228 lines
8.1 KiB
Plaintext
228 lines
8.1 KiB
Plaintext
XICHANGEPROPERTY(libmansuffix)
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==============================
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NAME
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----
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XIChangeProperty, XIGetProperty, XIDeleteProperty - change, retrieve
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or delete a device's property.
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SYNOPSIS
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--------
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#include <X11/extensions/XInput2.h>
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void XIChangeProperty( Display* dpy,
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int deviceid,
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Atom property,
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Atom type,
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int format,
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int mode,
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unsigned char *data,
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int num_items)
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void XIDeleteProperty( Display *dpy,
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int deviceid,
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Atom property)
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Status XIGetProperty( Display *dpy,
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int deviceid,
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Atom property,
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long offset,
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long length,
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Bool delete_property,
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Atom type,
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Atom *type_return,
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int *format_return,
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unsigned long *num_items_return,
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unsigned long *bytes_after_return,
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unsigned char **data)
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bytes_after_return
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Returns the number of bytes remaining to be read in the prop-
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erty if a partial read was performed.
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data
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Specifies the property data.
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display
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Specifies the connection to the X server.
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delete_property
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Specifies a Boolean value that determines whether the property
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is to be deleted.
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deviceid
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The device to list the properties for.
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format
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Specifies whether the data should be viewed as a list of
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8-bit, 16-bit, or 32-bit quantities. Possible values are 8,
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16, and 32. This information allows the X server to correctly
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perform byte-swap operations as necessary. If the
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format is 16-bit or 32-bit, you must explicitly cast your
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data pointer to an (unsigned char *) in the call to
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XIChangeProperty.
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format_return
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Returns the actual format of the property.
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length
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Specifies the length in 32-bit multiples of the data to be
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retrieved.
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offset
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Specifies the offset in the specified property (in 32-bit
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quantities) where the data is to be retrieved.
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mode
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One of PropModeAppend, PropModePrepend or PropModeReplace.
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num_items
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Number of items in data in the format specified.
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nitems_return
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Returns the actual number of 8-bit, 16-bit, or 32-bit items
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stored in data.
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property
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Specifies the property name.
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type
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Specifies the type of the property. The X server does not
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interpret the type but simply passes it back to an application
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that later calls XIGetProperty.
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type_return
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Returns the atom identifier that defines the actual type of
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the property.
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DESCRIPTION
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-----------
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The XIGetProperty function returns the actual type of the property;
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the actual format of the property; the number of 8-bit, 16-bit,
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or 32-bit items transferred; the number of bytes remaining to be read
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in the property; and a pointer to the data actually returned.
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XIGetProperty sets the return arguments as follows:
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- If the specified property does not exist for the specified device,
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XIGetProperty returns None to actual_type_return and the
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value zero to actual_format_return and bytes_after_return. The
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nitems_return argument is empty. In this case, the delete argument
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is ignored.
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- If the specified property exists but its type does not match the
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specified type, XIGetProperty returns the actual property
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type to actual_type_return, the actual property format (never
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zero) to actual_format_return, and the property length in bytes
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(even if the actual_format_return is 16 or 32) to
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bytes_after_return. It also ignores the delete argument. The
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nitems_return argument is empty.
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- If the specified property exists and either you assign
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AnyPropertyType to the req_type argument or the specified type
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matches the actual property type, XIGetProperty returns the
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actual property type to actual_type_return and the actual property
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format (never zero) to actual_format_return. It also returns a value
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to bytes_after_return and nitems_return, by defining the following
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values:
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N = length of the stored property in bytes
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I = 4 * offset
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T = N - I
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L = MINIMUM(T, 4 * length)
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A = N - (I + L)
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The returned value starts at byte index I in the property
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(indexing from zero), and its length in bytes is L. If the value
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for long_offset causes L to be negative, a BadValue error results.
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The value of bytes_after_return is A, giving the number of trailing
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unread bytes in the stored property.
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If the returned format is 8, the returned data is represented as a char
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array. If the returned format is 16, the returned data is represented
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as a uint16_t array and should be cast to that type to obtain the ele-
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ments. If the returned format is 32, the returned data is represented
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as a uint32_t array and should be cast to that type to obtain the elements.
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XIGetProperty always allocates one extra byte in prop_return (even
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if the property is zero length) and sets it to zero so that simple
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properties consisting of characters do not have to be copied into yet
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another string before use.
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If delete is True and bytes_after_return is zero, XIGetProperty
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deletes the property from the window and generates an XIPropertyNotify
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event on the window.
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The function returns Success if it executes successfully. To free the
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resulting data, use XFree.
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XIGetProperty can generate BadAtom, BadValue, and BadWindow
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errors.
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The XIChangeProperty function alters the property for the specified device
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and causes the X server to generate a XIPropertyNotify event for that
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device. XIChangeProperty performs the following:
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- If mode is PropModeReplace, XIChangeProperty discards the previous
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property value and stores the new data.
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- If mode is PropModePrepend or PropModeAppend, XIChangeProperty
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inserts the specified data before the beginning of the existing
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data or onto the end of the existing data, respectively. The type
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and format must match the existing property value, or a BadMatch
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error results. If the property is undefined, it is treated as
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defined with the correct type and format with zero-length data.
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If the specified format is 8, the property data must be a char array.
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If the specified format is 16, the property data must be a uint16_t array.
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If the specified format is 32, the property data must be a uint32_t array.
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The lifetime of a property is not tied to the storing client.
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Properties remain until explicitly deleted, until the device is removed,
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or until the server resets. The maximum size of a property is server
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dependent and can vary dynamically depending on the amount of memory
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the server has available. (If there is insufficient space, a BadAlloc
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error results.)
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XIChangeProperty can generate BadAlloc, BadAtom, BadMatch, BadValue, and
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BadDevice errors.
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The XIDeleteProperty function deletes the specified property only if the
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property was defined on the specified device and causes the X server to
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generate a XIPropertyNotify event for the device unless the property does
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not exist.
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XIDeleteProperty can generate BadAtom and BadDevice errors.
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DIAGNOSTICS
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-----------
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BadAlloc
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The server failed to allocate the requested resource or
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server memory.
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BadAtom
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A value for an Atom argument does not name a defined Atom.
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BadValue
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Some numeric value falls outside the range of values accepted
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by the request. Unless a specific range is specified for an
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argument, the full range defined by the argument’s type is
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accepted. Any argument defined as a set of alternatives can
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generate this error.
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BadDevice
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An invalid device was specified. The device does not
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exist.
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BadAtom
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An invalid property was specified. The property does not
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exist.
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SEE ALSO
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--------
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XIListProperties(libmansuffix)
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