4.13.1 Context class

The Context class provides the interface to the tablet driver.

class Context( ): The class takes no parameters. All the context attributes will be initialized with the default values as provided by the driver.

Context attributes:

name: Context name.

options

Specifies options for the context and must be a combination of the following flags:

Option	Description
`CXO_SYSTEM`	The context is a system cursor context
`CXO_PEN`	The context is a Pen Windows (and system cursor) context
`CXO_MESSAGES`	The context sends WT_PACKET messages to its owner
`CXO_MARGIN`	The input context will have a margin
`CXO_MGNINSIDE`	The margin will be inside the specified context
`CXO_CSRMESSAGES`	The context sends WT_CSRCHANGE messages to its owner

status

Specifies current status conditions for the context. The status value is a combination of the following bits:

Status bit	Description
`CXS_DISABLED`	The context has been disabled
`CXS_OBSCURED`	The context is at least partially obscured by another context
`CXS_ONTOP`	The context is the topmost context

locks

Specifies which attributes of the context the application wishes to be locked. The value can be a combination of the following bits:

Lock	Description
`CXL_INSIZE`	The input size cannot be changed
`CXL_INASPECT`	The input aspect ration cannot be changed
`CXL_MARGIN`	The margin options cannot be changed
`CXL_SENSITIVITY`	The sensitivity settings for x, y and z cannot be changed
`CXL_SYSOUT`	The system pointing control variables cannot be changed

msgbase: Base number for the message IDs.

device: Specifies the device whose input the context processes.

pktrate: Specifies the desired packet report rate in Hertz. Once the context is open, this field will contain the actual report rate.

pktdata: Specifies which optional data items will be in packets returned from the context.

pktmode: Specifies whether the packet data items will be returned in absolute or relative mode. If the item's bit is set in this field, the item will be returned in relative mode.

movemask: Specifies which packet data items can generate move events in the context.

btndnmask: Specifies the buttons for which button press events will be processed in the context.

btnupmask: Specifies the buttons for which button release events will be processed in the context.

inorgx: Specifies the origin of the context's input area in the tablet's native coordinates along the x axis.

inorgy: Specifies the origin of the context's input area in the tablet's native coordinates along the y axis.

inorgz: Specifies the origin of the context's input area in the tablet's native coordinates along the z axis.

inextx: Specifies the extent of the context's input area in the tablet's native coordinates along the x axis.

inexty: Specifies the extent of the context's input area in the tablet's native coordinates along the y axis.

inextz: Specifies the extent of the context's input area in the tablet's native coordinates along the z axis.

outorgx: Specifies the extent of the context's output area in context output coordinates along the x axis.

outorgy: Specifies the extent of the context's output area in context output coordinates along the y axis.

outorgz: Specifies the extent of the context's output area in context output coordinates along the z axis.

outextx: Specifies the extent of the context's output area in context output coordinates along the x axis.

outexty: Specifies the extent of the context's output area in context output coordinates along the y axis.

outextz: Specifies the extent of the context's output area in context output coordinates along the z axis.

sensx: Specifies the relative-mode sensitivity factor for the x axis.

sensy: Specifies the relative-mode sensitivity factor for the y axis.

sensz: Specifies the relative-mode sensitivity factor for the z axis.

sysmode: Specifies the system cursor tracking mode. True specifies absolute, False means relative.

sysorgx: Specifies the origin in screen coordinates of the screen mapping area for system cursor tracking.

sysorgy: Specifies the origin in screen coordinates of the screen mapping area for system cursor tracking.

sysextx: Specifies the extent in screen coordinates of the screen mapping area for system cursor tracking.

sysexty: Specifies the extent in screen coordinates of the screen mapping area for system cursor tracking.

syssensx: Specifies the system-cursor relative-mode sensitivity factor for the x axis.

syssensy: Specifies the system-cursor relative-mode sensitivity factor for the y axis.

Other attributes:

queuesize: The number of packets the context's queue can hole. Setting this attribute may result in an exception if the queue size could not be set. In such a case, you must try again with a smaller value.

id_packet: The final id of the WT_PACKET message.

id_csrchange: The final id of the WT_CSRCHANGE message.

id_ctxopen: The final id of the WT_CTXOPEN message.

id_ctxclose: The final id of the WT_CTXCLOSE message.

id_ctxupdate: The final id of the WT_CTXUPDATE message.

id_ctxoverlap: The final id of the WT_CTXOVERLAP message.

id_proximity: The final id of the WT_PROXIMITY message.

id_infochange: The final id of the WT_INFOCHANGE message.

Methods:

open( hwnd, enable): Opens the context. hwnd is the window handle (as integer) of the window that owns the context and that receives messages from the context. enable is a boolean that specifies whether the context will immediately begin processing input data.
Set the context attributes to the desired values before calling this method. Modifying context attributes after the context was opened is possible with the set() method.

restore( hwnd, saveinfo, enable): This method is equivalent to the open() method with the only difference that it takes the context attributes via the binary saveinfo string which was returned by the save() method in a previous session.

close( ): Closes the context if it was open (or do nothing if it was already closed or if it was not open at all).

save( ): Returns a binary saveinfo string containing the current context state. This string can be used as argument to the restore() method.

packet( serial): Returns the packet with the specified serial number.

enable( flag): If flag is True the context is enabled, otherwise it is disabled. Returns True if the operation was successful.

overlap( totop): If totop is True the context will become the topmost context, otherwise it will be send to the bottom. Returns True if the operation was successful.

config( hwnd=0): Prompts the user for changes to the context via a dialog box. hwnd is the window handle of the window that will be parent of the dialog. If it is 0, the context owning window will be used. The return value is True if the context was changed.

get( ): Update the local context attributes.

set( ): Update the tablet context with the settings stored in the local context attributes.

packetsGet( maxpkts): Return the next maxpkts packets and remove them from the queue.

packetsPeek( maxpkts): Return the next maxpkts packets without removing them from the queue.

dataGet( begin, end, maxpkts): Return all packets with serial numbers between begin and end inclusive and remove them from the queue. However, no more than maxpkts packets are returned. The return value is a 2-tuple (numpackets, packet list) where numpackets is the total number of packets found in the queue between begin and end.

dataPeek( begin, end, maxpkts): This is the same as dataGet() but it doesn't remove the packets from the queue.

queuePacketsEx( ): Returns the serial numbers of the oldest and newest packets currently in the queue.