experiment: slightly adaptive scrolling

Dependencies

• [2] LXTTOB33 extract a couple of files
• [3] ZPUQSPQP extract a few methods
• [4] KOYAJWE4 extract a couple more methods
• [5] ZLJGZYQG select text with shift + mouseclick
• [*] BULPIBEG beginnings of a module for the text editor

Change contents

• replacement in text_tests.lua at line 249
  [2.8522]→[2.8522:8691](∅→∅)
  − 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
  [2.8522]

  [2.8691]
  + function test_pagedown_often_shows_start_of_wrapping_line()

  + io.write('\ntest_pagedown_often_shows_start_of_wrapping_line')

  + -- draw a few lines ending in part of a wrapping line
• replacement in text_tests.lua at line 260
  [2.8930]→[2.8930:9030](∅→∅)
  − App.screen.check(y, 'abc', 'F - test_pagedown_shows_one_screen_line_in_common/baseline/screen:1')
  [2.8930]

  [2.9030]
  + App.screen.check(y, 'abc', 'F - test_pagedown_often_shows_start_of_wrapping_line/baseline/screen:1')
• replacement in text_tests.lua at line 262
  [2.9052]→[2.9052:9153](∅→∅)
  − App.screen.check(y, 'def ', 'F - test_pagedown_shows_one_screen_line_in_common/baseline/screen:2')
  [2.9052]

  [2.9153]
  + App.screen.check(y, 'def ', 'F - test_pagedown_often_shows_start_of_wrapping_line/baseline/screen:2')
• replacement in text_tests.lua at line 264
  [2.9175]→[2.9175:9335](∅→∅)
  − 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
  [2.9175]

  [2.9335]
  + App.screen.check(y, 'ghi ', 'F - test_pagedown_often_shows_start_of_wrapping_line/baseline/screen:3')

  + -- after pagedown we start drawing from the bottom _line_ (multiple screen lines)
• replacement in text_tests.lua at line 267
  [2.9372]→[2.9372:9756](∅→∅)
  − 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')
  [2.9372]

  [2.9756]
  + check_eq(Screen_top1.line, 2, 'F - test_pagedown_often_shows_start_of_wrapping_line/screen_top:line')

  + check_eq(Screen_top1.pos, 1, 'F - test_pagedown_often_shows_start_of_wrapping_line/screen_top:pos')

  + check_eq(Cursor1.line, 2, 'F - test_pagedown_often_shows_start_of_wrapping_line/cursor:line')

  + check_eq(Cursor1.pos, 1, 'F - test_pagedown_often_shows_start_of_wrapping_line/cursor:pos')
• replacement in text_tests.lua at line 272
  [2.9773]→[2.9773:9865](∅→∅)
  − App.screen.check(y, 'ghi ', 'F - test_pagedown_shows_one_screen_line_in_common/screen:1')
  [2.9773]

  [2.9865]
  + App.screen.check(y, 'def ', 'F - test_pagedown_often_shows_start_of_wrapping_line/screen:1')
• replacement in text_tests.lua at line 274
  [2.9887]→[2.9887:9978](∅→∅)
  − App.screen.check(y, 'jkl', 'F - test_pagedown_shows_one_screen_line_in_common/screen:2')
  [2.9887]

  [2.9978]
  + App.screen.check(y, 'ghi ', 'F - test_pagedown_often_shows_start_of_wrapping_line/screen:2')
• replacement in text_tests.lua at line 276
  [2.10000]→[2.10000:10090](∅→∅)
  − App.screen.check(y, 'mn', 'F - test_pagedown_shows_one_screen_line_in_common/screen:3')
  [2.10000]

  [2.10090]
  + App.screen.check(y, 'jkl', 'F - test_pagedown_often_shows_start_of_wrapping_line/screen:3')

  + end

  +

  + function test_pagedown_can_start_from_middle_of_long_wrapping_line()

  + io.write('\ntest_pagedown_can_start_from_middle_of_long_wrapping_line')

  + -- draw a few lines starting from a very long wrapping line

  + App.screen.init{width=25+30, height=60}

  + Lines = load_array{'abc def ghi jkl mno pqr stu vwx yza bcd efg hij', 'XYZ'}

  + Line_width = App.screen.width

  + Cursor1 = {line=1, pos=2}

  + Screen_top1 = {line=1, pos=1}

  + Screen_bottom1 = {}

  + App.draw()

  + local y = Margin_top

  + App.screen.check(y, 'abc ', 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/baseline/screen:1')

  + y = y + Line_height

  + App.screen.check(y, 'def ', 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/baseline/screen:2')

  + y = y + Line_height

  + App.screen.check(y, 'ghi ', 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/baseline/screen:3')

  + -- after pagedown we scroll down the very long wrapping line

  + App.run_after_keychord('pagedown')

  + check_eq(Screen_top1.line, 1, 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/screen_top:line')

  + check_eq(Screen_top1.pos, 9, 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/screen_top:pos')

  + y = Margin_top

  + App.screen.check(y, 'ghi ', 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/screen:1')

  + y = y + Line_height

  + App.screen.check(y, 'jkl m', 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/screen:2')

  + y = y + Line_height

  + App.screen.check(y, 'no ', 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/screen:3')
• replacement in text.lua at line 398
  [3.883]→[3.883:963](∅→∅)
  − Screen_top1.line = Screen_bottom1.line

  − Screen_top1.pos = Screen_bottom1.pos
  [3.883]

  [3.963]
  + -- If a line/paragraph gets to a page boundary, I often want to scroll

  + -- before I get to the bottom.

  + -- However, only do this if it makes forward progress.

  + local top2 = Text.to2(Screen_bottom1)

  + if top2.screen_line > 1 then

  + top2.screen_line = math.max(top2.screen_line-10, 1)

  + end

  + local new_top1 = Text.to1(top2)

  + if Text.lt1(Screen_top1, new_top1) then

  + Screen_top1 = new_top1

  + else

  + Screen_top1.line = Screen_bottom1.line

  + Screen_top1.pos = Screen_bottom1.pos

  + end