api/ui: win_viewport event for visible range and cursor position in window

src/nvim/api/ui_events.in.h

@@ -115,6 +115,10 @@ void win_close(Integer grid)
 void msg_set_pos(Integer grid, Integer row, Boolean scrolled, String sep_char)
   FUNC_API_SINCE(6) FUNC_API_BRIDGE_IMPL FUNC_API_COMPOSITOR_IMPL;
 
+void win_viewport(Integer grid, Window win, Integer topline,
+                  Integer botline, Integer curline, Integer curcol)
+  FUNC_API_SINCE(7) FUNC_API_REMOTE_ONLY;
+
 void popupmenu_show(Array items, Integer selected,
                     Integer row, Integer col, Integer grid)
   FUNC_API_SINCE(3) FUNC_API_REMOTE_ONLY;

src/nvim/buffer_defs.h

@@ -1190,6 +1190,8 @@ struct window_S {
                                        to adjust w_valid */
   colnr_T w_valid_leftcol;          /* last known w_leftcol */
 
+  bool w_viewport_invalid;
+
   /*
    * w_cline_height is the number of physical lines taken by the buffer line
    * that the cursor is on.  We use this to avoid extra calls to plines().

src/nvim/move.c

@@ -86,6 +86,7 @@ static void comp_botline(win_T *wp)
   /* wp->w_botline is the line that is just below the window */
   wp->w_botline = lnum;
   wp->w_valid |= VALID_BOTLINE|VALID_BOTLINE_AP;
+  wp->w_viewport_invalid = true;
 
   set_empty_rows(wp, done);
 
@@ -151,6 +152,7 @@ void update_topline(void)
     curwin->w_topline = curwin->w_cursor.lnum;
     curwin->w_botline = curwin->w_topline;
     curwin->w_valid |= VALID_BOTLINE|VALID_BOTLINE_AP;
+    curwin->w_viewport_invalid = true;
     curwin->w_scbind_pos = 1;
     return;
   }
@@ -175,6 +177,7 @@ void update_topline(void)
     curwin->w_topline = 1;
     curwin->w_botline = 2;
     curwin->w_valid |= VALID_BOTLINE|VALID_BOTLINE_AP;
+    curwin->w_viewport_invalid = true;
     curwin->w_scbind_pos = 1;
   }
   /*
@@ -311,6 +314,7 @@ void update_topline(void)
     }
   }
   curwin->w_valid |= VALID_TOPLINE;
+  curwin->w_viewport_invalid = true;
   win_check_anchored_floats(curwin);
 
   /*
@@ -407,6 +411,7 @@ void check_cursor_moved(win_T *wp)
                      |VALID_CHEIGHT|VALID_CROW|VALID_TOPLINE);
     wp->w_valid_cursor = wp->w_cursor;
     wp->w_valid_leftcol = wp->w_leftcol;
+    wp->w_viewport_invalid = true;
   } else if (wp->w_cursor.col != wp->w_valid_cursor.col
              || wp->w_leftcol != wp->w_valid_leftcol
              || wp->w_cursor.coladd != wp->w_valid_cursor.coladd
@@ -415,6 +420,7 @@ void check_cursor_moved(win_T *wp)
     wp->w_valid_cursor.col = wp->w_cursor.col;
     wp->w_valid_leftcol = wp->w_leftcol;
     wp->w_valid_cursor.coladd = wp->w_cursor.coladd;
+    wp->w_viewport_invalid = true;
   }
 }
 
@@ -1458,6 +1464,7 @@ void scroll_cursor_top(int min_scroll, int always)
       curwin->w_valid &=
         ~(VALID_WROW|VALID_CROW|VALID_BOTLINE|VALID_BOTLINE_AP);
     curwin->w_valid |= VALID_TOPLINE;
+    curwin->w_viewport_invalid = true;
   }
 }
 
@@ -1662,6 +1669,7 @@ void scroll_cursor_bot(int min_scroll, int set_topbot)
     curwin->w_valid = old_valid;
   }
   curwin->w_valid |= VALID_TOPLINE;
+  curwin->w_viewport_invalid = true;
 }
 
 /// Recompute topline to put the cursor halfway across the window
@@ -1818,6 +1826,7 @@ void cursor_correct(void)
     }
   }
   curwin->w_valid |= VALID_TOPLINE;
+  curwin->w_viewport_invalid = true;
 }
 
 

src/nvim/normal.c

@@ -4121,6 +4121,7 @@ void scroll_redraw(int up, long count)
   }
   if (curwin->w_cursor.lnum != prev_lnum)
     coladvance(curwin->w_curswant);
+  curwin->w_viewport_invalid = true;
   redraw_later(VALID);
 }
 

src/nvim/screen.c

@@ -417,7 +417,7 @@ int update_screen(int type)
     need_wait_return = false;
   }
 
-  win_ui_flush_positions();
+  win_ui_flush();
   msg_ext_check_clear();
 
   /* reset cmdline_row now (may have been changed temporarily) */
@@ -1629,6 +1629,7 @@ static void win_update(win_T *wp)
      * changes are relevant).
      */
     wp->w_valid |= VALID_BOTLINE;
+    wp->w_viewport_invalid = true;
     if (wp == curwin && wp->w_botline != old_botline && !recursive) {
       recursive = TRUE;
       curwin->w_valid &= ~VALID_TOPLINE;
@@ -1648,7 +1649,7 @@ static void win_update(win_T *wp)
   /* restore got_int, unless CTRL-C was hit while redrawing */
   if (!got_int)
     got_int = save_got_int;
-}
+}  // NOLINT(readability/fn_size)
 
 /// Returns width of the signcolumn that should be used for the whole window
 ///

src/nvim/ui.c

@@ -424,7 +424,7 @@ int ui_current_col(void)
 void ui_flush(void)
 {
   cmdline_ui_flush();
-  win_ui_flush_positions();
+  win_ui_flush();
   msg_ext_ui_flush();
   msg_scroll_flush();
 

src/nvim/window.c

@@ -773,6 +773,21 @@ static void ui_ext_win_position(win_T *wp)
 
 }
 
+void ui_ext_win_viewport(win_T *wp)
+{
+  if ((wp == curwin || ui_has(kUIMultigrid)) && wp->w_viewport_invalid) {
+    int botline = wp->w_botline;
+    if (botline == wp->w_buffer->b_ml.ml_line_count+1
+        && wp->w_empty_rows == 0) {
+      // TODO(bfredl): The might be more cases to consider, like how does this
+      // interact with incomplete final line? Diff filler lines?
+      botline = wp->w_buffer->b_ml.ml_line_count;
+    }
+    ui_call_win_viewport(wp->w_grid.handle, wp->handle, wp->w_topline-1,
+                         botline, wp->w_cursor.lnum-1, wp->w_cursor.col);
+    wp->w_viewport_invalid = false;
+  }
+}
 
 static bool parse_float_anchor(String anchor, FloatAnchor *out)
 {
@@ -4688,6 +4703,7 @@ static win_T *win_alloc(win_T *after, int hidden)
   new_wp->w_scbind_pos = 1;
   new_wp->w_floating = 0;
   new_wp->w_float_config = FLOAT_CONFIG_INIT;
+  new_wp->w_viewport_invalid = true;
 
   // use global option for global-local options
   new_wp->w_p_so = -1;
@@ -6992,7 +7008,7 @@ void get_framelayout(const frame_T *fr, list_T *l, bool outer)
   }
 }
 
-void win_ui_flush_positions(void)
+void win_ui_flush(void)
 {
   FOR_ALL_TAB_WINDOWS(tp, wp) {
     if (wp->w_pos_changed && wp->w_grid.chars != NULL) {
@@ -7003,6 +7019,9 @@ void win_ui_flush_positions(void)
       }
       wp->w_pos_changed = false;
     }
+    if (tp == curtab) {
+      ui_ext_win_viewport(wp);
+    }
   }
 }