MirOS Manual: XChangeProperty(3), XDeleteProperty(3), XGetWindowProperty(3), XListProperties(3), XRotateWindowProperties(3)


XGetWindowProperty(3X11) XLIB FUNCTIONS  XGetWindowProperty(3X11)

NAME

     XGetWindowProperty, XListProperties, XChangeProperty, XRota-
     teWindowProperties, XDeleteProperty - obtain and change win-
     dow properties

SYNTAX

     int XGetWindowProperty(Display *display, Window w, Atom pro-
          perty, 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 for-
          mat, 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 pro-
          perty);

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. Pos-
               sible 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.

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XGetWindowProperty(3X11) XLIB FUNCTIONS  XGetWindowProperty(3X11)

     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 PropModeAp-
               pend.

     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.

     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 XGetWin-
               dowProperty.

     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

XFree86                   Version 4.5.0                         2

XGetWindowProperty(3X11) XLIB FUNCTIONS  XGetWindowProperty(3X11)

     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 speci-
          fied 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 argu-
          ment. The nitems_return argument is empty.

     +    If the specified property exists and either you assign
          AnyPropertyType to the req_type argument or the speci-
          fied type matches the actual property type, XGetWin-
          dowProperty 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 pro-
          perty (indexing from zero), and its length in bytes is
          L. If the value for long_offset causes L to be nega-
          tive, 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 ele-
     ments.

XFree86                   Version 4.5.0                         3

XGetWindowProperty(3X11) XLIB FUNCTIONS  XGetWindowProperty(3X11)

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

     If delete is True and bytes_after_return is zero, XGetWin-
     dowProperty deletes the property from the window and gen-
     erates 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 Pro-
     pertyNotify 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.

XFree86                   Version 4.5.0                         4

XGetWindowProperty(3X11) XLIB FUNCTIONS  XGetWindowProperty(3X11)

     (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 proper-
     ties 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 nposi-
     tions). If npositions mod N is nonzero, the X server gen-
     erates 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 BadA-
     tom 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 gen-
               erate this error.

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

SEE ALSO

     XFree(3X11), XInternAtom(3X11)
     Xlib - C Language X Interface

XFree86                   Version 4.5.0                         5

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