399 lines
16 KiB
Markdown
399 lines
16 KiB
Markdown
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DBus Interface
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--------------
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Tuhi has two main components. A DBus session daemon that handles
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communication with the device and a GTK application that provides the
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graphical user interface.
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The DBus session daemon uses the following interface:
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```
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org.freedesktop.tuhi1.Manager
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Property: Devices (ao)
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Array of object paths to known (previously registered, but not necessarily
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connected) devices. Note that a "registered" device is one that has been
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initialized via the Wacom SmartPad custom protocol. A device does not
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need to be paired over Bluetooth to register.
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Property: Searching (b)
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Indicates whether the daemon is currently searching for devices.
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This property is set to True when a StartSearching() request initiates
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the search for device connections. When the StartSearching() request
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completes upon timeout, or when StopSearching() is called, the property
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is set to False.
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When a pariable device is found, the UnregisteredDevice signal is sent to
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the caller that initiated the search process.
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Read-only
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Property: JSONDataVersions (au)
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Specifies the JSON file format versions the server supports. The
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client must request one of these versions in Device.GetJSONData().
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Read-only, constant
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Method: StartSearch() -> ()
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Start searching for available devices ready for registering
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for an unspecified timeout. When the timeout expires or an error
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occurs, a SearchStopped signal is sent indicating success or error.
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If a client that successfully initated a listening process calls
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StartSearching() again, that call is ignored and no signal is
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generated for that call.
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Method: StopSearch() -> ()
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Stop listening to available devices ready for registering. If called after
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StartSearch() and before a SearchStopped signal has been received,
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this method triggers the SearchStopped signal. That signal indicates
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success or an error.
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If this method is called before StartSearch() or after the
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SearchStopped signal, it is ignored and no signal is generated.
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Note that between calling StopSearch() and the SearchStopped signal
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arriving, UnregisteredDevice signals may still arrive.
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Signal: UnregisteredDevice(o)
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Indicates that a device can be registered. This signal may be
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sent after a StartSearch() call and before SearchStopped(). This
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signal is sent once per available device and only to the client that
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initiated the search process with StartSearch.
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When this signal is sent, a org.freedesktop.tuhi1.Device object was
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created, the object path is the argument to this signal.
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A client must immediately call Register() on that object if
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registering with that object is desired. See the documentation for
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that interface for details.
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When the search timeout expires, the device may be removed by the
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daemon again. Note that until the device is registered, the device is not
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listed in the managers Devices property.
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Signal: SearchStopped(i)
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Sent when the search has stopped. An argument of 0 indicates a
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successful termination of the search process, either when a device
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has been registered or the timeout expired.
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If the errno is -EAGAIN, the daemon is already searching for devices
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on behalf of another client. In this case, this client should wait for
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the Searching property to change and StartSearching() once the
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property is set to False.
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Once this signal has been sent, all devices announced through
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UnregisteredDevice signals should be considered invalidated. Attempting to
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Register() one of the devices after the SearchStopped() signal may result
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in an error.
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In case of error, the argument is a negative errno.
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org.freedesktop.tuhi1.Device
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Interface to a device known by tuhi. Each object in Manager.Devices
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implements this interface.
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Property: BlueZDevice (o)
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Object path to the org.bluez.Device1 device that is this device.
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Read-only
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Property: Dimensions (uu)
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The physical dimensions (width, height) in µm
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Read-only
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Property: BatteryPercent (u)
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The last known battery charge level in percent. This charge level is
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only accurate when the BatteryState is other than Unknown.
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When the BatteryState is Unknown and BatteryPercent is nonzero, the
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value is the last known percentage value.
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Read-only
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Property: BatteryState (u)
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An enum describing the battery state. Permitted enum values are
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0: Unknown
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1: Charging
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2: Discharging
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'Unknown' may refer to a state that could not be read, a state
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that has not yet been updated, or a state that has not updated within
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a daemon-internal time period. Thus, a device that is connected but
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does not regularly send battery updates may eventually switch to
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'Unknown'.
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Read-only
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Property: DrawingsAvailable (at)
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An array of timestamps of the available drawings. The timestamp of
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each drawing can be used as argument to GetJSONData(). Timestamps are
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in seconds since the Epoch and may be used to display information to
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the user or sort data.
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Read-only
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Property: Listening (b)
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Indicates whether the daemon is currently listening for the device.
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This property is set to True when a StartListening() request initiates
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the search for device connections. When the StartListening() request
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completes upon timeout, or when StopListening() is called, the property
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is set to False.
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When the user press the button on the device, the daemon connects
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to the device, downloads all drawings from the device and disconnects
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from the device.
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If successfull, the drawings are deleted from the device. The data is
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held by the daemon in non-persistent storage until the daemon is stopped
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or we run out of memory, whichever happens earlier.
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Use GetJSONData() to retrieve the data from the daemon.
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DO NOT RELY ON THE DAEMON FOR PERMANENT STORAGE
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When drawings become available from the device, the DrawingsAvailable
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property updates to the number of available drawings.
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When the button is pressed multiple times, any new data is appended
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to the existing list of drawings as long as this property is True.
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Read-only
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Property: Live(b)
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Indicates whether the device is currently in Live mode. When in live
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mode, the device does not store drawings internally for a later sync
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but instead fowards the events immediately, similar to a traditional
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graphics tablet. See StartLive() for more details.
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Read-only
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Method: Register() -> (i)
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Register the device. If the device is already registered, calls to
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this method immediately return success.
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Otherwise, the device is registered and this function returns success (0)
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or a negative errno on failure.
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Method: StartListening() -> ()
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Listen for data from this device and connect to the device when it
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becomes available. The daemon listens to the device until the client
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calls StopListening() or the client disconnects, whichever happens
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earlier.
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The ListeningStopped signal is sent when the listening terminates,
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either on success or with an error. A client should handle this signal
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to be notified of any errors.
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When the daemon starts listening, the Listening property is updated
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accordingly.
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If a client that successfully initated a listening process calls
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StartListening() again, that call is ignored and no signal is
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generated for that call.
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Method: StopListening() -> ()
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Stop listening for data on this device. If called after
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StartListening(), this method triggers the ListenStopped signal.
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That signal indicates success or an error.
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If this method is called before StartListening() or after the
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ListeningStopped signal, it is ignored and no signal is generated.
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Note that between calling StopListening() and the ListeningStopped
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signal arriving, the property DrawingsAvailable may still be updated
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and it's the responsibility of the client to fetch the JSON data.
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Method: StartLive(fd: h) -> (i)
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Starts live mode on this device. This disables offline storage of
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drawing data on the device and instead switches the device to a mode
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where it immediately reports the pen data, similar to a traditional
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graphics tablet.
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The LiveStopped signal is sent when live mode terminates, either on
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success or with an error. A client should handle this signal to be
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notified of any errors.
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When live mode enables, the Live property is updated accordingly.
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If a client that successfully initated a listening process calls
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StartListening() again, that call is ignored and no signal is
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generated for that call.
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The fd argument is a file descriptor that will be used to forward
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events to. The format is the one used by the Linux kernel's UHID
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device, see linux/uhid.h for details.
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Method: StopLive() - >()
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Stop live mode on this device. If called after StartLive(), this
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method triggers the LiveStopped signal. That signal indicates
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success or an error.
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If this method is called before StartLive() or after the LiveStopped
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signal, it is ignored and no signal is generated.
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Note that between calling StopLive() and the LiveStopped signal
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arriving, the device may still send events. It's the responsibility of
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the client to handle events until the LiveStopped signal arrives.
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Method: GetJSONData(file-version: u, timestamp: t) -> (s)
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Returns a JSON file with the drawings specified by the timestamp
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argument. The requested timestamp must be one of the entries in the
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DrawingsAvailable property value. The file-version argument specifies
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the file format version the client requests. See section JSON FILE
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FORMAT for the format of the returned data.
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Returns a string representing the JSON data from the last drawings or
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the empty string if the timestamp is not available or the file format
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version is outside the server-supported range advertised in
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Manager.JSONDataVersions.
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Signal: ButtonPressRequired()
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Sent when the user is expected to press the physical button on the
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device. A client should display a notification in response, if the
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user does not press the button during the (firmware-specific) timeout
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the current operation will fail.
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Signal: ListeningStopped(i)
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Sent when the listen process has stopped. An argument of 0 indicates a
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successful termination, i.e. in response to the client calling
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StopListening(). Otherwise, the argument is a negative errno
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indicating the type of error.
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If the errno is -EAGAIN, the daemon is already listening to the device
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on behalf of another client. In this case, this client should wait for
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the Listening property to change and StartListening() once the
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property is set to False.
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If the error is -EBADE, the device is not ready for registering/in
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listening mode and registration/listening was requested. In
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this case, the client should indicate to the user that the device
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needs to be registered first or switched to listening mode.
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If the error is -EACCES, the device is not registered with the daemon
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or incorrectly registered. This may happen when the device was
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registered with another host since the last connection.
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The following other errnos may be sent by the daemon:
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-EPROTO: the daemon has encountered a protocol error with the device.
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-ETIME: timeout while communicating with the device.
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These errnos indicate a bug in the daemon, and the client should
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display a message to that effect.
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Signal: LiveStopped(i)
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Sent when live mode is stopped. An argument of 0 indicates a
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successful termination, i.e. in response to the client calling
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StopLive(). Otherwise, the argument is a negative errno
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indicating the type of error.
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If the errno is -EAGAIN, the daemon has already enabled live mode on
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device on behalf of another client. In this case, this client should
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wait for the Live property to change and StartLive() once the property
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is set to False.
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If the error is -EBADE, the device is not ready for live mode, most
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likely because it is in registration mode. In this case, the client
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should indicate to the user that the device needs to be registered
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first.
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If the error is -EACCES, the device is not registered with the daemon
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or incorrectly registered. This may happen when the device was
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registered with another host since the last connection.
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The following other errnos may be sent by the daemon:
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-EPROTO: the daemon has encountered a protocol error with the device.
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-ETIME: timeout while communicating with the device.
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These errnos indicate a bug in the daemon, and the client should
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display a message to that effect.
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Signal: SyncState(i)
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An enum to represent the current synchronization state of the device.
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When on (1), Tuhi is currently trying to download data from the
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device. When off (0), Tuhi is not currently connecting to the device.
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This signal should be used for UI feedback.
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This signal is only send when the device is **not** in Live mode.
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```
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JSON File Format
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----------------
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The current file format version is 1. A server may only support a subset of
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historical file formats, this subset is advertized as list of versions in
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the **org.freedesktop.tuhi1.Manager.JSONDataVersions** property. Likewise, a
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client may only support a subset of the possible formats. A client should
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always pick the highest format supported by both the client and the server.
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Below is the example file format (with comments, not present in the real
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files). The JSON objects are "drawing" (the root object), "strokes",
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"points". Pseudo-code is used to illustrate the objects in the file.
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```
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class Drawing {
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version: uint32
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devicename: string
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dimensions: [uint32, uint32] // x/y physical dimensions in µm
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timestamp: uint64
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strokes: [ Stroke, Stroke, ...]
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}
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```
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The **strokes** list contains all strokes of a single drawing, each stroke
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consisting of a number of **points**.
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```
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class Stroke {
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points: [Point, Point, ...]
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}
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```
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The **points** list contains the actual pen data.
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```
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class Point {
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toffset: uint32
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position: [uint32, uint32]
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pressure: uint32
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}
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```
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An expanded file looks like this:
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```
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{
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"version" : 1, // JSON file format version number
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"devicename": "Wacom Bamboo Spark",
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"dimensions": [ 100000, 200000], // width/height in µm
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"timestamp" : 12345,
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"strokes" : [
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{
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"points": [
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// all items in a point are optional. Unknown dictionary
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// entries must be ignored as future devices may add
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// new axes.
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{ "toffset" : 12366, "position" : [ 100, 200 ], "pressure" : 1000 },
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{ "toffset" : 12368, "pressure" : 800 },
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{ "toffset" : 12366, "position" : [ 120, 202 ] },
|
||
|
|
]
|
||
|
|
},
|
||
|
|
{ "points" : ... }
|
||
|
|
]
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
Units used by this interface
|
||
|
|
----------------------------
|
||
|
|
|
||
|
|
* Physical distances for x/y axes are in µm from the sensor's top-left
|
||
|
|
position. (Note that on the Spark and on the Slate at least, the sensor
|
||
|
|
is turned 90 degrees clockwise, so (0,0) is at the 'natural' top-right
|
||
|
|
corner)
|
||
|
|
* Stylus pressure is normalized to a range of [0, 0xffff], inclusive.
|
||
|
|
* Timestamps are in seconds in unix epoch, time offsets are in ms after the
|
||
|
|
most recent timestamp.
|
||
|
|
|