diff options
Diffstat (limited to 'tk8.6/doc/CrtSelHdlr.3')
-rw-r--r-- | tk8.6/doc/CrtSelHdlr.3 | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/tk8.6/doc/CrtSelHdlr.3 b/tk8.6/doc/CrtSelHdlr.3 new file mode 100644 index 0000000..2292ccc --- /dev/null +++ b/tk8.6/doc/CrtSelHdlr.3 @@ -0,0 +1,116 @@ +'\" +'\" Copyright (c) 1990-1994 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. +'\" +.TH Tk_CreateSelHandler 3 4.0 Tk "Tk Library Procedures" +.so man.macros +.BS +.SH NAME +Tk_CreateSelHandler, Tk_DeleteSelHandler \- arrange to handle requests for a selection +.SH SYNOPSIS +.nf +\fB#include <tk.h>\fR +.sp +\fBTk_CreateSelHandler\fR(\fItkwin, selection, target, proc, clientData, format\fR) +.sp +\fBTk_DeleteSelHandler\fR(\fItkwin, selection, target\fR) +.SH ARGUMENTS +.AS Tk_SelectionProc clientData +.AP Tk_Window tkwin in +Window for which \fIproc\fR will provide selection information. +.AP Atom selection in +The name of the selection for which \fIproc\fR will provide +selection information. +.AP Atom target in +Form in which \fIproc\fR can provide the selection (e.g. STRING +or FILE_NAME). Corresponds to \fItype\fR arguments in \fBselection\fR +commands. +.AP Tk_SelectionProc *proc in +Procedure to invoke whenever the selection is owned by \fItkwin\fR +and the selection contents are requested in the format given by +\fItarget\fR. +.AP ClientData clientData in +Arbitrary one-word value to pass to \fIproc\fR. +.AP Atom format in +If the selection requestor is not in this process, \fIformat\fR determines +the representation used to transmit the selection to its +requestor. +.BE +.SH DESCRIPTION +.PP +\fBTk_CreateSelHandler\fR arranges for a particular procedure +(\fIproc\fR) to be called whenever \fIselection\fR is owned by +\fItkwin\fR and the selection contents are requested in the +form given by \fItarget\fR. +\fITarget\fR should be one of +the entries defined in the left column of Table 2 of the +X Inter-Client Communication Conventions Manual (ICCCM) or +any other form in which an application is willing to present +the selection. The most common form is STRING. +.PP +\fIProc\fR should have arguments and result that match the +type \fBTk_SelectionProc\fR: +.CS +typedef int \fBTk_SelectionProc\fR( + ClientData \fIclientData\fR, + int \fIoffset\fR, + char *\fIbuffer\fR, + int \fImaxBytes\fR); +.CE +The \fIclientData\fR parameter to \fIproc\fR is a copy of the +\fIclientData\fR argument given to \fBTk_CreateSelHandler\fR. +Typically, \fIclientData\fR points to a data +structure containing application-specific information that is +needed to retrieve the selection. \fIOffset\fR specifies an +offset position into the selection, \fIbuffer\fR specifies a +location at which to copy information about the selection, and +\fImaxBytes\fR specifies the amount of space available at +\fIbuffer\fR. \fIProc\fR should place a NULL-terminated string +at \fIbuffer\fR containing \fImaxBytes\fR or fewer characters +(not including the terminating NULL), and it should return a +count of the number of non-NULL characters stored at +\fIbuffer\fR. If the selection no longer exists (e.g. it once +existed but the user deleted the range of characters containing +it), then \fIproc\fR should return \-1. +.PP +When transferring large selections, Tk will break them up into +smaller pieces (typically a few thousand bytes each) for more +efficient transmission. It will do this by calling \fIproc\fR +one or more times, using successively higher values of \fIoffset\fR +to retrieve successive portions of the selection. If \fIproc\fR +returns a count less than \fImaxBytes\fR it means that the entire +remainder of the selection has been returned. If \fIproc\fR's return +value is \fImaxBytes\fR it means there may be additional information +in the selection, so Tk must make another call to \fIproc\fR to +retrieve the next portion. +.PP +\fIProc\fR always returns selection information in the form of a +character string. However, the ICCCM allows for information to +be transmitted from the selection owner to the selection requestor +in any of several formats, such as a string, an array of atoms, an +array of integers, etc. The \fIformat\fR argument to +\fBTk_CreateSelHandler\fR indicates what format should be used to +transmit the selection to its requestor (see the middle column of +Table 2 of the ICCCM for examples). If \fIformat\fR is not +STRING, then Tk will take the value returned by \fIproc\fR and divided +it into fields separated by white space. If \fIformat\fR is ATOM, +then Tk will return the selection as an array of atoms, with each +field in \fIproc\fR's result treated as the name of one atom. For +any other value of \fIformat\fR, Tk will return the selection as an +array of 32-bit values where each field of \fIproc\fR's result is +treated as a number and translated to a 32-bit value. In any event, +the \fIformat\fR atom is returned to the selection requestor along +with the contents of the selection. +.PP +If \fBTk_CreateSelHandler\fR is called when there already exists a +handler for \fIselection\fR and \fItarget\fR on \fItkwin\fR, then the +existing handler is replaced with a new one. +.PP +\fBTk_DeleteSelHandler\fR removes the handler given by \fItkwin\fR, +\fIselection\fR, and \fItarget\fR, if such a handler exists. +If there is no such handler then it has no effect. +.SH KEYWORDS +format, handler, selection, target |