1/*
2 * Copyright (C) 1984-2012  Mark Nudelman
3 *
4 * You may distribute under the terms of either the GNU General Public
5 * License or the Less License, as specified in the README file.
6 *
7 * For more information, see the README file.
8 */
9
10
11/*
12 * Routines which jump to a new location in the file.
13 */
14
15#include "less.h"
16#include "position.h"
17
18extern int jump_sline;
19extern int squished;
20extern int screen_trashed;
21extern int sc_width, sc_height;
22extern int show_attn;
23extern int top_scroll;
24
25/*
26 * Jump to the end of the file.
27 */
28	public void
29jump_forw()
30{
31	POSITION pos;
32	POSITION end_pos;
33
34	if (ch_end_seek())
35	{
36		error("Cannot seek to end of file", NULL_PARG);
37		return;
38	}
39	/*
40	 * Note; lastmark will be called later by jump_loc, but it fails
41	 * because the position table has been cleared by pos_clear below.
42	 * So call it here before calling pos_clear.
43	 */
44	lastmark();
45	/*
46	 * Position the last line in the file at the last screen line.
47	 * Go back one line from the end of the file
48	 * to get to the beginning of the last line.
49	 */
50	pos_clear();
51	end_pos = ch_tell();
52	pos = back_line(end_pos);
53	if (pos == NULL_POSITION)
54		jump_loc((POSITION)0, sc_height-1);
55	else
56	{
57		jump_loc(pos, sc_height-1);
58		if (position(sc_height-1) != end_pos)
59			repaint();
60	}
61}
62
63/*
64 * Jump to line n in the file.
65 */
66	public void
67jump_back(linenum)
68	LINENUM linenum;
69{
70	POSITION pos;
71	PARG parg;
72
73	/*
74	 * Find the position of the specified line.
75	 * If we can seek there, just jump to it.
76	 * If we can't seek, but we're trying to go to line number 1,
77	 * use ch_beg_seek() to get as close as we can.
78	 */
79	pos = find_pos(linenum);
80	if (pos != NULL_POSITION && ch_seek(pos) == 0)
81	{
82		if (show_attn)
83			set_attnpos(pos);
84		jump_loc(pos, jump_sline);
85	} else if (linenum <= 1 && ch_beg_seek() == 0)
86	{
87		jump_loc(ch_tell(), jump_sline);
88		error("Cannot seek to beginning of file", NULL_PARG);
89	} else
90	{
91		parg.p_linenum = linenum;
92		error("Cannot seek to line number %n", &parg);
93	}
94}
95
96/*
97 * Repaint the screen.
98 */
99	public void
100repaint()
101{
102	struct scrpos scrpos;
103	/*
104	 * Start at the line currently at the top of the screen
105	 * and redisplay the screen.
106	 */
107	get_scrpos(&scrpos);
108	pos_clear();
109	jump_loc(scrpos.pos, scrpos.ln);
110}
111
112/*
113 * Jump to a specified percentage into the file.
114 */
115	public void
116jump_percent(percent, fraction)
117	int percent;
118	long fraction;
119{
120	POSITION pos, len;
121
122	/*
123	 * Determine the position in the file
124	 * (the specified percentage of the file's length).
125	 */
126	if ((len = ch_length()) == NULL_POSITION)
127	{
128		ierror("Determining length of file", NULL_PARG);
129		ch_end_seek();
130	}
131	if ((len = ch_length()) == NULL_POSITION)
132	{
133		error("Don't know length of file", NULL_PARG);
134		return;
135	}
136	pos = percent_pos(len, percent, fraction);
137	if (pos >= len)
138		pos = len-1;
139
140	jump_line_loc(pos, jump_sline);
141}
142
143/*
144 * Jump to a specified position in the file.
145 * Like jump_loc, but the position need not be
146 * the first character in a line.
147 */
148	public void
149jump_line_loc(pos, sline)
150	POSITION pos;
151	int sline;
152{
153	int c;
154
155	if (ch_seek(pos) == 0)
156	{
157		/*
158		 * Back up to the beginning of the line.
159		 */
160		while ((c = ch_back_get()) != '\n' && c != EOI)
161			;
162		if (c == '\n')
163			(void) ch_forw_get();
164		pos = ch_tell();
165	}
166	if (show_attn)
167		set_attnpos(pos);
168	jump_loc(pos, sline);
169}
170
171/*
172 * Jump to a specified position in the file.
173 * The position must be the first character in a line.
174 * Place the target line on a specified line on the screen.
175 */
176	public void
177jump_loc(pos, sline)
178	POSITION pos;
179	int sline;
180{
181	register int nline;
182	POSITION tpos;
183	POSITION bpos;
184
185	/*
186	 * Normalize sline.
187	 */
188	sline = adjsline(sline);
189
190	if ((nline = onscreen(pos)) >= 0)
191	{
192		/*
193		 * The line is currently displayed.
194		 * Just scroll there.
195		 */
196		nline -= sline;
197		if (nline > 0)
198			forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0);
199		else
200			back(-nline, position(TOP), 1, 0);
201#if HILITE_SEARCH
202		if (show_attn)
203			repaint_hilite(1);
204#endif
205		return;
206	}
207
208	/*
209	 * Line is not on screen.
210	 * Seek to the desired location.
211	 */
212	if (ch_seek(pos))
213	{
214		error("Cannot seek to that file position", NULL_PARG);
215		return;
216	}
217
218	/*
219	 * See if the desired line is before or after
220	 * the currently displayed screen.
221	 */
222	tpos = position(TOP);
223	bpos = position(BOTTOM_PLUS_ONE);
224	if (tpos == NULL_POSITION || pos >= tpos)
225	{
226		/*
227		 * The desired line is after the current screen.
228		 * Move back in the file far enough so that we can
229		 * call forw() and put the desired line at the
230		 * sline-th line on the screen.
231		 */
232		for (nline = 0;  nline < sline;  nline++)
233		{
234			if (bpos != NULL_POSITION && pos <= bpos)
235			{
236				/*
237				 * Surprise!  The desired line is
238				 * close enough to the current screen
239				 * that we can just scroll there after all.
240				 */
241				forw(sc_height-sline+nline-1, bpos, 1, 0, 0);
242#if HILITE_SEARCH
243				if (show_attn)
244					repaint_hilite(1);
245#endif
246				return;
247			}
248			pos = back_line(pos);
249			if (pos == NULL_POSITION)
250			{
251				/*
252				 * Oops.  Ran into the beginning of the file.
253				 * Exit the loop here and rely on forw()
254				 * below to draw the required number of
255				 * blank lines at the top of the screen.
256				 */
257				break;
258			}
259		}
260		lastmark();
261		squished = 0;
262		screen_trashed = 0;
263		forw(sc_height-1, pos, 1, 0, sline-nline);
264	} else
265	{
266		/*
267		 * The desired line is before the current screen.
268		 * Move forward in the file far enough so that we
269		 * can call back() and put the desired line at the
270		 * sline-th line on the screen.
271		 */
272		for (nline = sline;  nline < sc_height - 1;  nline++)
273		{
274			pos = forw_line(pos);
275			if (pos == NULL_POSITION)
276			{
277				/*
278				 * Ran into end of file.
279				 * This shouldn't normally happen,
280				 * but may if there is some kind of read error.
281				 */
282				break;
283			}
284			if (pos >= tpos)
285			{
286				/*
287				 * Surprise!  The desired line is
288				 * close enough to the current screen
289				 * that we can just scroll there after all.
290				 */
291				back(nline+1, tpos, 1, 0);
292#if HILITE_SEARCH
293				if (show_attn)
294					repaint_hilite(1);
295#endif
296				return;
297			}
298		}
299		lastmark();
300		if (!top_scroll)
301			clear();
302		else
303			home();
304		screen_trashed = 0;
305		add_back_pos(pos);
306		back(sc_height-1, pos, 1, 0);
307	}
308}
309