Volume 6A: Motif Programming Manual

Atom *type_return;

XtPointer *value_return;

unsigned long *length_return;

int *format_return;

{

Display *dpy;

Atom FILE_CONTENTS, FILE_NAME, MOTIF_DROP;

XtPointer ptr;

Widget label;

int i;

char *text;

struct stat s_buf;

FILE *fp;

long length;

String str;

/* intern the Atoms for data targets */

dpy = XtDisplay (widget);

FILE_CONTENTS = XmInternAtom (dpy, "FILE_CONTENTS", False);

FILE_NAME = XmInternAtom (dpy, "FILE_NAME", False);

MOTIF_DROP = XmInternAtom (dpy, "_MOTIF_DROP", False);

/* check if we are dealing with a drop */

if (*selection != MOTIF_DROP)

return False;

/* get the drag source widget */

XtVaGetValues (widget, XmNclientData, &ptr, NULL);

label = (Widget) ptr;

if (label == NULL)

return False;

/* get the index into the file array from XmNuserData from the

* drag source widget.

*/

XtVaGetValues (label, XmNuserData, &ptr, NULL);

i = (int) ptr;

/* this routine processes only file contents and file name */

if (*target == FILE_CONTENTS) {

/* get the contents of the file */

if (stat (files[i].file_name, &s_buf) == −1 ||

(s_buf.st_mode & S_IFMT) != S_IFREG ||

!(fp = fopen (files[i].file_name, "r")))

return False;

length = s_buf.st_size;

if (!(text = XtMalloc ((unsigned) (length + 1))))

return False;

else if (fread (text, sizeof (char), length, fp) != length)

return False;

else

text[length] = 0;

fclose (fp);

/* format the value for transfer */

*type_return = FILE_CONTENTS;

*value_return = (XtPointer) text;

*length_return = length;

*format_return = 8;

19 Drag and Drop 19.4 ...