+
+ if (noninteractive)
+ {
+ struct position pos;
+ pos = *vmotion (PT, XINT (lines), w);
+ SET_PT_BOTH (pos.bufpos, pos.bytepos);
+ }
+ else
+ {
+ int it_start;
+ int oselective;
+ int it_overshoot_expected_p;
+
+ SET_TEXT_POS (pt, PT, PT_BYTE);
+ start_display (&it, w, pt);
+
+ /* Scan from the start of the line containing PT. If we don't
+ do this, we start moving with IT->current_x == 0, while PT is
+ really at some x > 0. The effect is, in continuation lines, that
+ we end up with the iterator placed at where it thinks X is 0,
+ while the end position is really at some X > 0, the same X that
+ PT had. */
+ it_start = IT_CHARPOS (it);
+
+ /* We expect the call to move_it_to, further down, to overshoot
+ if the starting point is on an image, stretch glyph, or Lisp
+ string. We won't need to backtrack in this situation, except
+ for one corner case: when the Lisp string contains a
+ newline. */
+ if (it.method == GET_FROM_STRING)
+ {
+ const char *s = SDATA (it.string);
+ const char *e = s + SBYTES (it.string);
+
+ while (s < e && *s != '\n')
+ ++s;
+
+ it_overshoot_expected_p = (s == e);
+ }
+ else
+ it_overshoot_expected_p = (it.method == GET_FROM_IMAGE
+ || it.method == GET_FROM_STRETCH);
+
+ reseat_at_previous_visible_line_start (&it);
+ it.current_x = it.hpos = 0;
+ /* Temporarily disable selective display so we don't move too far */
+ oselective = it.selective;
+ it.selective = 0;
+ move_it_to (&it, PT, -1, -1, -1, MOVE_TO_POS);
+ it.selective = oselective;
+
+ /* Move back if we got too far. This may happen if
+ truncate-lines is on and PT is beyond right margin.
+ Don't go back if the overshoot is expected (see above). */
+ if (IT_CHARPOS (it) > it_start && XINT (lines) > 0
+ && !it_overshoot_expected_p)
+ move_it_by_lines (&it, -1, 0);
+
+ it.vpos = 0;
+ /* Do this even if LINES is 0, so that we move back
+ to the beginning of the current line as we ought. */
+ if (XINT (lines) >= 0 || IT_CHARPOS (it) > 0)
+ move_it_by_lines (&it, XINT (lines), 0);
+
+ SET_PT_BOTH (IT_CHARPOS (it), IT_BYTEPOS (it));
+ }