binary search to most natural up/down with proportional fonts

Dependencies

• [2] JS6JSYOT online contextual help
• [3] 3CS5KKCI up/down cursor movement
• [4] IYW7X3WL left/right cursor movement, deleting characters
• [5] XX7G2FFJ intermingle freehand line drawings with text
• [*] OTIBCAUJ love2d scaffold
• [*] H7OEU6WP experimental approach to combining keyboard and mouse while drawing

Change contents

• replacement in main.lua at line 160
  [3.88]→[3.88:411](∅→∅)
  − local line_before_cursor = lines[cursor_line]:sub(1, cursor_pos-1)

  − local text_before_cursor = love.graphics.newText(love.graphics.getFont(), line_before_cursor)

  − love.graphics.print('_', 25+text_before_cursor:getWidth()*1.5, y+6) -- drop the cursor down a bit to account for the increased font size
  [3.88]

  [3.411]
  + love.graphics.print('_', 25+cursor_x(lines[cursor_line], cursor_pos)*1.5, y+6) -- drop the cursor down a bit to account for the increased font size
• edit in main.lua at line 541
  [3.525]

  [3.525]
  + elseif chord == 'home' then

  + cursor_pos = 1

  + elseif chord == 'end' then

  + cursor_pos = #lines[cursor_line]+1
• edit in main.lua at line 547
  [3.581]

  [3.581]
  + local old_x = cursor_x(lines[cursor_line], cursor_pos)
• replacement in main.lua at line 549
  [3.615]→[3.615:715](∅→∅)
  − if cursor_pos > #lines[cursor_line] then

  − cursor_pos = #lines[cursor_line]+1

  − end
  [3.615]

  [4.1510]
  + cursor_pos = nearest_cursor_pos(lines[cursor_line], old_x)
• edit in main.lua at line 553
  [3.779]

  [3.779]
  + local old_x = cursor_x(lines[cursor_line], cursor_pos)
• replacement in main.lua at line 555
  [3.813]→[3.813:913](∅→∅)
  − if cursor_pos > #lines[cursor_line] then

  − cursor_pos = #lines[cursor_line]+1

  − end
  [3.813]

  [3.913]
  + cursor_pos = nearest_cursor_pos(lines[cursor_line], old_x)
• edit in main.lua at line 705
  [2.576]

  [2.576]
  + end

  + end

  + end

  +

  + function cursor_x(line, cursor_pos)

  + local line_before_cursor = line:sub(1, cursor_pos-1)

  + local text_before_cursor = love.graphics.newText(love.graphics.getFont(), line_before_cursor)

  + return text_before_cursor:getWidth()

  + end

  +

  + function nearest_cursor_pos(line, x)

  + if x == 0 then

  + return 1

  + end

  + local left, right = 1, #line+1

  + while left < right-1 do

  + local curr = math.floor((left+right)/2)

  + local currx = cursor_x(line, curr)

  + if currx > x-2 and currx < x+2 then

  + return curr
• edit in main.lua at line 726
  [2.584]

  [8.482]
  + if currx > x then

  + right = curr

  + else

  + left = curr

  + end
• edit in main.lua at line 732
  [8.488]

  [8.488]
  + return right