akkartik/lines-and-links - Change MYC7XR5QOT2AXHF6UNGSNFFD5VL6UHGUZQBP7PWWLZ5NNXE7UMTAC

bugfix: lines that aren't drawn from the start

I can't believe I didn't catch this until now. All I had to do is open MobyDick.markdown from https://www.hogbaysoftware.com/posts/moby-dick-workout, press page-down and click on the top screen line (or any screen line containing the same line as the top screen line). Easy to catch with any file containing lots of overly long lines, as happens in particular at the start of Moby Dick.

I had seen this problem before, but it seemed to disappear after unrelated changes, and I convinced myself I'd fixed it as a side-effect. The bug just failed to manifest if the top line happened to start at the top of the screen. Scroll down a few pages in Moby Dick and the dialogue starts and line length drops precipitously.

Created by Kartik K. Agaram on July 1, 2022

MYC7XR5QOT2AXHF6UNGSNFFD5VL6UHGUZQBP7PWWLZ5NNXE7UMTAC

Dependencies

In channels

main

Change contents

Insertion in text_tests.lua at line 187 [7.2]

[5.884]

function test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen()
  io.write('\ntest_click_on_wrapping_line_rendered_from_partway_at_top_of_screen')
  -- display a wrapping line from its second screen line
  App.screen.init{width=80, height=80}
                  --  12345678901234
  Lines = load_array{"madam I'm adam"}
  Line_width = 75
  Cursor1 = {line=1, pos=8}
  Screen_top1 = {line=1, pos=7}
  Screen_bottom1 = {}
  App.draw()
  local y = Margin_top
  App.screen.check(y, "I'm ada", 'F - test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen/baseline/screen:2')
  y = y + Line_height
  -- click past end of second screen line
  App.run_after_mouse_click(App.screen.width-2,y-2, 1)
  -- cursor moves to end of screen line
  check_eq(Cursor1.line, 1, 'F - test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen/cursor:line')
  check_eq(Cursor1.pos, 13, 'F - test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen/cursor:pos')
end

Replacement in text.lua at line 20 [9.1]
∅:D[3.2202] → [8.1783:1802]
B:BD[8.1783] → [8.1783:1802]
```
  local y = line.y
```
[3.2202]
[8.1802]
```
  local y = line.starty
```

Replacement in text.lua at line 662 [9.1]

∅:D[10.47] → [11.367:433]

B:BD[12.39] → [11.367:433]

  if line.y == nil then return false end  -- outside current page

[10.47]

[3.2342]

  if line.starty == nil then return false end  -- outside current page

Replacement in text.lua at line 664 [9.1]
∅:D[13.697] → [14.214:252]
∅:D[3.2385] → [14.214:252]
B:BD[14.214] → [14.214:252]
```
  if y < line.y then return false end
```
[3.2385]
[10.48]
```
  if y < line.starty then return false end
```

Replacement in text.lua at line 666 [9.1]

∅:D[10.101] → [15.3806:3873]

∅:D[16.224] → [15.3806:3873]

B:BD[15.3806] → [15.3806:3873]

  return y < line.y + #line.screen_line_starting_pos * Line_height

[10.101]

[12.95]

  return y < line.starty + Line_height*(#line.screen_line_starting_pos - Text.screen_line_index(line, line.startpos) + 1)

Replacement in text.lua at line 675 [9.1]
∅:D[17.86] → [14.653:676]
B:BD[14.653] → [14.653:676]
```
  assert(my >= line.y)
```
[17.86]
[14.863]
```
  assert(my >= line.starty)
```

Replacement in text.lua at line 677 [9.1]

B:BD[14.904] → [14.904:923]

B:BD[14.923] → [18.40:133]

B:BD[18.133] → [19.740:836]

  local y = line.y
  for screen_line_index,screen_line_starting_pos in ipairs(line.screen_line_starting_pos) do
      local screen_line_starting_byte_offset = Text.offset(line.data, screen_line_starting_pos)

[14.904]

[20.910]

  local y = line.starty
  local start_screen_line_index = Text.screen_line_index(line, line.startpos)
  for screen_line_index = start_screen_line_index,#line.screen_line_starting_pos do
    local screen_line_starting_pos = line.screen_line_starting_pos[screen_line_index]
    local screen_line_starting_byte_offset = Text.offset(line.data, screen_line_starting_pos)

Insertion in text.lua at line 728 [9.1]

[6.1644]

end
function Text.screen_line_index(line, pos)
  for i = #line.screen_line_starting_pos,1,-1 do
    if line.screen_line_starting_pos[i] <= pos then
      return i
    end
  end

Replacement in text.lua at line 922 [9.1]
B:BD[15.4058] → [21.3:20]
```
    line.y = nil
```
[15.4058]
[4.317]
```
    line.starty = nil
    line.startpos = nil
```

Replacement in main.lua at line 23 [22.2]

B:BD[2.44] → [2.44:105]

--    a (y) coord in pixels (updated while painting screen),

[2.44]

[2.105]

--    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

Replacement in main.lua at line 279 [22.2]

∅:D[23.153] → [24.194:213]

∅:D[25.2115] → [24.194:213]

∅:D[26.2400] → [24.194:213]

B:BD[11.1510] → [24.194:213]

        line.y = y

[23.153]

[27.335]

        line.starty = y
        line.startpos = 1
        if line_index == Screen_top1.line then
          line.startpos = Screen_top1.pos
        end