xqueryextension(3) [hpux man page]
XQueryExtension() XQueryExtension() Name XQueryExtension - get extension information. Synopsis Bool XQueryExtension(display, name, major_opcode_return, first_event_return, first_error_return) Display *display; char *name; int *major_opcode_return; int *first_event_return; int *first_error_return; Arguments display Specifies a connection to an X server; returned from XOpenDisplay(). name Specifies the name of the desired extension. Uppercase or lowercase is important. If the extension name is not in the Host Por- table Character Encoding, the result is implementation-dependent. major_opcode_return Returns the major opcode of the extension, for use in error handling routines. first_event_return Returns the code of the first custom event type created by the extension. first_error_return Returns the code of the first custom error defined by the extension. Returns True if the extension is present, else False. Description XQueryExtension() determines if the named extension is present, and returns True if it is. If so, the routines in the extension can be used just as if they were core Xlib requests, except that they may return new types of events or new error codes. The available extensions can be listed with XListExtensions(). The major_opcode_return for the extension is returned, if it has one. Otherwise, zero is returned. This opcode will appear in errors gen- erated in the extension. If the extension involves additional event types, the base event type code is returned in first_event_return. Otherwise, zero is returned in first_event_return. The format of the events is specific to the extension. If the extension involves additional error codes, the base error code is returned in first_error_return. Otherwise, zero is returned. The format of additional data in the errors is specific to the extension. See Volume One, Chapter 15, Other Programming Techniques, for more information on using extensions, and Volume One, Appendix C, Writing Extensions to X, for information on writing them. See Also XFreeExtensionList(), XListExtensions(). Xlib - Extensions XQueryExtension()
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XQueryExtension(3) X FUNCTIONS XQueryExtension(3) NAME
XQueryExtension, XListExtensions, XFreeExtensionList - list available extensions SYNTAX
Bool XQueryExtension(display, name, major_opcode_return, first_event_return, first_error_return) char **XListExtensions(display, nextensions_return) XFreeExtensionList(list) ARGUMENTS
display Specifies the connection to the X server. name Specifies the extension name. major_opcode_return Returns the major opcode. first_event_return Returns the first event code, if any. first_error_return Returns the first error code, if any. nextensions_return Returns the number of extensions listed. list Specifies the list of extension names. DESCRIPTION
The XQueryExtension function determines if the named extension is present. If the extension is not present, XQueryExtension returns False; otherwise, it returns True. If the extension is present, XQueryExtension returns the major opcode for the extension to major_opcode_return; otherwise, it returns zero. Any minor opcode and the request formats are specific to the extension. If the extension involves additional event types, XQueryExtension returns the base event type code to first_event_return; otherwise, it returns zero. The format of the events is specific to the extension. If the extension involves additional error codes, XQueryExtension returns the base error code to first_error_return; otherwise, it returns zero. The format of additional data in the errors is specific to the extension. If the extension name is not in the Host Portable Character Encoding the result is implementation-dependent. Uppercase and lowercase mat- ter; the strings ``thing'', ``Thing'', and ``thinG'' are all considered different names. The XListExtensions function returns a list of all extensions supported by the server. If the data returned by the server is in the Latin Portable Character Encoding, then the returned strings are in the Host Portable Character Encoding. Otherwise, the result is implementa- tion-dependent. The XFreeExtensionList function frees the memory allocated by XListExtensions. X Version 11 libX11 1.2.1 XQueryExtension(3)