terminal: Show character grid size in header bar when resizing

We don't have a reliable way to know when to clear this indicator.
Typically the pointer will still be over the window when the resize is
done and we'll get an enter event, but if the window sets a max size
the pointer may be over another window when the resize is done.

We'll need a new wl_shell (or more likely xdg_shell) event for this.

clients/terminal.c

@@ -428,6 +428,7 @@ struct terminal {
 	struct window *window;
 	struct widget *widget;
 	struct display *display;
+	char *title;
 	union utf8_char *data;
 	struct task io_task;
 	char *tab_ruler;
@@ -837,7 +838,7 @@ resize_handler(struct widget *widget,
 {
 	struct terminal *terminal = data;
 	int32_t columns, rows, m;
-
+	char *p;
 	m = 2 * terminal->margin;
 	columns = (width - m) / (int32_t) terminal->average_width;
 	rows = (height - m) / (int32_t) terminal->extents.height;
@@ -847,6 +848,9 @@ resize_handler(struct widget *widget,
 		width = columns * terminal->average_width + m;
 		height = rows * terminal->extents.height + m;
 		widget_set_size(terminal->widget, width, height);
+		asprintf(&p, "%s — [%dx%d]", terminal->title, columns, rows);
+		window_set_title(terminal->window, p);
+		free(p);
 	}
 
 	terminal_resize_cells(terminal, columns, rows);
@@ -1257,6 +1261,8 @@ handle_osc(struct terminal *terminal)
 	case 0: /* Icon name and window title */
 	case 1: /* Icon label */
 	case 2: /* Window title*/
+		free(terminal->title);
+		terminal->title = strdup(p);
 		window_set_title(terminal->window, p);
 		break;
 	case 7: /* shell cwd as uri */
@@ -2725,6 +2731,11 @@ static int
 enter_handler(struct widget *widget,
 	      struct input *input, float x, float y, void *data)
 {
+	struct terminal *terminal = data;
+
+	/* Reset title to get rid of resizing '[WxH]' in titlebar */
+	window_set_title(terminal->window, terminal->title);
+
 	return CURSOR_IBEAM;
 }
 
@@ -2776,7 +2787,8 @@ terminal_create(struct display *display)
 	terminal->margin_bottom = -1;
 	terminal->window = window_create(display);
 	terminal->widget = window_frame_create(terminal->window, terminal);
-	window_set_title(terminal->window, "Wayland Terminal");
+	terminal->title = strdup("Wayland Terminal");
+	window_set_title(terminal->window, terminal->title);
 	widget_set_transparent(terminal->widget, 0);
 
 	init_state_machine(&terminal->state_machine);
@@ -2851,6 +2863,7 @@ terminal_destroy(struct terminal *terminal)
 	if (wl_list_empty(&terminal_list))
 		display_exit(terminal->display);
 
+	free(terminal->title);
 	free(terminal);
 }