perf(statusline): UI elements are always redrawn on K_EVENT

Problem:    'statusline'-format UI elements are redrawn on each K_EVENT.
Solution:   Only redraw UI elements when something relevant has changed.

src/nvim/buffer_defs.h

@@ -1279,13 +1279,14 @@ struct window_S {
   bool w_redr_border;               // if true border must be redrawn
   bool w_redr_statuscol;            // if true 'statuscolumn' must be redrawn
 
-  // remember what is shown in the ruler for this window (if 'ruler' set)
+  // remember what is shown in the 'statusline'-format elements
-  pos_T w_ru_cursor;                // cursor position shown in ruler
+  pos_T w_stl_cursor;                // cursor position when last redrawn
-  colnr_T w_ru_virtcol;             // virtcol shown in ruler
+  colnr_T w_stl_virtcol;             // virtcol when last redrawn
-  linenr_T w_ru_topline;            // topline shown in ruler
+  linenr_T w_stl_topline;            // topline when last redrawn
-  linenr_T w_ru_line_count;         // line count used for ruler
+  linenr_T w_stl_line_count;         // line count when last redrawn
-  int w_ru_topfill;                 // topfill shown in ruler
+  int w_stl_topfill;                 // topfill when last redrawn
-  char w_ru_empty;                  // true if ruler shows 0-1 (empty line)
+  char w_stl_empty;                  // true if elements show 0-1 (empty line)
+  int w_stl_state;                   // State when last redrawn
 
   int w_alt_fnum;                   // alternate file (for # and CTRL-^)
 

src/nvim/drawscreen.c

@@ -92,6 +92,7 @@
 #include "nvim/profile.h"
 #include "nvim/regexp.h"
 #include "nvim/screen.h"
+#include "nvim/state.h"
 #include "nvim/statusline.h"
 #include "nvim/syntax.h"
 #include "nvim/terminal.h"
@@ -733,28 +734,53 @@ void show_cursor_info(bool always)
     return;
   }
 
-  win_check_ns_hl(curwin);
+  int state = get_real_state();
-  if ((*p_stl != NUL || *curwin->w_p_stl != NUL)
+  int empty_line = (State & MODE_INSERT) == 0
-      && (curwin->w_status_height || global_stl_height())) {
+                   && *ml_get_buf(curwin->w_buffer, curwin->w_cursor.lnum, false) == NUL;
-    redraw_custom_statusline(curwin);
+
-  } else {
+  // Only draw when something changed.
-    win_redr_ruler(curwin, always);
+  validate_virtcol_win(curwin);
-  }
+  if (always
-  if (*p_wbr != NUL || *curwin->w_p_wbr != NUL) {
+      || curwin->w_cursor.lnum != curwin->w_stl_cursor.lnum
-    win_redr_winbar(curwin);
+      || curwin->w_cursor.col != curwin->w_stl_cursor.col
+      || curwin->w_virtcol != curwin->w_stl_virtcol
+      || curwin->w_cursor.coladd != curwin->w_stl_cursor.coladd
+      || curwin->w_topline != curwin->w_stl_topline
+      || curwin->w_buffer->b_ml.ml_line_count != curwin->w_stl_line_count
+      || curwin->w_topfill != curwin->w_stl_topfill
+      || empty_line != curwin->w_stl_empty
+      || state != curwin->w_stl_state) {
+    win_check_ns_hl(curwin);
+    if ((*p_stl != NUL || *curwin->w_p_stl != NUL)
+        && (curwin->w_status_height || global_stl_height())) {
+      redraw_custom_statusline(curwin);
+    } else {
+      win_redr_ruler(curwin);
+    }
+    if (*p_wbr != NUL || *curwin->w_p_wbr != NUL) {
+      win_redr_winbar(curwin);
+    }
+
+    if (need_maketitle
+        || (p_icon && (stl_syntax & STL_IN_ICON))
+        || (p_title && (stl_syntax & STL_IN_TITLE))) {
+      maketitle();
+    }
+
+    win_check_ns_hl(NULL);
+    // Redraw the tab pages line if needed.
+    if (redraw_tabline) {
+      draw_tabline();
+    }
   }
 
-  if (need_maketitle
+  curwin->w_stl_cursor = curwin->w_cursor;
-      || (p_icon && (stl_syntax & STL_IN_ICON))
+  curwin->w_stl_virtcol = curwin->w_virtcol;
-      || (p_title && (stl_syntax & STL_IN_TITLE))) {
+  curwin->w_stl_empty = (char)empty_line;
-    maketitle();
+  curwin->w_stl_topline = curwin->w_topline;
-  }
+  curwin->w_stl_line_count = curwin->w_buffer->b_ml.ml_line_count;
-
+  curwin->w_stl_topfill = curwin->w_topfill;
-  win_check_ns_hl(NULL);
+  curwin->w_stl_state = state;
-  // Redraw the tab pages line if needed.
-  if (redraw_tabline) {
-    draw_tabline();
-  }
 }
 
 static void redraw_win_signcol(win_T *wp)

src/nvim/ex_getln.c

@@ -907,6 +907,9 @@ theend:
     ui_call_cmdline_hide(ccline.level);
     msg_ext_clear_later();
   }
+  if (!cmd_silent) {
+    status_redraw_all();  // redraw to show mode change
+  }
 
   cmdline_level--;
 

src/nvim/option.c

@@ -92,6 +92,7 @@
 #include "nvim/spell.h"
 #include "nvim/spellfile.h"
 #include "nvim/spellsuggest.h"
+#include "nvim/statusline.h"
 #include "nvim/strings.h"
 #include "nvim/tag.h"
 #include "nvim/terminal.h"
@@ -2251,8 +2252,13 @@ static char *set_bool_option(const int opt_idx, char *const varp, const int valu
     ui_call_option_set(cstr_as_string(options[opt_idx].fullname),
                        BOOLEAN_OBJ(*varp));
   }
-
+  if ((int *)varp == &p_ru || (int *)varp == &p_sc) {
-  comp_col();                       // in case 'ruler' or 'showcmd' changed
+    // in case 'ruler' or 'showcmd' changed
+    comp_col();
+    if ((int *)varp == &p_ru) {
+      win_redr_ruler(curwin);
+    }
+  }
   if (curwin->w_curswant != MAXCOL
       && (options[opt_idx].flags & (P_CURSWANT | P_RALL)) != 0) {
     curwin->w_set_curswant = true;

src/nvim/optionstr.c

@@ -49,6 +49,7 @@
 #include "nvim/spell.h"
 #include "nvim/spellfile.h"
 #include "nvim/spellsuggest.h"
+#include "nvim/statusline.h"
 #include "nvim/strings.h"
 #include "nvim/tag.h"
 #include "nvim/ui.h"
@@ -1220,6 +1221,7 @@ static void did_set_statusline(win_T *win, char **varp, char **gvarp, char **err
   }
   if (varp == &p_ruf && *errmsg == NULL) {
     comp_col();
+    win_redr_ruler(curwin);
   }
   // add / remove window bars for 'winbar'
   if (gvarp == &p_wbr) {

src/nvim/screen.c

@@ -611,7 +611,7 @@ int showmode(void)
   // the ruler is after the mode message and must be redrawn
   win_T *last = lastwin_nofloating();
   if (redrawing() && last->w_status_height == 0 && global_stl_height() == 0) {
-    win_redr_ruler(last, true);
+    win_redr_ruler(last);
   }
 
   redraw_cmdline = false;

src/nvim/statusline.c

@@ -162,7 +162,7 @@ void win_redr_status(win_T *wp)
                 (int)((size_t)this_ru_col - strlen(NameBuff) - 1), attr);
     }
 
-    win_redr_ruler(wp, true);
+    win_redr_ruler(wp);
 
     // Draw the 'showcmd' information if 'showcmdloc' == "statusline".
     if (p_sc && *p_sloc == 's') {
@@ -443,7 +443,7 @@ void win_redr_winbar(win_T *wp)
   entered = false;
 }
 
-void win_redr_ruler(win_T *wp, bool always)
+void win_redr_ruler(win_T *wp)
 {
   bool is_stl_global = global_stl_height() > 0;
   static bool did_show_ext_ruler = false;
@@ -473,138 +473,116 @@ void win_redr_ruler(win_T *wp, bool always)
   }
 
   // Check if not in Insert mode and the line is empty (will show "0-1").
-  int empty_line = false;
+  int empty_line = (State & MODE_INSERT) == 0
-  if ((State & MODE_INSERT) == 0 && *ml_get_buf(wp->w_buffer, wp->w_cursor.lnum, false) == NUL) {
+                   && *ml_get_buf(curwin->w_buffer, curwin->w_cursor.lnum, false) == NUL;
-    empty_line = true;
+
+  int width;
+  int row;
+  int fillchar;
+  int attr;
+  int off;
+  bool part_of_status = false;
+
+  if (wp->w_status_height) {
+    row = W_ENDROW(wp);
+    fillchar = fillchar_status(&attr, wp);
+    off = wp->w_wincol;
+    width = wp->w_width;
+    part_of_status = true;
+  } else if (is_stl_global) {
+    row = Rows - (int)p_ch - 1;
+    fillchar = fillchar_status(&attr, wp);
+    off = 0;
+    width = Columns;
+    part_of_status = true;
+  } else {
+    row = Rows - 1;
+    fillchar = ' ';
+    attr = HL_ATTR(HLF_MSG);
+    width = Columns;
+    off = 0;
   }
 
-  // Only draw the ruler when something changed.
+  if (!part_of_status && p_ch == 0 && !ui_has(kUIMessages)) {
-  validate_virtcol_win(wp);
+    return;
-  if (redraw_cmdline
+  }
-      || always
-      || wp->w_cursor.lnum != wp->w_ru_cursor.lnum
-      || wp->w_cursor.col != wp->w_ru_cursor.col
-      || wp->w_virtcol != wp->w_ru_virtcol
-      || wp->w_cursor.coladd != wp->w_ru_cursor.coladd
-      || wp->w_topline != wp->w_ru_topline
-      || wp->w_buffer->b_ml.ml_line_count != wp->w_ru_line_count
-      || wp->w_topfill != wp->w_ru_topfill
-      || empty_line != wp->w_ru_empty) {
-    int width;
-    int row;
-    int fillchar;
-    int attr;
-    int off;
-    bool part_of_status = false;
 
-    if (wp->w_status_height) {
+  // In list mode virtcol needs to be recomputed
-      row = W_ENDROW(wp);
+  colnr_T virtcol = wp->w_virtcol;
-      fillchar = fillchar_status(&attr, wp);
+  if (wp->w_p_list && wp->w_p_lcs_chars.tab1 == NUL) {
-      off = wp->w_wincol;
+    wp->w_p_list = false;
-      width = wp->w_width;
+    getvvcol(wp, &wp->w_cursor, NULL, &virtcol, NULL);
-      part_of_status = true;
+    wp->w_p_list = true;
-    } else if (is_stl_global) {
+  }
-      row = Rows - (int)p_ch - 1;
-      fillchar = fillchar_status(&attr, wp);
-      off = 0;
-      width = Columns;
-      part_of_status = true;
-    } else {
-      row = Rows - 1;
-      fillchar = ' ';
-      attr = HL_ATTR(HLF_MSG);
-      width = Columns;
-      off = 0;
-    }
-
-    if (!part_of_status && p_ch == 0 && !ui_has(kUIMessages)) {
-      return;
-    }
-
-    // In list mode virtcol needs to be recomputed
-    colnr_T virtcol = wp->w_virtcol;
-    if (wp->w_p_list && wp->w_p_lcs_chars.tab1 == NUL) {
-      wp->w_p_list = false;
-      getvvcol(wp, &wp->w_cursor, NULL, &virtcol, NULL);
-      wp->w_p_list = true;
-    }
 
 #define RULER_BUF_LEN 70
-    char buffer[RULER_BUF_LEN];
+  char buffer[RULER_BUF_LEN];
 
-    // Some sprintfs return the length, some return a pointer.
+  // Some sprintfs return the length, some return a pointer.
-    // To avoid portability problems we use strlen() here.
+  // To avoid portability problems we use strlen() here.
-    vim_snprintf(buffer, RULER_BUF_LEN, "%" PRId64 ",",
+  vim_snprintf(buffer, RULER_BUF_LEN, "%" PRId64 ",",
-                 (wp->w_buffer->b_ml.ml_flags &
+               (wp->w_buffer->b_ml.ml_flags &
-                  ML_EMPTY) ? (int64_t)0L : (int64_t)wp->w_cursor.lnum);
+                ML_EMPTY) ? (int64_t)0L : (int64_t)wp->w_cursor.lnum);
-    size_t len = strlen(buffer);
+  size_t len = strlen(buffer);
-    col_print(buffer + len, RULER_BUF_LEN - len,
+  col_print(buffer + len, RULER_BUF_LEN - len,
-              empty_line ? 0 : (int)wp->w_cursor.col + 1,
+            empty_line ? 0 : (int)wp->w_cursor.col + 1,
-              (int)virtcol + 1);
+            (int)virtcol + 1);
 
-    // Add a "50%" if there is room for it.
+  // Add a "50%" if there is room for it.
-    // On the last line, don't print in the last column (scrolls the
+  // On the last line, don't print in the last column (scrolls the
-    // screen up on some terminals).
+  // screen up on some terminals).
-    int i = (int)strlen(buffer);
+  int i = (int)strlen(buffer);
-    get_rel_pos(wp, buffer + i + 1, RULER_BUF_LEN - i - 1);
+  get_rel_pos(wp, buffer + i + 1, RULER_BUF_LEN - i - 1);
-    int o = i + vim_strsize(buffer + i + 1);
+  int o = i + vim_strsize(buffer + i + 1);
-    if (wp->w_status_height == 0 && !is_stl_global) {  // can't use last char of screen
+  if (wp->w_status_height == 0 && !is_stl_global) {  // can't use last char of screen
+    o++;
+  }
+  int this_ru_col = ru_col - (Columns - width);
+  if (this_ru_col < 0) {
+    this_ru_col = 0;
+  }
+  // Never use more than half the window/screen width, leave the other half
+  // for the filename.
+  if (this_ru_col < (width + 1) / 2) {
+    this_ru_col = (width + 1) / 2;
+  }
+  if (this_ru_col + o < width) {
+    // Need at least 3 chars left for get_rel_pos() + NUL.
+    while (this_ru_col + o < width && RULER_BUF_LEN > i + 4) {
+      i += utf_char2bytes(fillchar, buffer + i);
       o++;
     }
-    int this_ru_col = ru_col - (Columns - width);
+    get_rel_pos(wp, buffer + i, RULER_BUF_LEN - i);
-    if (this_ru_col < 0) {
+  }
-      this_ru_col = 0;
+
+  if (ui_has(kUIMessages) && !part_of_status) {
+    MAXSIZE_TEMP_ARRAY(content, 1);
+    MAXSIZE_TEMP_ARRAY(chunk, 2);
+    ADD_C(chunk, INTEGER_OBJ(attr));
+    ADD_C(chunk, STRING_OBJ(cstr_as_string(buffer)));
+    ADD_C(content, ARRAY_OBJ(chunk));
+    ui_call_msg_ruler(content);
+    did_show_ext_ruler = true;
+  } else {
+    if (did_show_ext_ruler) {
+      ui_call_msg_ruler((Array)ARRAY_DICT_INIT);
+      did_show_ext_ruler = false;
     }
-    // Never use more than half the window/screen width, leave the other half
+    // Truncate at window boundary.
-    // for the filename.
+    o = 0;
-    if (this_ru_col < (width + 1) / 2) {
+    for (i = 0; buffer[i] != NUL; i += utfc_ptr2len(buffer + i)) {
-      this_ru_col = (width + 1) / 2;
+      o += utf_ptr2cells(buffer + i);
-    }
+      if (this_ru_col + o > width) {
-    if (this_ru_col + o < width) {
+        buffer[i] = NUL;
-      // Need at least 3 chars left for get_rel_pos() + NUL.
+        break;
-      while (this_ru_col + o < width && RULER_BUF_LEN > i + 4) {
-        i += utf_char2bytes(fillchar, buffer + i);
-        o++;
       }
-      get_rel_pos(wp, buffer + i, RULER_BUF_LEN - i);
     }
 
-    if (ui_has(kUIMessages) && !part_of_status) {
+    ScreenGrid *grid = part_of_status ? &default_grid : &msg_grid_adj;
-      MAXSIZE_TEMP_ARRAY(content, 1);
+    grid_puts(grid, buffer, row, this_ru_col + off, attr);
-      MAXSIZE_TEMP_ARRAY(chunk, 2);
+    grid_fill(grid, row, row + 1,
-      ADD_C(chunk, INTEGER_OBJ(attr));
+              this_ru_col + off + (int)strlen(buffer), off + width, fillchar,
-      ADD_C(chunk, STRING_OBJ(cstr_as_string(buffer)));
+              fillchar, attr);
-      ADD_C(content, ARRAY_OBJ(chunk));
-      ui_call_msg_ruler(content);
-      did_show_ext_ruler = true;
-    } else {
-      if (did_show_ext_ruler) {
-        ui_call_msg_ruler((Array)ARRAY_DICT_INIT);
-        did_show_ext_ruler = false;
-      }
-      // Truncate at window boundary.
-      o = 0;
-      for (i = 0; buffer[i] != NUL; i += utfc_ptr2len(buffer + i)) {
-        o += utf_ptr2cells(buffer + i);
-        if (this_ru_col + o > width) {
-          buffer[i] = NUL;
-          break;
-        }
-      }
-
-      ScreenGrid *grid = part_of_status ? &default_grid : &msg_grid_adj;
-      grid_puts(grid, buffer, row, this_ru_col + off, attr);
-      grid_fill(grid, row, row + 1,
-                this_ru_col + off + (int)strlen(buffer), off + width, fillchar,
-                fillchar, attr);
-    }
-
-    wp->w_ru_cursor = wp->w_cursor;
-    wp->w_ru_virtcol = wp->w_virtcol;
-    wp->w_ru_empty = (char)empty_line;
-    wp->w_ru_topline = wp->w_topline;
-    wp->w_ru_line_count = wp->w_buffer->b_ml.ml_line_count;
-    wp->w_ru_topfill = wp->w_topfill;
   }
 }