Volume 7A: XView Programming Manual

Example 18-11. Sample conversion procedure

–

SelectionConvertProc (continued)

} else

/* Call the default selection conversion procedure.

* It handles requests for any pre-registered

* conversions, including TARGETS.

*/

return(sel_convert_proc(sel, target, data, length, format));

}

18.8.1 The Done Procedure

The selection done procedure is called after each conversion has happened. This gives the

application a chance to free up memory.

void

SelectionDoneProc(sel, data, target)

Selection_owner sel;

Xv_opaque data;

Atom target;

{

if (target == ATOM(server, "STRING"))

free((char *)data);

}

Note, in this example, we only alloc data for string requests so we only free it for string data.

18.8.2 The Lose Procedure

The lose procedure lets the selection package lose ownership a selection gracefully. For

example, the user can can be informed that the selection was lost, as in the following

example.

void

SelectionLoseProc(sel)

Selection_owner sel;

{

xv_set(frame, FRAME_LEFT_FOOTER, "Lost Selection...", NULL);

}

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18.9 Sample Selection Requestor Program

Example 18-12 shows three panel items that are created to handle the selection rank, the tar-

get(s) request, and initiating the request. Below them is a textsw that displays the response

to the request.

Example 18-12. Sample selection requestor program

–

sel_req.c

/*

* sel_req.c: Example of how to make requests to a selection owner for

* the selection contents.

*/

#include <stdio.h>

#include <X11/Xlib.h>

#include <xview/xview.h>

#include <xview/frame.h>

#include <xview/panel.h>

#include <xview/textsw.h>

#include <xview/font.h>

#include <xview/sel_pkg.h>

Frame frame;

Textsw textsw;

Xv_Server server;

Panel panel;

Panel_item p_selection,

p_target,

p_request;

Selection_requestor sel;

#define TARGETS 1<<0

#define TIMESTAMP 1<<1

#define LENGTH 1<<2

#define STRING 1<<3

#define DELETE 1<<4

#define LINE "--------------------------------------------"

#define ATOM(server, name) (Atom)xv_get(server, SERVER_ATOM, name)

main(argc, argv)

int argc;

char **argv;

{

void MakeRequest(),

SelectionReplyProc(),

RequestChoice();

Xv_Font font;

server = xv_init(XV_INIT_ARGC_PTR_ARGV, &argc, argv, NULL);

frame = xv_create((Window)NULL, FRAME,

XV_X, 10,

XV_Y, 10,

XV_LABEL, "Selection Requestor Example",

NULL);

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Example 18-12. Sample selection requestor program

–

sel_req.c (continued)

panel = xv_create(frame, PANEL,

PANEL_LAYOUT, PANEL_VERTICAL,

NULL);

p_selection = xv_create(panel, PANEL_TEXT,

PANEL_LABEL_STRING, "Selection:",

PANEL_VALUE_DISPLAY_LENGTH, 40,

PANEL_NOTIFY_PROC, MakeRequest,

NULL);

p_target = xv_create(panel, PANEL_TOGGLE,

PANEL_LABEL_STRING, "Request:",

PANEL_NOTIFY_PROC, RequestChoice,

PANEL_CHOICE_STRINGS, "TARGETS",

"TIMESTAMP",

"LENGTH",

"STRING",

"DELETE",

NULL,

NULL);

p_request = xv_create(panel, PANEL_BUTTON,

PANEL_LABEL_STRING, "Make Request",

PANEL_NOTIFY_PROC, MakeRequest,

PANEL_ITEM_X, xv_cols(panel, 20),

NULL);

window_fit(panel);

textsw = xv_create(frame, TEXTSW,

XV_X, 0,

XV_FONT, font,

WIN_BELOW, panel,

NULL);

/* Create a selection requestor object. */

sel = xv_create(panel, SELECTION_REQUESTOR,

SEL_REPLY_PROC, SelectionReplyProc,

NULL);

window_fit(frame);

xv_main_loop(frame);

exit(0);

}

In the requestor application, a PANEL_TEXT item is created where the selection rank can be

entered by the user. Next, a set of nonexclusive toggle buttons are created to allow the user to

choose the target type for the conversion by the selection owner. A “Make Request” button

is created that will send a request to the selection owner every time it is pressed. A TEXTSW is

created to display the output of the request and lastly, a selection-requestor object, sel, is

created.

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Example 18-13 shows the notify procedure associated for the selection requestor example

sel_req.c. It sets and/or appends selection types to the selection requestor based on the

choices selected by the user.

Example 18-13. Sample requestor notify procedure

void

RequestChoice(item, value, event)

Panel_item item;

unsigned int value;

Event *event;

{

int set = False;

/* Build the request based on the toggle items the user has selected. */

if (value & TARGETS) {

if (set)

xv_set(sel, SEL_APPEND_TYPE_NAMES, "TARGETS", NULL, NULL);

else

xv_set(sel, SEL_TYPE_NAME, "TARGETS", NULL);

set = True;

}

if (value & TIMESTAMP) {

if (set)

xv_set(sel, SEL_APPEND_TYPE_NAMES, "TIMESTAMP", NULL, NULL);

else

xv_set(sel, SEL_TYPE_NAME, "TIMESTAMP", NULL);

set = True;

}

if (value & LENGTH) {

if (set)

xv_set(sel, SEL_APPEND_TYPE_NAMES, "LENGTH", NULL, NULL);

else

xv_set(sel, SEL_TYPE_NAME, "LENGTH", NULL);

set = True;

}

if (value & STRING) {

if (set)

xv_set(sel, SEL_APPEND_TYPE_NAMES, "STRING", NULL, NULL);

else

xv_set(sel, SEL_TYPE_NAME, "STRING", NULL);

set = True;

}

if (value & DELETE) {

if (set)

xv_set(sel, SEL_APPEND_TYPE_NAMES, "DELETE", NULL, NULL);

else

xv_set(sel, SEL_TYPE_NAME, "DELETE", NULL);

set = True;

}

}

426 XView Programming Manual

The notify procedure, shown in Example 18-14, is associated with the “Make Request” but-

ton. It initiates the request by doing three things:

• Getting the selection rank.

• Setting the selection rank.

• Posting a selection request.

Example 18-14. Sample make request notify procedure

void

MakeRequest(item, event)

Panel_item item;

Event *event;

{

if (item == p_selection) {

char *rank = NULL;

/* Set the rank of the selection we are */

/* going to make requests to. */

rank = (char *)xv_get(item, PANEL_VALUE);

xv_set(sel, SEL_RANK_NAME, rank,

NULL);

}

else {

/* Post a non-blocking request to the selection owner. */

sel_post_req(sel);

textsw_erase(textsw, 0, TEXTSW_INFINITY);

}

}

18.9.0.1 Sample reply procedure

Example 18-15 shows the reply procedure for sel_req.c.

Example 18-15. Selection reply procedure

void

SelectionReplyProc(sel, target, type, value, length, format)

Selection_requestor sel;

Atom target;

Atom type;

Xv_opaque value;

unsigned long length;

int format;

{

if (length == SEL_ERROR) {

SelectionError(sel, target, *(int *)value);

return;

}

if (target == ATOM(server, "TARGETS")) {

textsw_insert(textsw,

"Holder will convert the following targets:\n", 43);

/* 43 is the size of the string */

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