| '\" |
| '\" Copyright (c) 1990 The Regents of the University of California. |
| '\" Copyright (c) 1994-1996 Sun Microsystems, Inc. |
| '\" |
| '\" See the file "license.terms" for information on usage and redistribution |
| '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
| '\" |
| '\" RCS: @(#) $Id: CrtErrHdlr.3,v 1.2 1998/09/14 18:22:46 stanton Exp $ |
| '\" |
| '\" The definitions below are for supplemental macros used in Tcl/Tk |
| '\" manual entries. |
| '\" |
| '\" .AP type name in/out ?indent? |
| '\" Start paragraph describing an argument to a library procedure. |
| '\" type is type of argument (int, etc.), in/out is either "in", "out", |
| '\" or "in/out" to describe whether procedure reads or modifies arg, |
| '\" and indent is equivalent to second arg of .IP (shouldn't ever be |
| '\" needed; use .AS below instead) |
| '\" |
| '\" .AS ?type? ?name? |
| '\" Give maximum sizes of arguments for setting tab stops. Type and |
| '\" name are examples of largest possible arguments that will be passed |
| '\" to .AP later. If args are omitted, default tab stops are used. |
| '\" |
| '\" .BS |
| '\" Start box enclosure. From here until next .BE, everything will be |
| '\" enclosed in one large box. |
| '\" |
| '\" .BE |
| '\" End of box enclosure. |
| '\" |
| '\" .CS |
| '\" Begin code excerpt. |
| '\" |
| '\" .CE |
| '\" End code excerpt. |
| '\" |
| '\" .VS ?version? ?br? |
| '\" Begin vertical sidebar, for use in marking newly-changed parts |
| '\" of man pages. The first argument is ignored and used for recording |
| '\" the version when the .VS was added, so that the sidebars can be |
| '\" found and removed when they reach a certain age. If another argument |
| '\" is present, then a line break is forced before starting the sidebar. |
| '\" |
| '\" .VE |
| '\" End of vertical sidebar. |
| '\" |
| '\" .DS |
| '\" Begin an indented unfilled display. |
| '\" |
| '\" .DE |
| '\" End of indented unfilled display. |
| '\" |
| '\" .SO |
| '\" Start of list of standard options for a Tk widget. The |
| '\" options follow on successive lines, in four columns separated |
| '\" by tabs. |
| '\" |
| '\" .SE |
| '\" End of list of standard options for a Tk widget. |
| '\" |
| '\" .OP cmdName dbName dbClass |
| '\" Start of description of a specific option. cmdName gives the |
| '\" option's name as specified in the class command, dbName gives |
| '\" the option's name in the option database, and dbClass gives |
| '\" the option's class in the option database. |
| '\" |
| '\" .UL arg1 arg2 |
| '\" Print arg1 underlined, then print arg2 normally. |
| '\" |
| '\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $ |
| '\" |
| '\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages. |
| .if t .wh -1.3i ^B |
| .nr ^l \n(.l |
| .ad b |
| '\" # Start an argument description |
| .de AP |
| .ie !"\\$4"" .TP \\$4 |
| .el \{\ |
| . ie !"\\$2"" .TP \\n()Cu |
| . el .TP 15 |
| .\} |
| .ta \\n()Au \\n()Bu |
| .ie !"\\$3"" \{\ |
| \&\\$1 \\fI\\$2\\fP (\\$3) |
| .\".b |
| .\} |
| .el \{\ |
| .br |
| .ie !"\\$2"" \{\ |
| \&\\$1 \\fI\\$2\\fP |
| .\} |
| .el \{\ |
| \&\\fI\\$1\\fP |
| .\} |
| .\} |
| .. |
| '\" # define tabbing values for .AP |
| .de AS |
| .nr )A 10n |
| .if !"\\$1"" .nr )A \\w'\\$1'u+3n |
| .nr )B \\n()Au+15n |
| .\" |
| .if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n |
| .nr )C \\n()Bu+\\w'(in/out)'u+2n |
| .. |
| .AS Tcl_Interp Tcl_CreateInterp in/out |
| '\" # BS - start boxed text |
| '\" # ^y = starting y location |
| '\" # ^b = 1 |
| .de BS |
| .br |
| .mk ^y |
| .nr ^b 1u |
| .if n .nf |
| .if n .ti 0 |
| .if n \l'\\n(.lu\(ul' |
| .if n .fi |
| .. |
| '\" # BE - end boxed text (draw box now) |
| .de BE |
| .nf |
| .ti 0 |
| .mk ^t |
| .ie n \l'\\n(^lu\(ul' |
| .el \{\ |
| .\" Draw four-sided box normally, but don't draw top of |
| .\" box if the box started on an earlier page. |
| .ie !\\n(^b-1 \{\ |
| \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' |
| .\} |
| .el \}\ |
| \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' |
| .\} |
| .\} |
| .fi |
| .br |
| .nr ^b 0 |
| .. |
| '\" # VS - start vertical sidebar |
| '\" # ^Y = starting y location |
| '\" # ^v = 1 (for troff; for nroff this doesn't matter) |
| .de VS |
| .if !"\\$2"" .br |
| .mk ^Y |
| .ie n 'mc \s12\(br\s0 |
| .el .nr ^v 1u |
| .. |
| '\" # VE - end of vertical sidebar |
| .de VE |
| .ie n 'mc |
| .el \{\ |
| .ev 2 |
| .nf |
| .ti 0 |
| .mk ^t |
| \h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n' |
| .sp -1 |
| .fi |
| .ev |
| .\} |
| .nr ^v 0 |
| .. |
| '\" # Special macro to handle page bottom: finish off current |
| '\" # box/sidebar if in box/sidebar mode, then invoked standard |
| '\" # page bottom macro. |
| .de ^B |
| .ev 2 |
| 'ti 0 |
| 'nf |
| .mk ^t |
| .if \\n(^b \{\ |
| .\" Draw three-sided box if this is the box's first page, |
| .\" draw two sides but no top otherwise. |
| .ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c |
| .el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c |
| .\} |
| .if \\n(^v \{\ |
| .nr ^x \\n(^tu+1v-\\n(^Yu |
| \kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c |
| .\} |
| .bp |
| 'fi |
| .ev |
| .if \\n(^b \{\ |
| .mk ^y |
| .nr ^b 2 |
| .\} |
| .if \\n(^v \{\ |
| .mk ^Y |
| .\} |
| .. |
| '\" # DS - begin display |
| .de DS |
| .RS |
| .nf |
| .sp |
| .. |
| '\" # DE - end display |
| .de DE |
| .fi |
| .RE |
| .sp |
| .. |
| '\" # SO - start of list of standard options |
| .de SO |
| .SH "STANDARD OPTIONS" |
| .LP |
| .nf |
| .ta 5.5c 11c |
| .ft B |
| .. |
| '\" # SE - end of list of standard options |
| .de SE |
| .fi |
| .ft R |
| .LP |
| See the \\fBoptions\\fR manual entry for details on the standard options. |
| .. |
| '\" # OP - start of full description for a single option |
| .de OP |
| .LP |
| .nf |
| .ta 4c |
| Command-Line Name: \\fB\\$1\\fR |
| Database Name: \\fB\\$2\\fR |
| Database Class: \\fB\\$3\\fR |
| .fi |
| .IP |
| .. |
| '\" # CS - begin code excerpt |
| .de CS |
| .RS |
| .nf |
| .ta .25i .5i .75i 1i |
| .. |
| '\" # CE - end code excerpt |
| .de CE |
| .fi |
| .RE |
| .. |
| .de UL |
| \\$1\l'|0\(ul'\\$2 |
| .. |
| .TH Tk_CreateErrorHandler 3 "" Tk "Tk Library Procedures" |
| .BS |
| .SH NAME |
| Tk_CreateErrorHandler, Tk_DeleteErrorHandler \- handle X protocol errors |
| .SH SYNOPSIS |
| .nf |
| \fB#include <tk.h>\fR |
| .sp |
| Tk_ErrorHandler |
| \fBTk_CreateErrorHandler\fR(\fIdisplay, error, request, minor, proc, clientData\fR) |
| .sp |
| \fBTk_DeleteErrorHandler\fR(\fIhandler\fR) |
| .SH ARGUMENTS |
| .AS "Tk_ErrorHandler" clientData |
| .AP Display *display in |
| Display whose errors are to be handled. |
| .AP int error in |
| Match only error events with this value in the \fIerror_code\fR |
| field. If -1, then match any \fIerror_code\fR value. |
| .AP int request in |
| Match only error events with this value in the \fIrequest_code\fR |
| field. If -1, then match any \fIrequest_code\fR value. |
| .AP int minor in |
| Match only error events with this value in the \fIminor_code\fR |
| field. If -1, then match any \fIminor_code\fR value. |
| .AP Tk_ErrorProc *proc in |
| Procedure to invoke whenever an error event is received for |
| \fIdisplay\fR and matches \fIerror\fR, \fIrequest\fR, and \fIminor\fR. |
| NULL means ignore any matching errors. |
| .AP ClientData clientData in |
| Arbitrary one-word value to pass to \fIproc\fR. |
| .AP Tk_ErrorHandler handler in |
| Token for error handler to delete (return value from a previous |
| call to \fBTk_CreateErrorHandler\fR). |
| .BE |
| |
| .SH DESCRIPTION |
| .PP |
| \fBTk_CreateErrorHandler\fR arranges for a particular procedure |
| (\fIproc\fR) to be called whenever certain protocol errors occur on a |
| particular display (\fIdisplay\fR). Protocol errors occur when |
| the X protocol is used incorrectly, such as attempting to map a window |
| that doesn't exist. See the Xlib documentation for \fBXSetErrorHandler\fR |
| for more information on the kinds of errors that can occur. |
| For \fIproc\fR to be invoked |
| to handle a particular error, five things must occur: |
| .IP [1] |
| The error must pertain to \fIdisplay\fR. |
| .IP [2] |
| Either the \fIerror\fR argument to \fBTk_CreateErrorHandler\fR |
| must have been -1, or the \fIerror\fR argument must match |
| the \fIerror_code\fR field from the error event. |
| .IP [3] |
| Either the \fIrequest\fR argument to \fBTk_CreateErrorHandler\fR |
| must have been -1, or the \fIrequest\fR argument must match |
| the \fIrequest_code\fR field from the error event. |
| .IP [4] |
| Either the \fIminor\fR argument to \fBTk_CreateErrorHandler\fR |
| must have been -1, or the \fIminor\fR argument must match |
| the \fIminor_code\fR field from the error event. |
| .IP [5] |
| The protocol request to which the error pertains must have been |
| made when the handler was active (see below for more information). |
| .PP |
| \fIProc\fR should have arguments and result that match the |
| following type: |
| .CS |
| typedef int Tk_ErrorProc( |
| ClientData \fIclientData\fR, |
| XErrorEvent *\fIerrEventPtr\fR); |
| .CE |
| The \fIclientData\fR parameter to \fIproc\fR is a copy of the \fIclientData\fR |
| argument given to \fBTcl_CreateErrorHandler\fR when the callback |
| was created. Typically, \fIclientData\fR points to a data |
| structure containing application-specific information that is |
| needed to deal with the error. \fIErrEventPtr\fR is |
| a pointer to the X error event. |
| The procedure \fIproc\fR should return an integer value. If it |
| returns 0 it means that \fIproc\fR handled the error completely and there |
| is no need to take any other action for the error. If it returns |
| non-zero it means \fIproc\fR was unable to handle the error. |
| .PP |
| If a value of NULL is specified for \fIproc\fR, all matching errors |
| will be ignored: this will produce the same result as if a procedure |
| had been specified that always returns 0. |
| .PP |
| If more than more than one handler matches a particular error, then |
| they are invoked in turn. The handlers will be invoked in reverse |
| order of creation: most recently declared handler first. |
| If any handler returns 0, then subsequent (older) handlers will |
| not be invoked. If no handler returns 0, then Tk invokes X'es |
| default error handler, which prints an error message and aborts the |
| program. If you wish to have a default handler that deals with errors |
| that no other handler can deal with, then declare it first. |
| .PP |
| The X documentation states that ``the error handler should not call |
| any functions (directly or indirectly) on the display that will |
| generate protocol requests or that will look for input events.'' |
| This restriction applies to handlers declared by \fBTk_CreateErrorHandler\fR; |
| disobey it at your own risk. |
| .PP |
| \fBTk_DeleteErrorHandler\fR may be called to delete a |
| previously-created error handler. The \fIhandler\fR argument |
| identifies the error handler, and should be a value returned by |
| a previous call to \fBTk_CreateEventHandler\fR. |
| .PP |
| A particular error handler applies to errors resulting |
| from protocol requests generated between |
| the call to \fBTk_CreateErrorHandler\fR and the call to |
| \fBTk_DeleteErrorHandler\fR. However, the actual callback |
| to \fIproc\fR may not occur until after the \fBTk_DeleteErrorHandler\fR |
| call, due to buffering in the client and server. |
| If an error event pertains to |
| a protocol request made just before calling \fBTk_DeleteErrorHandler\fR, |
| then the error event may not have been processed |
| before the \fBTk_DeleteErrorHandler\fR |
| call. When this situation arises, Tk will save information about |
| the handler and |
| invoke the handler's \fIproc\fR later when the error event |
| finally arrives. |
| If an application wishes to delete an error handler and know |
| for certain that all relevant errors have been processed, |
| it should first call \fBTk_DeleteErrorHandler\fR and then |
| call \fBXSync\fR; this will flush out any buffered requests and errors, |
| but will result in a performance penalty because |
| it requires communication to and from the X server. After the |
| \fBXSync\fR call Tk is guaranteed not to call any error |
| handlers deleted before the \fBXSync\fR call. |
| .PP |
| For the Tk error handling mechanism to work properly, it is essential |
| that application code never calls \fBXSetErrorHandler\fR directly; |
| applications should use only \fBTk_CreateErrorHandler\fR. |
| |
| .SH KEYWORDS |
| callback, error, event, handler |