Prefer werase to wclear when possible to reduce flickering

Use werase instead of wclear in redraw_view and optionally make
redraw_display use wclear before calling redraw_view. After this, wclear
is only used when there is possibility that the screen could have been
corrupted.

diff --git a/tig.c b/tig.c
index a8976b98d864ab25dc9014d99ff8bae5b10ca0d6..74f78df589921a65ae038903944c2f4c0be5029e 100644 (file)
--- a/tig.c
+++ b/tig.c
@@ -2050,7 +2050,7 @@ redraw_view_from(struct view *view, int lineno)
 static void
 redraw_view(struct view *view)
 {
-       wclear(view->win);
+       werase(view->win);
        redraw_view_from(view, 0);
 }
 
@@ -2167,12 +2167,14 @@ resize_display(void)
 }
 
 static void
-redraw_display(void)
+redraw_display(bool clear)
 {
        struct view *view;
        int i;
 
        foreach_displayed_view (view, i) {
+               if (clear)
+                       wclear(view->win);
                redraw_view(view);
                update_view_title(view);
        }
@@ -2195,7 +2197,7 @@ static void
 toggle_view_option(bool *option, const char *help)
 {
        *option = !*option;
-       redraw_display();
+       redraw_display(FALSE);
        report("%sabling %s", *option ? "En" : "Dis", help);
 }
 
@@ -2921,7 +2923,7 @@ open_external_viewer(const char *argv[], const char *dir)
        fprintf(stderr, "Press Enter to continue");
        getc(opt_tty);
        reset_prog_mode();
-       redraw_display();
+       redraw_display(TRUE);
 }
 
 static void
@@ -3169,7 +3171,7 @@ view_driver(struct view *view, enum request request)
                resize_display();
                /* Fall-through */
        case REQ_SCREEN_REDRAW:
-               redraw_display();
+               redraw_display(TRUE);
                break;
 
        case REQ_EDIT:
@@ -3191,7 +3193,7 @@ view_driver(struct view *view, enum request request)
                        display[current_view] = view->parent;
                        view->parent = view;
                        resize_display();
-                       redraw_display();
+                       redraw_display(FALSE);
                        report("");
                        break;
                }