OpenCpn Install on Android Tablets Easier Now.

[Wrong]

Instructions have been updated to warn anyone with android version 4.3 and later, and especially Lollipop, that a linux security scheme called selinux is probably enabled. This means you have two choices if you want to use OpenCPN on your android per my instructions. 1.) purchase a device with an android O.S. older than 4.3 or 2.) install a custom ROM with selinux disabled by default.

When Linux Deploy and VNC applications are changed so they can function properly in a selinux enforced operating environment I'll let you know. Until then...

[Neddy]

Originally Posted by sinbad7

Armido..

Like me,hundreds of sailors have spent years downloading and using a great variety of navigation utilities plus untold other useful applications with and without internet access on their laptops. Mine has a capacity of 500 GB. My Galaxy 10.1 Tablet has a mere 14 GB.

As I will continue bringing my laptop on board,I will conserve space on my tablet for the great number of FREE apps,using my laptop for heavy data such as all my world-wide nautical charts,videos and music.

My tablet can now be used to totally access and control OpenCPN and all other Windows based programs on my laptop,PLUS all the hundreds of free or low cost Android based apps. All you need on board is a local wi-fi or a LAN network.

On fine days at sea you can let the autopilot take command whilst sitting,leaning against the mast with the tablet in you lap,enjoying your navigation!!

But,if you prefer hitting yourself in the head with a hammer,be my guest!

Fair winds!


Tore

Problem is lots of us sail in the sea and could try without wifi, still lots of them around.

[Wrong]

Originally Posted by Neddy

Problem is lots of us sail in the sea and could try without wifi, still lots of them around.

Tor was a very early poster in this thread who couldn't quite grasp the impracticality of maintaining a wifi setup onboard, offshore in order to connect a tablet to a laptop in order to use OpenCPN via TeamViewer, a VNC server/client application.

Fortunately, he may have finally realized his posts were out of place here. Irrelevant.

We've overcome the early obstacles to using OpenCPN on android tablets in a linux chroot environment, the most significant being how to use built-in, bluetooth, wireless and usb GPS devices.

Most problems now have to do with the evolution of the android O.S., such as the implementation of enabled selinux. The other, being addressed by Dave (bdbcat) is adapting OpenCPN for use on high resolution displays.

Otherwise, OpenCPN is very usable on android devices running linux in a chroot environment.

[Marqus]

I'm partial to the low energy usage of my Android tablet compared to a laptop pc, and that's why I'm installing OpenCPN on the tablet.

Just a note for the benefit of anyone else setting up to run OpenCPN via the Linux Deploy chroot as documented by Wrong: I had a problem with my VNC client not communicating with the Linux host due to Android's SELinux security feature.

I disabled SElinux by setting it to "Permissive" mode, but the problems persisted for me (can't explain that one).

So I tried to circumvent them by installing a ROM that pre-dates the inclusion of SElinux.

Now my VNC client works, and I am accessing OpenCPN on Linux's Xfce desktop. I'm yet to load the chart data.

[RhythmDoctor]

Originally Posted by Marqus

...I disabled SElinux by setting it to "Permissive" mode, but the problems persisted for me (can't explain that one).

So I tried to circumvent them by installing a ROM that pre-dates the inclusion of SElinux.

Now my VNC client works, and I am accessing OpenCPN on Linux's Xfce desktop. I'm yet to load the chart data.

Using a legacy ROM might be fine if your Android tablet is dedicated for use with OpenCPN. But if the tablet is used for other things too, don't you run the risk of newer apps not working because they need a more up to date version of the OS?

[Wrong]

Originally Posted by RhythmDoctor

Using a legacy ROM might be fine if your Android tablet is dedicated for use with OpenCPN. But if the tablet is used for other things too, don't you run the risk of newer apps not working because they need a more up to date version of the OS?

As Marqus stated, his sole interest is using his device for OpenCPN.

And no, worries about 'newer apps' not working with a ROM that pre-dates Lollipop in which selinux is enabled is not a concern. You can hardly refer to a version of android that was the last available before selinux was enabled beginning with 4.3 as a 'legacy' ROM.

Of the thousands of android apps available from Google Play, how many are not going to be backward compatible? Developers adapt their apps to work with newer ROMS, but in so doing do not render them incompatible with preceding ROMS. Show me one that does...

Marqus,

Thanks for demonstrating with a bit of extra effort you can resolve the selinux issue and have OpenCPN running in a chroot environment on your android.

If you don't mind please post details of how you did it. This will be useful to others.

[Wrong]

Originally Posted by RhythmDoctor

Using a legacy ROM might be fine if your Android tablet is dedicated for use with OpenCPN. But if the tablet is used for other things too, don't you run the risk of newer apps not working because they need a more up to date version of the OS?

I want to add that a huge advantage of linux and linux programs over 'proprietary' operating systems like Windows and the Apple O.S. is backward compatibility. As long as you own the same architecture type over time, beginning with a 4.77 Mhz 8088 through an i386 chip the same programs will work accross the board. Moving to an i586 architecture requires the programs you were accustomed to using on older i386 chips be compiled for the i586 platform and cannot be used on an i386. But, the program is functionally the same you used on the older platform.

In this respect the android O.S. and applications are no different from a purely linux O.S.. An android O.S. and linux kernel must be compatible with the unique hardware and chipsets that vary between manufacturers; and android apps must sometimes be recoded when major changes in hardware capabilities occur, such as high resolution displays. But this change only adds to and in no way detracts from our ability to use the app on lower resolution devices.

On proprietary systems like Windows and Apple a newly introduced O.S. may require you to buy new applications because your old applications are incompatible.

[Wrong]

Just released OpenCPN Version 4.1.602 Beta compiles and installs in Ubuntu Precise. Instructions are here: Building on Motorola Xoom | Official OpenCPN Homepage

Warning: Stock android versions beginning with 4.3 have a security feature called selinux enabled by default! If you have android 4.3 and newer versions you will most likely not be able to use OpenCPN in a linux chroot environment on your android. Read posts preceding this one for more information.

It is possible however the recently announced 'android M' may provide a feature allowing greater user control over installed android apps. Whether or not this will apply to selinux remains to be seen. The ideal situation will be one where rooting your device is no longer necessary. But, I wouldn't expect as much...

[Marqus]

Just to recap my experience - my stock Android v5 ROM stopped my VNC client from working, giving an selinux error message.

In theory, you should be able to use a Terminal app on the Android host and use the commands GetEnforce and SetEnforce to change the selinux mode to "permissive", after which selinux should not block anything. I recommend you try those commands and see whether they solve any selinux problem you may experience.

In my case (Nexus 7 tablet) the SetEnforce command did not do the trick, so I reverted to a Android v4 Rom called SlimRom (minimal bloat) and it solved the problem.

On my 7-inch 1208 x 800 pixel touch tablet, the OpenCPN menus appear a bit tiny - is there an OpenCPN option to enlarge the menu text independent of the chart zoom level?

[RhythmDoctor]

Originally Posted by Marqus

On my 7-inch 1208 x 800 pixel touch tablet, the OpenCPN menus appear a bit tiny - is there an OpenCPN option to enlarge the menu text independent of the chart zoom level?

Go into User Interface and check "Enable Tablet Scaled Graphics Interface." That should enlarge the buttons to 9 mm, and may also enlarge the text.

If that doesn't work, go into Display-Advanced and manually enter the Physical Screen Width. OpenCPN will calculate the correct pixel size from this.

If that still doesn't work, go back to User Interface. Under "Fonts" you can manually choose the font and size for multiple text items, including menus.

[Wrong]

Originally Posted by Marqus

Just to recap my experience - my stock Android v5 ROM stopped my VNC client from working, giving an selinux error message.

In theory, you should be able to use a Terminal app on the Android host and use the commands GetEnforce and SetEnforce to change the selinux mode to "permissive", after which selinux should not block anything. I recommend you try those commands and see whether they solve any selinux problem you may experience.

In my case (Nexus 7 tablet) the SetEnforce command did not do the trick, so I reverted to a Android v4 Rom called SlimRom (minimal bloat) and it solved the problem.

On my 7-inch 1208 x 800 pixel touch tablet, the OpenCPN menus appear a bit tiny - is there an OpenCPN option to enlarge the menu text independent of the chart zoom level?

Marqus,

Thanks for following up. In linux on a PC or laptop there are commands used specifically to set exceptions allowing applications to perform actions normally prohibited by selinux. Even when selinux is 'enforcing'. But, it's necessary to know exactly what's being prevented from happening... Aside from running 'dmesg' that may or may not record a selinux event, I don't know how it's done in android. It's still pretty early in the selinux game on android to expect an app to be available to assist in dealing with selinux, but possibly in the not too distant future.

The 'tiny' issue on smaller android devices than 10" is why I recommend 10" devices.

Hope your experience once your charts are loaded is a positive one.

RythmDoctor,

Thanks for offering your suggestions to Marqus as to how he may be able to address the 'tiny' issue. Everyone who has or will lend support to others using the chroot approach to using OpenCPN on androids is appreciated for making the effort.

[Peter McNamara]

Originally Posted by sinbad7

Armido..

Like me,hundreds of sailors have spent years downloading and using a great variety of navigation utilities plus untold other useful applications with and without internet access on their laptops. Mine has a capacity of 500 GB. My Galaxy 10.1 Tablet has a mere 14 GB.

As I will continue bringing my laptop on board,I will conserve space on my tablet for the great number of FREE apps,using my laptop for heavy data such as all my world-wide nautical charts,videos and music.

My tablet can now be used to totally access and control OpenCPN and all other Windows based programs on my laptop,PLUS all the hundreds of free or low cost Android based apps. All you need on board is a local wi-fi or a LAN network.

On fine days at sea you can let the autopilot take command whilst sitting,leaning against the mast with the tablet in you lap,enjoying your navigation!!

But,if you prefer hitting yourself in the head with a hammer,be my guest!

Fair winds!


Tore

Hi Sinbad7


I am a relative newcomer to this OpenCPN forum but an IT professional with relatively out of date technical skills. The prospect of "rooting" my new Lenovo Android tablet and dealing with all the challenges others have faced in my reading on this forum and other BLOGs suggests the task of installing Open CPN on the Android platform is not trivial. So the solution you have suggested to remotely control my Windows Notebook which runs OpenCPN happily with all the required IO drivers to access my hardwired Garmin GPS and AIS receiver is attractive. I tried your suggestion today to use TeamViewer for the purpose viewing OpenCPN on the tablet. My investigations suggest an internet connection is at least initially required to enable connection of the client to the remote desktop. Is there something I am missing can this solution be used at sea where nothing more than the WiFi LAN is available?


Cheers


Peter McNamara

[petter5]

Hi !

Remote controlling without internet connection will work just fine, but you will need both devices to be on the same network/subnet. Normally Ip adresses on the same subnet is assigned by a router's dhcp server who also normally is your internet gateway/connection. If no DHCP server is present you will have to assign static IP address. A DHCP server normally assigns adresses for example in the range 192.168.1.100 - 192.168.1.200 If you assign a static IP outside the range of your DHCP server wich in this example means in the range 192.168.1.2 - 192.168.1.99 or 192.168.1.201 - 192.168.1.254 then you will not have to change anything if you turn off your router or is outside internet connection. Please first enshure in what ip range your router is configuerd to and renember that if you move to another location than your boat where you want to connect to another network, a static ip setting might cause ip conflicts or will prevent you from obtaining a IP adress from that networks router, so you must then change back to DHCP mode.

[Peter McNamara]

Originally Posted by petter5

Hi !

Remote controlling without internet connection will work just fine, but you will need both devices to be on the same network/subnet. Normally Ip adresses on the same subnet is assigned by a router's dhcp server who also normally is your internet gateway/connection. If no DHCP server is present you will have to assign static IP address. A DHCP server normally assigns adresses for example in the range 192.168.1.100 - 192.168.1.200 If you assign a static IP outside the range of your DHCP server wich in this example means in the range 192.168.1.2 - 192.168.1.99 or 192.168.1.201 - 192.168.1.254 then you will not have to change anything if you turn off your router or is outside internet connection. Please first enshure in what ip range your router is configuerd to and renember that if you move to another location than your boat where you want to connect to another network, a static ip setting might cause ip conflicts or will prevent you from obtaining a IP adress from that networks router, so you must then change back to DHCP mode.

Thanks for the effort to reply. I have setup my Notebook under Windows as a WiFi hotspot. The operating system provides the DHPC service. Other devices such as my Android phone and tablet acquire an IP address lease when they connect to the LAN. My comments suggest the TeamViewer application appears to require an Internet connection (presumably to an ID sever) to make the initial connection. Obviously this would not be possible at sea. Perhaps there is an alternative to this application that offers he same functionality without this requirement? Otherwise I must persevere with install of OpenCPN under Android and recognition of the tablet's built-in GPS.

[Wrong]

Originally Posted by Peter McNamara

Thanks for the effort to reply. I have setup my Notebook under Windows as a WiFi hotspot. The operating system provides the DHPC service. Other devices such as my Android phone and tablet acquire an IP address lease when they connect to the LAN. My comments suggest the TeamViewer application appears to require an Internet connection (presumably to an ID sever) to make the initial connection. Obviously this would not be possible at sea. Perhaps there is an alternative to this application that offers he same functionality without this requirement? Otherwise I must persevere with install of OpenCPN under Android and recognition of the tablet's built-in GPS.

In case you have not noticed, development of an android version of OpenCPN (OpenCPN.apk) is underway and downloadable from https://www.dropbox.com/s/rmvwpqzg0c...1.530.apk?dl=0 It's still got some bugs but will possibly be in a beta version in the not too distant future. I do not know how much will be charged, but it will be non-free from Google Play.

Using my method to run OpenCPN in a linux chroot environment offers the possibility to use freely available linux programs in addition to OpenCPN. ZyGrib, the grib downloader and viewer is only one of many such programs. While most people don't need a CADD program, I have one installed in my linux setup.

Teamviewer is impractical for the reason you cite, and having to run an energy intensive laptop - not to mention a network router - just to view OpenCPN on your android tablet makes little sense. Especially if you are a frugal sailor...

Choose the method that best suites your comfort level and needs.

Provided you have a tablet with an android operating system earlier than 4.3, or are willing to install a custom ROM without 'selinux' enabled, there's no reason a reasonably intelligent person cannot succeed in following my 'copy and paste' instructions here: Building on Motorola Xoom | Official OpenCPN Homepage