This document contains information on drawing boxes using curses calls in AIX 3.2. C programs and shell scripts are used to illustrate curses calls.
AIX 3.2 provides two curses libraries. The base curses library (libcurses) is similar to a very early AT&T curses library. It does not include support for box characters. The extended curses library (libcur) is IBMs extension of base curses. It is not compatible with any release of AT&T curses. Extended curses does include support for box characters.
AIX 4.1 includes a curses library consistent with a current release of the AT&T curses library. This document discusses ONLY AIX 3.2 and its extended curses library.
Included in the extended curses library are the following subroutines; box, cbox, cboxalt, drawbox, drawboxalt, fullbox, superbox, and superbox1.
The box, cbox, cboxalt, drawbox, drawboxalt, fullbox, superbox and superbox1 subroutines draw a box IN or AROUND a specified window. The box, cbox, cboxalt, and fullbox subroutines draw a box AROUND the window specified.
The strings of characters necessary to control cursor movement, terminal characteristics, etc. for all supported terminals are found in a family of files found in /usr/lib/terminfo. An examination of this directory will suggest that these terminal definition files are grouped generally by manufacturer and have a .ti suffix. These .ti files are flat (ascii) files in which terminal control attribute names are matched to character sequences. For example the terminal control attribute name 'clear' is defined as being to \EK (the escape character (0x2b) and the letter K) for the ibm3101 terminal.
These flat files are not used directly. For speed of access, they are digested into binary equivalents. This digestion is accomplished with the tic command. Therefore any changes made to a .ti file would not take effect until the .ti file was redigested with the tic command.
Terminal control sequences can be accessed at both the shell level and from within a C program. An example follows which illustrates the use of the tput command for accessing terminal control sequences from the shell.
A second example will illustrate the use of the extended curses subroutine calls to the same effect.
It is entirely possible that the methods defined herein will not work in a particular setting. In order for any terminal to draw box characters, that terminal must have access to a font in which box characters are defined. Further, the font in which box characters are defined may vary from one terminal type to another. Conventions exist which increase the probability of finding the box character set in a predictable location, but there is no standard which fixes it. That is to say that, if you find that box characters are not available at your terminal, you do not necessarily have a defect of any sort.
The tput command is used at the shell level to access a terminal control sequence. For example, tput clear results in the following:
The tput command will be used repeatedly throughout this document.
In the same way that a .ti file matches a string of characters to the clear attribute name, it also matches strings of characters to the box1 attribute and attributes whose names are font0, font1, etc.
We will select various fonts using the fontX attribute then write the string associated with the box1 attribute until we learn which font (if any) contains a set of characters suitable for drawing boxes.
At the command line, type in
tput font0; tput box1
If you see a string of non-box characters, then the font selected with the tput font0 command does not contain the necessary characters. Type the above command replacing font0 with font1, then font2, etc., until you see that the box characters are found, or you get an error:
tput: unknown capname
If you got to the error before finding a set of box characters, then the fonts that your terminal knows about do not include the necessary characters.
For the purpose of this discussion, we will assume that tput font0 results in the selection of a normal alphanumeric character set and that tput font1 gives access to a set of box characters.
This routine gets the characters with the tput box1 command and then changes the terminal into line drawing font and outputs the characters.
#!/bin/ksh GPH_OFF=$(tput font0) # select the alpha-num char set GPH_ON=$(tput font1) # select the font with box chars GRPH=$(tput box1) # get the box chars # Extract the individual characters into shell variables TL=$(echo $GRPH | cut -c1) # top left HB=$(echo $GRPH | cut -c2) # horiz bar TR=$(echo $GRPH | cut -c3) # top right VB=$(echo $GRPH | cut -c4) # vert bar BR=$(echo $GRPH | cut -c5) # bottom right BL=$(echo $GRPH | cut -c6) # bottom left TT=$(echo $GRPH | cut -c7) # top tee RT=$(echo $GRPH | cut -c8) # right tee BT=$(echo $GRPH | cut -c9) # bottom tee LT=$(echo $GRPH | cut -c10) # left tee CT=$(echo $GRPH | cut -c11) # center cross # Put the terminal into line drawing mode echo "$GPH_ON" # Output the box characters to the screen echo "$TL$HB$HB$HB$HB$HB$HB$HB$HB$HB$HB$TR" echo "$VB $VB" echo "$VB $VB" echo "$VB $VB" echo "$VB $VB" echo "$VB $VB" echo "$VB $VB" echo "$VB $VB" echo "$BL$HB$HB$HB$HB$HB$HB$HB$HB$HB$HB$BR" # Put the terminal back into character mode. echo "$GPH_OFF" # End of example script
Following a call to the setupterm function, global variables are set up for the names defined in:
/usr/include/term.h.
The applicable variables compared to the ones used in the shell script above are:
The following program shows the difference between displaying the box characters in both line drawing mode and in normal mode. The program does not attempt to draw a box with the characters, but simply displays them. The effect is similar to typing tput fontX at the shell command line.
This program uses the base curses library. To compile it, type:
cc -O <filename>.c -o <filename> -l curses
#include <curses.h>
#include <term.h>
main() {
int err;
int xcode;
char cap[40];
setupterm(0,1,&err);
printf ("This is it,font1 %s
",font_1);
printf ("Normal chars in line font
");
printf ("box1 = %s
",box_chars_1);
printf ("%s this is font0
",font_0);
printf ("back to normal
");
printf ("box1 = %s
",box_chars_1);
exit (0);
}
The following sample program shows a simple box drawn with the superbox1 or cbox call depending which line is commented out.
This program uses the extended curses library. To compile it, type:
cc -O <filename>.c -o <filename> -l cur
#include <cur00.h>
#include <cur03.h>
#define A_REVERSE -1
main () {
if( initscr() == NULL ) {
printf("%s
","Error in screen init");
sleep(1);
exit( 1 );
}
accessmenu ();
endwin();
exit(1);
}
accessmenu() {
WINDOW *menu;
menu = newwin(8,16,0,0);
cbox(menu);
wrefresh(menu);
mvwgetch(menu, 5, 5);
}
To see a variation, replace the cbox(menu) line with superbox1(menu, 0, 0, 8, 16, 32, 32, 32, 32, 32, 32, A_REVERSE);
Another example of a C routine to draw a box using drawbox. This program displays characters used to draw boxes similar to InfoExplorer using IBM3151 and vt100 screen types.
This program uses the extended curses library. To compile it, type:
cc -O <filename>.c -o <filename> -l cur
#include <cur00.h>
main() {
initscr();
refresh();
mvaddstr(1, 1, "Here's a string");
refresh();
chgat(5,FONT0);
drawbox(stdscr, 2, 2, 8, 20);
refresh();
mvaddstr(3, 3, "I'm in the box");
refresh();
system("sleep 5");
wclear(curscr);
wrefresh(curscr);
endwin();
}
[ Doc Ref: 90605200214614 Publish Date: Oct. 25, 1999 4FAX Ref: 2212 ]