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Fix line breaking algorithm
Break words longer than the screen width. The code is more complicated than I would like, but I have no better idea right now. Implement properly the notion of a row broken by a display inset. This is useful in different places. Also fix a bug with last line of a paragraph spotted by Kornel.
This commit is contained in:
Jean-Marc Lasgouttes
parent
ff608f46fd
commit
6258cebb77
@ -1,35 +1,41 @@
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This branch is where I (jmarc) try to implement string_wise metrics
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computation. This is done through a series of cleanups. The expected
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speed improvement will only be visible at the end of the road: indeed
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for now we intend to keep unchanged behavior for testing purposes.
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computation. This is done through a series of cleanups. The goal is to
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have both good metrics computation (and font with proper kerning and
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ligatures) and better performance than what we have with
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force_paint_single_char.
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Currently everything is supposed to work for LTR text, and RTL text
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should work too except possibly metrics with Arabic and Hebrew fonts.
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We'll see what to do after some feedback.
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What is done:
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* Make TextMetrics methods operate on Row objects: breakRow and
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setRowHeight instead of rowBreakPoint and rowHeight.
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* change breakRow operation to operate on text strings on which
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* Change breakRow operation to operate on text strings on which
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metrics are computed. The list of elements is stored in the row
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object in visual ordering, not logical.
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* re-implement cursorX using row elements
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* re-implement getColumnNearX using row elements.
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* Re-implement cursorX and getColumnNearX using row elements
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* Implement proper string metrics computation (with cache), when
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lyxrc.force_paint_single_char is false. In this case, remove also
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useless workarounds which disable kerning and ligatures.
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Next steps:
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* get rid of old code of cursorX and getColumnNearX (which have been
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Next possible steps:
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* Get rid of old code of cursorX and getColumnNearX (which have been
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kept for comparison purpose, guarded with KEEP_OLD_METRICS_CODE in
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order to check computations).
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* re-implement row painting using row elements (can it be done?)
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* Re-implement row painting using row elements. This is not difficult
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in principle, but the code is intricate and needs some careful
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analysis.
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* profile and see how performance can be improved.
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* Profile and see how performance can be improved.
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* Document the code
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Difference in behavior (aka bug fixes)
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@ -39,7 +45,7 @@ Difference in behavior (aka bug fixes)
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* When cursor is after a LTR separator just before a RTL chunk, the
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cursor posiiton is computed better with the new code.
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Other differences (aka real bugs)
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* words longer than the screen are no monger broken at an arbitrary
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point. This is a problem for languages like chinese that do not use
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separators.
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You tell me.
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60
src/Row.cpp
60
src/Row.cpp
@ -54,7 +54,7 @@ double Row::Element::pos2x(pos_type const i) const
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}
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pos_type Row::Element::x2pos(double &x, bool const low) const
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pos_type Row::Element::x2pos(double &x, bool const low) const
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{
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//lyxerr << "x2pos: x=" << x << " w=" << width() << " " << *this;
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// if element is rtl, flip x value
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@ -104,9 +104,9 @@ double Row::Element::pos2x(pos_type const i) const
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Row::Row()
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: separator(0), label_hfill(0), x(0), right_margin(0),
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sel_beg(-1), sel_end(-1),
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begin_margin_sel(false), end_margin_sel(false),
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changed_(false), crc_(0), pos_(0), end_(0)
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sel_beg(-1), sel_end(-1),
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begin_margin_sel(false), end_margin_sel(false),
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changed_(false), crc_(0), pos_(0), end_(0), right_boundary_(false)
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{}
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@ -117,18 +117,6 @@ void Row::setCrc(size_type crc) const
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}
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void Row::pos(pos_type p)
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{
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pos_ = p;
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}
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void Row::endpos(pos_type p)
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{
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end_ = p;
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}
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bool Row::isMarginSelected(bool left_margin, DocIterator const & beg,
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DocIterator const & end) const
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{
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@ -337,6 +325,10 @@ void Row::shorten_if_needed(pos_type const keep, int const w)
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{
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if (empty() || width() < w)
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return;
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/** First, we try to remove elements one by one from the end
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* until a separator is found.
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*/
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int i = elements_.size();
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int new_end = end_;
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int new_wid = dim_.wid;
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@ -352,23 +344,35 @@ void Row::shorten_if_needed(pos_type const keep, int const w)
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new_wid -= elements_[i].dim.wid;
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}
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if (i == 0) {
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if (elements_.size() != 1) {
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LYXERR0("Row is too large but has more than one element. " << *this);
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/* If we are here, it means that we have not found a
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* separator to shorten the row. There is one case
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* where we can do something: when we have one big
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* string, maybe with a paragraph marker after it.
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*/
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Element & front = elements_.front();
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if (!(front.type == STRING
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&& (elements_.size() == 1
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|| (elements_.size() == 2
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&& back().type == VIRTUAL))))
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return;
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}
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#if 1
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return;
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#else
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// does not work yet
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if (back().type != STRING)
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// If this is a string element, we can try to split it.
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if (front.type != STRING)
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return;
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double xstr = w - x;
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pos_type new_pos = back().x2pos(xstr, true);
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back().str = back().str.substr(0, new_pos);
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back().endpos = new_pos;
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// If there is a paragraph marker, it should be taken in account
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if (elements_.size() == 2)
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xstr -= back().width();
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pos_type new_pos = front.x2pos(xstr, true);
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front.str = front.str.substr(0, new_pos - pos_);
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front.dim.wid = xstr;
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front.endpos = new_pos;
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end_ = new_pos;
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dim_.wid = x + xstr;
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#endif
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// If there is a paragraph marker, it should be removed.
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if (elements_.size() == 2)
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elements_.pop_back();
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return;
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}
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end_ = new_end;
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dim_.wid = new_wid;
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11
src/Row.h
11
src/Row.h
@ -128,13 +128,18 @@ public:
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DocIterator const & end) const;
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///
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void pos(pos_type p);
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void pos(pos_type p) { pos_ = p; }
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///
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pos_type pos() const { return pos_; }
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///
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void endpos(pos_type p);
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void endpos(pos_type p) { end_ = p; }
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///
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pos_type endpos() const { return end_; }
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///
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void right_boundary(bool b) { right_boundary_ = b; }
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///
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bool right_boundary() const { return right_boundary_; }
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///
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Dimension const & dimension() const { return dim_; }
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///
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@ -256,6 +261,8 @@ private:
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pos_type pos_;
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/// one behind last pos covered by this row
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pos_type end_;
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// Is there is a boundary at the end of the row (display inset...)
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bool right_boundary_;
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/// Row dimension.
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Dimension dim_;
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};
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@ -619,18 +619,11 @@ void TextMetrics::computeRowMetrics(pit_type const pit,
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switch (align) {
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case LYX_ALIGN_BLOCK: {
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int const ns = numberOfSeparators(row);
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bool disp_inset = false;
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if (row.endpos() < par.size()) {
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Inset const * in = par.getInset(row.endpos());
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if (in)
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disp_inset = in->display();
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}
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// If we have separators, this is not the last row of a
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// par, does not end in newline, and is not row above a
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// display inset... then stretch it
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if (ns && row.endpos() < par.size()
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&& !par.isNewline(row.endpos() - 1)
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&& !disp_inset) {
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/** If we have separators, and this row has
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* not be broken abruptly by a display inset
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* or newline, then stretch it */
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if (ns && !row.right_boundary()
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&& row.endpos() != par.size()) {
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setSeparatorWidth(row, w / ns);
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row.dimension().wid = width;
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//lyxerr << "row.separator " << row.separator << endl;
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@ -803,6 +796,10 @@ private:
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} // anon namespace
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/** This is the function where the hard work is done. The code here is
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* very sensitive to small changes :) Note that part of the
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* intelligence is also in Row::shorten_if_needed
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*/
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void TextMetrics::breakRow(Row & row, int const right_margin, pit_type const pit) const
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{
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Paragraph const & par = text_->getPar(pit);
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@ -812,6 +809,7 @@ void TextMetrics::breakRow(Row & row, int const right_margin, pit_type const pit
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pos_type const body_pos = par.beginOfBody();
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row.clear();
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row.dimension().wid = leftMargin(max_width_, pit, pos);
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row.x = row.width();
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row.right_margin = right_margin;
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if (pos >= end || row.width() > width) {
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@ -893,6 +891,7 @@ void TextMetrics::breakRow(Row & row, int const right_margin, pit_type const pit
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&& inset->display())
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|| (!row.empty() && row.back().inset
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&& row.back().inset->display())) {
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row.right_boundary(true);
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++i;
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break;
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}
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@ -1153,13 +1152,11 @@ pos_type TextMetrics::getColumnNearX(pit_type const pit,
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/** This tests for the case where the cursor is set at the end
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* of a row which has been broken due to a display inset on
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* next row. This can be recognized because the end of the
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* last element is the same as the end of the row (there is no
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* separator at the end of the row)
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* next row. This is indicated by Row::right_boundary.
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*/
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if (!row.empty() && pos == row.back().endpos
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&& row.back().endpos == row.endpos())
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boundary = true;
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boundary = row.right_boundary();
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#if !defined(KEEP_OLD_METRICS_CODE)
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return pos - row.pos();
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