C/C++ Users Group Library 1996 July/C-C++ Users Group Library July 1996.iso/listings/v_02_04/2n04014b

Text File | 1991-02-09 | 6KB | 214 lines

/*
 *  VIDEO.C Copyright (C) 1990 by Mark R. Nelson
 *
 * This module contains a rudimentary set of routines to operate a set
 * of non-overlapping display windows.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <dos.h>
#include "video.h"
/*
 * These are all the line drawing constants defined.
 */
#define UL_CORNER       218
#define UR_CORNER       191
#define LL_CORNER       192
#define LR_CORNER       217
#define UPPER_TEE       194
#define LOWER_TEE       193
#define LEFT_TEE        195
#define RIGHT_TEE       180
#define CENTER_TEE      197
#define HORIZONTAL_LINE 196
#define VERTICAL_LINE   179

#define CHAR(w,r,c) \
 (*physical_screen)[(w)->first_row+(r)][(w)->first_col+(c)].character
#define ATTRIBUTE(w,r,c) \
 (*physical_screen)[(w)->first_row+(r)][(w)->first_col+(c)].attribute
#define ELEMENT(w,r,c) \
 (*physical_screen)[(w)->first_row+(r)][(w)->first_col+(c)]

WINDOW *current_window=NULL;

/*
 * I create a structure so I can write directly to screen as if it were
 * a big array.  That way the compiler takes care of computing the
 * addresses, all I have to do is insert the row and column.
 */
struct video_element {
                     unsigned char character;
                     unsigned char attribute;
                };

struct video_element (far *physical_screen)[25][80];
struct video_element saved_screen[25][80];
COORD saved_row;
COORD saved_col;
static int screen_initialized=0;

void window_printf(WINDOW *window ,char *format,...)
{
    char buffer[81];
    va_list args;
    int i;

    va_start(args,format);
    vsprintf(buffer,format,args);
    for ( i = 0; i < strlen( buffer ) ; i++ )
   window_putc( window, buffer[ i ] );
}

void window_putc( WINDOW *window, char c )
{
    if ( c == 13 )
   window->cursor_col = 0;
    else if (c == 10 ) {
   window->cursor_row++;
   window->cursor_col = 0;
    } else {
   CHAR( window, window->cursor_row, window->cursor_col) = c;
   window->cursor_col++;
    }
    if ( window->cursor_col >= window->width ) {
   window->cursor_col = 0;
   window->cursor_row++;
    }
    if ( window->cursor_row >= window->height ) {
   window->cursor_row--;
   scroll( window );
    }
    if ( window == current_window )
   set_cursor( window->first_row + window->cursor_row,
               window->first_col + window->cursor_col );
}

void scroll( WINDOW *window )
{
    int row;
    int col;

    for ( row = 0 ; row < ( window->height - 1 ) ; row++ )
   for ( col = 0 ; col < ( window->width ) ; col++ )
       CHAR( window, row, col ) = CHAR( window, row+1, col );
    for ( col = 0 ; col < ( window->width ) ; col++ )
   CHAR( window, window->height-1, col ) = ' ';
}

void restore_screen()
{
int row;
int col;

    if (screen_initialized != 0 ) {
   for (row=0;row<25;row++)
       for (col=0;col<80;col++)
            (*physical_screen)[row][col]=saved_screen[row][col];
   set_cursor( saved_row, saved_col );
   screen_initialized = 0;
    }
}

/*
 * Change the assignment of physical_screen from 0xb8000000L to 0xb0000000L
 * if you are on a monochrome system.
 */
void initialize_screen()
{
    int row;
    int col;

    if ( screen_initialized == 0 ) {
   get_cursor( &saved_row, &saved_col );
   physical_screen=(struct video_element (far *)[25][80])0xb8000000L;
   for (row=0;row<25;row++)
       for (col=0;col<80;col++)
       {
            saved_screen[row][col]=(*physical_screen)[row][col];
            (*physical_screen)[row][col].character=' ';
            (*physical_screen)[row][col].attribute=0x1b;
       }
   screen_initialized = 1;
   atexit( restore_screen );
    }
}

void set_cursor(COORD row, COORD col)
{
    union REGS inregs;
    union REGS outregs;

    inregs.h.dh=row;
    inregs.h.dl=col;
    inregs.h.bh=0;
    inregs.h.ah=2;
    int86( 0x10, &inregs, &outregs );
}

void get_cursor( COORD *row, COORD *col )
{
    union REGS inregs;
    union REGS outregs;

    inregs.h.ah = 3;
    inregs.h.bh = 0;
    int86( 0x10, &inregs, &outregs );
    *row = outregs.h.dh;
    *col = outregs.h.dl;
}

WINDOW *window_open( COORD row, COORD col, COORD width, COORD height )
{
    WINDOW *window;

    window = malloc( sizeof( WINDOW ) );
    if (window == NULL ) {
   restore_screen();
   printf( "Allocation failure!\n" );
   exit(1);
    }
    initialize_screen();
    window->first_row = row;
    window->first_col = col;
    window->width = width;
    window->height = height;
    window->cursor_row = 0;
    window->cursor_col = 0;
    current_window = window;
    draw_box( window );
    window_select( window );
    return( window );
}

void draw_box( WINDOW *window)
{
    COORD row;
    COORD col;

    for ( row = 0 ; row < window->height ; row++ ) {
   CHAR( window, row, -1 ) = VERTICAL_LINE ;
   CHAR( window, row, window->width ) = VERTICAL_LINE;
    }
    for ( col = 0 ; col < window->width ; col++ ) {
   CHAR( window, -1, col ) = HORIZONTAL_LINE;
   CHAR( window, window->height, col ) = HORIZONTAL_LINE;
    }
    CHAR( window, -1,             -1 )            = UL_CORNER;
    CHAR( window, -1,             window->width ) = UR_CORNER;
    CHAR( window, window->height, -1 )            = LL_CORNER;
    CHAR( window, window->height, window->width ) = LR_CORNER;
}

void window_select( WINDOW *window )
{
    current_window = window;
    set_cursor( window->first_row + window->cursor_row,
           window->first_col + window->cursor_col );

}