From 7f6ecb8d49854c8cfe83457c396de622918bbddb Mon Sep 17 00:00:00 2001
From: David Phillips <david@sighup.nz>
Date: Wed, 6 Jun 2018 22:30:41 +1200
Subject: Only update battery icon on change

---
 bat_tray.c | 42 ++++++++++++++++++++++++++++++++----------
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/bat_tray.c b/bat_tray.c
index c6e9f45..48a8488 100644
--- a/bat_tray.c
+++ b/bat_tray.c
@@ -9,6 +9,7 @@
 
 static GtkStatusIcon* tray;
 static char tooltip_text[1024];
+static int old_rounded;
 static int bat_num; // Shortcoming: we only detect one battery
 static char CHARGE_VALUE_PATH[1024];
 static char CHARGE_STATE_PATH[1024];
@@ -23,6 +24,27 @@ int get_bat_percent()
 
 
 /***********************************************************************
+ * Get battery level percentage, rounded to one of: 0, 20, 40, 60, 80
+ * or 100. These values match the icon files
+ **********************************************************************/
+int get_bat_percent_rounded()
+{
+	int rounded = 0;
+
+	rounded = 20 * (int)((get_bat_percent() + 10) / 20);
+
+	/* cap rounded value to safe bounds */
+	if (rounded < 0)
+		rounded = 0;
+
+	if (rounded > 100)
+		rounded = 100;
+
+	return rounded;
+}
+
+
+/***********************************************************************
  * Return number of seconds until battery is fully charged/discharged
  **********************************************************************/
 long get_bat_seconds_left()
@@ -140,15 +162,13 @@ static gboolean update()
 	char icon_file[1024];
 	int rounded = 0;
 
-	/* Round percentage to 0, 20, 40, 60, 80 or 100 */
-	rounded = 20 * (int)((get_bat_percent() + 10) / 20);
-
-	/* cap rounded value to safe bounds */
-	if (rounded < 0)
-		rounded = 0;
+	update_tooltip_cache();
 
-	if (rounded > 100)
-		rounded = 100;
+	/* if rounded hasn't changed, don't spend time changing icon */
+	rounded = get_bat_percent_rounded();
+	if (rounded == old_rounded) {
+		return true;
+	}
 
 	switch (get_battery_state())
 	{
@@ -165,7 +185,6 @@ static gboolean update()
 			break;
 	}
 
-	update_tooltip_cache();
 	gtk_status_icon_set_from_file(tray, icon_file);
 	return true;
 }
@@ -192,7 +211,10 @@ void bat_tray_init()
 	g_signal_connect(G_OBJECT(tray), "query-tooltip", GTK_SIGNAL_FUNC(show_tooltip), NULL);
 	g_timeout_add(120000, update, NULL);
 
-	/* Force useful cached tooltip text, force meaningful icon */
+	/* trigger icon refresh in update() below */
+	old_rounded = get_bat_percent_rounded() - 1;
+
+	/* pre-load cached tooltip text */
 	update();
 }
 
-- 
cgit v1.1