subsurface/Documentation/mobile-manual-v3.txt

// Subsurface-mobile User Manual
// =============================
// :author: Manual authors: Willem Ferguson, Dirk Hohndel
// :revnumber: 3.1.3
// :revdate: February 2021
:icons:
:toc:
:toc-placement: manual
:numbered:
// :website: http://subsurface-divelog.org

image::mobile-images/Banner.jpg["Banner",align="center"]

[big]#_Subsurface-mobile_ User Manual#

*Manual authors*: Willem Ferguson, Dirk Hohndel

// toc::[]

[blue]#_Version 3.2, March 2021_#

toc::[]

Welcome to _Subsurface-mobile_, the mobile version of _Subsurface_, advanced dive logging
software with extensive infrastructure to display, organize, and interpret scuba
and free dives. _Subsurface_ runs on Windows, macOS, most common distributions of Linux.
_Subsurface-mobile_ is available for Android and iOS. Both are
open-source software (in simple terms that means that there is no commercial interest behind
them, all the source code needed to build them is available, there are no ads, no one is
monetizing your data, etc).

_Subsurface-mobile_ is a limited mobile version of the desktop software _Subsurface_,
aimed at Android and iOS smartphone and tablet devices.
While the desktop version of _Subsurface_ shows much more detailed information
for each dive, the mobile version allows a more accessible dive log on the go. For example,
you can prove dive experience on a dive trip to dive shops or review
previous dives while on a dive boat. _Subsurface-mobile_ also allows
the gathering of GPS locations where dives are performed.
Assuming you have a dive computer that is supported by the mobile OS of
your choice, _Subsurface-mobile_ supports the downloading of dives from your dive computer.

Users of _Subsurface-mobile_ often use the
mobile app together with the desktop version of _Subsurface_,  sharing dive information
between the mobile and the desktop versions using a free _Subsurface Cloud_ account.
However _Subsurface-mobile_ is a fully fledged application in its own right that can
also be used independently of the desktop version with or without the use of cloud storage.
_Subsurface-mobile_ allows:

- Download and storage of dive log information using the _Subsurface_ cloud.
- Viewing this information on a mobile device.
- Manually creating and adding new dive records to your dive log.
- Download dive data directly from some dive computers.
- Editing most of the dive log data, e.g. dive-master, buddy,
  equipment or notes relating to a dive.
- Recording, storing and applying GPS positions to dive information.
- Viewing the localities of recorded GPS positions and of dives
  on a map.

These items are discussed in greater detail below.

_Subsurface-mobile_ has some limitations compared to _Subsurface_:

- Only a subset of the dive computers supported for download by the desktop
version work with _Subsurface-mobile_, this being determined
by hardware and OS limitations in the
two mobile platforms. On Android, a subset of
dive computers that use USB serial cables or a Bluetooth / Bluetooth LE interface
are accessible. On iOS, only Bluetooth LE based
dive computers are supported.
- No dive planner.
- No printing.
- No support for media embedded in dive profiles (_Subsurface_ allows access to
  images and video clips directly from the dive profile).

== Installing _Subsurface-mobile_ on your mobile device

Find _Subsurface-mobile_ in the _Google Play Store_ or the _Apple App Store_
and install it. For Android devices without access to the _Google Play Store_,
APKs can be found in the downloads folder on the _Subsurface_ website.

== Getting Support

The best place to get support is the https://subsurface-divelog.org/user-forum[_Subsurface_ User Forum]. Additionally, _Subsurface-mobile_ allows
you to send a support request by tapping on _Ask for support_ in the _Help_ menu. This will open an
email to our in-app-support address in the native email client, including the relevant logs.

== User Interface

_Subsurface-mobile_ uses the same user interface philosophy on both Android and iOS, based on an
open source project called _Kirigami_, maintained by the _KDE/Plasma_ development community.
It has a slightly different look and feel than many native Android and iOS apps,
but we find it easy and intuitive to work with.

You have access to the _Main menu_ through a _Hamburger_ button (three short
horizontal lines) in the lower left corner of the screen. Additionally, the _Main menu_ can be opened by swiping
towards the right from the very left edge of the screen.
In addition, many screens have a _Context menu_ available through a button with three vertical dots in
the lower right corner and that can be opened by tapping and holding a dive or trip header in the dive list.

image::mobile-images/ActionButton2.jpg["FIGURE: Action Button",float="left"]
At the bottom of many _Subsurface-mobile_ screens is a round
_Action button_ that provides quick access to the most commonly needed
actions on that screen (see image on the left). Some screens have only
the round central button, others have one or two additional
actions on either side of the central button.

unfloat::[]

On Android devices, use the Android Back
button for "cancel", "discard" or "back" actions. For example, when
editing dive information, tapping the action button saves the changes while the
Android back button can be used to cancel the edit without saving changes.

The image below indicates some of the important features of the menu system.
On the left is the main menu, activated as described above. On the right of the image
are the sub-menus.

image::mobile-images/Subsurface-mobile-menu-system.jpg["FIGURE: Subsurface-mobile menu system",align="center"]


All screenshots in this user manual are currently from the Android
version. The iOS screens look similar.

== Using _Subsurface-mobile_ for the first time

When you start _Subsurface-mobile_ for the first time, a _Subsurface_
splash screen is shown while the program loads. On some devices this
may take several seconds. Afterwards the _Cloud Credentials screen_ appears
(see left image below).

image::mobile-images/Credentials.jpg["FIGURE: Mobile credentials screen",align="center"]

=== Using _Subsurface-mobile_ without Cloud Storage
Tap the "No cloud mode" button. The app will only store dive log information locally
on your device. Following installation an empty dive log is created.

=== Using Cloud Storage
The _Subsurface_ maintainer provides a dedicated and
free Internet cloud storage account for users of _Subsurface_ and _Subsurface-mobile_.
You can use this to store your dive log and to share your data between several computers
and devices. The _Subsurface_ team never accesses your dive data without explicit
permission to do so, the data are not used for any other purpose than providing them to the user who
created them. There are no ads and no harvesting / analysis of the data / monetization of data
on the _Subsurface Cloud_ storage.

_Subsurface-mobile_ is sufficient to fully maintain a dive log. In addition you can use the
more advanced features in _Subsurface_ when you have access to a computer while still
being able to work with your dive data when only a mobile device is available.

The dive data in the cloud are cached locally on any device or computer that is connected to
the _Subsurface Cloud_ account.
It is easy to create backups of the data (for example in XML format) on the desktop: both the mobile
device and the desktop keep a local copy of the data so that the dive log is always accessible, even
without an Internet connection.

To create a _Subsurface Cloud_ account follow these steps:

1) Enter an e-mail address and a password in the fields indicated on the screen (see image above).
The e-mail address should be in lower case and the password should contain a combination of
upper and lower case letters and/or numbers.

2) Tap the "Sign-in or Register" button.

If you have already set
up an account on a different computer or device, simply enter the same credentials here.
_Subsurface-mobile_ will now download your existing dive log data. Once the dive
list has been downloaded from the cloud, _Subsurface-mobile_ usually works only with the the local
copy on the mobile device. This avoids long delays or even failure of operations if there is poor
internet connectivity. Remember to manually sync
with the server after making local changes (either by pulling down on the dive list, or by using the
manual sync entry in the Dive management menu entry).

3) If this is a new cloud account, a PIN screen will open (see right image above). A PIN is e-mailed
to the email address entered in the previous step. Enter this PIN into the field indicated
and tap the _Register_ button. After the PIN has been entered it
is no longer needed - it just proves that this is indeed your email account.

A https://www.youtube.com/watch?v=Vp_bEm5ZDRA[*video-tutorial*] is available that demonstrates
how to connect to the cloud.

At this point a new account has been created for you on the cloud server and access to the cloud is
enabled. In this case the dive list is initially empty. Start entering dives in the dive
log or download dive information from a supported dive computer.

Once registered, _Subsurface-mobile_ remembers the cloud credentials and it is not necessary to
provide these again when launching the program.

****
[icon="images/icons/important.png"]
[IMPORTANT]
*Cloud problems: FAQ*

[blue]#After filling in the correct information and submitting it, I did not receive a PIN by email#

1. Check *carefully* for spelling mistakes in the email address you provided. This is a common problem since autocorrect often mangles email addresses.
2. Check that the return email containing the PIN is not in the SPAM/Junk folder of your email client.
3. Wait for a few hours and check again for an email with a PIN.
4. If there is still no email containing a PIN, send mail to in-app-support@subsurface-divelog.org

[blue]#I want to access the _Subsurface Cloud_ storage but I have forgotten my password. How can I reset my password?#

The _Help menu_ has an option _Reset forgotten Subsurface Cloud password_. Use that or go to the https://cloud.subsurface-divelog.org/passwordreset[password reset website]

Simply enter the same email address that you used during cloud registration and follow the indicated steps.
To prevent abuse of this system a confirmation email will be sent to your account.

****

The dive log can be updated automatically. If there is Internet connectivity, _Subsurface-mobile_ accesses
the cloud-based dive log to verify that the local copy of the dive log is still the
same as the log in the cloud server. If not, the local copy and the copy on
the server are synchronized.

== The Dive List

The _Dive List_ is the heart of _Subsurface-mobile_ because most of the actions
center around the dives on the dive list. While the dive list is loading from the cloud,
a message appears at the bottom of the screen, indicating that the cloud is
being accessed, after which the dive list is shown. Once the list is loaded you can scroll up
and down through your dive history.

The Dive List consists of two types of entries:

1. *Trip headers*. A trip header is a line describing the year and month during which a dive trip 
took place, as well as the geographical area of the trip. The second line in the lefthand image below indicates that a 10-dive trip
was made to Guinjata, Moçambique during December 2016. 

2. *Individual dive records*. Tapping a trip header expands the dive list to show (or hide) the individual dives performed during the trip. Each dive is represented by a dive record. By default the dives during the last trip are listed with older dives at the bottom and recent dives at the top of the list. In the lefthand image below the last dive during
the Guinjata trip was in the Inhambane Estuary.

image::mobile-images/Divelist2.jpg["FIGURE: Dive list screen",align="center"]


[[S_View_Dive]]
=== View a dive: the Details view

When you tap on a dive in the _Dive List_, a _Dive Details_ page with the dive profile
and many important details about the dive is opened (image on right above). You can use a pinch gesture
to zoom into the profile. Tapping and holding with one finger (until
the profile becomes translucent) allows you
to pan the profile and see more details in specific parts of the profile.

You can view other dives by swiping the _Details view_ to the right (for the
previous dive) or to the left (next dive).
Using the Action Bar, it is also possible to delete the dive (tap the Trash Icon
on the Action Bar) or to view the dive location on an integrated map viewer.

The context menu (accessible by tapping on the vertical three dots in the lower right corner of the
screen) offers additional options to move dives between trips, the same delete and map options
already mentioned, and access to the undo and redo facility that allows you to step backwards and
forwards through recent changes.

=== Viewing the location of a dive on a map

image::mobile-images/DiveSiteMap.jpg["FIGURE: Map of dive site",align="center"]
In the _Details View_, you can either tap the name of a dive site
or the GPS pin on the
left hand side of the _Action Button_ at the bottom of the screen in order
to open a map with the dive site in an integrated map viewer.
This of course is only possible if the dive site is associated with GPS
information.

[[S_Filter]]
=== Filter the dive list

By default, all the dives in the dive log are shown in the dive list. After several years your dive
log can become quite long and, sometimes, you might like to list only the dives of a particular
type, e.g. those at a particular dive site or those with a specific buddy or dive master. Use the
Filter to achieve this. The filter mechanism searches through all the information for each dive,
looking for one or more key words. Only the dives containing these key words are listed in the dive
list. To Filter the dive list, tap the Filter action button:

unfloat::[]

image::mobile-images/FilterButton.jpg["FIGURE: Filter button",align="center"]

at the bottom of the dive list. A text box appears at the top of the screen (image below). Type the
word(s) that you would like to use as a filter.

image::mobile-images/Filter.jpg["FIGURE: Filter tool",align="center"]

Three filter modes exist. "Fulltext" searches all text strings. Selecting "People" lists buddies and
dive masters, while "Tags" only filters for tags containing the given text. Filters are not case-sensitive.
To clear the filter, remove the key words from the text box and select the Filter action button to
switch off filtering. The image above represents a full-text search for dives with the word "nitrox".


[[S_Dive_Management]]
== Dive List Management and adding dive information

[[S_Add_Dive]]
=== Manually adding a new dive to the dive list

This https://www.youtube.com/watch?v=sF8KB_r0rFw[*video-tutorial*] explains how to add information to a
manually-entered dive.

You can manually add a dive to the existing dive list. On the dive list
tap the "plus" sign in the action bar, or use the
main menu and tap _Dive management  ->  Add dive manually_. This opens  a screen that is
identical to the editing screen discussed above. When a dive is added manually, you
cannot directly add a dive profile from a dive computer. However, if you do not use a
dive computer, the duration, depth and several other bits of information about
the new dive can be entered. The _Action button_ at the bottom of the screen
contains a disk symbol. Tap this to save the new dive. To cancel any edits, tap the _Back_ button.
The left-hand image below shows a screenshot of a dive being created and the right-hand image shows
the same dive in _Details View_. After editing the dive information, the dive trip information
needs to be edited as described in the section above on xref:S_Divetrip[Dive trip editing].

image::mobile-images/Manualdive.jpg["FIGURE: Manual dive entry screen",align="center"]

[[S_Download]]
=== Download dives from a dive computer

There are several ways to get to the _Download Page_. You can either tap on the main _Action Button_ on
the bottom of the _Dive List_, or you can select _Dive management ->  Download from DC_ in the main menu.
On Android devices, when you plug in a USB serial cable for a dive computer, the _Download Page_ will be
opened automatically. A screen is shown requiring that the user specify
the names of the vendor and model of the dive computer. For instance, when using a Shearwater Petrel dive
computer, the vendor is _Shearwater_ and the Dive computer name is _Petrel_ (see image on the left, below).
*Caveats:* The download feature in smartphones supports only a limited number of dive computers. On
Android devices these are typically dive computers using a serial USB interface
using a USB OTG cable or a simple USB C-A adapter on newer devices.
Android devices also support Bluetooth dive computers that
are supported in _Subsurface_ on the desktop. Both Android and iOS devices allow direct
download of dive data from a handful of Bluetooth LE enabled dive
computers. Use the _Vendor name_ and _Dive Computer_ drop-downs to pick the correct
dive computer. When downloading from multiple different dive computers, shortcut
buttons appear below the drop-downs to easily switch between them. In the xref:S_Settings[_Settings_] menu
you can remove these buttons, a useful feature for removing buttons of dive
computers that are not used any more. Achieve this by selecting the option 
_Forget remembered dive computers_ in the xref:S_Settings[_Settings_] menu.
After all these caveats, let us proceed with download. 

*TODO: image of DL missing - or link to the 7.2.3 Start the download*

When downloading from multiple different dive computers, shortcut
buttons appear below the drop-downs to easily switch between them. In the xref:S_Settings[_Settings_] menu
you can remove these buttons, a useful feature for removing buttons of dive
computers that you do not use any more. Achieve this by selecting the option
_Forget remembered dive computers_ in the xref:S_Settings[_Settings_] menu.

==== Download from USB serial dive computers
This feature is not supported on iOS.

[width="100%", frame="None"]
|=======
a|image::mobile-images/USB-OTG.jpg["FIGURE: USB-OTG cable",align="center"] |
Most current Android devices now have a USB
Type C port and come with a simple A-to-C adapter plug, which lets you plug in
the dive computer cable into the phone or tablet.
For older Android devices with micro USB connector you will need to plug the USB
cable used with the dive computer into a USB OTG cable which,
in turn, plugs into the micro-USB port.
The OTG cable usually has a full-size ("Type A") female receptacle at one end which
accommodates the full-sized male plug
of the dive computer USB cable (see image on left). This means that two cables are used to connect
the dive computer to the mobile device. *Not all Android devices support OTG cables*
but usually all modern Android devices with a USB C plug can be used with a USB A-to-C adapter.
|=======

_Subsurface-mobile_ remembers the settings for dive computers that
have been successfully used (image on right, below). These appear
as buttons under a heading "_Previously used dive computers_".
Select the appropriate button. Having connected the USB dive computer to the
_Subsurface_ computer and having selected the appropriate vendor and dive computer,
ensure that the _Connection_ text box shows the corresponding connection. For a small number of dive
computers the connection name shows the dive computer vendor, for most only the cable chipset vendor
(and USB connection number) is shown. Most users only connect one USB dive computer to
their Android device and then things are fairly straightforward. A dialog appears asking if
you want to use _Subsurface-mobile_ to connect to the device. If you confirm, then _Subsurface-mobile_
opens the dive computer download screen with the correct connection selected (and if it can deduce
the correct dive computer based on the cable used, even that information is already pre-filled).

==== Download from Bluetooth and Bluetooth LE dive computers

This https://www.youtube.com/watch?v=DCi70WZMTws[*video-tutorial*] demonstrates downloading dives from a
Bluetooth-equipped dive computer.

The process for Bluetooth download differs between Android and iOS. In *iOS* the best
results are obtained when the dive computer was
in Bluetooth LE mode before _Subsurface-mobile_ is started. On most dive
computers this is done through a menu entry, others (e.g. Suunto) always respond to Bluetooth LE requests.

In contrast, for Bluetooth-equipped dive computers and *Android* devices, first establish a Bluetooth connection
between the dive computer and the
mobile device using Android system tools to achieve pairing.
For many Android devices,
the Settings -> Bluetooth tool of Android is probably appropriate.
_Subsurface-mobile_ performs communication using both Bluetooth and Bluetooth LE (BLE).
The best choice of Bluetooth communication is often made by the software and the user need not be concerned 
with this.
For dive computers with both Bluetooth and BLE, a separate dive computer button is presented on the download
screen for each mode of communication, allowing a choice. Use the _Connection_ value to distinguish between the
two options. In the image on the right, below, there are three buttons labeled "Shearwater Petrel 2".
These represent two Shearwater Petrel dive computers, one of which can communicate in both Bluetooth as well as BLE.
The _Connection_ information in the image below indicates that the Petrel with no BLE is selected. For 
Bluetooth LE dive computers, the _Connection_ value has an "LE" prefix.

This https://www.youtube.com/watch?v=4MtQqm4o7bw[*video-tutorial*] demonstrates setting up a
Bluetooth connection with an Android device.

==== Start the download

With communication between dive computer and _Subsurface-mobile_
having been set up, tap the _Download_ button. Be patient because the download can take a while - with many
long dives and a slow Bluetooth LE connection we have seen download times of 45 minutes or longer. But usually
downloading
a day's worth of diving happens reasonably quickly.
The downloaded dives appear in the bottom part of the screen,
the most recent dive at the top (see right image below).

Each dive has a check-box on the left hand side, used for selecting which dives you want to add to the
_Subsurface-mobile_ dive list: dives that are not checked are ignored. Once you have picked the dives
you want to add to the dive list, tap the button at the bottom left labeled _Accept_. The selected dives will
now appear as part of
the _Subsurface-mobile_ dive list. 

image::mobile-images/DC-Download.jpg["FIGURE: DC download screen",align="center"]

[[S_Edit_Dive]]
=== Edit the dive information

This https://www.youtube.com/watch?v=pE3ujzGw_7o[*video-tutorial*] explains how to add information about a dive.

image::mobile-images/Editdive.jpg["FIGURE: Dive edit screen",align="center"]

At the bottom of the _Dive Details_ screen the action button is a pencil.
Tapping the pencil button changes the page and enables edit boxes that allow
modifying the existing dive information, e.g. adding text to the dive notes
or changing the names or values of some of the information (see image above).
It may be necessary to scroll the window to access all the information.
At the bottom of the edit screen is a _Save_ action button. Tap this to save
the new information, after which the dive list screen is
updated and shown. To cancel any edits, tap the Android _Back_ Button or
the application back button at the top left of the screen on iOS.

[[S_Divetrip]]
== Edit the dive trip information

When a new dive(s) is entered manually or downloaded from dive computer, a trip header is created at the
top of the dive list only showing the month and the year of the dive trip as well as the number of dives
during the trip (image on left below, showing a trip header with "May 2018", the trip comprising two dives).
You would probably like to include information about the place
where the trip took place, e.g. "Channel Islands" or the dive charter company used. In this case long-press
the dive trip header to activate the context menu. Select the option "Edit trip details" to open a panel
for typing information about the trip (image on right, below). Having provided the required information,
tap the _Save_ action button at the bottom of the screen. This returns you to the dive list, showing some of
the dive trip information that has just been provided.

image::mobile-images/TripDetails.jpg["FIGURE: Edit trip details",align="center"]

=== Deleting a dive

Delete a dive from the dive list by long-pressing a dive and selecting delete in the context menu.
If the wrong dive was deleted by mistake you can easily undo the operation by using the context menu.

image::mobile-images/Delete_undo.jpg["FIGURE: Undo delete dive",align="center"]

== Interacting with the cloud storage

=== Manually sync the dive log with the _Subsurface Cloud_

As the name indicates, this ensures that the local changes on the mobile device and changes
made by other devices and computers to the data stored in the _Subsurface Cloud_ are synchronized.
It is highly recommended to sync with cloud storage after downloading new dives from a dive computer
or after manually adding or editing dive information on the mobile device.
This can also be triggered by pulling down (and briefly holding) the topmost entry of the _Dive List_.

=== Enable cloud auto sync

By default _Subsurface-mobile_ runs offline and only syncs the dive list
with cloud storage when explicitly told to do so (see the previous entry above).
You can choose to always sync with the cloud server. This is not
recommended unless you are in
an area with a fast and reliable Internet connection, as otherwise
_Subsurface-mobile_ might appear to hang between operations as it tries to
connect to the cloud server. Selecting _Enable cloud auto sync_ causes
the local dive log to be synchronized with the copy in the cloud after most changes as well
as (on Android) every time that _Subsurface-mobile_ is closed. iOS doesn't support the concept
of closing an app (you can just kill it, which doesn't allow for a final sync with the cloud).
In general it is safer to manually sync with the cloud once you are done making changes in
_Subsurface-mobile_.

== Dive Summary

The _Dive Summary_ page provides a very simple overview of your diving activities - which can for example
be useful when documenting total dive experience and recent dive activity for a dive center at
the beginning of a dive trip.

The summary page lists the date of your first dive in the dive list as well as your most recent dive.
It also provides two columns of data for selectable time ranges (by default all dives in the dive list
and the dives during the last six months.


[[S_Stats]]
== Dive Statistics

[width="100%", frame="None", cols="2,3"]
|===
a|image::mobile-images/StatsPanel.jpg["Image: Statistics panel",float="left"] |
Creating meaningful statistics that convey the information you are looking for is surprisingly hard.
Different users have very different needs and very different expectations. Subsurface-Mobile provides
a rather detailed set of statistics features to summarize information from the dive log in a graphical
way. To access the dive statistics tool, select _Main Menu_ -> _Statistics_. The statistics tool is
so flexible that it is impossible to cover every possible use case. Rather, we provide a conceptual
introduction, followed by specific examples. The tool can be closed using the _Back_ button (bottom
right in Android).

The Statistics tool has two panels (image on left):

1. A setup panel containing comboboxes for requesting a graph (top).

2. The graph that has been requested (bottom).

|===

[[S_Stats_Intro]]
****
*A diver's introduction to statistical graphs*
[icon="images/icons/important.png"]
[IMPORTANT]

The extreme flexibility of the Statistics tool means that you need to provide detailed information about
what information Subsurface should provide. It helps to have a clear objective, i.e. a solid understanding of
what you want Subsurface to show you. In other words, you need to formulate the correct question. There
are so many graphical display options that, if you do not formulate the question correctly, the information
is unlikely to be presented in a valid or appropriate way. Because all statistical results in Subsurface
are shown as graphs, formulating an appropriate specification requires four steps:

a) Which dives do you wish to graph? If required, use the xref:S_Filter[Filter button] for selecting specific dives to be analyzed.

b) Which variable should be displayed along the bottom horizontal axis of the graph?
Let's say you wish to see how many dives you performed each year. In this case the variable along the bottom
horizontal axis would be "Year". Alternatively, if you wished to compare the mean depth of your dives using
different suit types, then "Suit type" would be selected as the variable for the bottom horizontal axis.
Alternatively, if you wished to visualize the water temperature for dives of different dive depths,
then you would select "Max. depth" as the variable on the horizontal axis (see image below). The variable
along the horizontal axis is also called the "base variable", the "X-axis variable" or the "independent
variable": it defines the basic units or categories used for analysis.

image::mobile-images/StatsGraphAxes.jpg["Example: Statistics graph axes",align="left"]

c) Which variable should be displayed along the left-hand vertical axis of the graph? This is the variable
that you are primarily interested in. In some cases this could just be a count such as "No. of dives".
However, if you are interested in water temperature at different dive depths, you would select "Water
temperature" as the variable along the vertical axis (see image above). In this case you are primarily
interested in water temperature, not in dive depth (which would be the variable along the horizontal
axis). The variable along the vertical axis is also called the "data variable" or the "dependent variable":
it is the variable affected by (or dependent on) the values of the variable along the horizontal axis, as
in the graph above.

*NB:* Since, in Subsurface-Mobile, the graphs can be rotated to be horizontally-oriented or vertically oriented,
the terms "horizontal axis variable" and "vertical axis variable" are not appropriate. We use the term *Base
variable* to denote the conventional horizontal axis variable and the *Data variable* to denote the conventional
vertical axis variable.

d) Which chart type do you require? By default Subsurface selects the most appropriate graph type, but this
is a user-selectable option. Taking the example of water temperature at various depths above, the image below
shows three of the possible chart types of the same data: Image A shows the raw data by plotting the exact
temperature and depth for each dive. Image B, however, groups the dives in 5m depth intervals within which the
temperature for each dive is indicated (the red marks are explained below). Image C also groups the dives in 5m
depth intervals. However, in this case the minimum, maximum, mean, upper quartile and lower quartile are shown
for each depth class. 

image::mobile-images/StatsGraphOptions.jpg["Statistics graph options",align="left"]

The point of the discussion above is to show that, _before initiating a graph, you need to think carefully
about what you want Subsurface to show_, at least keeping the above four aspects in consideration.

*A more technical note on the valid use of statistical graphs*

When graphing variables from a dive log, there is an important distinction between _continuous variables_ and
_categorical variables_. These two data types are typically graphed in different ways. A continuous variable
can theoretically have any value. For instance dive depth can have any value greater than zero (theoretically
negative depths indicate height above the water but this is not a practical possibility). Consequently, depths
of 21.63857 meters or 44.7653 feet are entirely realistic. Dates are also continuous since the annual value
of any particular instant in time can be presented. For instance a dive at 12 noon on April 1st 2020 can be
presented by a value of 2020.24726 (90.5/366 days in that leap year). On the other hand dive mode is a
categorical variable: there are no values between "Freedive" and "Open circuit" or between "Open Circuit"
and "CCR". Other categorical variables include Buddy, Visibility, Rating and Suit type. Different methods
are used to represent these two types of variables, evident from the way in which the axes are organized.
It is perfectly valid to create a
graph with a continuous Base variable and a categorical Data variable and _vice versa_. However, when using
a continuous Base variable, use a
histogram, NOT a bar-chart. The images below show counts of dives at different depths. Image A is a histogram
showing that no dives were conducted between 55m and 60m depth. However two dives were performed between 60m
and 65m: these two bars (55-60m and 60-65m) have equally important information. Image B shows the bar-chart
of the same dataset where depth has been converted to a categorical type. Notice that the two bars with no
dives (55-60m and 75-80m) are omitted. Important information is lost because of the use of a bar-chart to
represent continuous data. It is easy to determine whether a specific graph is a barchart or a histogram:
when selecting "Chart type" the heading of the submenu should show either _Barchart_ or _Categorical_
in the case of categorical variables, and _histogram_ or _scattergraph_ in the case of continuous variables.
Subsurface-Mobile helps by showing a yellow triangle for graph types likely to be inappropriate (Image C).

image::mobile-images/StatsDataTypes.jpg["Statistics: bar-charts of continuous and categorical data types",align="left"]

****

=== Graph orientation

In many cases the values of the Base Variable along the horizontal axis are shown by dots, not numbers or names (Image B above).
This is because the screen of a mobile device often is not wide enough to show all the values, especially prevalent
in bar charts where the labels along the bottom axis are long. There are two ways of addressing this problem:


1. Turn the mobile device through 90 degrees so that the screen display is in landscape (wide) mode.


2. Rotate the bar chart through 90 degrees by selecting a horizontal bar chart (in the
Chart type combobox, select a horizontal chart type). In this case the bars are shown horizontally in both portrait and landscape orientation. For instance,
the image below shows the horizontal bar-chart produced when selecting "Categorical/Horizontal" in the Chart type combobox and
using the same dataset as in graph B in the image above. With the axes rotated there is much more horizontal space for showing
the relatively long label for each bar in the chart.

image::mobile-images/StatsBarchartRotated.jpg["Stats rotated barchart",align="left"]

=== Graphs of counts data

By default, when the Statistics panel is opened, a histogram is shown of the number of dives performed each year. 
This is an example of *counts* data. To request a graph representing counts, three comboboxes need to be set:

a) The top left combobox of the Base variable needs to be specified. Which variable should be along the horizontal
   axis? Examples are Year, Buddy, Rating, Max. depth.

b) The binning combobox (top right) for the Base variable needs to be specified. This represents the increment
for each bar along the horizontal axis. For instance, when counts of number of dives are extracted for years,
this could be in increments of a year, a quarter (3 month period) or a month. For some variables, e.g. Buddy
or Rating, a binning value is not relevant and cannot be selected. However, for others, e.g. Year or Max.
depth, selecting the appropriate binning is important.

c) For simple counts data, the left combobox of the Data variable needs to be set to "none". This is because
a data variable is not involved in this type of graph. Divers used to spreadsheets may prefer a *pie chart*
for these data, achieved by selecting "piechart" from the Chart type combobox. It is possible to
simultaneously provide counts for two variables. In this case one could specify a Data variable which
results in the counts being subdivided according to the data variable. This option does not have a piechart
equivalent.

For simple histograms, the default height of each bar is determined by the mean value for the observations
included in each bar. However, this can be manipulated using the Operation combobox to show the mean,
maximum, minimum, median and sum applicable to each bar. Image A below shows quarterly count data of
dives while image B shows quarterly count data, subdivided by dive mode (some dives open circuit,
other dives rebreather). The legend can be dragged around so that it does not obscure part of the graph.

image::mobile-images/StatsCountsData.jpg["Counts data example",align="center"]

=== Counts comprising more than one category in a bar

As mentioned in the section above, bar-charts showing a breakdown of each category for a number of
subcategories are easily created.

a) Select a variable with categories (along the horizontal axis) as a Base variable (e.g. dive mode or suite type).

b) Select another category of data as a Data variable (e.g. gas type or cylinder type).

The images below show two alternative bar-chart representations. If, in the Chart type combobox, one selects
"Barchart/stacked vertical", a graph similar to image A below is generated, summarizing a log of technical
dives where, for each cylinder gas type, the bar is subdivided into a count for open-circuit dives and for
rebreather dives. On the other hand, if "Barchart/grouped horizontal" is selected in the Chart type combobox, a graph
similar to image B, below, is produced. Here the subdivision within each gas type is shown as adjacent bars.

image::mobile-images/StatsBarchartSubdivided.jpg["Stats subdivided barchart",align="center"]

=== Scattergraphs

[width="100%", cols="2,3", frame="None"]
|=======
a|image::mobile-images/StatsRegression.jpg["Regression data example",align="center"] |
Sometimes you might wish to investigate the relationship between two dive variables. Has my SAC rate decreased over
the years? Is the water temperature colder at greater dive depth? One of the ways of investigating these questions
is to draw a scattergraph where the values of one variable is plotted against the other variable (see image on the left).
|=======


For the dataset in the image above the SAC rate appears to have decreased over time. If the relationship between the two variables
is statistically significant, a red line is shown that summarizes the best estimate of the relationship between SAC rate and year.
In this graph it appears that SAC rate has decreased from around 21 l/min to around 14 l/min between 2013 and 2021. The pink area
around the red line indicates the uncertainty of the precise orientation of the line. The line is expected to lie somewhere within
the pink area with a certainty of 95%. The intensity of the pink color also indicates the relative reliability of these estimates.
The procedure for obtaining a scattergrapth is:

a) Specify the Base variable: Which variable should be along the horizontal axis? Examples are Date, Temperature, Max. depth, SAC rate.

b) Set the binning value for the Base variable (top right) to "none".

c) Specify the Data variable: Which variable should be along the vertical axis?


=== Comparisons between categories of dives

You might wish to compare different categories of dives. Is the (5-star) Rating of a dive related to water temperature?
Is my SAC rate related to diving with different dive suits? Since dive suit and Rating are categories, a scattergraph is not
appropriate. The default is a categorical dot graph, which, in the case of image A below, shows the precise water temperatures
for each Rating. The red lines indicate the top quartile, the mean and the lower quartile of temperature for each rating. The
column with no star indicates dives for which a Rating has not been selected. It appears that dives with a 5-star rating have
higher temperatures than the other ratings. To obtain a categorical graph:

a) Select a variable with categories (along the horizontal axis) as a Base variable (Top left).

b) Select the data variable and set binning to "none" (middle right combobox).

c) By default the Chart type combobox shows "Categorical/data points". If this is not the case, select this value. 

image::mobile-images/StatsCategoricalData.jpg["Stats: Comparison of categories",align="center"]

Alternatively you could create a Box-whisker graph for the same data. In the Chart type combobox, select Categorical/"box-whisker".
This creates a graph indicating the maximum, top quartile (Q3), median, bottom quartile (Q1) and minimum for each category or
class. Image B above shows a box-whisker graph for the same data as image A above. You can see that the values for a Rating
of 5 stars tend to be higher than for other ratings.


== Export

The _Export_ feature is somewhat experimental. On Android it only allows the upload of your dive list
to two websites (_divelogs.de_ and _diveshare_). On iOS it also allows local file based exports as _Subsurface_
specific XML files (both for dives and dive sites) as well as _UDDF_.

Tapping on _Next_ opens an additional page for login information for the destination website (or a file selection dialog).

== Obtaining dive site locations using the GPS

The fact that almost all smartphones have GPS facilities allows
_Subsurface-mobile_ to record
the locations of dives. 

****
[icon="images/icons/important.png"]
[IMPORTANT]
*Accuracy of GPS coordinates*

GPS-derived coordinates on a smartphone
are not always accurate and can have an error greater than 1 km. GPS accuracy
is determined by the hardware and software of the
smartphone as well as by the GPS settings selected within Android/iOS.
As of Android V6 (Marshmallow) select Android _Settings -> Communication -> Location -> High accuracy_*.
If the smartphone is taken on the boat
during a dive, locations can be automatically recorded at regular intervals.
These locations can then be applied to dives in the dive list as described below
****
To collect dive site coordinates four step are required:

[[S_ConfigureGPS]]
=== Configuring the GPS service

For most users, the defaults for tracking GPS locations are
appropriate. If you would like to change them, go to
the _Main Menu_, select the xref:S_Settings[_Settings_] screen, and open
the _Advanced_ area on that page where there is a section for
configuring the GPS service (see image below). GPS location data
are collected at regular intervals, e.g. every 5 minutes, or at regular
distances, e.g. after the boat has moved more than 200m, or a combination of
both of these approaches. Provide the appropriate information and
tap the _Back_ button. The program is now ready to collect GPS positions.

image::mobile-images/GPSConfig.jpg["FIGURE: GPS configure",align="center"]

=== Collecting GPS positions

[width="100%", frame="None", cols="2,3"]
|=======
a|image::mobile-images/LocationMenu.jpg["FIGURE: GPS start",align="center"] |
In the _Location_ menu select _Run location service_.
_Subsurface-mobile_ starts to collect GPS locations automatically,
following the preferences specified as described above. While the GPS
location service is running, all menus have a GPS symbol at the bottom,
indicating that the service is active. After returning from
the dive, deactivate the collection of GPS data by tapping
the option _Location -> Disable location service_. The GPS symbol at the bottom
of menus disappears.
|=======


Collecting GPS fixes like this is relatively battery intensive and unfortunately
both Android and especially iOS have become increasingly aggressive in killing
applications that are running while the screen is turned off. It may make sense
to check between dives that the location service is still running. On the other hand
the battery consumption of a smartphone with GPS enabled is often significantly less than
the battery consumption of a dedicated GPS that is logging a track.

=== Viewing GPS data collected during a dive

From the _Location_ submenu select _Show GPS fixes_. This brings
up a list of GPS positions obtained by the location service (image
below). Two actions are possible for each of the locations, enabled by
dragging the right part of a location to the left. This exposes two
options. Tapping the dustbin deletes this particular GPS location. Tapping the
teardrop-shaped icon (actually a Google Maps pin) opens up Google Maps with a pin
indicating the exact map position of the GPS record being viewed. The two above
options can be hidden by drawing the GPS record to the right.

image::mobile-images/gpsmanagement.jpg["FIGURE: GPS management",align="center"]


=== Applying GPS data to dives in the dive log

After running the location service during a dive trip, first either download
the dives from your dive computer or manually enter the dives into the dive list.
Now you can apply the GPS positions to these dives.
From the _Dive management_ menu, tap _Apply GPS fixes_. The dive list contains the start
and end times of each dive. Now, _Subsurface-mobile_ applies the first
GPS position that falls within the dive period of each dive. This results
in a GPS position for each dive that is saved as part of the dive log.

== Viewing the locations of all dives in the dive list

image::mobile-images/DivesMap.jpg["FIGURE: Map of all dive sites",align="center"]

The locations of all dives in the dive list can be viewed from the _Location_ menu by selecting the _Map_ option.
A satellite image of the world is shown. At that scale no dive sites are shown. If you zoom into a particular region
of the world the dive sites appear, indicated by red flags. Zooming in even closer indicates the names of each
of the different dive sites.

[[S_Settings]]
== Specifying the settings for _Subsurface-mobile_

The _Settings_ page allows the customization of _Subsurface-mobile_.
It is grouped into four sections. Many of the settings involve dragging a slider switch to activate or deactivate a particular setting.

=== _General settings_ section

image::mobile-images/GeneralSettings.jpg["FIGURE: General Settings",align="center"]

[[S_ChangeCloudAccount]]
==== Cloud status: Changing to a different _Subsurface_ cloud account

Some users have more than one _Subsurface_ cloud account and need to switch between accounts.
Tap on the _Change_ button next to the _Email address_ in the _General settings_ on the _Settings_ page (see image above).
This opens the _Cloud credentials_ page.
Here you can change the email address and password used and then tap the button _Sign-in or register_.
The dive list of the newly-opened account is shown.

==== Default cylinder

When manually entering a dive or when downloading from a dive computer that doesn't explicitly
include cylinder size information (very few dive computers support that feature), _Subsurface-mobile_
uses the cylinder that you select here as the default, useful for divers that mostly use a particular
type of cylinder. If you don't set this entry, no default
cylinder is used.

==== Forget the remembered dive computers used during dive download

Tap the _Forget_ button to reset the dive computers that are stored in the shortcut
buttons on the _Download from dive computer_ page.

=== _Theme_ section

==== Color theme

[width="100%", frame="None"]
|=======
a|image::mobile-images/ThemeSettings.jpg["FIGURE: Theme Settings",align="center"] |
Besides the default blue color scheme, _Subsurface-mobile_ supports two additional color schemes
for users with different tastes (see image on left). All screenshots shown in this user manual are
based on the blue default color scheme. You can pick the _pink_ or _dark_ color theme from
the drop down menu.

The boxes in the image on the left show the various color choices in the theme of your choice.
|=======

==== Font size

Depending on the size and the screen resolution of your mobile device, you may prefer slightly
smaller or slightly larger fonts. You can make this selection with the three buttons here.

=== _Units_ section

Here you can pick _metric_, _imperial_, or _personalized_ units for the user interface.
In most cases _Subsurface-mobile_ should pick the regionally typical unit system for
your location.

=== _Advanced_ section

As the name indicates, most users do not need to make changes here.

==== GPS location service thresholds

As indicated above in the _Location_ section of this manual, here you can set the distance and time
thresholds for the _location service_

==== Bluetooth

Since most mobile devices tend to find a _LOT_ of BT/BLE devices that aren't dive computers, by
default _Subsurface-mobile_ only shows known dive computers to make the connection list
easier to use.

This setting tells _Subsurface-mobile_ to temporarily show _ALL_ Bluetooth and BLE devices as
possible connections on the _Download Page_, not just the ones recognized as dive computers.
If you end up needing this option in order to select a dive computer that is not recognized
by _Subsurface-mobile_, please send an email to the developers (using the _Help -> Ask for support_
menu entry) so we can add the missing code to recognize your dive computer as well.

==== Display

_Subsurface-mobile_ tries to make efficient use of the available screen real estate of your
mobile device. In most cases this leads to reasonable choices regarding the number of parallel
columns that are being displayed. Some users have expressed the desire to force _Subsurface-mobile_
to show only one column in portrait mode, even on large devices like tablets, as this results
in a larger profile on the _Dive Details_ page. Select this option if you want to enable that
feature.


==== Activating the Developer sub-menu

This enables an additional menu item in the _Main_ menu which contains options which are almost
never useful for a regular user. Here you can find the detailed app log file as well as several
test screens that help the developers track down issues you might encounter.

== Help

=== About

This page shows you the exact version of _Subsurface-mobile_ that you are running and provides
a convenient way to copy the application logs to the clipboard.

=== Show user manual

This menu entry opens the online version of this user manual in the native browser of your
device. Unfortunately this option is not available without Internet access.

=== Ask for support

This item opens your default email client with a pre-populated email to the _Subsurface_
support alias and copies the app logs into that email. Simply add your question or the
but that you are reporting and send us your message.

=== Reset forgotten _Subsurface Cloud_ password

As mentioned earlier in this manual, this is a convenient link to a web page that allows
you to reset the password for your _Subsurface Cloud_ account.