Volume 7A: XView Programming Manual

Example F-2. The scroll_cells2.c program (continued)

xv_set(vert_scrollbar,

SCROLLBAR_OBJECT_LENGTH, CELLS_PER_COL,

SCROLLBAR_PAGE_LENGTH, page_h,

SCROLLBAR_VIEW_LENGTH, page_h,

NULL);

}

F.3 menu_dir2.c

In Chapter 11, Menus, the program menu_dir.c demonstrates the use of an XView menu in a

canvas subwindow. A menu is brought up with the MENU mouse button and displays menu

choices representing the files in the directory. The problem with menu_dir.c is that the entire

menu cascade is created for all the subdirectories at the very beginning of the program. If the

directory stack is very deep, it could take a very long time to build. You could also run out of

memory in the process. Further, if the contents of the directory tree is dynamic, the menu

entries could become invalid over time.

These problems are solved in menu_dir2.c because it creates only the top-level menu. For

each directory entry under the top-level, rather than creating an associated pullright menu, a

MENU_GEN_PULLRIGHT procedure is specified. This routine creates that menu only at the

time it is needed. So, when the user invokes the menu and tries to descend into a submenu

representing a subdirectory in the directory tree, only then is the directory entry searched and

a new submenu created. When the user backs out of the menu, the menu is des-

troyed—attempting to re-enter the submenu causes the process to be repeated.

An exercise for the ambitious programmer would be to modify this program so that the sub-

menus are not destroyed until the entire menu cascade has been dismissed. This enhance-

ment would optimize the perceived performance of the program for the user because, once a

directory subpath has been searched and a menu created, the menu is cached so that re-entry

into the same submenu would be instantaneous.

Example F-3. The menu_dir2.c program

/*

* menu_dir2.c -

* Demonstrate the use of an XView menu in a canvas subwindow.

* A menu is brought up with the MENU mouse button and displays

* menu choices representing the files in the directory. If a

* directory entry is found, a new pullright item is created with

* that subdir as the pullright menu’s contents. This implementation

* creates directories on an as-needed basis. Thus, we provide a

* MENU_GEN_PULLRIGHT procedure.

*

* argv[1] indicates which directory to start from.

*/

#include <xview/xview.h>

#include <xview/canvas.h>

#include <sys/stat.h>

#include <sys/dir.h>

Example Programs

Example Programs 723

Example F-3. The menu_dir2.c program (continued)

#include <X11/Xos.h>

#ifndef MAXPATHLEN

#include <sys/param.h>

#endif /* MAXPATHLEN */

Frame frame;

main(argc,argv)

int argc;

char *argv[ ];

{

Canvas canvas;

extern void exit();

void my_event_proc();

Menu menu;

Menu_item mi, add_path_to_menu();

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

frame = (Frame)xv_create(NULL, FRAME,

FRAME_LABEL, argv[1]? argv[1 ] : "cwd",

FRAME_SHOW_FOOTER, TRUE,

NULL);

canvas = (Canvas)xv_create(frame, CANVAS,

FRAME_LABEL, argv[0 ],

XV_WIDTH, 400,

XV_HEIGHT, 100,

NULL);

mi = add_path_to_menu(argc > 1? argv[1 ] : ".");

menu = (Menu)xv_get(mi, MENU_PULLRIGHT);

/* We no longer need the item since we have the menu from it */

xv_destroy(mi);

/* associate the menu to the canvas win for easy etreival */

xv_set(canvas_paint_window(canvas),

WIN_CONSUME_EVENTS, WIN_MOUSE_BUTTONS, NULL,

WIN_EVENT_PROC, my_event_proc,

WIN_CLIENT_DATA, menu,

NULL);

window_fit(frame);

window_main_loop(frame);

}

/*

* my_action_proc - display the selected item in the frame footer.

*/

void

my_action_proc(menu, menu_item)

Menu menu;

Menu_item menu_item;

{

xv_set(frame,

FRAME_LEFT_FOOTER, xv_get(menu_item, MENU_STRING),

NULL);

724 XView Programming Manual

Example F-3. The menu_dir2.c program (continued)

}

/*

* Call menu_show() to display menu on right mouse button push.

*/

void

my_event_proc(canvas, event)

Canvas canvas;

Event *event;

{

if ((event_id(event) == MS_RIGHT) && event_is_down(event)) {

Menu menu = (Menu)xv_get(canvas, WIN_CLIENT_DATA);

menu_show(menu, canvas, event, NULL);

}

}

/*

* return an allocated char * that points to the last item in a path.

*/

char *

getfilename(path)

char *path;

{

char *p;

if (p = rindex(path, ’/’))

p++;

else

p = path;

return strcpy(malloc(strlen(p)+1), p);

}

/* gen_pullright() is called in the following order:

* Pullright menu needs to be displayed. (MENU_PULLRIGHT)

* Menu is about to be dismissed (MENU_DISPLAY_DONE)

* User made a selection (before menu notify function)

* After the notify routine has been called.

* The above order is done whether or not the user makes a

* menu selection.

*/

Menu

gen_pullright(mi, op)

Menu_item mi;

Menu_generate op;

{

Menu menu;

Menu_item new, old = mi;

char buf[MAXPATHLEN];

if (op == MENU_DISPLAY) {

menu = (Menu)xv_get(mi, MENU_PARENT);

sprintf(buf, "%s/%s",

xv_get(menu, MENU_CLIENT_DATA), xv_get(mi, MENU_STRING));

/* get old menu and free it -- we’re going to build another */

if (menu = (Menu)xv_get(mi, MENU_PULLRIGHT)) {

free(xv_get(menu, MENU_CLIENT_DATA));

Example Programs

Example Programs 725

Example F-3. The menu_dir2.c program (continued)

xv_destroy(menu);

}

if (new = add_path_to_menu(buf)) {

menu = (Menu)xv_get(new, MENU_PULLRIGHT);

xv_destroy(new);

return menu;

}

}

if (!(menu = (Menu)xv_get(mi, MENU_PULLRIGHT)))

menu = (Menu)xv_create(NULL, MENU,

MENU_STRINGS, "Couldn’t build a menu.", NULL,

NULL);

return menu;

}

/*

* The path passed in is scanned via readdir(). For each file in the

* path, a menu item is created and inserted into a new menu. That

* new menu is made the PULLRIGHT_MENU of a newly created panel item

* for the path item originally passed it. Since this routine is

* recursive, a new menu is created for each subdirectory under the

* original path.

*/

Menu_item

add_path_to_menu(path)

char *path;

{

DIR *dirp;

struct direct *dp;

struct stat s_buf;

Menu_item mi;

Menu next_menu;

char buf[MAXPATHLEN];

static int recursion;

/* don’t add a folder to the list if user can’t read it */

if (stat(path, &s_buf) == -1 || !(s_buf.st_mode & S_IREAD))

return NULL;

if (s_buf.st_mode & S_IFDIR) {

int cnt = 0;

if (!(dirp = opendir(path)))

/* don’t bother adding to list if we can’t scan it */

return NULL;

if (recursion)

return (Menu_item)-1;

recursion++;

next_menu = (Menu)xv_create(XV_NULL, MENU, NULL);

while (dp = readdir(dirp))

if (strcmp(dp->d_name, ".") && strcmp(dp->d_name, "..")) {

(void) sprintf(buf, "%s/%s", path, dp–>d_name);

mi = add_path_to_menu(buf);

if (!mi || mi == (Menu_item)-1) {

int do_gen_pullright = (mi == (Menu_item)-1);

/* unreadable file or dir - deactivate item */

mi = (Menu_item)xv_create(XV_NULL, MENUITEM,

MENU_STRING, getfilename(dp->d_name),

726 XView Programming Manual

Example F-3. The menu_dir2.c program (continued)

MENU_RELEASE,

MENU_RELEASE_IMAGE,

NULL);

if (do_gen_pullright)

xv_set(mi,

MENU_GEN_PULLRIGHT, gen_pullright,

NULL);

else

xv_set(mi, MENU_INACTIVE, TRUE, NULL);

}

xv_set(next_menu, MENU_APPEND_ITEM, mi, NULL);

cnt++;

}

closedir(dirp);

mi = (Menu_item)xv_create(XV_NULL, MENUITEM,

MENU_STRING, getfilename(path),

MENU_RELEASE,

MENU_RELEASE_IMAGE,

MENU_NOTIFY_PROC, my_action_proc,

NULL);

if (!cnt) {

xv_destroy(next_menu);

/* An empty or unsearchable directory - deactivate item */

xv_set(mi, MENU_INACTIVE, TRUE, NULL);

} else {

xv_set(next_menu,

MENU_TITLE_ITEM, strcpy(malloc(strlen(path)+1), path),

MENU_CLIENT_DATA, strcpy(malloc(strlen(path)+1), path),

NULL);

xv_set(mi, MENU_PULLRIGHT, next_menu, NULL);

}

recursion--;

return mi;

}

return (Menu_item)xv_create(NULL, MENUITEM,

MENU_STRING, getfilename(path),

MENU_RELEASE,

MENU_RELEASE_IMAGE,

MENU_NOTIFY_PROC, my_action_proc,

NULL);

}

F.4 type_font.c

This very simple program captures keyboard events in a canvas and uses XDrawString()

to render what the user types. It also looks for backspacing. This is not intended to replace

the text subwindow in any way, but rather to demonstrate how some text rendering functions

can be implemented. See Chapter 16, Fonts, for more information about fonts.

Example Programs

Example Programs 727