tkselect.c

linux系统下的音频通信

/* 
 * tkSelect.c --
 *
 *	This file manages the selection for the Tk toolkit,
 *	translating between the standard X ICCCM conventions
 *	and Tcl commands.
 *
 * Copyright (c) 1990-1993 The Regents of the University of California.
 * Copyright (c) 1994-1995 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * SCCS: @(#) tkSelect.c 1.57 96/05/03 10:52:40
 */

#include "tkInt.h"
#include "tkSelect.h"

/*
 * When a selection handler is set up by invoking "selection handle",
 * one of the following data structures is set up to hold information
 * about the command to invoke and its interpreter.
 */

typedef struct {
    Tcl_Interp *interp;		/* Interpreter in which to invoke command. */
    int cmdLength;		/* # of non-NULL bytes in command. */
    char command[4];		/* Command to invoke.  Actual space is
				 * allocated as large as necessary.  This
				 * must be the last entry in the structure. */
} CommandInfo;

/*
 * When selection ownership is claimed with the "selection own" Tcl command,
 * one of the following structures is created to record the Tcl command
 * to be executed when the selection is lost again.
 */

typedef struct LostCommand {
    Tcl_Interp *interp;		/* Interpreter in which to invoke command. */
    char command[4];		/* Command to invoke.  Actual space is
				 * allocated as large as necessary.  This
				 * must be the last entry in the structure. */
} LostCommand;

/*
 * Shared variables:
 */

TkSelInProgress *pendingPtr = NULL;
				/* Topmost search in progress, or
				 * NULL if none. */

/*
 * Forward declarations for procedures defined in this file:
 */

static int		HandleTclCommand _ANSI_ARGS_((ClientData clientData,
			    int offset, char *buffer, int maxBytes));
static void		LostSelection _ANSI_ARGS_((ClientData clientData));
static int		SelGetProc _ANSI_ARGS_((ClientData clientData,
			    Tcl_Interp *interp, char *portion));

/*
 *--------------------------------------------------------------
 *
 * Tk_CreateSelHandler --
 *
 *	This procedure is called to register a procedure
 *	as the handler for selection requests of a particular
 *	target type on a particular window for a particular
 *	selection.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	In the future, whenever the selection is in tkwin's
 *	window and someone requests the selection in the
 *	form given by target, proc will be invoked to provide
 *	part or all of the selection in the given form.  If
 *	there was already a handler declared for the given
 *	window, target and selection type, then it is replaced.
 *	Proc should have the following form:
 *
 *	int
 *	proc(clientData, offset, buffer, maxBytes)
 *	    ClientData clientData;
 *	    int offset;
 *	    char *buffer;
 *	    int maxBytes;
 *	{
 *	}
 *
 *	The clientData argument to proc will be the same as
 *	the clientData argument to this procedure.  The offset
 *	argument indicates which portion of the selection to
 *	return:  skip the first offset bytes.  Buffer is a
 *	pointer to an area in which to place the converted
 *	selection, and maxBytes gives the number of bytes
 *	available at buffer.  Proc should place the selection
 *	in buffer as a string, and return a count of the number
 *	of bytes of selection actually placed in buffer (not
 *	including the terminating NULL character).  If the
 *	return value equals maxBytes, this is a sign that there
 *	is probably still more selection information available.
 *
 *--------------------------------------------------------------
 */

void
Tk_CreateSelHandler(tkwin, selection, target, proc, clientData, format)
    Tk_Window tkwin;		/* Token for window. */
    Atom selection;		/* Selection to be handled. */
    Atom target;		/* The kind of selection conversions
				 * that can be handled by proc,
				 * e.g. TARGETS or STRING. */
    Tk_SelectionProc *proc;	/* Procedure to invoke to convert
				 * selection to type "target". */
    ClientData clientData;	/* Value to pass to proc. */
    Atom format;		/* Format in which the selection
				 * information should be returned to
				 * the requestor. XA_STRING is best by
				 * far, but anything listed in the ICCCM
				 * will be tolerated (blech). */
{
    register TkSelHandler *selPtr;
    TkWindow *winPtr = (TkWindow *) tkwin;

    if (winPtr->dispPtr->multipleAtom == None) {
	TkSelInit(tkwin);
    }

    /*
     * See if there's already a handler for this target and selection on
     * this window.  If so, re-use it.  If not, create a new one.
     */

    for (selPtr = winPtr->selHandlerList; ; selPtr = selPtr->nextPtr) {
	if (selPtr == NULL) {
	    selPtr = (TkSelHandler *) ckalloc(sizeof(TkSelHandler));
	    selPtr->nextPtr = winPtr->selHandlerList;
	    winPtr->selHandlerList = selPtr;
	    break;
	}
	if ((selPtr->selection == selection) && (selPtr->target == target)) {

	    /*
	     * Special case:  when replacing handler created by
	     * "selection handle", free up memory.  Should there be a
	     * callback to allow other clients to do this too?
	     */

	    if (selPtr->proc == HandleTclCommand) {
		ckfree((char *) selPtr->clientData);
	    }
	    break;
	}
    }
    selPtr->selection = selection;
    selPtr->target = target;
    selPtr->format = format;
    selPtr->proc = proc;
    selPtr->clientData = clientData;
    if (format == XA_STRING) {
	selPtr->size = 8;
    } else {
	selPtr->size = 32;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_DeleteSelHandler --
 *
 *	Remove the selection handler for a given window, target, and
 *	selection, if it exists.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The selection handler for tkwin and target is removed.  If there
 *	is no such handler then nothing happens.
 *
 *----------------------------------------------------------------------
 */

void
Tk_DeleteSelHandler(tkwin, selection, target)
    Tk_Window tkwin;			/* Token for window. */
    Atom selection;			/* The selection whose handler
					 * is to be removed. */
    Atom target;			/* The target whose selection
					 * handler is to be removed. */
{
    TkWindow *winPtr = (TkWindow *) tkwin;
    register TkSelHandler *selPtr, *prevPtr;
    register TkSelInProgress *ipPtr;

    /*
     * Find the selection handler to be deleted, or return if it doesn't
     * exist.
     */ 

    for (selPtr = winPtr->selHandlerList, prevPtr = NULL; ;
	    prevPtr = selPtr, selPtr = selPtr->nextPtr) {
	if (selPtr == NULL) {
	    return;
	}
	if ((selPtr->selection == selection) && (selPtr->target == target)) {
	    break;
	}
    }

    /*
     * If ConvertSelection is processing this handler, tell it that the
     * handler is dead.
     */

    for (ipPtr = pendingPtr; ipPtr != NULL; ipPtr = ipPtr->nextPtr) {
	if (ipPtr->selPtr == selPtr) {
	    ipPtr->selPtr = NULL;
	}
    }

    /*
     * Free resources associated with the handler.
     */

    if (prevPtr == NULL) {
	winPtr->selHandlerList = selPtr->nextPtr;
    } else {
	prevPtr->nextPtr = selPtr->nextPtr;
    }
    if (selPtr->proc == HandleTclCommand) {
	ckfree((char *) selPtr->clientData);
    }
    ckfree((char *) selPtr);
}

/*
 *--------------------------------------------------------------
 *
 * Tk_OwnSelection --
 *
 *	Arrange for tkwin to become the owner of a selection.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	From now on, requests for the selection will be directed
 *	to procedures associated with tkwin (they must have been
 *	declared with calls to Tk_CreateSelHandler).  When the
 *	selection is lost by this window, proc will be invoked
 *	(see the manual entry for details).  This procedure may
 *	invoke callbacks, including Tcl scripts, so any calling
 *	function should be reentrant at the point where
 *	Tk_OwnSelection is invoked.
 *
 *--------------------------------------------------------------
 */

void
Tk_OwnSelection(tkwin, selection, proc, clientData)
    Tk_Window tkwin;		/* Window to become new selection
				 * owner. */
    Atom selection;		/* Selection that window should own. */
    Tk_LostSelProc *proc;	/* Procedure to call when selection
				 * is taken away from tkwin. */
    ClientData clientData;	/* Arbitrary one-word argument to
				 * pass to proc. */
{
    register TkWindow *winPtr = (TkWindow *) tkwin;
    TkDisplay *dispPtr = winPtr->dispPtr;
    TkSelectionInfo *infoPtr;
    Tk_LostSelProc *clearProc = NULL;
    ClientData clearData = NULL;	/* Initialization needed only to
					 * prevent compiler warning. */
    
    
    if (dispPtr->multipleAtom == None) {
	TkSelInit(tkwin);
    }
    Tk_MakeWindowExist(tkwin);

    /*
     * This code is somewhat tricky.  First, we find the specified selection
     * on the selection list.  If the previous owner is in this process, and
     * is a different window, then we need to invoke the clearProc.  However,
     * it's dangerous to call the clearProc right now, because it could
     * invoke a Tcl script that wrecks the current state (e.g. it could
     * delete the window).  To be safe, defer the call until the end of the
     * procedure when we no longer care about the state.
     */

    for (infoPtr = dispPtr->selectionInfoPtr; infoPtr != NULL;
	    infoPtr = infoPtr->nextPtr) {
	if (infoPtr->selection == selection) {
	    break;
	}
    }
    if (infoPtr == NULL) {
	infoPtr = (TkSelectionInfo*) ckalloc(sizeof(TkSelectionInfo));
	infoPtr->selection = selection;
	infoPtr->nextPtr = dispPtr->selectionInfoPtr;
	dispPtr->selectionInfoPtr = infoPtr;
    } else if (infoPtr->clearProc != NULL) {
	if (infoPtr->owner != tkwin) {
	    clearProc = infoPtr->clearProc;
	    clearData = infoPtr->clearData;
	} else if (infoPtr->clearProc == LostSelection) {
	    /*
	     * If the selection handler is one created by "selection own",
	     * be sure to free the record for it;  otherwise there will be
	     * a memory leak.
	     */

	    ckfree((char *) infoPtr->clearData);
	}
    }

    infoPtr->owner = tkwin;
    infoPtr->serial = NextRequest(winPtr->display);
    infoPtr->clearProc = proc;
    infoPtr->clearData = clientData;

    /*
     * Note that we are using CurrentTime, even though ICCCM recommends against
     * this practice (the problem is that we don't necessarily have a valid
     * time to use).  We will not be able to retrieve a useful timestamp for
     * the TIMESTAMP target later.
     */

    infoPtr->time = CurrentTime;

    /*
     * Note that we are not checking to see if the selection claim succeeded.
     * If the ownership does not change, then the clearProc may never be
     * invoked, and we will return incorrect information when queried for the
     * current selection owner.
     */

    XSetSelectionOwner(winPtr->display, infoPtr->selection, winPtr->window,
	    infoPtr->time);

    /*
     * Now that we are done, we can invoke clearProc without running into
     * reentrancy problems.
     */

    if (clearProc != NULL) {
	(*clearProc)(clearData);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_ClearSelection --
 *
 *	Eliminate the specified selection on tkwin's display, if there is one.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The specified selection is cleared, so that future requests to retrieve
 *	it will fail until some application owns it again.  This procedure
 *	invokes callbacks, possibly including Tcl scripts, so any calling
 *	function should be reentrant at the point Tk_ClearSelection is invoked.
 *
 *----------------------------------------------------------------------
 */

void
Tk_ClearSelection(tkwin, selection)
    Tk_Window tkwin;		/* Window that selects a display. */
    Atom selection;		/* Selection to be cancelled. */
{
    register TkWindow *winPtr = (TkWindow *) tkwin;
    TkDisplay *dispPtr = winPtr->dispPtr;
    TkSelectionInfo *infoPtr;
    TkSelectionInfo *prevPtr;
    TkSelectionInfo *nextPtr;
    Tk_LostSelProc *clearProc = NULL;
    ClientData clearData = NULL;	/* Initialization needed only to
					 * prevent compiler warning. */

    if (dispPtr->multipleAtom == None) {
	TkSelInit(tkwin);
    }

    for (infoPtr = dispPtr->selectionInfoPtr, prevPtr = NULL;
	     infoPtr != NULL; infoPtr = nextPtr) {
	nextPtr = infoPtr->nextPtr;
	if (infoPtr->selection == selection) {
	    if (prevPtr == NULL) {
		dispPtr->selectionInfoPtr = nextPtr;
	    } else {
		prevPtr->nextPtr = nextPtr;
	    }
	    break;
	}
	prevPtr = infoPtr;
    }
    
    if (infoPtr != NULL) {
	clearProc = infoPtr->clearProc;
	clearData = infoPtr->clearData;
	ckfree((char *) infoPtr);
    }
    XSetSelectionOwner(winPtr->display, selection, None, CurrentTime);

    if (clearProc != NULL) {
	(*clearProc)(clearData);
    }
}

/*
 *--------------------------------------------------------------
 *
 * Tk_GetSelection --
 *
 *	Retrieve the value of a selection and pass it off (in
 *	pieces, possibly) to a given procedure.
 *
 * Results:
 *	The return value is a standard Tcl return value.
 *	If an error occurs (such as no selection exists)
 *	then an error message is left in interp->result.
 *
 * Side effects:
 *	The standard X11 protocols are used to retrieve the
 *	selection.  When it arrives, it is passed to proc.  If
 *	the selection is very large, it will be passed to proc
 *	in several pieces.  Proc should have the following
 *	structure:
 *
 *	int
 *	proc(clientData, interp, portion)
 *	    ClientData clientData;
 *	    Tcl_Interp *interp;
 *	    char *portion;
 *	{