1 /* 2 * Copyright (C) 1984-2015 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() 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 the last buffered line in the file. 65 */ 66 public void 67 jump_forw_buffered() 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() 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); 126 pos_clear(); 127 jump_loc(scrpos.pos, scrpos.ln); 128 } 129 130 /* 131 * Jump to a specified percentage into the file. 132 */ 133 public void 134 jump_percent(percent, fraction) 135 int percent; 136 long fraction; 137 { 138 POSITION pos, len; 139 140 /* 141 * Determine the position in the file 142 * (the specified percentage of the file's length). 143 */ 144 if ((len = ch_length()) == NULL_POSITION) 145 { 146 ierror("Determining length of file", NULL_PARG); 147 ch_end_seek(); 148 } 149 if ((len = ch_length()) == NULL_POSITION) 150 { 151 error("Don't know length of file", NULL_PARG); 152 return; 153 } 154 pos = percent_pos(len, percent, fraction); 155 if (pos >= len) 156 pos = len-1; 157 158 jump_line_loc(pos, jump_sline); 159 } 160 161 /* 162 * Jump to a specified position in the file. 163 * Like jump_loc, but the position need not be 164 * the first character in a line. 165 */ 166 public void 167 jump_line_loc(pos, sline) 168 POSITION pos; 169 int sline; 170 { 171 int c; 172 173 if (ch_seek(pos) == 0) 174 { 175 /* 176 * Back up to the beginning of the line. 177 */ 178 while ((c = ch_back_get()) != '\n' && c != EOI) 179 ; 180 if (c == '\n') 181 (void) ch_forw_get(); 182 pos = ch_tell(); 183 } 184 if (show_attn) 185 set_attnpos(pos); 186 jump_loc(pos, sline); 187 } 188 189 /* 190 * Jump to a specified position in the file. 191 * The position must be the first character in a line. 192 * Place the target line on a specified line on the screen. 193 */ 194 public void 195 jump_loc(pos, sline) 196 POSITION pos; 197 int sline; 198 { 199 register int nline; 200 POSITION tpos; 201 POSITION bpos; 202 203 /* 204 * Normalize sline. 205 */ 206 sline = adjsline(sline); 207 208 if ((nline = onscreen(pos)) >= 0) 209 { 210 /* 211 * The line is currently displayed. 212 * Just scroll there. 213 */ 214 nline -= sline; 215 if (nline > 0) 216 forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0); 217 else 218 back(-nline, position(TOP), 1, 0); 219 #if HILITE_SEARCH 220 if (show_attn) 221 repaint_hilite(1); 222 #endif 223 return; 224 } 225 226 /* 227 * Line is not on screen. 228 * Seek to the desired location. 229 */ 230 if (ch_seek(pos)) 231 { 232 error("Cannot seek to that file position", NULL_PARG); 233 return; 234 } 235 236 /* 237 * See if the desired line is before or after 238 * the currently displayed screen. 239 */ 240 tpos = position(TOP); 241 bpos = position(BOTTOM_PLUS_ONE); 242 if (tpos == NULL_POSITION || pos >= tpos) 243 { 244 /* 245 * The desired line is after the current screen. 246 * Move back in the file far enough so that we can 247 * call forw() and put the desired line at the 248 * sline-th line on the screen. 249 */ 250 for (nline = 0; nline < sline; nline++) 251 { 252 if (bpos != NULL_POSITION && pos <= bpos) 253 { 254 /* 255 * Surprise! The desired line is 256 * close enough to the current screen 257 * that we can just scroll there after all. 258 */ 259 forw(sc_height-sline+nline-1, bpos, 1, 0, 0); 260 #if HILITE_SEARCH 261 if (show_attn) 262 repaint_hilite(1); 263 #endif 264 return; 265 } 266 pos = back_line(pos); 267 if (pos == NULL_POSITION) 268 { 269 /* 270 * Oops. Ran into the beginning of the file. 271 * Exit the loop here and rely on forw() 272 * below to draw the required number of 273 * blank lines at the top of the screen. 274 */ 275 break; 276 } 277 } 278 lastmark(); 279 squished = 0; 280 screen_trashed = 0; 281 forw(sc_height-1, pos, 1, 0, sline-nline); 282 } else 283 { 284 /* 285 * The desired line is before the current screen. 286 * Move forward in the file far enough so that we 287 * can call back() and put the desired line at the 288 * sline-th line on the screen. 289 */ 290 for (nline = sline; nline < sc_height - 1; nline++) 291 { 292 pos = forw_line(pos); 293 if (pos == NULL_POSITION) 294 { 295 /* 296 * Ran into end of file. 297 * This shouldn't normally happen, 298 * but may if there is some kind of read error. 299 */ 300 break; 301 } 302 #if HILITE_SEARCH 303 pos = next_unfiltered(pos); 304 #endif 305 if (pos >= tpos) 306 { 307 /* 308 * Surprise! The desired line is 309 * close enough to the current screen 310 * that we can just scroll there after all. 311 */ 312 back(nline+1, tpos, 1, 0); 313 #if HILITE_SEARCH 314 if (show_attn) 315 repaint_hilite(1); 316 #endif 317 return; 318 } 319 } 320 lastmark(); 321 if (!top_scroll) 322 clear(); 323 else 324 home(); 325 screen_trashed = 0; 326 add_back_pos(pos); 327 back(sc_height-1, pos, 1, 0); 328 } 329 } 330