_lt)
   if a_ge and b_lt then
     -- fully contained
     return apos,bpos
@@ -62,7 +59,6 @@ function Text.draw_highlight(State, line, x,y, pos, lo,hi)
       local before = line.data:sub(pos_offset, lo_offset-1)
       lo_px = App.width(before)
     end
---?     print(lo,pos,hi, '--', lo_offset,pos_offset,hi_offset, '--', lo_px)
     local s = line.data:sub(lo_offset, hi_offset-1)
     App.color(Highlight_color)
     love.graphics.rectangle('fill', x+lo_px,y, App.width(s),State.line_height)
@@ -71,22 +67,11 @@ function Text.draw_highlight(State, line, x,y, pos, lo,hi)
   end
 end
 
--- inefficient for some reason, so don't do it on every frame
 function Text.mouse_pos(State)
-  local time = love.timer.getTime()
-  if State.recent_mouse.time and State.recent_mouse.time > time-0.1 then
-    return State.recent_mouse.line, State.recent_mouse.pos
+  local x,y = App.mouse_x(), App.mouse_y()
+  if y < State.line_cache[State.screen_top1.line].starty then
+    return State.screen_top1.line, State.screen_top1.pos
   end
-  State.recent_mouse.time = time
-  local line,pos = Text.to_pos(State, App.mouse_x(), App.mouse_y())
-  if line then
-    State.recent_mouse.line = line
-    State.recent_mouse.pos = pos
-  end
-  return State.recent_mouse.line, State.recent_mouse.pos
-end
-
-function Text.to_pos(State, x,y)
   for line_index,line in ipairs(State.lines) do
     if line.mode == 'text' then
       if Text.in_line(State, line_index, x,y) then
@@ -94,6 +79,7 @@ function Text.to_pos(State, x,y)
       end
     end
   end
+  return State.screen_bottom1.line, Text.pos_at_end_of_screen_line(State, State.screen_bottom1)
 end
 
 function Text.cut_selection(State)
diff --git a/source_text.lua b/source_text.lua
index 290d982..1a42310 100644
--- a/source_text.lua
+++ b/source_text.lua
@@ -650,6 +650,7 @@ function Text.right_without_scroll(State)
   end
 end
 
+-- result: pos, index of screen line
 function Text.pos_at_start_of_screen_line(State, loc1)
   Text.populate_screen_line_starting_pos(State, loc1.line)
   local line_cache = State.line_cache[loc1.line]
@@ -662,6 +663,20 @@ function Text.pos_at_start_of_screen_line(State, loc1)
   assert(false)
 end
 
+function Text.pos_at_end_of_screen_line(State, loc1)
+  Text.populate_screen_line_starting_pos(State, loc1.line)
+  local line_cache = State.line_cache[loc1.line]
+  local most_recent_final_pos = utf8.len(State.lines[loc1.line].data)+1
+  for i=#line_cache.screen_line_starting_pos,1,-1 do
+    local spos = line_cache.screen_line_starting_pos[i]
+    if spos <= loc1.pos then
+      return most_recent_final_pos
+    end
+    most_recent_final_pos = spos-1
+  end
+  assert(false)
+end
+
 function Text.cursor_at_final_screen_line(State)
   Text.populate_screen_line_starting_pos(State, State.cursor1.line)
   local screen_lines = State.line_cache[State.cursor1.line].screen_line_starting_pos
diff --git a/source_text_tests.lua b/source_text_tests.lua
index 11e7613..c2e054a 100644
--- a/source_text_tests.lua
+++ b/source_text_tests.lua
@@ -1,4 +1,6 @@
 -- major tests for text editing flows
+-- Arguably this should be called source_edit_tests.lua,
+-- but that would mess up the git blame at this point.
 
 function test_initial_state()
   App.screen.init{width=120, height=60}
@@ -828,6 +830,67 @@ function test_select_text_using_mouse()
   check_eq(Editor_state.cursor1.pos, 4, 'cursor:pos')
 end
 
+function test_select_text_using_mouse_starting_above_text()
+  App.screen.init{width=50, height=60}
+  Editor_state = edit.initialize_test_state()
+  Editor_state.lines = load_array{'abc', 'def', 'xyz'}
+  Text.redraw_all(Editor_state)
+  Editor_state.cursor1 = {line=1, pos=1}
+  Editor_state.screen_top1 = {line=1, pos=1}
+  Editor_state.screen_bottom1 = {}
+  Editor_state.selection1 = {}
+  edit.draw(Editor_state)  -- populate line_cache.starty for each line Editor_state.line_cache
+  -- press mouse above first line of text
+  edit.run_after_mouse_press(Editor_state, Editor_state.left+8,5, 1)
+  check(Editor_state.selection1.line ~= nil, 'selection:line-not-nil')
+  check_eq(Editor_state.selection1.line, 1, 'selection:line')
+  check_eq(Editor_state.selection1.pos, 1, 'selection:pos')
+end
+
+function test_select_text_using_mouse_starting_above_text_wrapping_line()
+  -- first screen line starts in the middle of a line
+  App.screen.init{width=50, height=60}
+  Editor_state = edit.initialize_test_state()
+  Editor_state.lines = load_array{'abc', 'defgh', 'xyz'}
+  Text.redraw_all(Editor_state)
+  Editor_state.cursor1 = {line=2, pos=5}
+  Editor_state.screen_top1 = {line=2, pos=3}
+  Editor_state.screen_bottom1 = {}
+  -- press mouse above first line of text
+  edit.run_after_mouse_press(Editor_state, Editor_state.left+8,5, 1)
+  -- selection is at screen top
+  check(Editor_state.selection1.line ~= nil, 'selection:line-not-nil')
+  check_eq(Editor_state.selection1.line, 2, 'selection:line')
+  check_eq(Editor_state.selection1.pos, 3, 'selection:pos')
+end
+
+function test_select_text_using_mouse_starting_below_text()
+  -- I'd like to test what happens when a mouse click is below some page of
+  -- text, potentially even in the middle of a line.
+  -- However, it's brittle to set up a text line boundary just right.
+  -- So I'm going to just check things below the bottom of the final line of
+  -- text when it's in the middle of the screen.
+  -- final screen line ends in the middle of screen
+  App.screen.init{width=50, height=60}
+  Editor_state = edit.initialize_test_state()
+  Editor_state.lines = load_array{'abcde'}
+  Text.redraw_all(Editor_state)
+  Editor_state.cursor1 = {line=1, pos=1}
+  Editor_state.screen_top1 = {line=1, pos=1}
+  Editor_state.screen_bottom1 = {}
+  edit.draw(Editor_state)
+  local y = Editor_state.top
+  App.screen.check(y, 'ab', 'baseline:screen:1')
+  y = y + Editor_state.line_height
+  App.screen.check(y, 'cde', 'baseline:screen:2')
+  -- press mouse above first line of text
+  edit.run_after_mouse_press(Editor_state, 5,App.screen.height-5, 1)
+  -- selection is past bottom-most text in screen
+  check(Editor_state.selection1.line ~= nil, 'selection:line-not-nil')
+  check_eq(Editor_state.selection1.line, 1, 'selection:line')
+  check_eq(Editor_state.selection1.pos, 6, 'selection:pos')
+end
+
 function test_select_text_using_mouse_and_shift()
   App.screen.init{width=50, height=60}
   Editor_state = edit.initialize_test_state()
@@ -882,6 +945,28 @@ function test_select_text_repeatedly_using_mouse_and_shift()
   check_eq(Editor_state.cursor1.pos, 2, 'cursor:pos')
 end
 
+function test_select_all_text()
+  -- display a single line of text
+  App.screen.init{width=75, height=80}
+  Editor_state = edit.initialize_test_state()
+  Editor_state.lines = load_array{'abc def'}
+  Text.redraw_all(Editor_state)
+  Editor_state.cursor1 = {line=1, pos=1}
+  Editor_state.screen_top1 = {line=1, pos=1}
+  Editor_state.screen_bottom1 = {}
+  edit.draw(Editor_state)
+  -- select all
+  App.fake_key_press('lctrl')
+  edit.run_after_keychord(Editor_state, 'C-a')
+  App.fake_key_release('lctrl')
+  edit.key_release(Editor_state, 'lctrl')
+  -- selection
+  check_eq(Editor_state.selection1.line, 1, 'selection:line')
+  check_eq(Editor_state.selection1.pos, 1, 'selection:pos')
+  check_eq(Editor_state.cursor1.line, 1, 'cursor:line')
+  check_eq(Editor_state.cursor1.pos, 8, 'cursor:pos')
+end
+
 function test_cut_without_selection()
   -- display a few lines
   App.screen.init{width=Editor_state.left+30, height=60}