+ ParagraphMetrics const & pm = tm.parMetrics(rowSlice.pit());
+ Row const & row = pm.getRow(rowSlice.pos(),
+ d->cursor_.boundary() && rowSlice == d->cursor_.top());
+ rowSlice.pos() = row.pos();
+
+ // Set the row on which the cursor lives.
+ setCurrentRowSlice(rowSlice);
+
+ // Current x position of the cursor in pixels
+ int cur_x = getPos(d->cursor_).x_;
+
+ // Horizontal scroll offset of the cursor row in pixels
+ int offset = d->horiz_scroll_offset_;
+ int const MARGIN = 2 * theFontMetrics(d->cursor_.real_current_font).em()
+ + row.right_margin;
+ if (row.right_x() <= workWidth() - row.right_margin) {
+ // Row is narrower than the work area, no offset needed.
+ offset = 0;
+ } else {
+ if (cur_x - offset < MARGIN) {
+ // cursor would be too far right
+ offset = cur_x - MARGIN;
+ } else if (cur_x - offset > workWidth() - MARGIN) {
+ // cursor would be too far left
+ offset = cur_x - workWidth() + MARGIN;
+ }
+ // Correct the offset to make sure that we do not scroll too much
+ if (offset < 0)
+ offset = 0;
+ if (row.right_x() - offset < workWidth() - row.right_margin)
+ offset = row.right_x() - workWidth() + row.right_margin;
+ }
+
+ //lyxerr << "cur_x=" << cur_x << ", offset=" << offset << ", row.wid=" << row.width() << ", margin=" << MARGIN << endl;
+
+ if (offset != d->horiz_scroll_offset_)
+ LYXERR(Debug::PAINTING, "Horiz. scroll offset changed from "
+ << d->horiz_scroll_offset_ << " to " << offset);
+
+ if (d->update_strategy_ == NoScreenUpdate
+ && offset != d->horiz_scroll_offset_) {
+ // FIXME: if one uses SingleParUpdate, then home/end
+ // will not work on long rows. Why?
+ d->update_strategy_ = FullScreenUpdate;
+ }
+
+ d->horiz_scroll_offset_ = offset;
+}