Volume 6A: Motif Programming Manual

21.3 An Example

The signal handling problem can also be solved with a timer, using the same approach as with a work procedure. the

source code demonstrates the use of a timer in a more realistic application. The program displays an array of

DrawnButtons that start application programs. While an application is running, the associated button is insensitive, so

that the user can only run one instance of the application. When the application exits, the button is reactivated, so that

the user can select it again. XtSetLanguageProc() is only available in X11R5; there is no corresponding

function in X11R4.

/* app_box.c −− make an array of DrawnButtons that, when activated,

* executes a program. When the program is running, the drawn button

* associated with the program is insensitive. When the program dies,

* reactivate the button so the user can select it again.

*/

#include <Xm/DrawnB.h>

#include <Xm/RowColumn.h>

#include <signal.h>

#ifndef SYSV

#include <sys/wait.h>

#else

#define SIGCHLD SIGCLD

#endif /* SYSV */

#define MAIL_PROG "/bin/mail"

typedef struct {

Widget drawn_w;

char *pixmap_file;

char *exec_argv[6]; /* 6 is arbitrary, but big enough */

int pid;

} ExecItem;

ExecItem prog_list[] = {

{ NULL, "terminal", { "xterm", NULL }, 0 },

{ NULL, "flagup", { "xterm", "−e", MAIL_PROG, NULL }, 0 },

{ NULL, "calculator", { "xcalc", NULL }, 0 },

{ NULL, "xlogo64", { "foo", NULL }, 0 },

};

XtAppContext app; /* application context for the whole program */

GC gc; /* used to render pixmaps in the ...