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(void) 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(void) 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 linenum) 86 { 87 POSITION pos; 88 PARG parg; 89 90 /* 91 * Find the position of the specified line. 92 * If we can seek there, just jump to it. 93 * If we can't seek, but we're trying to go to line number 1, 94 * use ch_beg_seek() to get as close as we can. 95 */ 96 pos = find_pos(linenum); 97 if (pos != NULL_POSITION && ch_seek(pos) == 0) 98 { 99 if (show_attn) 100 set_attnpos(pos); 101 jump_loc(pos, jump_sline); 102 } else if (linenum <= 1 && ch_beg_seek() == 0) 103 { 104 jump_loc(ch_tell(), jump_sline); 105 error("Cannot seek to beginning of file", NULL_PARG); 106 } else 107 { 108 parg.p_linenum = linenum; 109 error("Cannot seek to line number %n", &parg); 110 } 111 } 112 113 /* 114 * Repaint the screen. 115 */ 116 public void 117 repaint(void) 118 { 119 struct scrpos scrpos; 120 /* 121 * Start at the line currently at the top of the screen 122 * and redisplay the screen. 123 */ 124 get_scrpos(&scrpos); 125 pos_clear(); 126 jump_loc(scrpos.pos, scrpos.ln); 127 } 128 129 /* 130 * Jump to a specified percentage into the file. 131 */ 132 public void 133 jump_percent(int percent, long fraction) 134 { 135 POSITION pos, len; 136 137 /* 138 * Determine the position in the file 139 * (the specified percentage of the file's length). 140 */ 141 if ((len = ch_length()) == NULL_POSITION) 142 { 143 ierror("Determining length of file", NULL_PARG); 144 ch_end_seek(); 145 } 146 if ((len = ch_length()) == NULL_POSITION) 147 { 148 error("Don't know length of file", NULL_PARG); 149 return; 150 } 151 pos = percent_pos(len, percent, fraction); 152 if (pos >= len) 153 pos = len-1; 154 155 jump_line_loc(pos, jump_sline); 156 } 157 158 /* 159 * Jump to a specified position in the file. 160 * Like jump_loc, but the position need not be 161 * the first character in a line. 162 */ 163 public void 164 jump_line_loc(POSITION pos, int sline) 165 { 166 int c; 167 168 if (ch_seek(pos) == 0) 169 { 170 /* 171 * Back up to the beginning of the line. 172 */ 173 while ((c = ch_back_get()) != '\n' && c != EOI) 174 ; 175 if (c == '\n') 176 (void) ch_forw_get(); 177 pos = ch_tell(); 178 } 179 if (show_attn) 180 set_attnpos(pos); 181 jump_loc(pos, sline); 182 } 183 184 /* 185 * Jump to a specified position in the file. 186 * The position must be the first character in a line. 187 * Place the target line on a specified line on the screen. 188 */ 189 public void 190 jump_loc(POSITION pos, int sline) 191 { 192 int nline; 193 POSITION tpos; 194 POSITION bpos; 195 196 /* 197 * Normalize sline. 198 */ 199 sline = adjsline(sline); 200 201 if ((nline = onscreen(pos)) >= 0) 202 { 203 /* 204 * The line is currently displayed. 205 * Just scroll there. 206 */ 207 nline -= sline; 208 if (nline > 0) 209 forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0); 210 else 211 back(-nline, position(TOP), 1, 0); 212 #if HILITE_SEARCH 213 if (show_attn) 214 repaint_hilite(1); 215 #endif 216 return; 217 } 218 219 /* 220 * Line is not on screen. 221 * Seek to the desired location. 222 */ 223 if (ch_seek(pos)) 224 { 225 error("Cannot seek to that file position", NULL_PARG); 226 return; 227 } 228 229 /* 230 * See if the desired line is before or after 231 * the currently displayed screen. 232 */ 233 tpos = position(TOP); 234 bpos = position(BOTTOM_PLUS_ONE); 235 if (tpos == NULL_POSITION || pos >= tpos) 236 { 237 /* 238 * The desired line is after the current screen. 239 * Move back in the file far enough so that we can 240 * call forw() and put the desired line at the 241 * sline-th line on the screen. 242 */ 243 for (nline = 0; nline < sline; nline++) 244 { 245 if (bpos != NULL_POSITION && pos <= bpos) 246 { 247 /* 248 * Surprise! The desired line is 249 * close enough to the current screen 250 * that we can just scroll there after all. 251 */ 252 forw(sc_height-sline+nline-1, bpos, 1, 0, 0); 253 #if HILITE_SEARCH 254 if (show_attn) 255 repaint_hilite(1); 256 #endif 257 return; 258 } 259 pos = back_line(pos); 260 if (pos == NULL_POSITION) 261 { 262 /* 263 * Oops. Ran into the beginning of the file. 264 * Exit the loop here and rely on forw() 265 * below to draw the required number of 266 * blank lines at the top of the screen. 267 */ 268 break; 269 } 270 } 271 lastmark(); 272 squished = 0; 273 screen_trashed = 0; 274 forw(sc_height-1, pos, 1, 0, sline-nline); 275 } else 276 { 277 /* 278 * The desired line is before the current screen. 279 * Move forward in the file far enough so that we 280 * can call back() and put the desired line at the 281 * sline-th line on the screen. 282 */ 283 for (nline = sline; nline < sc_height - 1; nline++) 284 { 285 pos = forw_line(pos); 286 if (pos == NULL_POSITION) 287 { 288 /* 289 * Ran into end of file. 290 * This shouldn't normally happen, 291 * but may if there is some kind of read error. 292 */ 293 break; 294 } 295 #if HILITE_SEARCH 296 pos = next_unfiltered(pos); 297 #endif 298 if (pos >= tpos) 299 { 300 /* 301 * Surprise! The desired line is 302 * close enough to the current screen 303 * that we can just scroll there after all. 304 */ 305 back(nline+1, tpos, 1, 0); 306 #if HILITE_SEARCH 307 if (show_attn) 308 repaint_hilite(1); 309 #endif 310 return; 311 } 312 } 313 lastmark(); 314 if (!top_scroll) 315 clear(); 316 else 317 home(); 318 screen_trashed = 0; 319 add_back_pos(pos); 320 back(sc_height-1, pos, 1, 0); 321 } 322 } 323