fix(extmark): fix cursor position with both left and right gravity inline text

src/nvim/charset.c

@@ -1053,11 +1053,8 @@ void getvcol(win_T *wp, pos_T *pos, colnr_T *start, colnr_T *cursor, colnr_T *en
 
       // make sure we don't go past the end of the line
       if (*cts.cts_ptr == NUL) {
-        // NUL at end of line only takes one column
+        // NUL at end of line only takes one column, unless there is virtual text
-        incr = 1;
+        incr = MAX(1, cts.cts_cur_text_width_left + cts.cts_cur_text_width_right);
-        if (cts.cts_cur_text_width > 0) {
-          incr = cts.cts_cur_text_width;
-        }
         on_NUL = true;
         break;
       }
@@ -1092,9 +1089,12 @@ void getvcol(win_T *wp, pos_T *pos, colnr_T *start, colnr_T *cursor, colnr_T *en
       // cursor at end
       *cursor = vcol + incr - 1;
     } else {
-      if (((State & MODE_INSERT) == 0 || !cts.cts_has_right_gravity) && !on_NUL) {
+      if (!on_NUL) {
         // cursor is after inserted text, unless on the NUL
-        vcol += cts.cts_cur_text_width;
+        vcol += cts.cts_cur_text_width_left;
+        if ((State & MODE_INSERT) == 0) {
+          vcol += cts.cts_cur_text_width_right;
+        }
       }
       // cursor at start
       *cursor = vcol + head;

src/nvim/drawline.c

@@ -1757,7 +1757,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
                                         selected, &decor_state);
 
         while (true) {
-          // we could already be inside an existing virt_line with multiple chunks
+          // we could already be inside an existing inline text with multiple chunks
           if (!(virt_inline_i < kv_size(virt_inline))) {
             DecorState *state = &decor_state;
             for (size_t i = 0; i < kv_size(state->active); i++) {

src/nvim/plines.c

@@ -269,7 +269,7 @@ int linetabsize_col(int startcol, char *s)
   if (cts.cts_has_virt_text && cts.cts_ptr == cts.cts_line) {
     // check for virtual text in an empty line
     (void)lbr_chartabsize_adv(&cts);
-    cts.cts_vcol += cts.cts_cur_text_width;
+    cts.cts_vcol += cts.cts_cur_text_width_left + cts.cts_cur_text_width_right;
   }
   clear_chartabsize_arg(&cts);
   return cts.cts_vcol;
@@ -308,7 +308,7 @@ void win_linetabsize_cts(chartabsize_T *cts, colnr_T len)
   if (cts->cts_has_virt_text && *cts->cts_ptr == NUL
       && cts->cts_ptr == cts->cts_line) {
     (void)win_lbr_chartabsize(cts, NULL);
-    cts->cts_vcol += cts->cts_cur_text_width;
+    cts->cts_vcol += cts->cts_cur_text_width_left + cts->cts_cur_text_width_right;
   }
 }
 
@@ -323,9 +323,9 @@ void init_chartabsize_arg(chartabsize_T *cts, win_T *wp, linenr_T lnum, colnr_T
   cts->cts_vcol = col;
   cts->cts_line = line;
   cts->cts_ptr = ptr;
-  cts->cts_cur_text_width = 0;
+  cts->cts_cur_text_width_left = 0;
+  cts->cts_cur_text_width_right = 0;
   cts->cts_has_virt_text = false;
-  cts->cts_has_right_gravity = true;
   cts->cts_row = lnum - 1;
 
   if (cts->cts_row >= 0) {
@@ -398,7 +398,8 @@ int win_lbr_chartabsize(chartabsize_T *cts, int *headp)
   int mb_added = 0;
   int numberextra;
 
-  cts->cts_cur_text_width = 0;
+  cts->cts_cur_text_width_left = 0;
+  cts->cts_cur_text_width_right = 0;
 
   // No 'linebreak', 'showbreak' and 'breakindent': return quickly.
   if (!wp->w_p_lbr && !wp->w_p_bri && *get_showbreak_value(wp) == NUL
@@ -419,14 +420,15 @@ int win_lbr_chartabsize(chartabsize_T *cts, int *headp)
       mtkey_t mark = marktree_itr_current(cts->cts_iter);
       if (mark.pos.row != cts->cts_row || mark.pos.col > col) {
         break;
-      } else if (mark.pos.col >= col
+      } else if (mark.pos.col >= col && mark.pos.col < col + charlen) {
-                 && mark.pos.col < col + charlen) {  // TODO(bfredl): or maybe unconditionally, what
-                                                     // if byte-misaligned?
         if (!mt_end(mark)) {
           Decoration decor = get_decor(mark);
           if (decor.virt_text_pos == kVTInline) {
-            cts->cts_cur_text_width += decor.virt_text_width;
+            if (mt_right(mark)) {
-            cts->cts_has_right_gravity = mt_right(mark);
+              cts->cts_cur_text_width_right += decor.virt_text_width;
+            } else {
+              cts->cts_cur_text_width_left += decor.virt_text_width;
+            }
             size += decor.virt_text_width;
             if (*s == TAB) {
               // tab size changes because of the inserted text

src/nvim/plines.h

@@ -14,8 +14,8 @@ typedef struct {
   int cts_row;
 
   bool cts_has_virt_text;  // true if if a property inserts text
-  bool cts_has_right_gravity;
+  int cts_cur_text_width_left;     // width of virtual text left of cursor
-  int cts_cur_text_width;     // width of current inserted text
+  int cts_cur_text_width_right;     // width of virtual text right of cursor
   MarkTreeIter cts_iter[1];
   // TODO(bfredl): iterator in to the marktree for scanning virt text
 

test/functional/ui/decorations_spec.lua

@@ -1745,6 +1745,49 @@ bbbbbbb]])
       ]]}
   end)
 
+  it('cursor position is correct when inserting around virtual texts with both left and right gravity ', function()
+    insert('foo foo foo foo')
+    meths.buf_set_extmark(0, ns, 0, 8, { virt_text = {{ '>>', 'Special' }}, virt_text_pos = 'inline', right_gravity = false })
+    meths.buf_set_extmark(0, ns, 0, 8, { virt_text = {{ '<<', 'Special' }}, virt_text_pos = 'inline', right_gravity = true })
+    feed('08l')
+    screen:expect{ grid = [[
+      foo foo {28:>><<}^foo foo                               |
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+                                                        |
+      ]]}
+
+    feed('i')
+    screen:expect { grid = [[
+      foo foo {28:>>^<<}foo foo                               |
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {1:~                                                 }|
+      {24:-- INSERT --}                                      |
+      ]]}
+  end)
+
   it('draws correctly with no wrap multiple virtual text, where one is hidden', function()
     insert('abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz')
     command("set nowrap")