patch 9.0.0900: cursor moves too far with 'smoothscroll'

Problem:    Cursor moves too far with 'smoothscroll'.
Solution:   Only move as far as really needed. (Yee Cheng Chin, closes #11504)

src/testdir/dumps/Test_smooth_long_showbreak_2.dump

@@ -1,6 +1,6 @@
-|++0#4040ff13#ffffff0@2| |o+0#0000000&|f| |t|e|x|t| |i|n| |o|n|e| |l|i|n|e| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x
-|++0#4040ff13&@2| >t+0#0000000&| |i|n| |o|n|e| |l|i|n|e| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x|t| |i|n| |o
+|++0#4040ff13#ffffff0@2| >o+0#0000000&|f| |t|e|x|t| |i|n| |o|n|e| |l|i|n|e| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x
+|++0#4040ff13&@2| |t+0#0000000&| |i|n| |o|n|e| |l|i|n|e| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x|t| |i|n| |o
 |++0#4040ff13&@2| |n+0#0000000&|e| |l|i|n|e| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x|t| |i|n| |o|n|e| |l|i|n
 |++0#4040ff13&@2| |e+0#0000000&| |w|i|t|h| |l|o|t|s| |o|f| |t|e|x|t| |i|n| |o|n|e| |l|i|n|e| @4
 |~+0#4040ff13&| @38
-| +0#0000000&@21|1|,|7@1|-|8|5| @6|A|l@1| 
+| +0#0000000&@21|1|,|4|1|-|4|5| @6|A|l@1| 

src/testdir/dumps/Test_smooth_number_7.dump

@@ -1,5 +1,5 @@
-|2+0#af5f00255#ffffff0|<+0#4040ff13&@2|o+0#0000000&|n|g| |t|e|x|t| |v|e|r|y| |l|o|n|g| |t|e|x|t| |v|e|r|y| |l|o|n|g| |t|e
-| +0#af5f00255&@3>x+0#0000000&|t| |v|e|r|y| |l|o|n|g| |t|e|x|t| |v|e|r|y| |l|o|n|g| |t|e|x|t| |v|e|r
+|2+0#af5f00255#ffffff0|<+0#4040ff13&@2>o+0#0000000&|n|g| |t|e|x|t| |v|e|r|y| |l|o|n|g| |t|e|x|t| |v|e|r|y| |l|o|n|g| |t|e
+| +0#af5f00255&@3|x+0#0000000&|t| |v|e|r|y| |l|o|n|g| |t|e|x|t| |v|e|r|y| |l|o|n|g| |t|e|x|t| |v|e|r
 | +0#af5f00255&@3|y+0#0000000&| |l|o|n|g| |t|e|x|t| |v|e|r|y| |l|o|n|g| |t|e|x|t| |v|e|r|y| |l|o|n|g
 | +0#af5f00255&@3| +0#0000000&|t|e|x|t| |v|e|r|y| |l|o|n|g| |t|e|x|t| |v|e|r|y| |l|o|n|g| |t|e|x|t| 
 | +0#af5f00255&@1|1| |t+0#0000000&|h|r|e@1| @30
@@ -9,4 +9,4 @@
 |~| @38
 |~| @38
 |~| @38
-|-+0#0000000&@1|N|o|.@2|e|r|-@1| @10|2|,|7|3| @9|B|o|t| 
+|-+0#0000000&@1|N|o|.@2|e|r|-@1| @10|2|,|3|7| @9|B|o|t| 

src/testdir/dumps/Test_smooth_wrap_5.dump

@@ -1,8 +1,8 @@
->L+0&#ffffff0|i|n|e| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| 
+|<+0#4040ff13#ffffff0@2>h+0#0000000&| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| @10
+|L|i|n|e| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| 
 |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| 
 |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| @10
 |L|i|n|e| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| 
 |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| 
 |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| @10
-|@+0#4040ff13&@2| @36
-| +0#0000000&@21|5|,|1| @10|8|0|%| 
+@22|5|,|8|4| @9|B|o|t| 

src/testdir/dumps/Test_smooth_wrap_6.dump

@@ -0,0 +1,8 @@
+>L+0&#ffffff0|i|n|e| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| 
+|s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| 
+|w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| @10
+|L|i|n|e| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| 
+|s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| 
+|w|i|t|h| |s|o|m|e| |t|e|x|t| |w|i|t|h| |s|o|m|e| |t|e|x|t| @10
+|@+0#4040ff13&@2| @36
+| +0#0000000&@21|5|,|1| @10|8|0|%| 

src/testdir/test_scroll_opt.vim

@@ -230,10 +230,14 @@ func Test_smoothscroll_wrap_scrolloff_zero()
   call term_sendkeys(buf, "G")
   call VerifyScreenDump(buf, 'Test_smooth_wrap_4', {})
 
-  " moving cursor up - whole top line shows
-  call term_sendkeys(buf, "2k")
+  " moving cursor up right after the >>> marker - no need to show whole line
+  call term_sendkeys(buf, "2gj3l2k")
   call VerifyScreenDump(buf, 'Test_smooth_wrap_5', {})
 
+  " moving cursor up where the >>> marker is - whole top line shows
+  call term_sendkeys(buf, "2j02k")
+  call VerifyScreenDump(buf, 'Test_smooth_wrap_6', {})
+
   call StopVimInTerminal(buf)
 endfunc
 
@@ -321,7 +325,6 @@ func Test_smoothscroll_long_line_showbreak()
   let buf = RunVimInTerminal('-S XSmoothLongShowbreak', #{rows: 6, cols: 40})
   call VerifyScreenDump(buf, 'Test_smooth_long_showbreak_1', {})
   
-  " FIXME: this currently has the cursor in screen line 2, should be one up.
   call term_sendkeys(buf, "\<C-E>")
   call VerifyScreenDump(buf, 'Test_smooth_long_showbreak_2', {})
 
@@ -353,10 +356,16 @@ func Test_smoothscroll_cursor_position()
   call s:check_col_calc(1, 2, 41)
   exe "normal \<C-Y>"
   call s:check_col_calc(1, 3, 41)
-  normal ggg$
+
+  normal gg3l
   exe "normal \<C-E>"
 
   " Move down only 1 line when we are out of the range of the <<< display
+  call s:check_col_calc(4, 1, 24)
+  exe "normal \<C-Y>"
+  call s:check_col_calc(4, 2, 24)
+  normal ggg$
+  exe "normal \<C-E>"
   call s:check_col_calc(20, 1, 40)
   exe "normal \<C-Y>"
   call s:check_col_calc(20, 2, 40)
@@ -366,9 +375,11 @@ func Test_smoothscroll_cursor_position()
   setl number
   call s:check_col_calc(5, 1, 1)
   exe "normal \<C-E>"
-  call s:check_col_calc(5, 2, 33)
+
+  " Move down only 1 line when the <<< display is on the number column
+  call s:check_col_calc(5, 1, 17)
   exe "normal \<C-Y>"
-  call s:check_col_calc(5, 3, 33)
+  call s:check_col_calc(5, 2, 17)
   normal ggg$
   exe "normal \<C-E>"
   call s:check_col_calc(20, 1, 32)
@@ -376,13 +387,33 @@ func Test_smoothscroll_cursor_position()
   call s:check_col_calc(20, 2, 32)
   normal gg
 
+  setl numberwidth=1
+
+  " Move down another line when numberwidth is too short to cover the whole
+  " <<< display
+  call s:check_col_calc(3, 1, 1)
+  exe "normal \<C-E>"
+  call s:check_col_calc(3, 2, 37)
+  exe "normal \<C-Y>"
+  call s:check_col_calc(3, 3, 37)
+  normal ggl
+
+  " Only move 1 line down when we are just past the <<< display
+  call s:check_col_calc(4, 1, 2)
+  exe "normal \<C-E>"
+  call s:check_col_calc(4, 1, 20)
+  exe "normal \<C-Y>"
+  call s:check_col_calc(4, 2, 20)
+  normal gg
+  setl numberwidth&
+
   " Test number + showbreak, so test that the additional indentation works
   setl number showbreak=+++
   call s:check_col_calc(5, 1, 1)
   exe "normal \<C-E>"
-  call s:check_col_calc(8, 2, 30)
+  call s:check_col_calc(8, 1, 17)
   exe "normal \<C-Y>"
-  call s:check_col_calc(8, 3, 30)
+  call s:check_col_calc(8, 2, 17)
   normal gg
 
   " Test number + cpo+=n mode, where wrapped lines aren't indented