# revent¶

## Overview and Usage¶

revent utility can be used to record and later play back a sequence of user input events, such as key presses and touch screen taps. This is an alternative to Android UI Automator for providing automation for workloads.

usage:
revent [record time file|replay file|info] [verbose]
record: stops after either return on stdin
or time (in seconds)
and stores in file
replay: replays eventlog from file
info:shows info about each event char device
any additional parameters make it verbose


### Recording¶

WA features a record command that will automatically deploy and start revent on the target device:

wa record
INFO     Connecting to device...
INFO     Press Enter when you are ready to record...
[Pressed Enter]
INFO     Press Enter when you have finished recording...
[Pressed Enter]
INFO     Pulling files from device


Once started, you will need to get the target device ready to record (e.g. unlock screen, navigate menus and launch an app) then press ENTER. The recording has now started and button presses, taps, etc you perform on the device will go into the .revent file. To stop the recording simply press ENTER again.

Once you have finished recording the revent file will be pulled from the device to the current directory. It will be named {device_model}.revent. When recording revent files for a GameWorkload you can use the -s option to add run or setup suffixes.

From version 2.6 of WA onwards, a “gamepad” recording mode is also supported. This mode requires a gamepad to be connected to the device when recoridng, but the recordings produced in this mode should be portable across devices.

### Replaying¶

To replay a recorded file, run wa replay, giving it the file you want to replay:

wa replay my_recording.revent


Some workloads (pretty much all games) rely on recorded revents for their execution. wlauto.common.GameWorkload-derived workloads expect two revent files – one for performing the initial setup (navigating menus, selecting game modes, etc), and one for the actual execution of the game. Because revents are very device-specific[*], these two files would need to be recorded for each device.

The files must be called <device name>.(setup|run).revent, where <device name> is the name of your device (as defined by the name attribute of your device’s class). WA will look for these files in two places: <install dir>/wlauto/workloads/<workload name>/revent_files and ~/.workload_automation/dependencies/<workload name>. The first location is primarily intended for revent files that come with WA (and if you did a system-wide install, you’ll need sudo to add files there), so it’s probably easier to use the second location for the files you record. Also, if revent files for a workload exist in both locations, the files under ~/.workload_automation/dependencies will be used in favor of those installed with WA.

For example, if you wanted to run angrybirds workload on “Acme” device, you would record the setup and run revent files using the method outlined in the section above and then pull them for the devices into the following locations:

~/workload_automation/dependencies/angrybirds/Acme.setup.revent


(you may need to create the intermediate directories if they don’t already exist).

 [*] It’s not just about screen resolution – the event codes may be different even if devices use the same screen.

### revent vs. UiAutomator¶

In general, Android UI Automator is the preferred way of automating user input for workloads because, unlike revent, UI Automator does not depend on a particular screen resolution, and so is more portable across different devices. It also gives better control and can potentially be faster for ling UI manipulations, as input events are scripted based on the available UI elements, rather than generated by human input.

On the other hand, revent can be used to manipulate pretty much any workload, where as UI Automator only works for Android UI elements (such as text boxes or radio buttons), which makes the latter useless for things like games. Recording revent sequence is also faster than writing automation code (on the other hand, one would need maintain a different revent log for each screen resolution).

## Using state detection with revent¶

State detection can be used to verify that a workload is executing as expected. This utility, if enabled, and if state definitions are available for the particular workload, takes a screenshot after the setup and the run revent sequence, matches the screenshot to a state and compares with the expected state. A WorkloadError is raised if an unexpected state is encountered.

To enable state detection, make sure a valid state definition file and templates exist for your workload and set the check_states parameter to True.

### State definition directory¶

State and phase definitions should be placed in a directory of the following structure inside the dependencies directory of each workload (along with revent files etc):

dependencies/
state_definitions/
definition.yaml
templates/
<oneTemplate>.png
<anotherTemplate>.png
...


### definition.yaml file¶

This defines each state of the workload and lists which templates are expected to be found and how many are required to be detected for a conclusive match. It also defines the expected state in each workload phase where a state detection is run (currently those are setup_complete and run_complete).

Templates are picture elements to be matched in a screenshot. Each template mentioned in the definition file should be placed as a file with the same name and a .png extension inside the templates folder. Creating template png files is as simple as taking a screenshot of the workload in a given state, cropping out the relevant templates (eg. a button, label or other unique element that is present in that state) and storing them in PNG format.

Please see the definition file for Angry Birds below as an example to understand the format. Note that more than just two states (for the afterSetup and afterRun phase) can be defined and this helps track the cause of errors in case an unexpected state is encountered.

workload_name: angrybirds

- state_name: titleScreen
templates:
- play_button
- logo
matches: 2
- state_name: worldSelection
templates:
- first_world_thumb
- second_world_thumb
- third_world_thumb
- fourth_world_thumb
matches: 3
- state_name: level_selection
templates:
- locked_level
- first_level
matches: 2
- state_name: gameplay
templates:
- pause_button
- score_label_text
matches: 2
- state_name: pause_screen
templates:
- replay_button
- resume_button
- help_button
matches: 4
- state_name: level_cleared_screen
templates:
- level_cleared_text
- replay_button
- fast_forward_button
matches: 4

- phase_name: setup_complete
expected_state: gameplay
- phase_name: run_complete
expected_state: level_cleared_screen


## File format of revent recordings¶

You do not need to understand recording format in order to use revent. This section is intended for those looking to extend revent in some way, or to utilize revent recordings for other purposes.

### Format Overview¶

Recordings are stored in a binary format. A recording consists of three sections:

+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+
|                     |
|  Device Description |
|                     |
+-+-+-+-+-+-+-+-+-+-+-+
|                     |
|                     |
|     Event Stream    |
|                     |
|                     |
+-+-+-+-+-+-+-+-+-+-+-+


The header contains metadata describing the recording. The device description contains information about input devices involved in this recording. Finally, the event stream contains the recorded input events.

All fields are either fixed size or prefixed with their length or the number of (fixed-sized) elements.

Note

All values below are little endian

An revent recoding header has the following structure

• It starts with the “magic” string REVENT to indicate that this is an revent recording.

• The magic is followed by a 16 bit version number. This indicates the format version of the recording that follows. Current version is 2.

• The next 16 bits indicate the type of the recording. This dictates the structure of the Device Description section. Valid values are:

0

This is a general input event recording. The device description contains a list of paths from which the events where recorded.

1

This a gamepad recording. The device description contains the description of the gamepad used to create the recording.

 0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|      'R'      |      'E'      |      'V'      |      'E'      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|      'N'      |      'T'      |            Version            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


### Device Description¶

This section describes the input devices used in the recording. Its structure is determined by the value of Mode field in the header.

#### general recording¶

Note

This is the only format supported prior to version 2.

The recording has been made from all available input devices. This section contains the list of /dev/input paths for the devices, prefixed with total number of the devices recorded.

 0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       Number of devices                       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
|             Device paths              +-+-+-+-+-+-+-+-+-+-+-+-+
|                                       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


Similarly, each device path is a length-prefixed string. Unlike C strings, the path is not NULL-terminated.

 0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                     Length of device path                     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
|                          Device path                          |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


The recording has been made from a specific gamepad. All events in the stream will be for that device only. The section describes the device properties that will be used to create a virtual input device using /dev/uinput. Please see linux/input.h header in the Linux kernel source for more information about the fields in this section.

 0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|            bustype            |             vendor            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|            product            |            version            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                         name_length                           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
|                             name                              |
|                                                               |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                            ev_bits                            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
|                                                               |
|                       key_bits (96 bytes)                     |
|                                                               |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
|                                                               |
|                       rel_bits (96 bytes)                     |
|                                                               |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
|                                                               |
|                       abs_bits (96 bytes)                     |
|                                                               |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                          num_absinfo                          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                                                               |
|                                                               |
|                                                               |
|                                                               |
|                        absinfo entries                        |
|                                                               |
|                                                               |
|                                                               |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


Each absinfo entry consists of six 32 bit values. The number of entries is determined by the abs_bits field.

 0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                            value                              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                           minimum                             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                           maximum                             |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                             fuzz                              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                             flat                              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                          resolution                           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


### Event structure¶

The majority of an revent recording will be made up of the input events that were recorded. The event stream is prefixed with the number of events in the stream.

Each event entry structured as follows:

• An unsigned integer representing which device from the list of device paths this event is for (zero indexed). E.g. Device ID = 3 would be the 4th device in the list of device paths.
• A signed integer representing the number of seconds since “epoch” when the event was recorded.
• A signed integer representing the microseconds part of the timestamp.
• An unsigned integer representing the event type
• An unsigned integer representing the event code
• An unsigned integer representing the event value

 0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|           Device ID           |        Timestamp Seconds      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                       Timestamp Seconds (cont.)               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   Timestamp Seconds (cont.)   |        stamp Micoseconds      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|              Timestamp Micoseconds (cont.)                    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp Micoseconds (cont.) |          Event Type           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|          Event Code           |          Event Value          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|       Event Value (cont.)     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


### Parser¶

WA has a parser for revent recordings. This can be used to work with revent recordings in scripts. Here is an example:

from wlauto.utils.revent import ReventRecording

with ReventRecording('/path/to/recording.revent') as recording:
print "Recording: {}".format(recording.filepath)
print "There are {} input events".format(recording.num_events)
print "Over a total of {} seconds".format(recording.duration)