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 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 line n in the file. 65 */ 66 public void 67 jump_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 100 repaint() 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 116 jump_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 149 jump_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 177 jump_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