From 037a256392db862b04c38d8f0831545173ff2e69 Mon Sep 17 00:00:00 2001
From: Lars Brinkhoff <lars@nocrew.org>
Date: Thu, 15 Aug 2019 11:15:35 +0200
Subject: [PATCH] display: Add function to determine if display is blank.

---
 display/display.c | 9 +++++++++
 display/display.h | 5 +++++
 2 files changed, 14 insertions(+)

diff --git a/display/display.c b/display/display.c
index 94bf86c..5ad0691 100644
--- a/display/display.c
+++ b/display/display.c
@@ -439,6 +439,15 @@ queue_point(struct point *p)
     p->delay = d;
 }
 
+/*
+ * Return true if the display is blank, i.e. no active points in list.
+ */
+int
+display_is_blank(void)
+{
+    return head->next == head;
+}
+
 /*
  * here to to dynamically adjust interval for examination
  * of elapsed vs. simulated time, and fritter away
diff --git a/display/display.h b/display/display.h
index 0470f46..391bf4e 100644
--- a/display/display.h
+++ b/display/display.h
@@ -83,6 +83,11 @@ extern int display_scale(void);
  */
 extern int display_age(int,int);
 
+/*
+ * Return true if the display is blank.
+ */
+extern int display_is_blank(void);
+
 /*
  * display intensity levels.
  * always at least 8 (for VT11/VS60) -- may be mapped internally