Camera: trigger_pic sends do-digicam-control to components

This (optionally) allows pictures triggered from ch7/ch8
switch to send a mavlink do-digicam-control message to
components

libraries/AP_Camera/AP_Camera.cpp

@@ -74,8 +74,9 @@ AP_Camera::relay_pic()
 }
 
 /// single entry point to take pictures
+///  set send_mavlink_msg to true to send DO_DIGICAM_CONTROL message to all components
 void
-AP_Camera::trigger_pic()
+AP_Camera::trigger_pic(bool send_mavlink_msg)
 {
     _image_index++;
     switch (_trigger_type)
@@ -87,6 +88,20 @@ AP_Camera::trigger_pic()
         relay_pic();                    // basic relay activation
         break;
     }
+
+    if (send_mavlink_msg) {
+        // create command long mavlink message
+        mavlink_command_long_t cmd_msg;
+        memset(&cmd_msg, 0, sizeof(cmd_msg));
+        cmd_msg.command = MAV_CMD_DO_DIGICAM_CONTROL;
+
+        // create message
+        mavlink_message_t msg;
+        mavlink_msg_command_long_encode(0, 0, &msg, &cmd_msg);
+
+        // forward to all components
+        GCS_MAVLINK::send_to_components(&msg);
+    }
 }
 
 /// de-activate the trigger after some delay, but without using a delay() function
@@ -150,7 +165,7 @@ AP_Camera::control_msg(mavlink_message_t* msg)
      */
     if (packet.shot)
     {
-        trigger_pic();
+        trigger_pic(false);
     }
 }
 

libraries/AP_Camera/AP_Camera.h

@@ -9,6 +9,7 @@
 #include <AP_Param.h>
 #include <AP_Common.h>
 #include <GCS_MAVLink.h>
+#include <GCS.h>
 #include <AP_Relay.h>
 #include <AP_GPS.h>
 #include <AP_AHRS.h>
@@ -39,7 +40,8 @@ public:
     }
 
     // single entry point to take pictures
-    void            trigger_pic();
+    //  set send_mavlink_msg to true to send DO_DIGICAM_CONTROL message to all components
+    void            trigger_pic(bool send_mavlink_msg);
 
     // de-activate the trigger after some delay, but without using a delay() function
     // should be called at 50hz from main program