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.\"

.ds xT X Toolkit Intrinsics \- C Language Interface

.ds xW Athena X Widgets \- C Language X Toolkit Interface

.ds xL Xlib \- C Language X Interface

.ds xC Inter-Client Communication Conventions Manual

.na

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.ny0

.TH XGetWindowProperty __libmansuffix__ __xorgversion__ "XLIB FUNCTIONS"

.SH NAME

XGetWindowProperty, XListProperties, XChangeProperty, XRotateWindowProperties, XDeleteProperty \- obtain and change window properties

.SH SYNTAX

.HP

int XGetWindowProperty\^(\^Display *\fIdisplay\fP\^, Window \fIw\fP\^, Atom

\fIproperty\fP\^, long \fIlong_offset\fP\^, long \fIlong_length\fP\^, Bool

\fIdelete\fP\^, Atom \fIreq_type\fP\^, Atom *\fIactual_type_return\fP\^, int

*\fIactual_format_return\fP\^, unsigned long *\fInitems_return\fP\^, unsigned

long *\fIbytes_after_return\fP\^, unsigned char **\fIprop_return\fP\^); 

.HP

Atom *XListProperties\^(\^Display *\fIdisplay\fP\^, Window \fIw\fP\^, int

*\fInum_prop_return\fP\^); 

.HP

int XChangeProperty\^(\^Display *\fIdisplay\fP\^, Window \fIw\fP\^, Atom

\fIproperty\fP\^, Atom \fItype\fP\^, int \fIformat\fP\^, int \fImode\fP\^,

unsigned char *\fIdata\fP\^, int \fInelements\fP\^); 

.HP

int XRotateWindowProperties\^(\^Display *\fIdisplay\fP\^, Window \fIw\fP\^,

Atom \fIproperties\fP\^[]\^, int \fInum_prop\fP\^, int \fInpositions\fP\^); 

.HP

int XDeleteProperty\^(\^Display *\fIdisplay\fP\^, Window \fIw\fP\^, Atom

\fIproperty\fP\^); 

.SH ARGUMENTS

.IP \fIactual_format_return\fP 1i

Returns the actual format of the property.

.IP \fIactual_type_return\fP 1i

Returns the atom identifier  that defines the actual type of the property.

.IP \fIbytes_after_return\fP 1i

Returns the number of bytes remaining to be read in the property if 

a partial read was performed.

.IP \fIdata\fP 1i

Specifies the property data.

.IP \fIdelete\fP 1i

Specifies a Boolean value that determines whether the property is deleted.

.IP \fIdisplay\fP 1i

Specifies the connection to the X server.

.IP \fIformat\fP 1i

Specifies whether the data should be viewed as a list

of 8-bit, 16-bit, or 32-bit quantities.

Possible values are 8, 16, and 32.

This information allows the X server to correctly perform

byte-swap operations as necessary.

If the format is 16-bit or 32-bit,

you must explicitly cast your data pointer to an (unsigned char *) in the call

to 

.ZN XChangeProperty .

.IP \fIlong_length\fP 1i

Specifies the length in 32-bit multiples of the data to be retrieved.

.IP \fIlong_offset\fP 1i

Specifies the offset in the specified property (in 32-bit quantities) 

where the data is to be retrieved.

.\" Changed name of this file to prop_mode.a on 1/13/87

.IP \fImode\fP 1i

Specifies the mode of the operation.

You can pass

.ZN PropModeReplace ,

.ZN PropModePrepend ,

or

.ZN PropModeAppend .

.IP \fInelements\fP 1i

Specifies the number of elements of the specified data format.

.IP \fInitems_return\fP 1i

Returns the actual number of 8-bit, 16-bit, or 32-bit items 

stored in the prop_return data.

.IP \fInum_prop\fP 1i

Specifies the length of the properties array.

.IP \fInum_prop_return\fP 1i

Returns the length of the properties array.

.IP \fInpositions\fP 1i

Specifies the rotation amount.

.IP \fIprop_return\fP 1i

Returns the data in the specified format.

If the returned format is 8, the returned data is represented as a

char array. If the returned format is 16, the returned data is

represented as a array of short int type and should be cast to that

type to obtain the elements. If the returned format is 32, the

property data will be stored as an array of longs (which in a 64-bit

application will be 64-bit values that are padded in the upper 4 bytes).

.IP \fIproperty\fP 1i

Specifies the property name.

.IP \fIproperties\fP 1i

Specifies the array of properties that are to be rotated.

.IP \fIreq_type\fP 1i

Specifies the atom identifier associated with the property type or

.ZN AnyPropertyType .

.IP \fItype\fP 1i

Specifies the type of the property.

The X server does not interpret the type but simply

passes it back to an application that later calls 

.ZN XGetWindowProperty .

.ds Wi whose property you want to obtain, change, rotate or delete

.IP \fIw\fP 1i

Specifies the window \*(Wi.

.SH DESCRIPTION

The

.ZN XGetWindowProperty

function returns the actual type of the property; the actual format of the property;

the number of 8-bit, 16-bit, or 32-bit items transferred; the number of bytes remaining

to be read in the property; and a pointer to the data actually returned.

.ZN XGetWindowProperty

sets the return arguments as follows:

.IP \(bu 5

If the specified property does not exist for the specified window,

.ZN XGetWindowProperty 

returns 

.ZN None

to actual_type_return and the value zero to 

actual_format_return and bytes_after_return.

The nitems_return argument is empty.

In this case, the delete argument is ignored.

.IP \(bu 5

If the specified property exists 

but its type does not match the specified type,

.ZN XGetWindowProperty 

returns the actual property type to actual_type_return, 

the actual property format (never zero) to actual_format_return, 

and the property length in bytes

(even if the actual_format_return is 16 or 32) 

to bytes_after_return.

It also ignores the delete argument.

The nitems_return argument is empty.

.IP \(bu 5

If the specified property exists and either you assign 

.ZN AnyPropertyType 

to the req_type argument or the specified type matches the actual property type,

.ZN XGetWindowProperty 

returns the actual property type to actual_type_return and the actual

property format (never zero) to actual_format_return. 

It also returns a value to bytes_after_return and nitems_return, by 

defining the following

values:

.IP

.nf

	N = actual length of the stored property in bytes

	     (even if the format is 16 or 32)

	I = 4 * long_offset

	T = N - I

	L = MINIMUM(T, 4 * long_length)

	A = N - (I + L)

.fi

.IP

The returned value starts at byte index I in the property (indexing

from zero), and its length in bytes is L.

If the value for long_offset causes L to be negative,

a

.ZN BadValue

error results. 

The value of bytes_after_return is A, 

giving the number of trailing unread bytes in the stored property.

.LP

If the returned format is 8, the returned data is represented as a

.ZN char

array.

If the returned format is 16, the returned data is represented as a

.ZN short

array and should be cast to that type to obtain the elements.

If the returned format is 32, the returned data is represented as a

.ZN long

array and should be cast to that type to obtain the elements.

.LP

.ZN XGetWindowProperty

always allocates one extra byte in prop_return 

(even if the property is zero length) 

and sets it to zero so that simple properties consisting of characters

do not have to be copied into yet another string before use.

.LP

If delete is 

.ZN True 

and bytes_after_return is zero, 

.ZN XGetWindowProperty

deletes the property 

from the window and generates a 

.ZN PropertyNotify 

event on the window.

.LP

The function returns

.ZN Success

if it executes successfully.

To free the resulting data,

use

.ZN XFree .

.LP

.ZN XGetWindowProperty

can generate

.ZN BadAtom ,

.ZN BadValue ,

and

.ZN BadWindow 

errors.

.LP

The

.ZN XListProperties

function returns a pointer to an array of atom properties that are defined for 

the specified window or returns NULL if no properties were found.

To free the memory allocated by this function, use

.ZN XFree .

.LP

.ZN XListProperties

can generate a

.ZN BadWindow 

error.

.LP

The

.ZN XChangeProperty

function alters the property for the specified window and

causes the X server to generate a

.ZN PropertyNotify

event on that window.

.ZN XChangeProperty

performs the following:

.IP \(bu 5

If mode is

.ZN PropModeReplace ,

.ZN XChangeProperty

discards the previous property value and stores the new data.

.IP \(bu 5

If mode is

.ZN PropModePrepend

or

.ZN PropModeAppend ,

.ZN XChangeProperty

inserts the specified data before the beginning of the existing data

or onto the end of the existing data, respectively.

The type and format must match the existing property value,

or a

.ZN BadMatch

error results.

If the property is undefined, 

it is treated as defined with the correct type and

format with zero-length data.

.LP

If the specified format is 8, the property data must be a

.ZN char

array.

If the specified format is 16, the property data must be a

.ZN short

array.

If the specified format is 32, the property data must be a

.ZN long

array.

.LP

The lifetime of a property is not tied to the storing client.

Properties remain until explicitly deleted, until the window is destroyed,

or until the server resets.

For a discussion of what happens when the connection to the X server is closed,

see section 2.6. 

The maximum size of a property is server dependent and can vary dynamically

depending on the amount of memory the server has available.

(If there is insufficient space, a

.ZN BadAlloc

error results.)

.LP

.ZN XChangeProperty

can generate

.ZN BadAlloc ,

.ZN BadAtom ,

.ZN BadMatch ,

.ZN BadValue ,

and

.ZN BadWindow 

errors.

.LP

The

.ZN XRotateWindowProperties

function allows you to rotate properties on a window and causes

the X server to generate

.ZN PropertyNotify

events.

If the property names in the properties array are viewed as being numbered 

starting from zero and if there are num_prop property names in the list,

then the value associated with property name I becomes the value associated 

with property name (I + npositions) mod N for all I from zero to N \- 1.

The effect is to rotate the states by npositions places around the virtual ring

of property names (right for positive npositions, 

left for negative npositions).

If npositions mod N is nonzero,

the X server generates a

.ZN PropertyNotify

event for each property in the order that they are listed in the array.

If an atom occurs more than once in the list or no property with that 

name is defined for the window,

a 

.ZN BadMatch 

error results.

If a 

.ZN BadAtom 

or 

.ZN BadMatch 

error results,

no properties are changed.

.LP

.ZN XRotateWindowProperties

can generate

.ZN BadAtom ,

.ZN BadMatch ,

and

.ZN BadWindow 

errors.

.LP

The

.ZN XDeleteProperty

function deletes the specified property only if the

property was defined on the specified window

and causes the X server to generate a

.ZN PropertyNotify

event on the window unless the property does not exist.

.LP

.ZN XDeleteProperty

can generate

.ZN BadAtom

and

.ZN BadWindow 

errors.

.SH DIAGNOSTICS

.TP 1i

.ZN BadAlloc

The server failed to allocate the requested resource or server memory.

.TP 1i

.ZN BadAtom

A value for an Atom argument does not name a defined Atom.

.TP 1i

.ZN BadValue

Some numeric value falls outside the range of values accepted by the request.

Unless a specific range is specified for an argument, the full range defined

by the argument's type is accepted.  Any argument defined as a set of

alternatives can generate this error.

.TP 1i

.ZN BadWindow

A value for a Window argument does not name a defined Window.

.SH "SEE ALSO"

XFree(__libmansuffix__),

XInternAtom(__libmansuffix__)

.br

\fI\*(xL\fP