envy24control save state of LRGang button in config file

From: Dirk Jagdmann <doj@cubic.org>
this patch saves the state of the "LR Gang" buttons in a config/pref file,
because this button's state is not preserved throughout runs of
envy24control. At present it only works, when envy24control is compiled with
GTK2 as I have used routines which were introduced with Glib2.

envy24control/config.c

@@ -0,0 +1,75 @@
+#include <gtk/gtk.h>
+#include "envy24control.h"
+
+#if GLIB_CHECK_VERSION(2,2,0)
+
+#if GLIB_CHECK_VERSION(2,8,0)
+#define MYMKDIR g_mkdir_with_parents
+#else
+#include <sys/stat.h>
+#include <sys/types.h>
+#define MYMKDIR mkdir
+#endif
+
+GKeyFile *config_file;
+gboolean config_stereo[20];
+gchar *config_filename;
+
+void config_open()
+{
+  config_filename=g_strdup_printf("%s/%s", g_get_user_config_dir(), "envy24control");
+  config_file=g_key_file_new();
+  g_key_file_load_from_file(config_file, config_filename, G_KEY_FILE_KEEP_COMMENTS, NULL);
+}
+
+void config_close()
+{
+  gsize len=0;
+  gchar *s;
+  g_key_file_set_boolean_list(config_file, "mixer", "stereo",
+			      config_stereo, sizeof(config_stereo)/sizeof(config_stereo[0]));
+  s=g_key_file_to_data(config_file, &len, NULL);
+  if(s && len)
+    {
+      MYMKDIR(g_get_user_config_dir(), 0700);
+      FILE *f=fopen(config_filename, "wb");
+      if(f)
+	{
+	  fwrite(s, len, 1, f);
+	  fclose(f);
+	}
+    }
+
+  g_free(config_filename); config_filename=0;
+  g_key_file_free(config_file); config_file=0;
+}
+
+void config_set_stereo(GtkWidget *but, gpointer data)
+{
+  gint i=(gint)data;
+  config_stereo[i]=GTK_TOGGLE_BUTTON(but)->active;
+}
+
+void config_restore_stereo()
+{
+  gint i;
+  gsize len=0;
+  gboolean *s=g_key_file_get_boolean_list(config_file, "mixer", "stereo", &len, NULL);
+  if(s)
+      for(i=0; i!=len; ++i)
+	{
+	  config_stereo[i]=s[i];
+	  if(mixer_stereo_toggle[i])
+	    gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(mixer_stereo_toggle[i]), s[i]);
+	}
+}
+
+#else
+
+/* to be done */
+void config_open() { }
+void config_close() { }
+void config_set_stereo(GtkWidget *but, gpointer data) { }
+void config_restore_stereo() { }
+
+#endif

envy24control/config.h

@@ -0,0 +1,9 @@
+#ifndef CONFIG__H
+#define CONFIG__H
+
+void config_open();
+void config_close();
+void config_set_stereo(GtkWidget *but, gpointer data);
+void config_restore_stereo();
+
+#endif