akkartik/snap.love - Change LERERVPHE5SEWDHQ7IAGQSXUAI2QHQJ33NBNRMRXZ34X7P23I2IAC

keep one screen line of overlap on pagedown

I'm now extracting the concern of computing line.screen_line_starting_pos out of Text.draw. Earlier I had to make sure I ran through the whole line to compute screen_line_starting_pos, but that had the side-effect of updating Screen_bottom1.pos as well with lines that had never been rendered.

In this process I hit my first bug due to an accidental global. It doesn't show up in the patch because I accidentally deleted a local declaration. (I thought I didn't need screen_line_starting_pos anymore, deleted everywhere, then brought it back everywhere from the bottom of the function up, but forgot to put back the very first occurrence.)

The amount of yoyoing this caused between App.draw and Text.draw, I very much have spaghetti on my hands.

Accidental globals are terrible in a program with tests. Cross test contamination X-(

Created by Kartik K. Agaram on May 24, 2022

LERERVPHE5SEWDHQ7IAGQSXUAI2QHQJ33NBNRMRXZ34X7P23I2IAC

Dependencies

In channels

main

Change contents

Replacement in text.lua at line 22 [5.1]

B:BD[4.1901] → [2.1:84]

  line.screen_line_starting_pos = nil  -- TODO: avoid recomputing on every repaint

[4.1901]

[6.32]

  if line.screen_line_starting_pos == nil then
    Text.populate_screen_line_starting_pos(line_index)
  end

Replacement in text.lua at line 31 [5.1]

B:BD[7.22] → [8.1:184]

--?     print('('..s(x)..','..s(y)..') '..frag..'('..s(frag_width)..' vs '..s(line_width)..') '..s(line_index)..' vs '..s(Screen_top1.line)..'; '..s(pos)..' vs '..s(Screen_top1.pos))

[7.22]

[4.2068]

--?     print('('..s(x)..','..s(y)..') '..frag..'('..s(frag_width)..' vs '..s(line_width)..') '..s(line_index)..' vs '..s(Screen_top1.line)..'; '..s(pos)..' vs '..s(Screen_top1.pos)..'; bottom: '..s(Screen_bottom1.line)..'/'..s(Screen_bottom1.pos))

Replacement in text.lua at line 37 [5.1]

B:BD[9.119] → [3.181:272]

--?         print('text: new screen line', y, App.screen.height, screen_line_starting_pos)

[9.119]

[10.255]

        if y + math.floor(15*Zoom) > App.screen.height then
--?           print('b', y, App.screen.height, '=>', screen_line_starting_pos)
          return y, screen_line_starting_pos
        end

Insertion in text.lua at line 42 [5.1]

[10.294]

[6.76]

--?         print('text: new screen line', y, App.screen.height, screen_line_starting_pos)

Deletion in text.lua at line 46 [5.1]

B:BD[4.2198] → [11.1:169]

B:BD[11.169] → [12.105:115]

B:BD[12.115] → [7.244:306]

B:BD[7.306] → [3.273:379]

∅:D[3.379] → [8.326:349]

B:BD[8.326] → [8.326:349]

∅:D[8.349] → [7.326:386]

B:BD[7.326] → [7.326:386]

B:BD[7.386] → [8.350:397]

∅:D[13.170] → [12.241:298]

∅:D[14.264] → [12.241:298]

∅:D[8.397] → [12.241:298]

B:BD[12.241] → [12.241:298]

∅:D[12.298] → [11.169:179]

B:BD[11.169] → [11.169:179]

      if line.screen_line_starting_pos == nil then
        line.screen_line_starting_pos = {1, pos}
      else
        table.insert(line.screen_line_starting_pos, pos)
      end
      -- if we updated y, check if we're done with the screen
      if line_index > Screen_top1.line or (line_index == Screen_top1.line and pos > Screen_top1.pos) then
--?         print('a')
        if y + math.floor(15*Zoom) > App.screen.height then
--?           print('b', y, App.screen.height)
          return y, screen_line_starting_pos
        end
      end

Replacement in text.lua at line 47 [5.1]

B:BD[4.2206] → [15.71:152]

    if Debug_new_render then print('checking to draw', pos, Screen_top1.pos) end

[4.2206]

[7.387]

--?     print('checking to draw', pos, Screen_top1.pos)

Deletion in text.lua at line 144 [5.1]
B:BD[13.1590] → [16.283:308]
```
  local text height = 15
```

Insertion in text.lua at line 159 [5.1]

[17.379]

function test_pagedown_shows_one_screen_line_in_common()
  io.write('\ntest_pagedown_shows_one_screen_line_in_common')
  -- some lines of text with a drawing intermixed
  App.screen.init{width=50, height=60}
  Lines = load_array{'abc', 'def ghi jkl', 'mno'}
  Line_width = App.screen.width
  Cursor1 = {line=1, pos=1}
  Screen_top1 = {line=1, pos=1}
  Screen_bottom1 = {}
  Zoom = 1
  local screen_top_margin = 15  -- pixels
  local line_height = math.floor(15*Zoom)  -- pixels
  App.draw()
  local y = screen_top_margin
  App.screen.check(y, 'abc', 'F - test_pagedown_shows_one_screen_line_in_common/baseline/screen:1')
  y = y + line_height
  App.screen.check(y, 'def ', 'F - test_pagedown_shows_one_screen_line_in_common/baseline/screen:2')
  y = y + line_height
  App.screen.check(y, 'ghi ', 'F - test_pagedown_shows_one_screen_line_in_common/baseline/screen:3')
  -- after pagedown the bottom screen line becomes the top
  App.run_after_keychord('pagedown')
  check_eq(Screen_top1.line, 2, 'F - test_pagedown_shows_one_screen_line_in_common/screen_top:line')
  check_eq(Screen_top1.pos, 5, 'F - test_pagedown_shows_one_screen_line_in_common/screen_top:pos')
  check_eq(Cursor1.line, 2, 'F - test_pagedown_shows_one_screen_line_in_common/cursor:line')
  check_eq(Cursor1.pos, 5, 'F - test_pagedown_shows_one_screen_line_in_common/cursor:pos')
  y = screen_top_margin
  App.screen.check(y, 'ghi ', 'F - test_pagedown_shows_one_screen_line_in_common/screen:1')
  y = y + line_height
  App.screen.check(y, 'jkl', 'F - test_pagedown_shows_one_screen_line_in_common/screen:2')
  y = y + line_height
  App.screen.check(y, 'mn', 'F - test_pagedown_shows_one_screen_line_in_common/screen:3')
end

Replacement in main.lua at line 238 [18.2]

B:BD[10.562] → [8.1585:1635]

--?     print('setting top to', Screen_top1.line)

[10.562]

[15.9557]

--?     print('setting top to', Screen_top1.line, Screen_top1.pos)