datetime: do our own serialisation so we can serialise microseconds as well

We still don't do that in _to_iso8601_string() though, since
this will probably mostly be used in tags, where it doesn't
matter so much and the microsecond argument might not be
well-received by some tag readers.

gst/gstdatetime.c

@@ -671,6 +671,74 @@ gst_date_time_new (gfloat tzoffset, gint year, gint month, gint day, gint hour,
   return datetime;
 }
 
+gchar *
+__gst_date_time_serialize (GstDateTime * datetime, gboolean serialize_usecs)
+{
+  GString *s;
+  gfloat gmt_offset;
+  guint msecs;
+
+  /* we always have at least the year */
+  s = g_string_new (NULL);
+  g_string_append_printf (s, "%04u", gst_date_time_get_year (datetime));
+
+  if (datetime->fields == GST_DATE_TIME_FIELDS_Y)
+    goto done;
+
+  /* add month */
+  g_string_append_printf (s, "-%02u", gst_date_time_get_month (datetime));
+
+  if (datetime->fields == GST_DATE_TIME_FIELDS_YM)
+    goto done;
+
+  /* add day of month */
+  g_string_append_printf (s, "-%02u", gst_date_time_get_day (datetime));
+
+  if (datetime->fields == GST_DATE_TIME_FIELDS_YMD)
+    goto done;
+
+  /* add time */
+  g_string_append_printf (s, "T%02u:%02u", gst_date_time_get_hour (datetime),
+      gst_date_time_get_minute (datetime));
+
+  if (datetime->fields == GST_DATE_TIME_FIELDS_YMD_HM)
+    goto add_timezone;
+
+  /* add seconds */
+  g_string_append_printf (s, ":%02u", gst_date_time_get_second (datetime));
+
+  /* add microseconds */
+  if (serialize_usecs) {
+    msecs = gst_date_time_get_microsecond (datetime);
+    if (msecs != 0) {
+      g_string_append_printf (s, ".%06u", msecs);
+      /* trim trailing 0s */
+      while (s->str[s->len - 1] == '0')
+        g_string_truncate (s, s->len - 1);
+    }
+  }
+
+  /* add timezone */
+
+add_timezone:
+
+  gmt_offset = gst_date_time_get_time_zone_offset (datetime);
+  if (gmt_offset == 0) {
+    g_string_append_c (s, 'Z');
+  } else {
+    guint tzhour, tzminute;
+
+    tzhour = (guint) ABS (gmt_offset);
+    tzminute = (guint) ((ABS (gmt_offset) - tzhour) * 60);
+
+    g_string_append_c (s, (gmt_offset >= 0) ? '+' : '-');
+    g_string_append_printf (s, "%02u%02u", tzhour, tzminute);
+  }
+
+done:
+
+  return g_string_free (s, FALSE);
+}
 
 /**
  * gst_date_time_to_iso8601_string:
@@ -687,30 +755,12 @@ gst_date_time_new (gfloat tzoffset, gint year, gint month, gint day, gint hour,
 gchar *
 gst_date_time_to_iso8601_string (GstDateTime * datetime)
 {
-  gfloat gmt_offset;
+  g_return_val_if_fail (datetime != NULL, NULL);
 
-  switch (datetime->fields) {
+  if (datetime->fields == GST_DATE_TIME_FIELDS_INVALID)
-    case GST_DATE_TIME_FIELDS_Y:
+    return NULL;
-      return g_date_time_format (datetime->datetime, "%Y");
+
-    case GST_DATE_TIME_FIELDS_YM:
+  return __gst_date_time_serialize (datetime, FALSE);
-      return g_date_time_format (datetime->datetime, "%Y-%m");
-    case GST_DATE_TIME_FIELDS_YMD:
-      return g_date_time_format (datetime->datetime, "%F");
-    case GST_DATE_TIME_FIELDS_YMD_HM:
-      gmt_offset = gst_date_time_get_time_zone_offset (datetime);
-      if (gmt_offset == 0)
-        return g_date_time_format (datetime->datetime, "%FT%RZ");
-      else
-        return g_date_time_format (datetime->datetime, "%FT%R%z");
-    case GST_DATE_TIME_FIELDS_YMD_HMS:
-      gmt_offset = gst_date_time_get_time_zone_offset (datetime);
-      if (gmt_offset == 0)
-        return g_date_time_format (datetime->datetime, "%FT%TZ");
-      else
-        return g_date_time_format (datetime->datetime, "%FT%T%z");
-    default:
-      return NULL;
-  }
 }
 
 /**