Thread: Scrolling in a text buffer

That's one little question that bugged me for quite a while. You know what? I never solved it, and have never needed to since.


^^^ Disclaimer: I know this post had no usefull content and I should be slapped. To avoid possible retaliation, I disown all knowledge that I ever posted it

Something like this?

Code:

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>

#define length(x) ( sizeof (x) / sizeof *(x) )

enum {
  KEY_ESC = 27,
  ARROW_UP = 256 + 72,
  ARROW_DOWN = 256 + 80,
};

static const char *text[] = {
  "Line 1",
  "Line 2",
  "Line 3",
  "Line 4",
  "Line 5",
  "Line 6"
};

static int get_code ( void )
{
  int ch = getch();

  if ( ch == 0 || ch == 224 )
    ch = 256 + getch();

  return ch;
}

static void redraw ( int start, int end )
{
  int i;

  clrscr();

  for ( i = start; i < end; i++ )
    puts ( text[i] );
}

int main ( void )
{
  int start = 0, end = 3;
  int op = 0;

  while ( redraw ( start, end ), ( op = get_code() ) != KEY_ESC ) {
    switch ( op ) {
    case ARROW_UP:
      if ( start == 0 ) {
        end = length ( text );
        start = end - 3;
      }
      else {
        --start;
        --end;
      }
      break;
    case ARROW_DOWN:
      if ( end == length ( text ) ) {
        start = 0;
        end = start + 3;
      }
      else {
        ++start;
        ++end;
      }
      break;
    default: break;
    }
  }

  return 0;
}