~~~~~~~~~~~~~~~~~ BRLTTY on Android ~~~~~~~~~~~~~~~~~ .. |SDK build tools version| replace:: 26.0.1 .. |NDK version| replace:: r16b .. |JDK version| replace:: 1.8 .. include:: prologue.rst Using BRLTTY ============ System Requirements ------------------- BRLTTY has been designed to run on at least Android 4.1 (Jelly Bean). While it does run on Android 4.0 (Ice Cream Sandwich), many of its highly desirable features won't work. BRLTTY requires access to a number of privileged Android operating system capabilities. The required permissions are as follows: ``BIND_ACCESSIBILITY_SERVICE`` This permission is required so that BRLTTY can inspect the layout and content of the screen. ``BIND_INPUT_METHOD`` This permission is required so that Android will accept input from your braille device's keyboard. ``WAKE_LOCK`` This permission is required so that BRLTTY can reset the Android device's lock timer each time you interact with a control on your braille device. ``BLUETOOTH`` This permission is required so that BRLTTY can use Bluetooth to communicate with your braille device. ``BLUETOOTH_ADMIN`` This permission is required on Android 4.0 (Ice Cream Sandwich) so that BRLTTY can use Bluetooth to communicate with your braille device. ``INTERNET`` This permission is required so that BRLTTY can listen on a TCP/IP port for BrlAPI client connection requests. ``READ_EXTERNAL_STORAGE`` This permission is required so that BRLTTY can read customized data files from your SD card. Quick Start ----------- If you'd just like to install BRLTTY onto your Android device and get going, then here's what you need to do. These instructions are from the perspective of a Firefox user on Windows, but the process should be much the same when using a different web browser and/or operating system. On Your Computer ~~~~~~~~~~~~~~~~ 1) Go to `BRLTTY's Web Site`_. 2) Find the ``Download`` link and press Enter on it. 3) Go to the ``Android`` section, down-arrow from there to the link that says ``Latest APK``, and press Enter on it. 4) You'll be prompted to open or save the file at this point. Save it. 5) Go to your ``Downloads`` folder (or wherever you save downloads), and find the ``brltty-latest.apk`` file. 6) If the file has been saved on your computer as ``brltty-latest.zip``, then press the ``Context`` key, arrow to and press Enter on ``Rename``, and change the file extension from ``zip`` to ``apk``. Don't worry if you get a warning about the possibility of rendering the file unusable. Go ahead with the rename. On Your Android Device ~~~~~~~~~~~~~~~~~~~~~~ 1) Go into ``Settings`` -> ``Security``, and ensure that ``Unknown Sources`` is enabled. This option says something like: Allow the installation of apps from unknown sources This is a one-time step. Once the box has been checked, it stays checked. 2) Copy the ``apk`` file to your device. There are a number of ways to do this: * The easiest way may be to email it to yourself as a file attachment so that it will go to the email on your Android device. * Another option is to save the file in Dropbox on your computer, and then wait for it to show up in Dropbox on your Android device. * Another option is to connect your Android device to your computer via a USB cable, and then to copy the file to it in the same way that you'd copy a file to a thumb drive. 3) Tap the ``brltty-latest.apk`` file to start its installation, and answer any prompts. If you use the Dropbox method, you might need to tap on the file twice - once to download it, and a second time to install it. 4) Tap ``OK`` when installation is complete. Activation and Configuration ---------------------------- At this point, BRLTTY has been installed. Next, you'll need to go into ``Settings`` -> ``Accessibility`` -> ``BRLTTY`` in order to start the ``BRLTTY`` accessibility service, adjust its settings, and select your braille device. If you'll be connecting to your braille device via Bluetooth, see `Connecting Via Bluetooth`_. If you'll be connecting to your braille device via USB, see `Connecting Via USB`_. If your braille device has a braille keyboard, see `Using a Braille Keyboard`_. Starting and Stopping BRLTTY ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ BRLTTY isn't a regular Android application - it's an accessibility service. As such, it can't be started and stopped in the usual way, i.e. from the launcher. In fact, it can't even be found within the applications list. BRLTTY must be started and stopped from the ``Accessibility Settings`` screen. To get there, launch the ``Settings`` application, and then tap on ``Accessibility`` (near the bottom). This screen contains a "Services" section that lists all of the accessibility services that are currently installed on the device. For each installed accessibility service, there's an associated indicator that says ``On`` if that service is currently running, and ``Off`` if it isn't. Find ``BRLTTY`` and tap on it. This brings up a window with two items in it. One is a "switch" for turning BRLTTY on and off. The other is a button that takes you to BRLTTY's ``Settings`` screen. You can go through BRLTTY's settings, making changes as desired, as well as define your braille device(s), either before starting BRLTTY or while it's running. Connecting Your Braille Device ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Connecting Via Bluetooth ```````````````````````` In order to use a Bluetooth braille device, you'll need to first "pair" it with your Android device. Go into ``Settings`` -> ``Bluetooth``. If your braille device is already listed within the ``Paired Devices`` section of that screen then it has already been paired. If you still need to pair it then tap ``Search for Devices``. This will add an ``Available Devices`` section to the screen. If your braille device isn't listed then you'll probably need to perform a model-specific action on it in order to make it visible (also known as discoverable) - see its manual for details. After doing that, tap ``Search for Devices`` again. Tap on your braille device to begin the Bluetooth Pairing Request, enter its PIN (see its manual for details), and tap ``OK``. Connecting Via USB `````````````````` In order to use a USB braille device, you'll need a special cable known as a "Micro USB Host Adapter". The reason for this is that the USB port on an Android device usually acts as a "device" (rather than as a "host") port. This is so that, for example, you can control your Android device from your computer. The Micro USB Host Adapter has a special plug, known as an OTG (on-the-go) connector, that, when inserted into the Android device's USB port, instructs Android to act as the USB host. The Micro USB Host Adapter also allows you to connect any other USB device (keyboard, mouse, printer, hub, etc) to your Android device. Be aware, though, that if any such device, including your braille device, draws power via its USB port then your Android device's battery will become the source of that power. If portability isn't an issue, you may wish to consider using your Micro USB Host Adapter to connect your Android device to a powered hub so that your USB devices will draw power from the hub rather than from your Android device's battery. You may also wish to consider disabling USB charging on any devices that offer this capability. Defining Your Braille Device ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You don't actually need to define your braille device, but BRLTTY will connect to it much faster if you do. If you don't, BRLTTY will search through all of the devices that have been connected via either Bluetooth or USB (see `Connecting Your Braille Device`_) for one that it recognizes. If there's more than one, it'll select the first one that it finds. To define your braille device, go to BRLTTY's ``Settings`` screen, tap on ``Manage Devices``, and then on ``Add Device``. From there, find your braille device, and then tap ``Add``. To find your braille device: 1) Select its communication method (Bluetooth, USB). 2) Select your device from the list that's presented. 3) Select the correct braille driver. This step is optional, i.e. you can usually leave it set to ``autodetect``. Going through the effort of selecting the correct driver, however, ensures a fast and reliable connection. After you've added your braille device to BRLTTY, tap on ``Selected Device`` and select it from the list of devices that BRLTTY knows about. Using a Braille Keyboard ~~~~~~~~~~~~~~~~~~~~~~~~ Braille device keyboard input is supported, but, like all Android input methods, it must be explicitly enabled, and then explicitly selected. Android doesn't permit BRLTTY to do either of these automatically on your behalf. Although it's inconvenient, Android imposes this manual process so that you're very consciously aware of which input methods can process, and which input method is currently processing, whatever you're typing. Such applications, after all, handle extremely sensitive personal data (such as passwords, credit card numbers, etc), so it's crucial that you make your own decisions regarding which of them you're willing to trust. If you type on your braille device's keyboard when BRLTTY's input method is either disabled or enabled but not selected, then BRLTTY will alert you to this fact via a message on your braille display. You may wish to enable BRLTTY's keyboard support ahead of time, but you probably don't want to select it ahead of time. The reason for this is that Android only allows exactly one input method to be in use at a time. When you explicitly select BRLTTY's input method, therefore, you're also implicitly deselecting the on-screen keyboard. You can enable BRLTTY's keyboard support in one of the following ways: * Launch Android's ``Settings`` application and tap on ``Language and Input``. The ``Keyboard and Input Methods`` section of this screen shows the ``Default`` (currently selected) input method, and contains a check box for each installed input method. An input method is enabled if its check box is checked, so, to enable BRLTTY's keyboard support, check the box labeled ``BRLTTY Input Service``. Once it's been enabled, you can select it at any time by adjusting the ``Default`` setting. * If BRLTTY is running then switching between input methods is much easier. Go to `BRLTTY's Actions Screen`_ and tap ``Switch Input Method``. This brings up Android's Input Method Picker, which presents a set of radio buttons - one for each enabled input method. If there's no radio button for BRLTTY's input method then it hasn't been enabled yet. To enable it, tap the button labeled ``Set up input methods``. This screen contains a check box for each installed input method. Check the box labeled ``BRLTTY Input Service``. Then tap the ``Back`` button to return to the ``Language and Input`` screen, find the ``Keyboard and Input Methods`` section, and set the ``Default`` input method to BRLTTY's input method. BRLTTY's Actions Screen ~~~~~~~~~~~~~~~~~~~~~~~ This screen presents several common actions that you may wish to perform: * Switch Input Method * BRLTTY Settings * View User Guide * Browse Web Site * Browse Community Messages * Post Community Message * Manage Community Membership * Update Application * About Application You can get to this screen using any of the following methods: * From your braille device via global action #5. See `Performing Global Actions`_ for details. * From the notifications shade. Open it by dragging the status bar downward: * With two fingers if Explore By Touch is active. * With one finger if Explore By Touch isn't active. Then find BRLTTY's service notification and tap it. * Via the Accessibility button within the system navigation area. This capability was introduced in Android 8.0 (Oreo). The button may not be visible for a number of reasons, for example: * The device's system navigation area isn't rendered via software. * An application has chosen to hide the system navigation area. Navigating the Screen --------------------- Using Multiple Hosts ~~~~~~~~~~~~~~~~~~~~ BRLTTY only remains connected to your braille device while your Android device is unlocked or while its screen is on. If your Android device is locked and its screen is off then BRLTTY automatically disconnects from your braille device. This is so that you can easily share your braille device amongst multiple hosts. Pressing your Android device's power button (or similar action) to wake it up, even though it may still be locked, is sufficient to cause BRLTTY to automatically reconnect to your braille device. This allows you to enter your password or PIN via your braille keyboard. You can continue using your braille device even though your Android device's screen may have turned off, as long as its lock timer hasn't yet expired. Pressing keys on your braille device resets your Android device's lock timer in the same way that pressing its keys, touching its screen, etc does. This means that your Android device will stay awake and unlocked even though you're only controlling it from your braille device, and that it'll also still automatically lock once you're no longer using it. Accessibility Focus ~~~~~~~~~~~~~~~~~~~ The "accessibility focus" feature of Android is used for cursor tracking and routing. It's a soft cursor, not visible on the screen, that can be programmatically associated with any screen element. All screen readers that use it to define the current element for actions (like tapping) will implicitly cooperate reasonably seamlessly with one another. The cursor is usually placed on the first character of the screen element that currently has accessibility focus. The one exception to this is within an input area. If that area has input focus then the cursor is placed at the location within it where input will be inserted. When a home screen folder is opened, BRLTTY automatically sets accessibility focus to that folder's first entry. This eliminates the need to search for it. The Cursor Routing Keys ~~~~~~~~~~~~~~~~~~~~~~~ The cursor routing keys of the braille device perform their usual function when within an input area if it has input focus - the key above a given character brings the cursor to that character. In any other context, however, a cursor routing key performs an action on the screen element under it. Starting with the leftmost routing key over a screen element, which we'll call key #1, these actions are as follows: 1) set accessibility focus (used for cursor tracking and routing) 2) tap (click) 3) hold (long click) 4) scroll backward (up or left) 5) scroll forward (down or right) 6) context click A range control (progress bar, volume slider, etc) can be adjusted up/down via the scroll forward/backward actions. Input Areas ~~~~~~~~~~~ When an input area has input focus, BRLTTY's attribute underlining feature is used to highlight the selected text region. Widget Representations ~~~~~~~~~~~~~~~~~~~~~~ Check Boxes ``````````` A check box is rendered as a three-cell symbol: 1) dots 123478 (the left side of the box) 2) dots 2356 (the check mark) 3) dots 145678 (the right side of the box) The check mark is present if the box is checked and absent if it isn't. If the check box has a label then it appears to the right of the symbol. The braille representations are: * ⣏⠶⣹ checked * ⣏ ⣹ not checked Radio Buttons ````````````` A radio button is rendered as a three-cell symbol: 1) dots 2348 (the left side of the button) 2) dots 2356 (the check mark) 3) dots 1567 (the right side of the button) The check mark shows which of the radio buttons is currently selected. The label for each radio button appears to the right of its symbol. The braille representations are: * ⢎⠶⡱ selected * ⢎ ⡱ not selected Switches ```````` A (two-position) switch is rendered as a three-cell symbol: 1) dots 4568 (the left side of the switch) 2) dots 1478 (the top and bottom of the switch) 3) dots 1237 (the right side of the switch) Dots 25 are added to the middle cell if the switch is on, and dots 36 are added to the middle cell if the switch is off. In other words, the switch is up when on and down when off. The label for the switch's current state appears to the right of the symbol. The braille representations are: * ⢸⣛⡇ on * ⢸⣭⡇ off Range Controls `````````````` A range control is one which can be adjusted (rather than set or edited). They include widgets like progress bars, volume sliders, etc. They're rendered as a three-value summary:: * An at sign followed by the current setting. * The minimum and maximum settings, separated by a dash, within parentheses. The developer of an application can choose which value range a given control uses. For example, a 16-position volume control currently set to 75% might look like this:: @11 (0 - 15) It could, however, also look like this:: @75% (0% - 100%) Disabled Controls ````````````````` If a control is currently disabled then the word ``disabled``, enclosed within parentheses, appears to the right of its label. For example:: Connect /path/to/logfile The ``-v time`` option means to add a timestamp to each log record. The ``-d`` option means to dump the current Android system log. The ``adb logcat`` command writes the log to its standard output, so you need to redirect its standard output (with ``>``) to wherever you'd like the log to be written. The reason for capturing the log as soon as possible after a problem is that Android imposes limits on its log storage so that the log can't consume too much of your device's resources. If the log becomes too large, Android automatically removes older entries from it. If you wait too long, therefore, the part of it that shows how BRLTTY crashed may already have been automatically removed. Known Issues ------------ Serial devices aren't supported. Even though Android devices don't have serial ports, serial devices still can be connected via a USB to Serial adapter. Users who have older, serial-only braille devices should still be able to use them with their Android devices. Building BRLTTY =============== Preparing Your Host Environment ------------------------------- BRLTTY is currently being built using: * Version |SDK build tools version| of the Android SDK build tools. * Version |NDK version| of the Android NDK. * Version |JDK version| of OpenJDK. You need the Android SDK (Software Development Kit) for: * installing an application onto your device * removing an application from your device You can get it from `The Android SDK Web Page`_. You need the Android NDK (Native Development Kit) if you want to do your own builds. You can get it from `The Android NDK Web Page`_. The SDK initially only includes support for the current Android API (Application Programming Interface) level. BRLTTY, however, needs to support earlier API levels so that it can run on older releases of Android. Support for any missing API levels is added whenever the SDK is updated. To do this, use the following command:: android update sdk -u The ``-u`` option, which is the short form of the ``--no-ui`` option, means to bypass the graphical interface. There may be password prompts for installing packages that are provided by various vendours. Any of these can be easily skipped. The 64-bit versions of the SDK and NDK depend on 32-bit system libraries. If you're using a 64-bit version then you need to first ensure that these are installed on your system. This at least includes: * libc6 (or glibc) * libz (or zlib) * libstdc++6 (or libstdc++) * libncurses If you're using a modern Debian GNU/Linux system (``Wheezy`` or later), you can install these packages for a foreign architecture (in this case, i386) with the following commands (as root):: dpkg --add-architecture i386 apt-get install libncurses5:i386 libstdc++6:i386 zlib1g:i386 libc6:i386 Installing and Preparing the BRLTTY Source Tree ----------------------------------------------- Choose the directory that should contain BRLTTY's source tree (which needn't yet exist). Then extract the latest BRLTTY source into it with the following command:: git clone https://github.com/brltty/brltty.git /path/to/brltty The directory operand (of ``git clone``) is optional. If you don't specify it then the directory named ``brltty`` within the current working directory is assumed. Next, you need to prepare the source tree. This is done as follows:: cd /path/to/brltty ./autogen At this point, the source tree is essentially just like what you'd get were you to unpack an officially released BRLTTY archive. It doesn't yet know anything about the specifics of your system. It also doesn't yet know anything about the platform you intend to build BRLTTY for. Adding information to BRLTTY's source tree regarding the specifics of your system, as well as of your intent to build BRLTTY for Android, is done as follows:: export ANDROID_NDK=/path/to/Android/NDK ./cfg-android -q The ``-q`` option, which is the short form of the ``configure`` command's ``--quiet`` option, means to not display any progress information (there's usually quite a lot of it) - only warnings and errors are displayed. All of the options you give to the ``cfg-android`` command are passed directly through to the ``configure`` command. So, while ``cfg-android`` supplies a default set of options to ``configure``, it's easy for you to do your own customization. Building BRLTTY for Android --------------------------- In order to be able to build an Android application, a number of Android build tools need to be added to your command search path. This is done via the following command:: export PATH="/path/to/Android/SDK/tools:/path/to/Android/SDK/platform-tools:$PATH" The final step is to build the BRLTTY service for Android. This is done as follows:: cd /path/to/brltty/Android/Application make -s The ``-s`` option of the ``make`` command, which is short for its ``--silent`` option, means to not display any progress information (there's usually quite a lot of it) - only warnings and errors are displayed. The result of the build is the file ``BRLTTY_App-debug.apk``. It will be in the ``bin/`` subdirectory of BRLTTY's Android Application directory:: /path/to/brltty/Android/Application/bin/BRLTTY_App-debug.apk ``apk`` is the file extension used for an installable Android package. Preparing Your Android Device ----------------------------- You need ``USB Debugging`` to be enabled. This is done from the ``Developer Options`` screen. You can get to it from the ``Settings`` screen. Launch the ``Settings`` application, and look, near the bottom, for ``Developer Options``. If you can't find it, the most likely cause is a new feature that was introduced in Android 4.2 (Jelly Bean). If you need to enable it, tap on ``About Phone``, which, again, can be found near the bottom of the ``Settings`` screen. Then, on the ``About Phone`` screen, look for the ``Build Number`` line. Tap on ``Build Number`` seven times and your device will officially declare you to be a developer. You should then be able to find ``Developer Options`` on the ``Settings`` screen. There's a check box at the top-right of the ``Developer Options`` screen. It needs to be checked so that all of the other controls on that screen will be enabled. After doing that, check the ``USB Debugging`` check box (which can be found within the ``Debugging`` section). This enables the ``adb`` (Android Debug Bridge) tool to perform functions on your Android device. Installing BRLTTY on Your Android Device ---------------------------------------- In order to install BRLTTY onto your device, or to remove it from your device, you need to be in BRLTTY's Android Application directory:: cd /path/to/brltty/Android/Application You also need to connect your device to your host via USB. To install BRLTTY, use this command:: make -s install To remove BRLTTY, use this command:: make -s uninstall The ``make install`` command will fail if BRLTTY is already installed. If you're wanting to upgrade BRLTTY, however, then removing it first is probably what you don't want to be doing. This is because removing BRLTTY also causes its settings to be lost. What you should do instead is reinstall it. You can do this with the following command:: make -s reinstall If you've obtained your Android package file (``apk``) for BRLTTY from some other source (than building it for yourself), then it may have a different name than the make file is expecting. It's useful, therefore, to know what the actual host commands are for installing and removing Android applications. The host command for installing an Android application is:: adb install /path/to/file The host command for reinstalling an Android application is:: adb install -r /path/to/file The host command for removing an Android application is:: adb uninstall application.package.name So, to remove BRLTTY, the host command is:: adb uninstall org.a11y.brltty.android If any of these ``make`` or ``adb`` commands fails with an error like ``device not found``, it's probably because your host's USB device permissions are requiring root access. The solution to this problem is to restart the ``adb`` server such that it is running as root. With this done, you yourself will still be able to use ``adb`` as a regular user. The commands to restart the ``adb`` server such that it's running as root are as follows:: su cd /path/to/Android/SDK/platform-tools ./adb kill-server ./adb start-server exit