Added dbus logic

configure.ac

@@ -12,6 +12,7 @@ AC_CONFIG_HEADERS([config.h.in])
 pkg_modules="glib-2.0 >= 2.6.0 \
              gtk+-2.0 >= 2.6.0 \
              gthread-2.0 \
+             dbus-glib-1 \
              lxpanel"
 
 PKG_CHECK_MODULES(PACKAGE, [$pkg_modules])

src/Makefile.am

@@ -10,7 +10,8 @@ module_LTLIBRARIES = cutiepi_battery.la
 moduledir = $(libdir)
 
 cutiepi_battery_la_SOURCES = \
-	main.c
+	main.c \
+	dbus.c
 
 cutiepi_battery_la_LIBADD = \
 	$(PACKAGE_LIBS)

src/dbus.c

@@ -0,0 +1,147 @@
+/**
+ *
+ * Copyright (c) 2022 Fabio Manganiello, see the file AUTHORS for details.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/param.h>
+#include <glib.h>
+
+#include "dbus.h"
+
+static DBusConnection* conn;
+
+static DBusConnection *dbus_connect()
+{
+    DBusError err;
+
+    dbus_error_init(&err);
+    conn = dbus_bus_get(DBUS_BUS_SESSION, &err);
+
+    if (dbus_error_is_set(&err))
+    {
+        fprintf(stderr, "Connection Error (%s)\n", err.message);
+        dbus_error_free(&err);
+    }
+
+    if (!conn)
+    {
+        fprintf(stderr, "Cannot initialize the DBus connection");
+        exit(1);
+    }
+
+    return conn;
+}
+
+static void add_signal_listener()
+{
+    DBusError err;
+    dbus_bus_add_match(
+        conn,
+        "type='signal',interface='io.cutiepi.interface',path='/mcu'",
+        &err);
+
+    dbus_connection_flush(conn);
+    if (dbus_error_is_set(&err))
+    {
+        fprintf(stderr, "Match Error (%s)\n", err.message);
+        exit(1);
+    }
+}
+
+static void reset_battery_info(BatteryInfo* info)
+{
+    info->_is_parsed[0] = info->_is_parsed[1] = false;
+}
+
+static bool is_battery_info_parsed(BatteryInfo* info)
+{
+    return info->_is_parsed[0] && info->_is_parsed[1];
+}
+
+static void process_signal(DBusMessage* msg, DBusMessageIter* iter, BatteryInfo* info)
+{
+    char current_type;
+    char* str_val = NO_STRING_VAL;
+    int int_val = NO_INT_VAL;
+
+    while ((current_type = dbus_message_iter_get_arg_type(iter)) != DBUS_TYPE_INVALID)
+    {
+        if (current_type == DBUS_TYPE_STRING)
+            dbus_message_iter_get_basic(iter, &str_val);
+        else if (current_type == DBUS_TYPE_INT32)
+            dbus_message_iter_get_basic(iter, &int_val);
+
+        if (strlen(str_val) && int_val != NO_INT_VAL)
+        {
+            if (!strncmp(str_val, BATTERY_LEVEL_VARNAME, strlen(str_val)-1))
+            {
+                info->level = (int) MIN(MAX(((int_val * 100) / MAX_BATTERY_VOLTAGE), 0), 100);
+                info->_is_parsed[0] = true;
+            }
+            else if (!strncmp(str_val, BATTERY_STATE_VARNAME, strlen(str_val)-1))
+            {
+                info->is_charging = int_val == BATTERY_STATE_CHARGING;
+                info->_is_parsed[1] = true;
+            }
+
+            str_val = NO_STRING_VAL;
+            int_val = NO_INT_VAL;
+        }
+
+        dbus_message_iter_next(iter);
+    }
+}
+
+void dbus_init()
+{
+    dbus_connect();
+    add_signal_listener();
+}
+
+void get_battery_info(BatteryInfo* info)
+{
+    DBusMessage* msg;
+    DBusMessageIter iter;
+    reset_battery_info(info);
+
+    while (!is_battery_info_parsed(info))
+    {
+        dbus_connection_read_write(conn, 0);
+        msg = dbus_connection_pop_message(conn);
+
+        if (!msg)
+        {
+            sleep(1);
+            continue;
+        }
+
+        if (dbus_message_is_signal(msg, "io.cutiepi.interface", "updateEvent"))
+        {
+            if (!dbus_message_iter_init(msg, &iter))
+                fprintf(stderr, "Message has no arguments!\n");
+            else
+                process_signal(msg, &iter, info);
+        }
+
+        dbus_message_unref(msg);
+    }
+}
+

src/dbus.h

@@ -0,0 +1,47 @@
+/**
+ *
+ * Copyright (c) 2022 Fabio Manganiello, see the file AUTHORS for details.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+
+#ifndef _DBUS_BATTERY_H
+#define _DBUS_BATTERY_H
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <dbus/dbus.h>
+#include <dbus/dbus-glib.h>
+
+#define   BATTERY_STATE_CHARGING       (4)
+#define   BATTERY_STATE_DISCHARGING    (5)
+#define   NO_STRING_VAL                ("")
+#define   NO_INT_VAL                   (-1)
+#define   BATTERY_LEVEL_VARNAME        ("battery")
+#define   BATTERY_STATE_VARNAME        ("charge")
+/* Expressed in mV (I guess). Value based on empirical evidence */
+#define   MAX_BATTERY_VOLTAGE          (4000)
+
+typedef struct {
+    uint8_t level;  /* Battery level in percentage between 0-100 */
+    bool    is_charging;
+    bool    _is_parsed[2];
+} BatteryInfo;
+
+extern void dbus_init();
+extern void get_battery_info(BatteryInfo* info);
+
+#endif   /* _DBUS_BATTERY_H */

src/main.c

@@ -19,59 +19,62 @@
  */
 
 #include <stdio.h>
+#include <glib.h>
 #include <lxpanel/plugin.h>
 
-#define LabelSize 32
+#include "dbus.h"
+
+#define    POLL_INTERVAL_MS    1000
+
+static gboolean refresh_state(void* data)
+{
+    GtkWidget* label = (GtkWidget *) data;
+    BatteryInfo info;
+    char label_str[32] = {0};
+
+    get_battery_info(&info);
+    snprintf(
+        label_str,
+        sizeof(label_str)-1,
+        "%s %d%%",
+        info.is_charging ? "⚡" : "🔋",
+        info.level
+    );
+
+    gtk_label_set_text(GTK_LABEL(label), label_str);
+    return TRUE;
+}
 
 GtkWidget *constructor(LXPanel *panel, config_setting_t *settings)
 {
     /* panel is a pointer to the panel and
-        settings is a pointer to the configuration data
-        since we don't use it, we'll make sure it doesn't
-        give us an error at compilation time */
+       settings is a pointer to the configuration data
+       since we don't use it, we'll make sure it doesn't
+       give us an error at compilation time */
     (void)panel;
     (void)settings;
 
-    // make a label out of the hostname
-    char cIdBuf[LabelSize + 1] = {'\0'};
-    FILE *fp;
-    fp = fopen("/etc/hostname", "r");
-    fgets(cIdBuf, LabelSize, fp);
-    fclose(fp);
-
-    // create a label widget instance
-    GtkWidget *pLabel = gtk_label_new(cIdBuf);
-
-    // set the label to be visible
-    gtk_widget_show(pLabel);
-
-    // need to create a container to be able to set a border
+    dbus_init();
     GtkWidget *p = gtk_event_box_new();
-
-    // our widget doesn't have a window...
-    // it is usually illegal to call gtk_widget_set_has_window() from application but for GtkEventBox it doesn't hurt
     gtk_widget_set_has_window(p, FALSE);
-
-    // set border width
     gtk_container_set_border_width(GTK_CONTAINER(p), 1);
 
-    // add the label to the container
-    gtk_container_add(GTK_CONTAINER(p), pLabel);
+    GtkWidget *label = gtk_label_new("");
+    gtk_container_add(GTK_CONTAINER(p), label);
+    gtk_widget_show(label);
+
+    g_timeout_add(POLL_INTERVAL_MS, refresh_state, label);
 
     // set the size we want
     // gtk_widget_set_size_request(p, 100, 25);
 
-    // success!!!
     return p;
 }
 
 FM_DEFINE_MODULE(lxpanel_gtk, test)
 
-/* Plugin descriptor. */
 LXPanelPluginInit fm_module_init_lxpanel_gtk = {
-    .name = "CutiePi battery",
-    .description = "Displays the current state of the CutiePi battery",
-    .one_per_system = 1,
-
-    // assigning our functions to provided pointers.
-    .new_instance = constructor};
+   .name = "CutiePi battery",
+   .description = "Displays the current state of the CutiePi battery",
+   .new_instance = constructor
+};