Enhancement: SHOW or HIDE NMEA Debug and AIS Target List Windows

[antipole2]

This started as issue #119

@plfinch writes:
Create ability to show or hide/close the OpenCPN NMEA Debug and AIS Target List windows from the javascript plugin. There may also be other OpenCPN windows I am not familiar with yet or in the future that this would be useful for so I propose a generic solution rather than new functions for each such window.

OCPNwindowShow(windowName)
OCPNwindowHide(windowName)

Where windowName is the string "NMEA Debug" or "AIS Target List".

I want to be able to programmatically from javascript open and close these windows as needed.

[antipole2]

Please explain more about why you need this or what you are wanting to achieve.

[antipole2]

@plfinch replied:

I have a land-based AIS monitoring and reporting station and use OpenCPN for viewing the nearby vessels reporting AIS data.

On boot or restart of OpenCPN I want to automatically display the NMEA Debug and AIS Targets windows to verify proper operation and then close the windows after 5 minutes.

Anytime AIS data is not received for 2 minutes I want the NMEA Debug window to open until resolved.

Anytime a new vessel is acquired I want the AIS Targets window to display for 20 seconds.

I already have the javascript plugin installed and use it for various housekeeping tasks as well as highlighting new vessels.

[antipole2]

@plfinch... I am reluctant to provide the extensions you have requested as they seem specific to you and I want to avoid plugin bloat.
I think you can achieve what you want in other ways.
Below I offer a script which demonstrates various capabilities. You could use it 'as is' or adopt as suits you.

Firstly, the script sets up a time-delayed call to function noAIS after lostLimit seconds which will raise an alert and sound an alarm.
However, function gotAIS is invoked every time AIS data is received over NMEA0183 and this function resets the timer. So the alert will only be raised if the source of AIS data fails.

Secondly, every sampleInterval seconds, function sampleAIS is invoked. This collects the array of targets and looks for MMSI numbers not in the previous sample. It raises an alert identifying any new ones. It then looks for any in the previous sample but not in the new sample. It raises an alert for these lost targets. These alerts are automatically dismissed after announceDuration seconds.

I do not have a source of AIS data here at home. So I have not been able to test the script - that's for you.

For your information, a forthcoming version of OpenCPN is to have a new arrangement for raising alerts and this may be useful to you. But the methods used in this sample script will still work.

const lostLimit = 10;		// time in seconds before alerting to lost AIS
const sampleInterval = 10;	// interval in seconds to sample AIS data
const announceDuration = 10;	// time in seconds to display announcements

var previousTargets = [];		// array of previous AIS targets

OCPNonAllAIS(gotAIS);			// listen for AIS data
lostTimer = onSeconds(noAIS, lostLimit);		// start checking received
alertTimer = onSeconds(clear, 0);	//  this to initialise alertTimer
onAllSeconds(sampleAIS, sampleInterval);

function gotAIS(data){			// got AIS data
	onSeconds(lostTimer);		// cancel old timer
	onSeconds(noAIS, lostLimit);	// start timer again
	}

function noAIS(){
	onSeconds();				// cancel all timers
	alert("No AIS data seen");
	OCPNsoundAlarm();
	}

function sampleAIS(){	// alert to any new or lost targets
	currentTargets = OCPNgetAISTargets();
	for (var t = 0; t < currentTargets.length; t++){
		mmsi = currentTargets[t].MMSI;
		if (!targetInList(mmsi, previousTargets)){
			announce("New  MMSI " + mmsi + " " + currentTargets[t].shipName, announceDuration);
			}
		}
	for (var t = 0; t < previousTargets.length; t++){
		mmsi = previousTargets[t].MMSI;
		if (!targetInList(mmsi, currentTargets)){
			announce("Lost MMSI " + mmsi + " " + currentTargets[t].shipName, announceDuration);
			}
		}
	previousTargets = currentTargets;
	}

function targetInList(mmsi, list){	// returns true if mmsi in target list
	for (var i = 0; i < list.length; i++) if (mmsi == list[i].MMSI) return true;
	return false;
	}

function announce(text, duration){
	alert(text + "\n");
	onSeconds(alertTimer);
	alertTimer = onSeconds(clear, duration);
	}

function clear(){
	onSeconds(alertTimer);
	alert(false);
	}

[plfinch]

Thanks for taking the time to reply, Tony. I have actually developed a quite sophisticated javascript to maintain my own AIS table, track vessels, alert on new vessels detected, alert on NMEA AIS stream loss, alert on vessel beyond range (anything over 20 miles indicates atmospheric or tropospheric ducting, an interesting phenomenon with my current AIS ship distance record at 253 miles), send me a text messages when NMEA stream is down, etc. I keep the OpenCPN screen up on my TV when not watching or streaming anything as it is fun to watch the arrival, departure, and transit of ships and tugs.I do understand your desire to not bloat the API although I do feel the feature I am asking for, simply show or hide any of the UI menu accessible windows, does have general usefulness beyond myself for those customizing OpenCPN. I looked through the C++ API but, at first glance, did not find any menu/submenu navigation functions or I would have just switched all my stuff to a custom C++ plugin. Of course, that also means adding that feature to the Javascript API may be non-trivial. Cheers,Peter