1 /* 2 * Copyright (C) 1984-2023 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 18 extern int jump_sline; 19 extern int squished; 20 extern int screen_trashed; 21 extern int sc_width, sc_height; 22 extern int show_attn; 23 extern int top_scroll; 24 25 /* 26 * Jump to the end of the file. 27 */ 28 public void jump_forw(void) 29 { 30 POSITION pos; 31 POSITION end_pos; 32 33 if (ch_end_seek()) 34 { 35 error("Cannot seek to end of file", NULL_PARG); 36 return; 37 } 38 end_pos = ch_tell(); 39 if (position(sc_height-1) == end_pos) 40 { 41 eof_bell(); 42 return; 43 } 44 /* 45 * Note; lastmark will be called later by jump_loc, but it fails 46 * because the position table has been cleared by pos_clear below. 47 * So call it here before calling pos_clear. 48 */ 49 lastmark(); 50 /* 51 * Position the last line in the file at the last screen line. 52 * Go back one line from the end of the file 53 * to get to the beginning of the last line. 54 */ 55 pos_clear(); 56 pos = back_line(end_pos); 57 if (pos == NULL_POSITION) 58 jump_loc(ch_zero(), sc_height-1); 59 else 60 { 61 jump_loc(pos, sc_height-1); 62 if (position(sc_height-1) != end_pos) 63 repaint(); 64 } 65 } 66 67 /* 68 * Jump to the last buffered line in the file. 69 */ 70 public void jump_forw_buffered(void) 71 { 72 POSITION end; 73 74 if (ch_end_buffer_seek()) 75 { 76 error("Cannot seek to end of buffers", NULL_PARG); 77 return; 78 } 79 end = ch_tell(); 80 if (end != NULL_POSITION && end > 0) 81 jump_line_loc(end-1, sc_height-1); 82 } 83 84 /* 85 * Jump to line n in the file. 86 */ 87 public void jump_back(LINENUM linenum) 88 { 89 POSITION pos; 90 PARG parg; 91 92 /* 93 * Find the position of the specified line. 94 * If we can seek there, just jump to it. 95 * If we can't seek, but we're trying to go to line number 1, 96 * use ch_beg_seek() to get as close as we can. 97 */ 98 pos = find_pos(linenum); 99 if (pos != NULL_POSITION && ch_seek(pos) == 0) 100 { 101 if (show_attn) 102 set_attnpos(pos); 103 jump_loc(pos, jump_sline); 104 } else if (linenum <= 1 && ch_beg_seek() == 0) 105 { 106 jump_loc(ch_tell(), jump_sline); 107 error("Cannot seek to beginning of file", NULL_PARG); 108 } else 109 { 110 parg.p_linenum = linenum; 111 error("Cannot seek to line number %n", &parg); 112 } 113 } 114 115 /* 116 * Repaint the screen. 117 */ 118 public void repaint(void) 119 { 120 struct scrpos scrpos; 121 /* 122 * Start at the line currently at the top of the screen 123 * and redisplay the screen. 124 */ 125 get_scrpos(&scrpos, TOP); 126 pos_clear(); 127 if (scrpos.pos == NULL_POSITION) 128 /* Screen hasn't been drawn yet. */ 129 jump_loc(ch_zero(), 1); 130 else 131 jump_loc(scrpos.pos, scrpos.ln); 132 } 133 134 /* 135 * Jump to a specified percentage into the file. 136 */ 137 public void jump_percent(int percent, long fraction) 138 { 139 POSITION pos, len; 140 141 /* 142 * Determine the position in the file 143 * (the specified percentage of the file's length). 144 */ 145 if ((len = ch_length()) == NULL_POSITION) 146 { 147 ierror("Determining length of file", NULL_PARG); 148 ch_end_seek(); 149 } 150 if ((len = ch_length()) == NULL_POSITION) 151 { 152 error("Don't know length of file", NULL_PARG); 153 return; 154 } 155 pos = percent_pos(len, percent, fraction); 156 if (pos >= len) 157 pos = len-1; 158 159 jump_line_loc(pos, jump_sline); 160 } 161 162 /* 163 * Jump to a specified position in the file. 164 * Like jump_loc, but the position need not be 165 * the first character in a line. 166 */ 167 public void jump_line_loc(POSITION pos, int sline) 168 { 169 int c; 170 171 if (ch_seek(pos) == 0) 172 { 173 /* 174 * Back up to the beginning of the line. 175 */ 176 while ((c = ch_back_get()) != '\n' && c != EOI) 177 ; 178 if (c == '\n') 179 (void) ch_forw_get(); 180 pos = ch_tell(); 181 } 182 if (show_attn) 183 set_attnpos(pos); 184 jump_loc(pos, sline); 185 } 186 187 /* 188 * Jump to a specified position in the file. 189 * The position must be the first character in a line. 190 * Place the target line on a specified line on the screen. 191 */ 192 public void jump_loc(POSITION pos, int sline) 193 { 194 int nline; 195 int sindex; 196 POSITION tpos; 197 POSITION bpos; 198 199 /* 200 * Normalize sline. 201 */ 202 sindex = sindex_from_sline(sline); 203 204 if ((nline = onscreen(pos)) >= 0) 205 { 206 /* 207 * The line is currently displayed. 208 * Just scroll there. 209 */ 210 nline -= sindex; 211 if (nline > 0) 212 forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0); 213 else 214 back(-nline, position(TOP), 1, 0); 215 #if HILITE_SEARCH 216 if (show_attn) 217 repaint_hilite(1); 218 #endif 219 return; 220 } 221 222 /* 223 * Line is not on screen. 224 * Seek to the desired location. 225 */ 226 if (ch_seek(pos)) 227 { 228 error("Cannot seek to that file position", NULL_PARG); 229 return; 230 } 231 232 /* 233 * See if the desired line is before or after 234 * the currently displayed screen. 235 */ 236 tpos = position(TOP); 237 bpos = position(BOTTOM_PLUS_ONE); 238 if (tpos == NULL_POSITION || pos >= tpos) 239 { 240 /* 241 * The desired line is after the current screen. 242 * Move back in the file far enough so that we can 243 * call forw() and put the desired line at the 244 * sline-th line on the screen. 245 */ 246 for (nline = 0; nline < sindex; nline++) 247 { 248 if (bpos != NULL_POSITION && pos <= bpos) 249 { 250 /* 251 * Surprise! The desired line is 252 * close enough to the current screen 253 * that we can just scroll there after all. 254 */ 255 forw(sc_height-sindex+nline-1, bpos, 1, 0, 0); 256 #if HILITE_SEARCH 257 if (show_attn) 258 repaint_hilite(1); 259 #endif 260 return; 261 } 262 pos = back_line(pos); 263 if (pos == NULL_POSITION) 264 { 265 /* 266 * Oops. Ran into the beginning of the file. 267 * Exit the loop here and rely on forw() 268 * below to draw the required number of 269 * blank lines at the top of the screen. 270 */ 271 break; 272 } 273 } 274 lastmark(); 275 squished = 0; 276 screen_trashed = 0; 277 forw(sc_height-1, pos, 1, 0, sindex-nline); 278 } else 279 { 280 /* 281 * The desired line is before the current screen. 282 * Move forward in the file far enough so that we 283 * can call back() and put the desired line at the 284 * sindex-th line on the screen. 285 */ 286 for (nline = sindex; nline < sc_height - 1; nline++) 287 { 288 pos = forw_line(pos); 289 if (pos == NULL_POSITION) 290 { 291 /* 292 * Ran into end of file. 293 * This shouldn't normally happen, 294 * but may if there is some kind of read error. 295 */ 296 break; 297 } 298 #if HILITE_SEARCH 299 pos = next_unfiltered(pos); 300 #endif 301 if (pos >= tpos) 302 { 303 /* 304 * Surprise! The desired line is 305 * close enough to the current screen 306 * that we can just scroll there after all. 307 */ 308 back(nline+1, tpos, 1, 0); 309 #if HILITE_SEARCH 310 if (show_attn) 311 repaint_hilite(1); 312 #endif 313 return; 314 } 315 } 316 lastmark(); 317 if (!top_scroll) 318 clear(); 319 else 320 home(); 321 screen_trashed = 0; 322 add_back_pos(pos); 323 back(sc_height-1, pos, 1, 0); 324 } 325 } 326