Provided by: libx11-doc_1.6.4-3ubuntu0.4_all bug

NAME

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

SYNTAX

       int XGetWindowProperty(Display *display, Window w, Atom property, long long_offset, long long_length,
              Bool delete, Atom req_type, Atom *actual_type_return, int *actual_format_return, unsigned long
              *nitems_return, unsigned long *bytes_after_return, unsigned char **prop_return);

       Atom *XListProperties(Display *display, Window w, int *num_prop_return);

       int XChangeProperty(Display *display, Window w, Atom property, Atom type, int format, int mode, unsigned
              char *data, int nelements);

       int XRotateWindowProperties(Display *display, Window w, Atom properties[], int num_prop, int npositions);

       int XDeleteProperty(Display *display, Window w, Atom property);

ARGUMENTS

       actual_format_return
                 Returns the actual format of the property.

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

       bytes_after_return
                 Returns the number of bytes remaining to be read in the property if a partial read was
                 performed.

       data      Specifies the property data.

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

       display   Specifies the connection to the X server.

       format    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 XChangeProperty.

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

       long_offset
                 Specifies the offset in the specified property (in 32-bit quantities) where the data is to be
                 retrieved.

       mode      Specifies the mode of the operation.  You can pass PropModeReplace, PropModePrepend, or
                 PropModeAppend.

       nelements Specifies the number of elements of the specified data format.

       nitems_return
                 Returns the actual number of 8-bit, 16-bit, or 32-bit items stored in the prop_return data.

       num_prop  Specifies the length of the properties array.

       num_prop_return
                 Returns the length of the properties array.

       npositions
                 Specifies the rotation amount.

       prop_return
                 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).

       property  Specifies the property name.

       properties
                 Specifies the array of properties that are to be rotated.

       req_type  Specifies the atom identifier associated with the property type or AnyPropertyType.

       type      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 XGetWindowProperty.

       w         Specifies the window whose property you want to obtain, change, rotate or delete.

DESCRIPTION

       The 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.  XGetWindowProperty sets the return
       arguments as follows:

       •    If the specified property does not exist for the specified window, XGetWindowProperty returns 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.

       •    If the specified property exists but its type does not match the specified type, 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.

       •    If the specified property exists and either you assign AnyPropertyType to the req_type argument or
            the specified type matches the actual property type, 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:

                 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)

            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 BadValue error results.  The
            value of bytes_after_return is A, giving the number of trailing unread bytes in the stored property.

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

       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.

       If delete is True and bytes_after_return is zero, XGetWindowProperty deletes the property from the window
       and generates a PropertyNotify event on the window.

       The function returns Success if it executes successfully.  To free the resulting data, use XFree.

       XGetWindowProperty can generate BadAtom, BadValue, and BadWindow errors.

       The 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 XFree.

       XListProperties can generate a BadWindow error.

       The XChangeProperty function alters the property for the specified window and causes the X server to
       generate a PropertyNotify event on that window.  XChangeProperty performs the following:

       •    If mode is PropModeReplace, XChangeProperty discards the previous property value and stores the new
            data.

       •    If mode is PropModePrepend or PropModeAppend, 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 BadMatch error results.  If the property is
            undefined, it is treated as defined with the correct type and format with zero-length data.

       If the specified format is 8, the property data must be a char array.  If the specified format is 16, the
       property data must be a short array.  If the specified format is 32, the property data must be a long
       array.

       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 BadAlloc error results.)

       XChangeProperty can generate BadAlloc, BadAtom, BadMatch, BadValue, and BadWindow errors.

       The XRotateWindowProperties function allows you to rotate properties on a window and causes the X server
       to generate 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 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 BadMatch error results.  If a BadAtom or BadMatch error results, no properties
       are changed.

       XRotateWindowProperties can generate BadAtom, BadMatch, and BadWindow errors.

       The XDeleteProperty function deletes the specified property only if the property was defined on the
       specified window and causes the X server to generate a PropertyNotify event on the window unless the
       property does not exist.

       XDeleteProperty can generate BadAtom and BadWindow errors.

DIAGNOSTICS

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

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

       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.

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

SEE ALSO

       XFree(3), XInternAtom(3)
       Xlib - C Language X Interface