--- /dev/null
+/*
+ * Copyright (C) 1984-2011 Mark Nudelman
+ *
+ * You may distribute under the terms of either the GNU General Public
+ * License or the Less License, as specified in the README file.
+ *
+ * For more information about less, or for information on how to
+ * contact the author, see the README file.
+ */
+
+
+/*
+ * Primitives for displaying the file on the screen,
+ * scrolling either forward or backward.
+ */
+
+#include "less.h"
+#include "position.h"
+
+public int screen_trashed;
+public int squished;
+public int no_back_scroll = 0;
+public int forw_prompt;
+
+extern int sigs;
+extern int top_scroll;
+extern int quiet;
+extern int sc_width, sc_height;
+extern int plusoption;
+extern int forw_scroll;
+extern int back_scroll;
+extern int ignore_eoi;
+extern int clear_bg;
+extern int final_attr;
+extern int oldbot;
+#if TAGS
+extern char *tagoption;
+#endif
+
+/*
+ * Sound the bell to indicate user is trying to move past end of file.
+ */
+ static void
+eof_bell()
+{
+ if (quiet == NOT_QUIET)
+ bell();
+ else
+ vbell();
+}
+
+/*
+ * Check to see if the end of file is currently displayed.
+ */
+ public int
+eof_displayed()
+{
+ POSITION pos;
+
+ if (ignore_eoi)
+ return (0);
+
+ if (ch_length() == NULL_POSITION)
+ /*
+ * If the file length is not known,
+ * we can't possibly be displaying EOF.
+ */
+ return (0);
+
+ /*
+ * If the bottom line is empty, we are at EOF.
+ * If the bottom line ends at the file length,
+ * we must be just at EOF.
+ */
+ pos = position(BOTTOM_PLUS_ONE);
+ return (pos == NULL_POSITION || pos == ch_length());
+}
+
+/*
+ * Check to see if the entire file is currently displayed.
+ */
+ public int
+entire_file_displayed()
+{
+ POSITION pos;
+
+ /* Make sure last line of file is displayed. */
+ if (!eof_displayed())
+ return (0);
+
+ /* Make sure first line of file is displayed. */
+ pos = position(0);
+ return (pos == NULL_POSITION || pos == 0);
+}
+
+/*
+ * If the screen is "squished", repaint it.
+ * "Squished" means the first displayed line is not at the top
+ * of the screen; this can happen when we display a short file
+ * for the first time.
+ */
+ public void
+squish_check()
+{
+ if (!squished)
+ return;
+ squished = 0;
+ repaint();
+}
+
+/*
+ * Display n lines, scrolling forward,
+ * starting at position pos in the input file.
+ * "force" means display the n lines even if we hit end of file.
+ * "only_last" means display only the last screenful if n > screen size.
+ * "nblank" is the number of blank lines to draw before the first
+ * real line. If nblank > 0, the pos must be NULL_POSITION.
+ * The first real line after the blanks will start at ch_zero().
+ */
+ public void
+forw(n, pos, force, only_last, nblank)
+ register int n;
+ POSITION pos;
+ int force;
+ int only_last;
+ int nblank;
+{
+ int eof = 0;
+ int nlines = 0;
+ int do_repaint;
+ static int first_time = 1;
+
+ squish_check();
+
+ /*
+ * do_repaint tells us not to display anything till the end,
+ * then just repaint the entire screen.
+ * We repaint if we are supposed to display only the last
+ * screenful and the request is for more than a screenful.
+ * Also if the request exceeds the forward scroll limit
+ * (but not if the request is for exactly a screenful, since
+ * repainting itself involves scrolling forward a screenful).
+ */
+ do_repaint = (only_last && n > sc_height-1) ||
+ (forw_scroll >= 0 && n > forw_scroll && n != sc_height-1);
+
+ if (!do_repaint)
+ {
+ if (top_scroll && n >= sc_height - 1 && pos != ch_length())
+ {
+ /*
+ * Start a new screen.
+ * {{ This is not really desirable if we happen
+ * to hit eof in the middle of this screen,
+ * but we don't yet know if that will happen. }}
+ */
+ pos_clear();
+ add_forw_pos(pos);
+ force = 1;
+ clear();
+ home();
+ }
+
+ if (pos != position(BOTTOM_PLUS_ONE) || empty_screen())
+ {
+ /*
+ * This is not contiguous with what is
+ * currently displayed. Clear the screen image
+ * (position table) and start a new screen.
+ */
+ pos_clear();
+ add_forw_pos(pos);
+ force = 1;
+ if (top_scroll)
+ {
+ clear();
+ home();
+ } else if (!first_time)
+ {
+ putstr("...skipping...\n");
+ }
+ }
+ }
+
+ while (--n >= 0)
+ {
+ /*
+ * Read the next line of input.
+ */
+ if (nblank > 0)
+ {
+ /*
+ * Still drawing blanks; don't get a line
+ * from the file yet.
+ * If this is the last blank line, get ready to
+ * read a line starting at ch_zero() next time.
+ */
+ if (--nblank == 0)
+ pos = ch_zero();
+ } else
+ {
+ /*
+ * Get the next line from the file.
+ */
+ pos = forw_line(pos);
+ if (pos == NULL_POSITION)
+ {
+ /*
+ * End of file: stop here unless the top line
+ * is still empty, or "force" is true.
+ * Even if force is true, stop when the last
+ * line in the file reaches the top of screen.
+ */
+ eof = 1;
+ if (!force && position(TOP) != NULL_POSITION)
+ break;
+ if (!empty_lines(0, 0) &&
+ !empty_lines(1, 1) &&
+ empty_lines(2, sc_height-1))
+ break;
+ }
+ }
+ /*
+ * Add the position of the next line to the position table.
+ * Display the current line on the screen.
+ */
+ add_forw_pos(pos);
+ nlines++;
+ if (do_repaint)
+ continue;
+ /*
+ * If this is the first screen displayed and
+ * we hit an early EOF (i.e. before the requested
+ * number of lines), we "squish" the display down
+ * at the bottom of the screen.
+ * But don't do this if a + option or a -t option
+ * was given. These options can cause us to
+ * start the display after the beginning of the file,
+ * and it is not appropriate to squish in that case.
+ */
+ if (first_time && pos == NULL_POSITION && !top_scroll &&
+#if TAGS
+ tagoption == NULL &&
+#endif
+ !plusoption)
+ {
+ squished = 1;
+ continue;
+ }
+ put_line();
+#if 0
+ /* {{
+ * Can't call clear_eol here. The cursor might be at end of line
+ * on an ignaw terminal, so clear_eol would clear the last char
+ * of the current line instead of all of the next line.
+ * If we really need to do this on clear_bg terminals, we need
+ * to find a better way.
+ * }}
+ */
+ if (clear_bg && apply_at_specials(final_attr) != AT_NORMAL)
+ {
+ /*
+ * Writing the last character on the last line
+ * of the display may have scrolled the screen.
+ * If we were in standout mode, clear_bg terminals
+ * will fill the new line with the standout color.
+ * Now we're in normal mode again, so clear the line.
+ */
+ clear_eol();
+ }
+#endif
+ forw_prompt = 1;
+ }
+
+ if (nlines == 0)
+ eof_bell();
+ else if (do_repaint)
+ repaint();
+ first_time = 0;
+ (void) currline(BOTTOM);
+}
+
+/*
+ * Display n lines, scrolling backward.
+ */
+ public void
+back(n, pos, force, only_last)
+ register int n;
+ POSITION pos;
+ int force;
+ int only_last;
+{
+ int nlines = 0;
+ int do_repaint;
+
+ squish_check();
+ do_repaint = (n > get_back_scroll() || (only_last && n > sc_height-1));
+ while (--n >= 0)
+ {
+ /*
+ * Get the previous line of input.
+ */
+ pos = back_line(pos);
+ if (pos == NULL_POSITION)
+ {
+ /*
+ * Beginning of file: stop here unless "force" is true.
+ */
+ if (!force)
+ break;
+ }
+ /*
+ * Add the position of the previous line to the position table.
+ * Display the line on the screen.
+ */
+ add_back_pos(pos);
+ nlines++;
+ if (!do_repaint)
+ {
+ home();
+ add_line();
+ put_line();
+ }
+ }
+
+ if (nlines == 0)
+ eof_bell();
+ else if (do_repaint)
+ repaint();
+ else if (!oldbot)
+ lower_left();
+ (void) currline(BOTTOM);
+}
+
+/*
+ * Display n more lines, forward.
+ * Start just after the line currently displayed at the bottom of the screen.
+ */
+ public void
+forward(n, force, only_last)
+ int n;
+ int force;
+ int only_last;
+{
+ POSITION pos;
+
+ if (get_quit_at_eof() && eof_displayed() && !(ch_getflags() & CH_HELPFILE))
+ {
+ /*
+ * If the -e flag is set and we're trying to go
+ * forward from end-of-file, go on to the next file.
+ */
+ if (edit_next(1))
+ quit(QUIT_OK);
+ return;
+ }
+
+ pos = position(BOTTOM_PLUS_ONE);
+ if (pos == NULL_POSITION && (!force || empty_lines(2, sc_height-1)))
+ {
+ if (ignore_eoi)
+ {
+ /*
+ * ignore_eoi is to support A_F_FOREVER.
+ * Back up until there is a line at the bottom
+ * of the screen.
+ */
+ if (empty_screen())
+ pos = ch_zero();
+ else
+ {
+ do
+ {
+ back(1, position(TOP), 1, 0);
+ pos = position(BOTTOM_PLUS_ONE);
+ } while (pos == NULL_POSITION);
+ }
+ } else
+ {
+ eof_bell();
+ return;
+ }
+ }
+ forw(n, pos, force, only_last, 0);
+}
+
+/*
+ * Display n more lines, backward.
+ * Start just before the line currently displayed at the top of the screen.
+ */
+ public void
+backward(n, force, only_last)
+ int n;
+ int force;
+ int only_last;
+{
+ POSITION pos;
+
+ pos = position(TOP);
+ if (pos == NULL_POSITION && (!force || position(BOTTOM) == 0))
+ {
+ eof_bell();
+ return;
+ }
+ back(n, pos, force, only_last);
+}
+
+/*
+ * Get the backwards scroll limit.
+ * Must call this function instead of just using the value of
+ * back_scroll, because the default case depends on sc_height and
+ * top_scroll, as well as back_scroll.
+ */
+ public int
+get_back_scroll()
+{
+ if (no_back_scroll)
+ return (0);
+ if (back_scroll >= 0)
+ return (back_scroll);
+ if (top_scroll)
+ return (sc_height - 2);
+ return (10000); /* infinity */
+}
projects / apitrace / blobdiff