1 /* 2 * Copyright (C) 1984-2021 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 29 jump_forw(VOID_PARAM) 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(ch_zero(), 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 the last buffered line in the file. 65 */ 66 public void 67 jump_forw_buffered(VOID_PARAM) 68 { 69 POSITION end; 70 71 if (ch_end_buffer_seek()) 72 { 73 error("Cannot seek to end of buffers", NULL_PARG); 74 return; 75 } 76 end = ch_tell(); 77 if (end != NULL_POSITION && end > 0) 78 jump_line_loc(end-1, sc_height-1); 79 } 80 81 /* 82 * Jump to line n in the file. 83 */ 84 public void 85 jump_back(linenum) 86 LINENUM linenum; 87 { 88 POSITION pos; 89 PARG parg; 90 91 /* 92 * Find the position of the specified line. 93 * If we can seek there, just jump to it. 94 * If we can't seek, but we're trying to go to line number 1, 95 * use ch_beg_seek() to get as close as we can. 96 */ 97 pos = find_pos(linenum); 98 if (pos != NULL_POSITION && ch_seek(pos) == 0) 99 { 100 if (show_attn) 101 set_attnpos(pos); 102 jump_loc(pos, jump_sline); 103 } else if (linenum <= 1 && ch_beg_seek() == 0) 104 { 105 jump_loc(ch_tell(), jump_sline); 106 error("Cannot seek to beginning of file", NULL_PARG); 107 } else 108 { 109 parg.p_linenum = linenum; 110 error("Cannot seek to line number %n", &parg); 111 } 112 } 113 114 /* 115 * Repaint the screen. 116 */ 117 public void 118 repaint(VOID_PARAM) 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 138 jump_percent(percent, fraction) 139 int percent; 140 long fraction; 141 { 142 POSITION pos, len; 143 144 /* 145 * Determine the position in the file 146 * (the specified percentage of the file's length). 147 */ 148 if ((len = ch_length()) == NULL_POSITION) 149 { 150 ierror("Determining length of file", NULL_PARG); 151 ch_end_seek(); 152 } 153 if ((len = ch_length()) == NULL_POSITION) 154 { 155 error("Don't know length of file", NULL_PARG); 156 return; 157 } 158 pos = percent_pos(len, percent, fraction); 159 if (pos >= len) 160 pos = len-1; 161 162 jump_line_loc(pos, jump_sline); 163 } 164 165 /* 166 * Jump to a specified position in the file. 167 * Like jump_loc, but the position need not be 168 * the first character in a line. 169 */ 170 public void 171 jump_line_loc(pos, sline) 172 POSITION pos; 173 int sline; 174 { 175 int c; 176 177 if (ch_seek(pos) == 0) 178 { 179 /* 180 * Back up to the beginning of the line. 181 */ 182 while ((c = ch_back_get()) != '\n' && c != EOI) 183 ; 184 if (c == '\n') 185 (void) ch_forw_get(); 186 pos = ch_tell(); 187 } 188 if (show_attn) 189 set_attnpos(pos); 190 jump_loc(pos, sline); 191 } 192 193 /* 194 * Jump to a specified position in the file. 195 * The position must be the first character in a line. 196 * Place the target line on a specified line on the screen. 197 */ 198 public void 199 jump_loc(pos, sline) 200 POSITION pos; 201 int sline; 202 { 203 int nline; 204 int sindex; 205 POSITION tpos; 206 POSITION bpos; 207 208 /* 209 * Normalize sline. 210 */ 211 sindex = sindex_from_sline(sline); 212 213 if ((nline = onscreen(pos)) >= 0) 214 { 215 /* 216 * The line is currently displayed. 217 * Just scroll there. 218 */ 219 nline -= sindex; 220 if (nline > 0) 221 forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0); 222 else 223 back(-nline, position(TOP), 1, 0); 224 #if HILITE_SEARCH 225 if (show_attn) 226 repaint_hilite(1); 227 #endif 228 return; 229 } 230 231 /* 232 * Line is not on screen. 233 * Seek to the desired location. 234 */ 235 if (ch_seek(pos)) 236 { 237 error("Cannot seek to that file position", NULL_PARG); 238 return; 239 } 240 241 /* 242 * See if the desired line is before or after 243 * the currently displayed screen. 244 */ 245 tpos = position(TOP); 246 bpos = position(BOTTOM_PLUS_ONE); 247 if (tpos == NULL_POSITION || pos >= tpos) 248 { 249 /* 250 * The desired line is after the current screen. 251 * Move back in the file far enough so that we can 252 * call forw() and put the desired line at the 253 * sline-th line on the screen. 254 */ 255 for (nline = 0; nline < sindex; nline++) 256 { 257 if (bpos != NULL_POSITION && pos <= bpos) 258 { 259 /* 260 * Surprise! The desired line is 261 * close enough to the current screen 262 * that we can just scroll there after all. 263 */ 264 forw(sc_height-sindex+nline-1, bpos, 1, 0, 0); 265 #if HILITE_SEARCH 266 if (show_attn) 267 repaint_hilite(1); 268 #endif 269 return; 270 } 271 pos = back_line(pos); 272 if (pos == NULL_POSITION) 273 { 274 /* 275 * Oops. Ran into the beginning of the file. 276 * Exit the loop here and rely on forw() 277 * below to draw the required number of 278 * blank lines at the top of the screen. 279 */ 280 break; 281 } 282 } 283 lastmark(); 284 squished = 0; 285 screen_trashed = 0; 286 forw(sc_height-1, pos, 1, 0, sindex-nline); 287 } else 288 { 289 /* 290 * The desired line is before the current screen. 291 * Move forward in the file far enough so that we 292 * can call back() and put the desired line at the 293 * sindex-th line on the screen. 294 */ 295 for (nline = sindex; nline < sc_height - 1; nline++) 296 { 297 pos = forw_line(pos); 298 if (pos == NULL_POSITION) 299 { 300 /* 301 * Ran into end of file. 302 * This shouldn't normally happen, 303 * but may if there is some kind of read error. 304 */ 305 break; 306 } 307 #if HILITE_SEARCH 308 pos = next_unfiltered(pos); 309 #endif 310 if (pos >= tpos) 311 { 312 /* 313 * Surprise! The desired line is 314 * close enough to the current screen 315 * that we can just scroll there after all. 316 */ 317 back(nline+1, tpos, 1, 0); 318 #if HILITE_SEARCH 319 if (show_attn) 320 repaint_hilite(1); 321 #endif 322 return; 323 } 324 } 325 lastmark(); 326 if (!top_scroll) 327 clear(); 328 else 329 home(); 330 screen_trashed = 0; 331 add_back_pos(pos); 332 back(sc_height-1, pos, 1, 0); 333 } 334 } 335