1 /* 2 * Copyright (C) 1984-2005 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 about less, or for information on how to 8 * contact the author, see the README file. 9 */ 10 11 12 /* 13 * Routines which jump to a new location in the file. 14 */ 15 16 #include "less.h" 17 #include "position.h" 18 19 extern int hit_eof; 20 extern int jump_sline; 21 extern int squished; 22 extern int screen_trashed; 23 extern int sc_width, sc_height; 24 extern int show_attn; 25 extern int top_scroll; 26 27 /* 28 * Jump to the end of the file. 29 */ 30 public void 31 jump_forw() 32 { 33 POSITION pos; 34 35 if (ch_end_seek()) 36 { 37 error("Cannot seek to end of file", NULL_PARG); 38 return; 39 } 40 /* 41 * Position the last line in the file at the last screen line. 42 * Go back one line from the end of the file 43 * to get to the beginning of the last line. 44 */ 45 pos = back_line(ch_tell()); 46 if (pos == NULL_POSITION) 47 jump_loc((POSITION)0, sc_height-1); 48 else 49 jump_loc(pos, sc_height-1); 50 } 51 52 /* 53 * Jump to line n in the file. 54 */ 55 public void 56 jump_back(linenum) 57 LINENUM linenum; 58 { 59 POSITION pos; 60 PARG parg; 61 62 /* 63 * Find the position of the specified line. 64 * If we can seek there, just jump to it. 65 * If we can't seek, but we're trying to go to line number 1, 66 * use ch_beg_seek() to get as close as we can. 67 */ 68 pos = find_pos(linenum); 69 if (pos != NULL_POSITION && ch_seek(pos) == 0) 70 { 71 if (show_attn) 72 set_attnpos(pos); 73 jump_loc(pos, jump_sline); 74 } else if (linenum <= 1 && ch_beg_seek() == 0) 75 { 76 jump_loc(ch_tell(), jump_sline); 77 error("Cannot seek to beginning of file", NULL_PARG); 78 } else 79 { 80 parg.p_linenum = linenum; 81 error("Cannot seek to line number %n", &parg); 82 } 83 } 84 85 /* 86 * Repaint the screen. 87 */ 88 public void 89 repaint() 90 { 91 struct scrpos scrpos; 92 /* 93 * Start at the line currently at the top of the screen 94 * and redisplay the screen. 95 */ 96 get_scrpos(&scrpos); 97 pos_clear(); 98 jump_loc(scrpos.pos, scrpos.ln); 99 } 100 101 /* 102 * Jump to a specified percentage into the file. 103 */ 104 public void 105 jump_percent(percent) 106 int percent; 107 { 108 POSITION pos, len; 109 110 /* 111 * Determine the position in the file 112 * (the specified percentage of the file's length). 113 */ 114 if ((len = ch_length()) == NULL_POSITION) 115 { 116 ierror("Determining length of file", NULL_PARG); 117 ch_end_seek(); 118 } 119 if ((len = ch_length()) == NULL_POSITION) 120 { 121 error("Don't know length of file", NULL_PARG); 122 return; 123 } 124 pos = percent_pos(len, percent); 125 if (pos >= len) 126 pos = len-1; 127 128 jump_line_loc(pos, jump_sline); 129 } 130 131 /* 132 * Jump to a specified position in the file. 133 * Like jump_loc, but the position need not be 134 * the first character in a line. 135 */ 136 public void 137 jump_line_loc(pos, sline) 138 POSITION pos; 139 int sline; 140 { 141 int c; 142 143 if (ch_seek(pos) == 0) 144 { 145 /* 146 * Back up to the beginning of the line. 147 */ 148 while ((c = ch_back_get()) != '\n' && c != EOI) 149 ; 150 if (c == '\n') 151 (void) ch_forw_get(); 152 pos = ch_tell(); 153 } 154 if (show_attn) 155 set_attnpos(pos); 156 jump_loc(pos, sline); 157 } 158 159 /* 160 * Jump to a specified position in the file. 161 * The position must be the first character in a line. 162 * Place the target line on a specified line on the screen. 163 */ 164 public void 165 jump_loc(pos, sline) 166 POSITION pos; 167 int sline; 168 { 169 register int nline; 170 POSITION tpos; 171 POSITION bpos; 172 173 /* 174 * Normalize sline. 175 */ 176 sline = adjsline(sline); 177 178 if ((nline = onscreen(pos)) >= 0) 179 { 180 /* 181 * The line is currently displayed. 182 * Just scroll there. 183 */ 184 nline -= sline; 185 if (nline > 0) 186 forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0); 187 else 188 back(-nline, position(TOP), 1, 0); 189 if (show_attn) 190 repaint_hilite(1); 191 return; 192 } 193 194 /* 195 * Line is not on screen. 196 * Seek to the desired location. 197 */ 198 if (ch_seek(pos)) 199 { 200 error("Cannot seek to that file position", NULL_PARG); 201 return; 202 } 203 204 /* 205 * See if the desired line is before or after 206 * the currently displayed screen. 207 */ 208 tpos = position(TOP); 209 bpos = position(BOTTOM_PLUS_ONE); 210 if (tpos == NULL_POSITION || pos >= tpos) 211 { 212 /* 213 * The desired line is after the current screen. 214 * Move back in the file far enough so that we can 215 * call forw() and put the desired line at the 216 * sline-th line on the screen. 217 */ 218 for (nline = 0; nline < sline; nline++) 219 { 220 if (bpos != NULL_POSITION && pos <= bpos) 221 { 222 /* 223 * Surprise! The desired line is 224 * close enough to the current screen 225 * that we can just scroll there after all. 226 */ 227 forw(sc_height-sline+nline-1, bpos, 1, 0, 0); 228 if (show_attn) 229 repaint_hilite(1); 230 return; 231 } 232 pos = back_line(pos); 233 if (pos == NULL_POSITION) 234 { 235 /* 236 * Oops. Ran into the beginning of the file. 237 * Exit the loop here and rely on forw() 238 * below to draw the required number of 239 * blank lines at the top of the screen. 240 */ 241 break; 242 } 243 } 244 lastmark(); 245 hit_eof = 0; 246 squished = 0; 247 screen_trashed = 0; 248 forw(sc_height-1, pos, 1, 0, sline-nline); 249 } else 250 { 251 /* 252 * The desired line is before the current screen. 253 * Move forward in the file far enough so that we 254 * can call back() and put the desired line at the 255 * sline-th line on the screen. 256 */ 257 for (nline = sline; nline < sc_height - 1; nline++) 258 { 259 pos = forw_line(pos); 260 if (pos == NULL_POSITION) 261 { 262 /* 263 * Ran into end of file. 264 * This shouldn't normally happen, 265 * but may if there is some kind of read error. 266 */ 267 break; 268 } 269 if (pos >= tpos) 270 { 271 /* 272 * Surprise! The desired line is 273 * close enough to the current screen 274 * that we can just scroll there after all. 275 */ 276 back(nline+1, tpos, 1, 0); 277 if (show_attn) 278 repaint_hilite(1); 279 return; 280 } 281 } 282 lastmark(); 283 if (top_scroll != OPT_ON) 284 clear(); 285 else 286 home(); 287 screen_trashed = 0; 288 add_back_pos(pos); 289 back(sc_height-1, pos, 1, 0); 290 } 291 } 292