terminal: simplify sizing logic

src/nvim/option.c

@@ -4339,7 +4339,7 @@ static char *set_num_option(int opt_idx, char_u *varp, long value,
   } else if (pp == &curbuf->b_p_scbk || pp == &p_scbk) {
     if (curbuf->terminal) {
       // Force the scrollback to take effect.
-      terminal_resize(curbuf->terminal, UINT16_MAX, UINT16_MAX);
+      terminal_check_size(curbuf->terminal);
     }
   } else if (pp == &curwin->w_p_nuw) {
     curwin->w_nrwidth_line_count = 0;

src/nvim/screen.c

@@ -629,9 +629,7 @@ static void win_update(win_T *wp)
     wp->w_nrwidth = i;
 
     if (buf->terminal) {
-      terminal_resize(buf->terminal,
-                      (uint16_t)(MAX(0, wp->w_grid.Columns - win_col_off(wp))),
-                      (uint16_t)wp->w_grid.Rows);
+      terminal_check_size(buf->terminal);
     }
   } else if (buf->b_mod_set
              && buf->b_mod_xlines != 0

src/nvim/terminal.c

@@ -334,34 +334,22 @@ void terminal_close(Terminal *term, char *msg)
   }
 }
 
-void terminal_resize(Terminal *term, uint16_t width, uint16_t height)
+void terminal_check_size(Terminal *term)
 {
   if (term->closed) {
+    // TODO: WTF does this mean:
     // If two windows display the same terminal and one is closed by keypress.
     return;
   }
-  bool force = width == UINT16_MAX || height == UINT16_MAX;
   int curwidth, curheight;
   vterm_get_size(term->vt, &curheight, &curwidth);
+  uint16_t width = 0, height = 0;
 
-  if (force || !width) {
-    width = (uint16_t)curwidth;
-  }
-
-  if (force || !height) {
-    height = (uint16_t)curheight;
-  }
-
-  if (!force && curheight == height && curwidth == width) {
-    return;
-  }
-
-  if (height == 0 || width == 0) {
-    return;
-  }
+  bool window_seen = false;
 
   FOR_ALL_TAB_WINDOWS(tp, wp) {
     if (wp->w_buffer && wp->w_buffer->terminal == term) {
+      window_seen = true;
       const uint16_t win_width =
         (uint16_t)(MAX(0, wp->w_width - win_col_off(wp)));
       width = MAX(width, win_width);
@@ -369,6 +357,10 @@ void terminal_resize(Terminal *term, uint16_t width, uint16_t height)
     }
   }
 
+  if ((curheight == height && curwidth == width) || height == 0 || width == 0) {
+    return;
+  }
+
   vterm_set_size(term->vt, height, width);
   vterm_screen_flush_damage(term->vts);
   term->pending_resize = true;
@@ -383,8 +375,10 @@ void terminal_enter(void)
   memset(s, 0, sizeof(TerminalState));
   s->term = buf->terminal;
 
-  // Ensure the terminal is properly sized.
-  terminal_resize(s->term, 0, 0);
+  // Ensure the terminal is properly sized. Ideally window size management
+  // code should always have resized the terminal already, but check here to
+  // be sure.
+  terminal_check_size(s->term);
 
   int save_state = State;
   s->save_rd = RedrawingDisabled;

src/nvim/window.c

@@ -5026,7 +5026,8 @@ void scroll_to_fraction(win_T *wp, int prev_height)
   invalidate_botline_win(wp);
 
   if (wp->w_buffer->terminal) {
-    terminal_resize(wp->w_buffer->terminal, 0, wp->w_height);
+    terminal_check_size(wp->w_buffer->terminal);
+    // TODO: terminal should this itself:
     redraw_win_later(wp, NOT_VALID);
   }
 }
@@ -5048,8 +5049,8 @@ void win_new_width(win_T *wp, int width)
   wp->w_width = width;
   // TODO(bfredl): refactor this. There should be some variable
   // wp->w_inner_width which always contains the final actual width.
-  // Alternatively use wp->w_width for this and introduce wp->w_outer_width
-  // Then use this to fix terminal_resize.
+  // Alternatively use wp->w_width for this and introduce wp->w_outer_width.
+  // Then use this to fix terminal_check_size.
   if (!ui_is_external(kUIMultigrid) || wp->w_grid.requested_cols == 0) {
     win_inner_width_changed(wp);
   }
@@ -5059,9 +5060,7 @@ void win_new_width(win_T *wp, int width)
 
   if (wp->w_buffer->terminal) {
     if (wp->w_height != 0) {
-      terminal_resize(wp->w_buffer->terminal,
-                      (uint16_t)(MAX(0, wp->w_width - win_col_off(wp))),
-                      0);
+      terminal_check_size(wp->w_buffer->terminal);
     }
   }
   wp->w_pos_changed = true;