OpenCPN PlugIn Development

[nohal]

Originally Posted by cryptik

I will probably need some pointers, at some point, on how to submit a plugin and/or a PR. I have not done that sort of thing before with git. I am somewhat still old school with SVN...lol

https://help.github.com/articles/cre...-pull-request/ (and https://git-scm.com/book/en/v2 if you want to stop suffering with SVN completely)

[Hakan]

Originally Posted by bcn

What might be handy is an interface to edit the voyage related data of the Class A AIS from OpenCPN.

Dirk linked this I never touch before. Thanks!

rooiedirk Re: OpenCPN PlugIn Development
https://github.com/RooieDirk/AIS_VD_pi/tree/master Quote:

After some minor local adjustment it builds fine on Win10 and nicely produce the VSD sentence to all open outgoing connections. See shot
Could be handy if you've a class A connected.
Håkan

[cryptik]

Trying to get the mouse geo coordinates after clicking on a context menu item. I have a context menu item that I added for my plugin. The scenario is that the user moves the mouse pointer to a location on the chart. They then right click the mouse and select the context menu item. I can trap the callback for the menu click (in OnContextMenuItemCallback()) ...but then I want to get the lat and lon of where the mouse pointer is at the time of the menu click. I am not sure how to do that. I am able to get lat lon using SetCursorLatLon() callback, but is there a call to OCPN that I can make from inside OnContextMenuItemCallback() that will return the cursor Lat and Lon? I have looked through the OCPN plugin API header, but I did not see anything.

thx
Ken

[nohal]

Originally Posted by cryptik

Trying to get the mouse geo coordinates after clicking on a context menu item. I have a context menu item that I added for my plugin. The scenario is that the user moves the mouse pointer to a location on the chart. They then right click the mouse and select the context menu item. I can trap the callback for the menu click (in OnContextMenuItemCallback()) ...but then I want to get the lat and lon of where the mouse pointer is at the time of the menu click. I am not sure how to do that. I am able to get lat lon using SetCursorLatLon() callback, but is there a call to OCPN that I can make from inside OnContextMenuItemCallback() that will return the cursor Lat and Lon? I have looked through the OCPN plugin API header, but I did not see anything.

thx
Ken

Why would you do this? You already do know where the cursor was before the context menu was invoked (as in for example https://github.com/OpenCPN/OpenCPN/b...ib_pi.cpp#L536 and https://github.com/OpenCPN/OpenCPN/b...ib_pi.cpp#L542).

[cryptik]

LOL, thank you for redirecting me on that. I was actually doing that, and did not understand why it was not working. I went back and looked at my code and found a bug in my implementation of the SetCursorLatLon() callback. Its working now. Thanks man.

[cryptik]

I do have two other questions. Where does OCPN store the configuration settings? I was trying to look at the file where OCPN actually stores it's (and the plugin) settings and I can't seem to locate it. The second question is, I have a data file that I store information in relative to the plugin. The data is user specific. The problem I have is that on Windows 10, I can't write to the plugin data folder when OCPN is running as a user. I can manually add users to the plugin data folder. Is there a way to have the installer set the proper permissions on this folder? Or is there another way to write to this folder that does not have the user permissions problem. OCPN seems to be able to write to its log file...and I am not sure how that happens.

[nohal]

Originally Posted by cryptik

I do have two other questions. Where does OCPN store the configuration settings? I was trying to look at the file where OCPN actually stores it's (and the plugin) settings and I can't seem to locate it.

What can't you locate? The file or your saved settings in it? If the former, click on the "?" icon, if the later, make sure the config file was already saved (Close OpenCPN to be 100% sure)

The second question is, I have a data file that I store information in relative to the plugin. The data is user specific. The problem I have is that on Windows 10, I can't write to the plugin data folder when OCPN is running as a user. I can manually add users to the plugin data folder. Is there a way to have the installer set the proper permissions on this folder? Or is there another way to write to this folder that does not have the user permissions problem. OCPN seems to be able to write to its log file...and I am not sure how that happens.

Store it like all the others, in the correct user data location, on all platforms: https://github.com/nohal/objsearch_p...rch_pi.cpp#L93

[cryptik]

ah... your a lifesaver nohal. I could not find the file, but this works great. Also, thanks for the location to store my other file. I was using another calling setup to get the data folder.

wxFileName dFN;
dFN.SetPath(*GetpSharedDataLocation());
dFN.AppendDir(_T("plugins"));
dFN.AppendDir(_T("myPlugin_pi"));
dFN.AppendDir(_T("data"));

The folder above is not writable by default. I will follow the code examples you provided. Perfect. Thanks a million.

[cryptik]

Looking at my code, I may be doing this wrong as well. I use the SetPluginMessage() to build an internal AIS target list by parsing the message_id and message_body parameters looking for message_id = AIS. I then build up an internal array with target objects.

I do this because I don't seem to get any calls to SetAISSentence() even with WANTS_AIS_SENTENCES set in the capability statement.

Looking at the AIS radar display plugin, there are calls to get such an array directly from OCPN...GetAISTargetArray()...which I just discovered by looking at the AIS radar display code. The advantage of using this call as opposed to creating my own array is that when targets age out, they are removed from the OCPN array.

My question is that the AIS radar plugin uses the SetAISSentence() event to update its view of the AIS targets. The plugin seems to work well... so I am wondering why I do not get any callbacks to this method? Perhaps this callback is not really necessary or am I missing something else?

Thx,
Ken

[nohal]

Fixed in https://github.com/OpenCPN/OpenCPN/c...fd4dfdeccbe21e. I'm not sure we don't want to remove this from the API completely and keep just WANTS_NMEA_SENTENCES & SetNMEASentence() though.

[cryptik]

Okay, no worries. I think it makes sense to remove it from the API. I currently use the SetNMEASentence() and parse the VDM statements... and that seems to work.

[nohal]

I of course don't know what you are doing, but would probably consume the AIS JSON messages instead myself.

[nohal]

You get them with WANTS_PLUGIN_MESSAGING / SetPluginMessage
and they look like

AIS : {
   "Msg" : "AIS Target",
   "class" : 0,
   "mmsi" : 366970020,
   "callsign" : "       ",
   "sog" : 11.8,
   "lon" : -122.390815,
   "Source" : "AIS_Decoder",
   "MsgId" : -568852698,
   "active" : true,
   "lat" : 37.80016167,
   "cog" : 147,
   "ownship" : false,
   "lost" : false,
   "Type" : "Information",
   "shipname" : "Unknown             ",
   "hdg" : 144
}

[cryptik]

Yes, that is what I am doing now... parsing the JSON as you mention... from inside the SetPluginMessage(). What I am doing is building a target array with those JSON messages and then looking through the list to find a user specified MMSI. The plugin lets you then send a ABM message to that MMSI. As part of the GUI, it paints a circle around that target that moves with the target. I basically update my target list in SetPluginMessage() and use it in the Render() call to draw the circle.

The problem I have is that doing it that way, when the target ages out and disappears from the OCPN target list, I can't figure out how to get notification of that. So I was thinking that maybe I should use the GetAISTargetArray() call instead. What happens now is that when the target drops off the map...my circle graphic is still being painted at the last known position...since it is still in my plugin target array. Do you know of another event that I could consume that would tell me a target has dropped from the list?

[nohal]

You may simply let them time out as well in case you don't receive a message with the MMSI for X amount of time (OpenCPN can be set not to remove lost targets at all, which is probably not exactly always viable if you are implementing live communication methods with them)
To realise that the target is being considered lost by the core program, check if the message with lost set to true (https://github.com/OpenCPN/OpenCPN/c...8bee195488689f)