Improved patch for MATE Power Manager 1.8.0 to fix backlight brightness reset on login (AC-power only)

1004_save-backlight-key-brightness.patch

From: Nachanon Vetjasit <nachanon@users.noreply.github.com>
Subject: Save AC-power backlight set via brightness keys in GSettings
Bug: https://github.com/mate-desktop/mate-power-manager/issues/76
Bug-Debian: https://bugs.debian.org/785017

Based on a patch by Flos Lonicerae.

--- a/src/gpm-backlight.c
+++ b/src/gpm-backlight.c
@@ -429,6 +429,7 @@
 	GError *error = NULL;
 	guint percentage;
 	gboolean hw_changed;
+	gboolean on_battery;
 	egg_debug ("Button press event type=%s", type);
 
 	if (g_strcmp0 (type, GPM_BUTTON_BRIGHT_UP) == 0) {
@@ -444,6 +445,13 @@
 			gpm_backlight_dialog_show (backlight);
 			/* save the new percentage */
 			backlight->priv->master_percentage = percentage;
+			/* if using AC power supply, save the new brightness settings */
+			g_object_get (backlight->priv->client, "on-battery", &on_battery, NULL);
+			if (!on_battery) {
+				egg_debug ("saving brightness for ac supply: %i", percentage);
+				g_settings_set_double (backlight->priv->settings, GPM_SETTINGS_BRIGHTNESS_AC,
+						       percentage*1.0);
+			}
 		}
 		/* we emit a signal for the brightness applet */
 		if (ret && hw_changed) {
@@ -463,6 +471,13 @@
 			gpm_backlight_dialog_show (backlight);
 			/* save the new percentage */
 			backlight->priv->master_percentage = percentage;
+			/* if using AC power supply, save the new brightness settings */
+			g_object_get (backlight->priv->client, "on-battery", &on_battery, NULL);
+			if (!on_battery) {
+				egg_debug ("saving brightness for ac supply: %i", percentage);
+				g_settings_set_double (backlight->priv->settings, GPM_SETTINGS_BRIGHTNESS_AC,
+						       percentage*1.0);
+			}
 		}
 		/* we emit a signal for the brightness applet */
 		if (ret && hw_changed) {