XTEST Extension Protocol

Version 2.2 X Consortium Standard

Kieron Drake
UniSoft Ltd.

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1. Overview

This extension is a minimal set of client and server extensions required to completely test the X11 server with no user intervention.

This extension is not intended to support general journaling and playback of user actions. This is a difficult area [XTrap, 89] as it attempts to synchronize synthetic user interactions with their effects; it is at the higher level of dialogue recording/playback rather than at the strictly lexical level. We are interested only in the latter, simpler, case. A more detailed discussion and justification of the extension functionality is given in [Drake, 91].

We are aiming only to provide a minimum set of facilities that solve immediate testing and validation problems. The testing extension itself needs testing, where possible, and so should be as simple as possible.

We have also tried to:

•	Confine the extension to an appropriate high level within the server to minimize portability problems. In practice this means that the extension should be at the DIX level or use the DIX/DDX interface, or both. This has effects, in particular, on the level at which "input synthesis" can occur.
•	Minimize the changes required in the rest of the server.
•	Minimize performance penalties on normal server operation.

2. Description

The functions provided by this extension fall into two groups:

Client Operations
These routines manipulate otherwise hidden client-side behavior. The actual implementation will depend on the details of the actual language binding and what degree of request buffering, GContext caching, and so on, is provided. In the C binding, defined in ‘‘XTEST Extension Library’’, routines are provided to access the internals of two opaque data structures --GCs and Visuals-- and to discard any requests pending within the output buffer of a connection. The exact details can be expected to differ for other language bindings.

Server Requests
The first of these requests is similar to that provided in most extensions: it allows a client to specify a major and minor version number to the server and for the server to respond with major and minor versions of its own. The remaining two requests allow the following:

	•	Access to an otherwise "write-only" server resource: the cursor associated with a given window
	•	Perhaps most importantly, limited synthesis of input device events, almost as if a cooperative user had moved the pointing device or pressed a key or button.

3. Types

The following types are used in the request and event definitions in subsequent sections:

FAKE_EVENT_TYPE {KeyPress, KeyRelease, MotionNotify, ButtonPress, ButtonRelease}

FAKE_EVENT		[type: FAKE_EVENT_TYPE,
		detail: BYTE,
		time: TIME,
		root: WINDOW,
		rootX, rootY: INT16]

CURSOR {CurrentCursor, None} or a cursor as defined by the X11 Protocol.

4. Client Operations

These are abstract definitions of functionality. They refer to client-side objects such as "GC" and "VISUAL" that are quoted to denote their abstract nature. Concrete versions of these functions are defined only for particular language bindings. In some circumstances a particular language binding may not implement the relevant abstract type or may provide it as a transparent, rather than opaque, type, with the result that the corresponding function does not make sense or is not required, respectively. __ │
XTestSetGContextOfGC

gc: "GC"
gid: GCONTEXT │__

Sets the GCONTEXT within the "GC" gc to have the value specified by gid. __ │
XTestSetVisualIDOfVisual

visual: "VISUAL"
visualid: VISUALID │__

Sets the VISUALID within the "VISUAL" visual to have the value specified by visualid. __ │
XTestDiscard

dpy: "CONNECTION"

status: BOOL │__

Discards any requests that are present in the request buffer associated with the "CONNECTION" dpy. The status returned is True if there were one or more requests in the buffer and False otherwise.

5. Server Requests __ │
XTestGetVersion

clientMajorVersion: CARD16
clientMinorVersion: CARD16

serverMajorVersion: CARD16
serverMinorVersion: CARD16

Errors: Length │__

This request can be used to ensure that the server version of the XTEST extension is usable by the client. This document defines major version two (2), minor version one (1). __ │
XTestCompareCursor

window: WINDOW
cursor-id: CURSOR or CurrentCursor or None

same: BOOL

Errors: Window, Length, Cursor │__

This request looks up the cursor associated with the window and compares it with either the null cursor if cursor-id is None, or the current cursor (that is, the one being displayed), or the cursor whose ID is cursor-id, and returns the result of the comparison in same. __ │
XTestFakeInput

events: LISTofFAKE_EVENT

Errors: Window, Length, Alloc, Value │__

This request simulates the limited set of core protocol events within the set FAKE_EVENT_TYPE. Only the following event fields, defined in FAKE_EVENT, are interpreted:

type	This must be one of KeyPress, KeyRelease, MotionNotify, ButtonPress, or ButtonRelease, or else a Value error occurs.
detail	For key events, this field is interpreted as the physical keycode. If the keycode is less than min-keycode or greater than max-keycode, as returned in the connection setup, then a Value error occurs. For button events, this field is interpreted as the physical (or core) button, meaning it will be mapped to the corresponding logical button according to the most recent SetPointerMapping request. If the button number is less than one or greater than the number of physical buttons, then a Value error occurs. For motion events, if this field is True, then rootX and rootY are relative distances from the current pointer location; if this field is False, then they are absolute positions.
time	This is either CurrentTime (meaning no delay) or the delay in milliseconds that the server should wait before simulating this event. No other requests from this client will be processed until this delay, if any, has expired and subsequent processing of the simulated event has been completed.
root	In the case of motion events this field is the ID of the root window on which the new motion is to take place. If None is specified, the root window of the screen the pointer is currently on is used instead. If this field is not a valid window, then a Window error occurs.

rootX & rootY
In the case of motion events these fields indicate relative distance or absolute pointer coordinates, according to the setting of detail. If the specified coordinates are off-screen, the closest on-screen coordinates will be substituted.

When the simulated event(s) are processed, they cause event propagation, passive grab activation, and so on, just as if the corresponding input device action had occurred. However, motion events might not be recorded in the motion history buffer.

For the currently supported event types, the event list must have length one, otherwise a BadLength error occurs. __ │
XTestGrabControl

impervious: BOOL │__

If impervious is True, then the executing client becomes impervious to server grabs; that is, it can continue executing requests even if another client grabs the server. If impervious is False, then the executing client returns to the normal state of being susceptible to server grabs.

6. Encoding

Please refer to the X11 Protocol Encoding document as this document uses conventions established there.

The name of this extension is ‘‘XTEST’’.

6.1. New Types

FAKE_EVENT_TYPE

	2	KeyPress
	3	KeyRelease
	4	ButtonPress
	5	ButtonRelease
	6	MotionNotify

NOTE that the above values are defined to be the same as those for the corresponding core protocol event types.

6.2. Requests

XTestGetVersion

1	CARD8	opcode
1	0	xtest opcode
2	2	request length
1	CARD8	client major version
1		unused
2	CARD16	client minor version

1	1	Reply
1	CARD8	server major version
2	CARD16	sequence number
4	0	reply length
2	CARD16	server minor version
22		unused

XTestCompareCursor

1	CARD8		opcode
1	1		xtest opcode
2	3		request length
4	WINDOW		window
4	CURSOR		cursor-id
	0	None
	1	CurrentCursor

1	1	Reply
1	BOOL	cursors are the same
2	CARD16	sequence number
4	0	reply length
24		unused

XTestFakeInput

1	CARD8		opcode
1	2		xtest opcode
2	1+(1*8)		request length
1	FAKE_EVENT_TYPE		fake device event type
1	BYTE		detail: button or keycode
2			unused
4	TIME		delay (milliseconds)
	0	CurrentTime
4	WINDOW		root window for MotionNotify
	0	None
8			unused
2	INT16		x position for MotionNotify
2	INT16		y position for MotionNotify
8			unused

XTestGrabControl

1	CARD8	opcode
1	3	xtest opcode
2	2	request length
1	BOOL	impervious
3		unused

7. References

Annicchiarico, D., et al., XTrap: The XTrap Architecture. Digital Equipment Corporation, July 1991.

Drake, K. J., Some Proposals for a Minimum X11 Testing Extension. UniSoft Ltd., June 1991.