+int BufferView::horizScrollOffset() const
+{
+ return d->horiz_scroll_offset_;
+}
+
+
+int BufferView::horizScrollOffset(Text const * text,
+ pit_type pit, pos_type pos) const
+{
+ // Is this a row that is currently scrolled?
+ if (!d->current_row_slice_.empty()
+ && &text->inset() == d->current_row_slice_.inset().asInsetText()
+ && pit == d->current_row_slice_.pit()
+ && pos == d->current_row_slice_.pos())
+ return d->horiz_scroll_offset_;
+ return 0;
+}
+
+
+bool BufferView::hadHorizScrollOffset(Text const * text,
+ pit_type pit, pos_type pos) const
+{
+ return !d->last_row_slice_.empty()
+ && &text->inset() == d->last_row_slice_.inset().asInsetText()
+ && pit == d->last_row_slice_.pit()
+ && pos == d->last_row_slice_.pos();
+}
+
+
+void BufferView::setCurrentRowSlice(CursorSlice const & rowSlice)
+{
+ // nothing to do if the cursor was already on this row
+ if (d->current_row_slice_ == rowSlice) {
+ d->last_row_slice_ = CursorSlice();
+ return;
+ }
+
+ // if the (previous) current row was scrolled, we have to
+ // remember it in order to repaint it next time.
+ if (d->horiz_scroll_offset_ != 0)
+ d->last_row_slice_ = d->current_row_slice_;
+ else
+ d->last_row_slice_ = CursorSlice();
+
+ // Since we changed row, the scroll offset is not valid anymore
+ d->horiz_scroll_offset_ = 0;
+ d->current_row_slice_ = rowSlice;
+}
+
+
+void BufferView::checkCursorScrollOffset(PainterInfo & pi)
+{
+ CursorSlice rowSlice = d->cursor_.bottom();
+ TextMetrics const & tm = textMetrics(rowSlice.text());
+
+ // Stop if metrics have not been computed yet, since it means
+ // that there is nothing to do.
+ if (!tm.contains(rowSlice.pit()))
+ return;
+ 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);
+
+ // If insets referred to by cursor are not all in the cache, the positions
+ // need to be recomputed.
+ if (!d->cursor_.inCoordCache()) {
+ /** FIXME: the code below adds an extraneous computation of
+ * inset positions, and can therefore be bad for performance
+ * (think for example about a very large tabular inset.
+ * Redawing the row where it is means redrawing the whole
+ * screen).
+ *
+ * The bug that this fixes is the following: assume that there
+ * is a very large math inset. Upon entering the inset, when
+ * pressing `End', the row is not scrolled and the cursor is
+ * not visible. The extra row computation makes sure that the
+ * inset positions are correctly computed and set in the
+ * cache. This would not happen if we did not have two-stage
+ * drawing.
+ *
+ * A proper fix would be to always have proper inset positions
+ * at this point.
+ */
+ // Force the recomputation of inset positions
+ bool const drawing = pi.pain.isDrawingEnabled();
+ pi.pain.setDrawingEnabled(false);
+ // No need to care about vertical position.
+ RowPainter rp(pi, buffer().text(), row, -d->horiz_scroll_offset_, 0);
+ rp.paintText();
+ pi.pain.setDrawingEnabled(drawing);
+ }
+
+ // 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_
+ || !d->last_row_slice_.empty())) {
+ // FIXME: if one uses SingleParUpdate, then home/end
+ // will not work on long rows. Why?
+ d->update_strategy_ = FullScreenUpdate;
+ }
+
+ d->horiz_scroll_offset_ = offset;
+}
+
+