vim-patch:8.1.0994: fix relative cursor position #9676

Problem:    Relative cursor position is not calculated correctly.
Solution:   Always set topline, also when window is one line only.
            (Robert Webb) Add more info to getwininfo() for testing.
https://github.com/vim/vim/commit/8fcb60f961bdd134599fb016c6537fd496e800f5

10 files changed, 177 insertions, 38 deletions

diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 3efe651dfe..da17faaaf6 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -4504,11 +4504,13 @@ getwininfo([{winid}])					*getwininfo()*
 		tab pages is returned.
 
 		Each List item is a Dictionary with the following entries:
+			botline		last displayed buffer line
 			bufnr		number of buffer in the window
 			height		window height (excluding winbar)
 			loclist		1 if showing a location list
 			quickfix	1 if quickfix or location list window
 			tabnr		tab page number
+			topline		first displayed buffer line 
 			variables	a reference to the dictionary with
 					window-local variables
 			width		window width
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 57777f049a..c23177f23a 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -10316,6 +10316,8 @@ static dict_T *get_win_info(win_T *wp, int16_t tpnr, int16_t winnr)
   tv_dict_add_nr(dict, S_LEN("winid"), wp->handle);
   tv_dict_add_nr(dict, S_LEN("height"), wp->w_height);
   tv_dict_add_nr(dict, S_LEN("winrow"), wp->w_winrow);
+  tv_dict_add_nr(dict, S_LEN("topline"), wp->w_topline);
+  tv_dict_add_nr(dict, S_LEN("botline"), wp->w_botline - 1);
   tv_dict_add_nr(dict, S_LEN("width"), wp->w_width);
   tv_dict_add_nr(dict, S_LEN("bufnr"), wp->w_buffer->b_fnum);
   tv_dict_add_nr(dict, S_LEN("wincol"), wp->w_wincol);
diff --git a/src/nvim/testdir/test_window_cmd.vim b/src/nvim/testdir/test_window_cmd.vim
index b3ab6957dc..57fb36abb8 100644
--- a/src/nvim/testdir/test_window_cmd.vim
+++ b/src/nvim/testdir/test_window_cmd.vim
@@ -518,4 +518,132 @@ func Test_winrestcmd()
   only
 endfunc
 
+func Test_relative_cursor_position_in_one_line_window()
+  new
+  only
+  call setline(1, range(1, 10000))
+  normal 50%
+  let lnum = getcurpos()[1]
+  split
+  split
+  " make third window take as many lines as possible, other windows will
+  " become one line
+  3wincmd w
+  for i in range(1, &lines - 6)
+    wincmd +
+    redraw!
+  endfor
+
+  " first and second window should show cursor line
+  let wininfo = getwininfo()
+  call assert_equal(lnum, wininfo[0].topline)
+  call assert_equal(lnum, wininfo[1].topline)
+
+  only!
+  bwipe!
+endfunc
+
+func Test_relative_cursor_position_after_move_and_resize()
+  let so_save = &so
+  set so=0
+  enew
+  call setline(1, range(1, 10000))
+  normal 50%
+  split
+  1wincmd w
+  " Move cursor to first line in window
+  normal H
+  redraw!
+  " Reduce window height to two lines
+  let height = winheight(0)
+  while winheight(0) > 2
+    wincmd -
+    redraw!
+  endwhile
+  " move cursor to second/last line in window
+  normal j
+  " restore previous height
+  while winheight(0) < height
+    wincmd +
+    redraw!
+  endwhile
+  " make window two lines again
+  while winheight(0) > 2
+    wincmd -
+    redraw!
+  endwhile
+
+  " cursor should be at bottom line
+  let info = getwininfo(win_getid())[0]
+  call assert_equal(info.topline + 1, getcurpos()[1])
+
+  only!
+  bwipe!
+  let &so = so_save
+endfunc
+
+func Test_relative_cursor_position_after_resize()
+  let so_save = &so
+  set so=0
+  enew
+  call setline(1, range(1, 10000))
+  normal 50%
+  split
+  1wincmd w
+  let winid1 = win_getid()
+  let info = getwininfo(winid1)[0]
+  " Move cursor to second line in window
+  exe "normal " . (info.topline + 1) . "G"
+  redraw!
+  let lnum = getcurpos()[1]
+
+  " Make the window only two lines high, cursor should end up in top line
+  2wincmd w
+  exe (info.height - 2) . "wincmd +"
+  redraw!
+  let info = getwininfo(winid1)[0]
+  call assert_equal(lnum, info.topline)
+
+  only!
+  bwipe!
+  let &so = so_save
+endfunc
+
+func Test_relative_cursor_second_line_after_resize()
+  let so_save = &so
+  set so=0
+  enew
+  call setline(1, range(1, 10000))
+  normal 50%
+  split
+  1wincmd w
+  let winid1 = win_getid()
+  let info = getwininfo(winid1)[0]
+
+  " Make the window only two lines high
+  2wincmd _
+
+  " Move cursor to second line in window
+  normal H
+  normal j
+
+  " Make window size bigger, then back to 2 lines
+  for i in range(1, 10)
+    wincmd +
+    redraw!
+  endfor
+  for i in range(1, 10)
+    wincmd -
+    redraw!
+  endfor
+
+  " cursor should end up in bottom line
+  let info = getwininfo(winid1)[0]
+  call assert_equal(info.topline + 1, getcurpos()[1])
+
+  only!
+  bwipe!
+  let &so = so_save
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/nvim/window.c b/src/nvim/window.c
index 2d71c19230..efdee34c10 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -5332,7 +5332,10 @@ void win_drag_vsep_line(win_T *dragwin, int offset)
 void set_fraction(win_T *wp)
 {
   if (wp->w_height_inner > 1) {
-    wp->w_fraction = ((long)wp->w_wrow * FRACTION_MULT + wp->w_height_inner / 2)
+    // When cursor is in the first line the percentage is computed as if
+    // it's halfway that line.  Thus with two lines it is 25%, with three
+    // lines 17%, etc.  Similarly for the last line: 75%, 83%, etc.
+    wp->w_fraction = ((long)wp->w_wrow * FRACTION_MULT + FRACTION_MULT / 2)
                    / (long)wp->w_height_inner;
   }
 }
@@ -5364,8 +5367,8 @@ void scroll_to_fraction(win_T *wp, int prev_height)
     int sline, line_size;
     int height = wp->w_height_inner;
 
-  /* Don't change w_topline when height is zero.  Don't set w_topline when
-   * 'scrollbind' is set and this isn't the current window. */
+    // Don't change w_topline when height is zero.  Don't set w_topline when
+    // 'scrollbind' is set and this isn't the current window.
   if (height > 0
       && (!wp->w_p_scb || wp == curwin)
       ) {
@@ -5376,8 +5379,7 @@ void scroll_to_fraction(win_T *wp, int prev_height)
     lnum = wp->w_cursor.lnum;
     if (lnum < 1)               /* can happen when starting up */
       lnum = 1;
-    wp->w_wrow = ((long)wp->w_fraction * (long)height - 1L + FRACTION_MULT / 2)
-                 / FRACTION_MULT;
+    wp->w_wrow = ((long)wp->w_fraction * (long)height - 1L) / FRACTION_MULT;
     line_size = plines_win_col(wp, lnum, (long)(wp->w_cursor.col)) - 1;
     sline = wp->w_wrow - line_size;
 
@@ -5408,7 +5410,6 @@ void scroll_to_fraction(win_T *wp, int prev_height)
           wp->w_wrow--;
         }
       }
-      set_topline(wp, lnum);
     } else if (sline > 0) {
       while (sline > 0 && lnum > 1) {
         (void)hasFoldingWin(wp, lnum, &lnum, NULL, true, NULL);
@@ -5437,12 +5438,12 @@ void scroll_to_fraction(win_T *wp, int prev_height)
         lnum++;
         wp->w_wrow -= line_size + sline;
       } else if (sline > 0) {
-        /* First line of file reached, use that as topline. */
+        // First line of file reached, use that as topline.
         lnum = 1;
         wp->w_wrow -= sline;
       }
-      set_topline(wp, lnum);
     }
+    set_topline(wp, lnum);
   }
 
   if (wp == curwin) {
diff --git a/test/functional/terminal/window_split_tab_spec.lua b/test/functional/terminal/window_split_tab_spec.lua
index f3d0b45d09..c0ce656bb1 100644
--- a/test/functional/terminal/window_split_tab_spec.lua
+++ b/test/functional/terminal/window_split_tab_spec.lua
@@ -39,10 +39,11 @@ describe(':terminal', function()
   it('does not change size on WinEnter', function()
     if helpers.pending_win32(pending) then return end
     feed('<c-\\><c-n>')
+    feed('k')
     feed_command('2split')
     screen:expect([[
-      tty ready                                         |
-      ^rows: 5, cols: 50                                 |
+      ^tty ready                                         |
+      rows: 5, cols: 50                                 |
       ==========                                        |
       tty ready                                         |
       rows: 5, cols: 50                                 |
@@ -57,8 +58,8 @@ describe(':terminal', function()
       tty ready                                         |
       rows: 5, cols: 50                                 |
       ==========                                        |
-      tty ready                                         |
-      ^rows: 5, cols: 50                                 |
+      ^tty ready                                         |
+      rows: 5, cols: 50                                 |
       {2: }                                                 |
                                                         |
                                                         |
diff --git a/test/functional/ui/highlight_spec.lua b/test/functional/ui/highlight_spec.lua
index 39170337d7..3ee3f173d6 100644
--- a/test/functional/ui/highlight_spec.lua
+++ b/test/functional/ui/highlight_spec.lua
@@ -1274,17 +1274,18 @@ describe("'winhighlight' highlight", function()
     command('set number')
     command('set colorcolumn=2')
     command('set cursorcolumn')
+    feed('k')
 
     command('split')
     command('set winhl=LineNr:Background1,CursorColumn:Background2,'
             ..'ColorColumn:ErrorMsg')
     screen:expect([[
-      {1:  1 }v{15:e}ry tex{5:t}       |
-      {1:  2 }m{15:o}re tex^t       |
+      {1:  1 }v{15:e}ry tex^t       |
+      {1:  2 }m{15:o}re tex{5:t}       |
       {0:~                   }|
       {3:[No Name] [+]       }|
-      {9:  1 }v{17:e}ry tex{18:t}       |
-      {9:  2 }m{17:o}re text       |
+      {9:  1 }v{17:e}ry text       |
+      {9:  2 }m{17:o}re tex{18:t}       |
       {4:[No Name] [+]       }|
                           |
     ]])
diff --git a/test/functional/ui/inccommand_spec.lua b/test/functional/ui/inccommand_spec.lua
index 536264019c..c215ece2f2 100644
--- a/test/functional/ui/inccommand_spec.lua
+++ b/test/functional/ui/inccommand_spec.lua
@@ -938,11 +938,11 @@ describe(":substitute, inccommand=split", function()
     feed(":%s/tw")
     -- 'cursorline' is NOT active during preview.
     screen:expect([[
-      Inc substitution on           |
       {12:tw}o lines                     |
       Inc substitution on           |
       {12:tw}o lines                     |
                                     |
+      {15:~                             }|
       {11:[No Name] [+]                 }|
       |2| {12:tw}o lines                 |
       |4| {12:tw}o lines                 |
@@ -1185,6 +1185,7 @@ describe(":substitute, inccommand=split", function()
   end)
 
   it("clears preview if non-previewable command is edited #5585", function()
+    feed('gg')
     -- Put a non-previewable command in history.
     feed_command("echo 'foo'")
     -- Start an incomplete :substitute command.
@@ -2084,11 +2085,11 @@ describe(":substitute", function()
 
     feed(":%s/[0-9]\\n\\zs[A-Z]/OKO")
     screen:expect([[
-      1 2 3                         |
       {12:OKO} B C                       |
       4 5 6                         |
       {12:OKO} Y Z                       |
       7 8 9                         |
+                                    |
       {11:[No Name] [+]                 }|
       |1| 1 2 3                     |
       |2| {12:OKO} B C                   |
@@ -2204,11 +2205,11 @@ describe(":substitute", function()
 
     feed("/KKK")
     screen:expect([[
-      x                             |
       afa {12:KKK}adf la;lkd {12:KKK}alx      |
                                     |
       {15:~                             }|
       {15:~                             }|
+      {15:~                             }|
       {11:[No Name] [+]                 }|
       |3| afa {12:KKK}adf la;lkd {12:KKK}alx  |
       {15:~                             }|
@@ -2256,11 +2257,11 @@ describe(":substitute", function()
     common_setup(screen, "split", multibyte_text)
     feed(":%s/£.*ѫ/X¥¥")
     screen:expect([[
-      {12:X¥¥}                           |
        a{12:X¥¥}¥KOL                     |
       £ ¥  libm                     |
       £ ¥                           |
                                     |
+      {15:~                             }|
       {11:[No Name] [+]                 }|
       |1|  {12:X¥¥} PEPPERS              |
       |2| {12:X¥¥}                       |
@@ -2275,11 +2276,11 @@ describe(":substitute", function()
 
     feed("\\ra££   ¥")
     screen:expect([[
-      {12:a££   ¥}                       |
        a{12:X¥¥}                         |
       {12:a££   ¥}¥KOL                   |
       £ ¥  libm                     |
       £ ¥                           |
+                                    |
       {11:[No Name] [+]                 }|
       |1|  {12:X¥¥}                      |
       |2|{12: a££   ¥} PEPPERS           |
@@ -2378,7 +2379,6 @@ describe(":substitute", function()
 
     feed("\\rѫ ab   \\rXXXX")
     screen:expect([[
-      7 8 9                         |
       K L M                         |
       {12:JLKR £}                        |
       {12:ѫ ab   }                       |
@@ -2387,6 +2387,7 @@ describe(":substitute", function()
       {12:ѫ ab   }                       |
       {12:XXXX} e f                      |
       {12:JLKR £}                        |
+      {12:ѫ ab   }                       |
       {11:[No Name] [+]                 }|
       | 7| {12:JLKR £}                   |
       | 8|{12: ѫ ab   }                  |
@@ -2480,14 +2481,15 @@ describe(":substitute", function()
     ]])
 
     feed("<C-c>")
+    feed('gg')
     wait()
     feed([[:%s/\(some\)\@<lt>!thing/one/]])
     screen:expect([[
-      something                     |
       every{12:one}                      |
       someone                       |
       {15:~                             }|
       {15:~                             }|
+      {15:~                             }|
       {11:[No Name] [+]                 }|
       |2| every{12:one}                  |
       {15:~                             }|
@@ -2525,11 +2527,11 @@ describe(":substitute", function()
     wait()
     feed([[:%s/some\(thing\)\@!/every/]])
     screen:expect([[
-      everything                    |
       {12:every}one                      |
       {15:~                             }|
       {15:~                             }|
       {15:~                             }|
+      {15:~                             }|
       {11:[No Name] [+]                 }|
       |3| {12:every}one                  |
       {15:~                             }|
diff --git a/test/functional/ui/mouse_spec.lua b/test/functional/ui/mouse_spec.lua
index 7805ed3cb9..c1a350dc34 100644
--- a/test/functional/ui/mouse_spec.lua
+++ b/test/functional/ui/mouse_spec.lua
@@ -649,13 +649,14 @@ describe('ui/mouse/input', function()
     mouse scrolling
     ]])
     screen:try_resize(53, 14)
+    feed('k')
     feed_command('sp', 'vsp')
     screen:expect([[
       lines                     {4:│}lines                     |
       to                        {4:│}to                        |
       test                      {4:│}test                      |
-      mouse scrolling           {4:│}mouse scrolling           |
-      ^                          {4:│}                          |
+      ^mouse scrolling           {4:│}mouse scrolling           |
+                                {4:│}                          |
       {0:~                         }{4:│}{0:~                         }|
       {5:[No Name] [+]              }{4:[No Name] [+]             }|
       to                                                   |
@@ -672,8 +673,8 @@ describe('ui/mouse/input', function()
       feed('<ScrollWheelDown><0,0>')
     end
     screen:expect([[
-      mouse scrolling           {4:│}lines                     |
-      ^                          {4:│}to                        |
+      ^mouse scrolling           {4:│}lines                     |
+                                {4:│}to                        |
       {0:~                         }{4:│}test                      |
       {0:~                         }{4:│}mouse scrolling           |
       {0:~                         }{4:│}                          |
@@ -693,8 +694,8 @@ describe('ui/mouse/input', function()
       feed('<ScrollWheelUp><27,0>')
     end
     screen:expect([[
-      mouse scrolling           {4:│}text                      |
-      ^                          {4:│}with                      |
+      ^mouse scrolling           {4:│}text                      |
+                                {4:│}with                      |
       {0:~                         }{4:│}many                      |
       {0:~                         }{4:│}lines                     |
       {0:~                         }{4:│}to                        |
@@ -715,8 +716,8 @@ describe('ui/mouse/input', function()
       feed('<ScrollWheelUp><27,7><ScrollWheelUp>')
     end
     screen:expect([[
-      mouse scrolling           {4:│}text                      |
-      ^                          {4:│}with                      |
+      ^mouse scrolling           {4:│}text                      |
+                                {4:│}with                      |
       {0:~                         }{4:│}many                      |
       {0:~                         }{4:│}lines                     |
       {0:~                         }{4:│}to                        |
diff --git a/test/functional/ui/popupmenu_spec.lua b/test/functional/ui/popupmenu_spec.lua
index 9a8c5a5789..1e6ebb87f5 100644
--- a/test/functional/ui/popupmenu_spec.lua
+++ b/test/functional/ui/popupmenu_spec.lua
@@ -1198,20 +1198,20 @@ describe('builtin popupmenu', function()
 
     command("split")
     screen:expect([[
-      xx                                      |
       choice^                                  |
+      {1:~                                       }|
       {n:word           }{1:                         }|
       {s:choice         }{4:                         }|
       {n:text           }                         |
-      {n:thing          }                         |
+      {n:thing          }{1:                         }|
       {3:[No Name] [+]                           }|
       {2:-- INSERT --}                            |
     ]])
 
     meths.input_mouse('wheel', 'down', '', 0, 6, 15)
     screen:expect([[
-      xx                                      |
       choice^                                  |
+      {1:~                                       }|
       {n:word           }{1:                         }|
       {s:choice         }{4:                         }|
       {n:text           }                         |
diff --git a/test/functional/ui/syntax_conceal_spec.lua b/test/functional/ui/syntax_conceal_spec.lua
index d678784dc9..00e94ef94b 100644
--- a/test/functional/ui/syntax_conceal_spec.lua
+++ b/test/functional/ui/syntax_conceal_spec.lua
@@ -356,16 +356,17 @@ describe('Screen', function()
     end)
 
     it('between windows', function()
+      feed('k')
       command("split")
       screen:expect([[
         foo {1:b} bar {1:b} eggs                                     |
-        foo {1:b} bar {1:b} eggs                                     |
         foo barf bar barf egg^s                               |
+        foo {1:b} bar {1:b} eggs                                     |
                                                              |
         {2:[No Name] [+]                                        }|
         foo {1:b} bar {1:b} eggs                                     |
         foo {1:b} bar {1:b} eggs                                     |
-                                                             |
+        foo {1:b} bar {1:b} eggs                                     |
         {3:[No Name] [+]                                        }|
                                                              |
       ]])
@@ -379,7 +380,7 @@ describe('Screen', function()
         {3:[No Name] [+]                                        }|
         foo {1:b} bar {1:b} eggs                                     |
         foo barf bar barf egg^s                               |
-                                                             |
+        foo {1:b} bar {1:b} eggs                                     |
         {2:[No Name] [+]                                        }|
                                                              |
       ]])