1 /* 2 * Copyright (C) 1984-2007 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, fraction) 106 int percent; 107 long fraction; 108 { 109 POSITION pos, len; 110 111 /* 112 * Determine the position in the file 113 * (the specified percentage of the file's length). 114 */ 115 if ((len = ch_length()) == NULL_POSITION) 116 { 117 ierror("Determining length of file", NULL_PARG); 118 ch_end_seek(); 119 } 120 if ((len = ch_length()) == NULL_POSITION) 121 { 122 error("Don't know length of file", NULL_PARG); 123 return; 124 } 125 pos = percent_pos(len, percent, fraction); 126 if (pos >= len) 127 pos = len-1; 128 129 jump_line_loc(pos, jump_sline); 130 } 131 132 /* 133 * Jump to a specified position in the file. 134 * Like jump_loc, but the position need not be 135 * the first character in a line. 136 */ 137 public void 138 jump_line_loc(pos, sline) 139 POSITION pos; 140 int sline; 141 { 142 int c; 143 144 if (ch_seek(pos) == 0) 145 { 146 /* 147 * Back up to the beginning of the line. 148 */ 149 while ((c = ch_back_get()) != '\n' && c != EOI) 150 ; 151 if (c == '\n') 152 (void) ch_forw_get(); 153 pos = ch_tell(); 154 } 155 if (show_attn) 156 set_attnpos(pos); 157 jump_loc(pos, sline); 158 } 159 160 /* 161 * Jump to a specified position in the file. 162 * The position must be the first character in a line. 163 * Place the target line on a specified line on the screen. 164 */ 165 public void 166 jump_loc(pos, sline) 167 POSITION pos; 168 int sline; 169 { 170 register int nline; 171 POSITION tpos; 172 POSITION bpos; 173 174 /* 175 * Normalize sline. 176 */ 177 sline = adjsline(sline); 178 179 if ((nline = onscreen(pos)) >= 0) 180 { 181 /* 182 * The line is currently displayed. 183 * Just scroll there. 184 */ 185 nline -= sline; 186 if (nline > 0) 187 forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0); 188 else 189 back(-nline, position(TOP), 1, 0); 190 if (show_attn) 191 repaint_hilite(1); 192 return; 193 } 194 195 /* 196 * Line is not on screen. 197 * Seek to the desired location. 198 */ 199 if (ch_seek(pos)) 200 { 201 error("Cannot seek to that file position", NULL_PARG); 202 return; 203 } 204 205 /* 206 * See if the desired line is before or after 207 * the currently displayed screen. 208 */ 209 tpos = position(TOP); 210 bpos = position(BOTTOM_PLUS_ONE); 211 if (tpos == NULL_POSITION || pos >= tpos) 212 { 213 /* 214 * The desired line is after the current screen. 215 * Move back in the file far enough so that we can 216 * call forw() and put the desired line at the 217 * sline-th line on the screen. 218 */ 219 for (nline = 0; nline < sline; nline++) 220 { 221 if (bpos != NULL_POSITION && pos <= bpos) 222 { 223 /* 224 * Surprise! The desired line is 225 * close enough to the current screen 226 * that we can just scroll there after all. 227 */ 228 forw(sc_height-sline+nline-1, bpos, 1, 0, 0); 229 if (show_attn) 230 repaint_hilite(1); 231 return; 232 } 233 pos = back_line(pos); 234 if (pos == NULL_POSITION) 235 { 236 /* 237 * Oops. Ran into the beginning of the file. 238 * Exit the loop here and rely on forw() 239 * below to draw the required number of 240 * blank lines at the top of the screen. 241 */ 242 break; 243 } 244 } 245 lastmark(); 246 hit_eof = 0; 247 squished = 0; 248 screen_trashed = 0; 249 forw(sc_height-1, pos, 1, 0, sline-nline); 250 } else 251 { 252 /* 253 * The desired line is before the current screen. 254 * Move forward in the file far enough so that we 255 * can call back() and put the desired line at the 256 * sline-th line on the screen. 257 */ 258 for (nline = sline; nline < sc_height - 1; nline++) 259 { 260 pos = forw_line(pos); 261 if (pos == NULL_POSITION) 262 { 263 /* 264 * Ran into end of file. 265 * This shouldn't normally happen, 266 * but may if there is some kind of read error. 267 */ 268 break; 269 } 270 if (pos >= tpos) 271 { 272 /* 273 * Surprise! The desired line is 274 * close enough to the current screen 275 * that we can just scroll there after all. 276 */ 277 back(nline+1, tpos, 1, 0); 278 if (show_attn) 279 repaint_hilite(1); 280 return; 281 } 282 } 283 lastmark(); 284 if (!top_scroll) 285 clear(); 286 else 287 home(); 288 screen_trashed = 0; 289 add_back_pos(pos); 290 back(sc_height-1, pos, 1, 0); 291 } 292 } 293