NAME
XGetWindowProperty, XListProperties, XChangeProperty, XRotateWindowProperties, XDeleteProperty - obtain and change window propertiesSYNTAX
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, _Xconst
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 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.
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)libX11 1.8.4 | X Version 11 |