/* * Copyright (c) 1984,1985,1989,1994,1995 Mark Nudelman * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice in the documentation and/or other materials provided with * the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /* * Routines dealing with the "position" table. * This is a table which tells the position (in the input file) of the * first char on each currently displayed line. * * {{ The position table is scrolled by moving all the entries. * Would be better to have a circular table * and just change a couple of pointers. }} */ #include "less.h" #include "position.h" static POSITION *table = NULL; /* The position table */ static int table_size; extern int sc_width, sc_height; /* * Return the starting file position of a line displayed on the screen. * The line may be specified as a line number relative to the top * of the screen, but is usually one of these special cases: * the top (first) line on the screen * the second line on the screen * the bottom line on the screen * the line after the bottom line on the screen */ public POSITION position(where) int where; { if (where >= table_size) where = BOTTOM; switch (where) { case BOTTOM: where = sc_height - 2; break; case BOTTOM_PLUS_ONE: where = sc_height - 1; break; case MIDDLE: where = (sc_height - 1) / 2; } return (table[where]); } /* * Add a new file position to the bottom of the position table. */ public void add_forw_pos(pos) POSITION pos; { register int i; /* * Scroll the position table up. */ for (i = 1; i < sc_height; i++) table[i-1] = table[i]; table[sc_height - 1] = pos; } /* * Add a new file position to the top of the position table. */ public void add_back_pos(pos) POSITION pos; { register int i; /* * Scroll the position table down. */ for (i = sc_height - 1; i > 0; i--) table[i] = table[i-1]; table[0] = pos; } /* * Initialize the position table, done whenever we clear the screen. */ public void pos_clear() { register int i; for (i = 0; i < sc_height; i++) table[i] = NULL_POSITION; } /* * Allocate or reallocate the position table. */ public void pos_init() { struct scrpos scrpos; if (sc_height <= table_size) return; /* * If we already have a table, remember the first line in it * before we free it, so we can copy that line to the new table. */ if (table != NULL) { get_scrpos(&scrpos); free((char*)table); } else scrpos.pos = NULL_POSITION; table = (POSITION *) ecalloc(sc_height, sizeof(POSITION)); table_size = sc_height; pos_clear(); if (scrpos.pos != NULL_POSITION) table[scrpos.ln-1] = scrpos.pos; } /* * See if the byte at a specified position is currently on the screen. * Check the position table to see if the position falls within its range. * Return the position table entry if found, -1 if not. */ public int onscreen(pos) POSITION pos; { register int i; if (pos < table[0]) return (-1); for (i = 1; i < sc_height; i++) if (pos < table[i]) return (i-1); return (-1); } /* * See if the entire screen is empty. */ public int empty_screen() { return (empty_lines(0, sc_height-1)); } public int empty_lines(s, e) int s; int e; { register int i; for (i = s; i <= e; i++) if (table[i] != NULL_POSITION) return (0); return (1); } /* * Get the current screen position. * The screen position consists of both a file position and * a screen line number where the file position is placed on the screen. * Normally the screen line number is 0, but if we are positioned * such that the top few lines are empty, we may have to set * the screen line to a number > 0. */ public void get_scrpos(scrpos) struct scrpos *scrpos; { register int i; /* * Find the first line on the screen which has something on it, * and return the screen line number and the file position. */ for (i = 0; i < sc_height; i++) if (table[i] != NULL_POSITION) { scrpos->ln = i+1; scrpos->pos = table[i]; return; } /* * The screen is empty. */ scrpos->pos = NULL_POSITION; } /* * Adjust a screen line number to be a simple positive integer * in the range { 0 .. sc_height-2 }. * (The bottom line, sc_height-1, is reserved for prompts, etc.) * The given "sline" may be in the range { 1 .. sc_height-1 } * to refer to lines relative to the top of the screen (starting from 1), * or it may be in { -1 .. -(sc_height-1) } to refer to lines * relative to the bottom of the screen. */ public int adjsline(sline) int sline; { /* * Negative screen line number means * relative to the bottom of the screen. */ if (sline < 0) sline += sc_height; /* * Can't be less than 1 or greater than sc_height-1. */ if (sline <= 0) sline = 1; if (sline >= sc_height) sline = sc_height - 1; /* * Return zero-based line number, not one-based. */ return (sline-1); }