GCS_MAVLink: a send_text method on the GCS singleton

libraries/GCS_MAVLink/GCS.cpp

@@ -0,0 +1,17 @@
+#include "GCS.h"
+
+extern const AP_HAL::HAL& hal;
+
+/*
+  send a text message to all GCS
+ */
+void GCS::send_text(MAV_SEVERITY severity, const char *fmt, ...)
+{
+    char text[MAVLINK_MSG_STATUSTEXT_FIELD_TEXT_LEN+1] {};
+    va_list arg_list;
+    va_start(arg_list, fmt);
+    hal.util->vsnprintf((char *)text, sizeof(text)-1, fmt, arg_list);
+    va_end(arg_list);
+    text[MAVLINK_MSG_STATUSTEXT_FIELD_TEXT_LEN] = 0;
+    send_statustext(severity, GCS_MAVLINK::active_channel_mask() | GCS_MAVLINK::streaming_channel_mask(), text);
+}

libraries/GCS_MAVLink/GCS.h

@@ -429,6 +429,7 @@ public:
         return _singleton;
     }
 
+    void send_text(MAV_SEVERITY severity, const char *fmt, ...);
     virtual void send_statustext(MAV_SEVERITY severity, uint8_t dest_bitmask, const char *text);
     void service_statustext(void);
     virtual GCS_MAVLINK &chan(const uint8_t ofs) = 0;