Fix display of a math hull inset in a tight inset

This is a kind of hack. This allows InsetMathHull to state that it
needs some elbow room beyond its width, in order to fit the numbering
and/or the left margin (with left alignment), which are outside of the
inset itself.

To this end, InsetMathHull::metrics() sets a value in
MetricsInfo::extrawidth and this value is added later to the width of
the row that contains the inset (when this row is tight or shorter
than the max allowed width).

Fixes bug #12320.

src/MetricsInfo.cpp

@@ -152,7 +152,8 @@ int MetricsBase::inPixels(Length const & len) const
 
 MetricsInfo::MetricsInfo(BufferView * bv, FontInfo font, int textwidth,
                          MacroContext const & mc, bool vm, bool tight)
-	: base(bv, font, textwidth), macrocontext(mc), vmode(vm), tight_insets(tight)
+	: base(bv, font, textwidth), macrocontext(mc), vmode(vm), tight_insets(tight),
+	  extrawidth(0)
 {}
 
 

src/MetricsInfo.h

@@ -109,6 +109,8 @@ public:
 	bool vmode;
 	/// if true, do not expand insets to max width artificially
 	bool tight_insets;
+	/// Extra width required by an inset, in addition to its dimension
+	int extrawidth;
 };
 
 

src/TextMetrics.cpp

@@ -485,6 +485,7 @@ bool TextMetrics::redoParagraph(pit_type const pit, bool const align_rows)
 	par.setBeginOfBody();
 	Font const bufferfont = buffer.params().getFont();
 	CoordCache::Insets & insetCache = bv_->coordCache().insets();
+	map <Inset const *, int> extrawidths;
 	for (auto const & e : par.insetList()) {
 		// FIXME Doesn't this HAVE to be non-empty?
 		// position already initialized?
@@ -521,6 +522,20 @@ bool TextMetrics::redoParagraph(pit_type const pit, bool const align_rows)
 		MetricsInfo mi(bv_, font.fontInfo(), w, mc, e.pos == 0, tight_);
 		mi.base.outer_font = displayFont(pit, e.pos).fontInfo();
 		e.inset->metrics(mi, dim);
+		/* FIXME: This is a hack. This allows InsetMathHull to state
+		 * that it needs some elbow room beyond its width, in order to
+		 * fit the numbering and/or the left margin (with left
+		 * alignment), which are outside of the inset itself.
+		 *
+		 * To this end, InsetMathHull::metrics() sets a value in
+		 * MetricsInfo::extrawidth and this value is added later to
+		 * the width of the row that contains the inset (when this row
+		 * is tight or shorter than the max allowed width).
+		 *
+		 * See ticket #12320 for details.
+		*/
+		extrawidths[e.inset] = mi.extrawidth;
+
 		if (!insetCache.has(e.inset) || insetCache.dim(e.inset) != dim) {
 			insetCache.add(e.inset, dim);
 			changed = true;
@@ -532,6 +547,12 @@ bool TextMetrics::redoParagraph(pit_type const pit, bool const align_rows)
 	// Split the row in several rows fitting in available width
 	pm.rows() = breakParagraph(bigrow);
 
+	// Add the needed extra width to the rows that contain the insets that request it
+	for (Row & row : pm.rows())
+		for (Row::Element & e : row)
+			if (e.type == Row::INSET && (row.width() < max_width_ || tight_))
+				row.dim().wid += extrawidths[e.inset];
+
 	/* If there is more than one row, expand the text to the full
 	 * allowable width. This setting here is needed for the
 	 * setRowAlignment() below. We do nothing when tight insets are

src/mathed/InsetMathHull.cpp

@@ -523,6 +523,9 @@ void InsetMathHull::metrics(MetricsInfo & mi, Dimension & dim) const
 	if (mi.vmode)
 		top_display_margin += theFontMetrics(mi.base.font).maxHeight() + 2;
 
+	int const ind = indent(*mi.base.bv);
+	mi.extrawidth = ind;
+
 	if (previewState(mi.base.bv)) {
 		preview_->metrics(mi, dim);
 		if (previewTooSmall(dim)) {
@@ -554,6 +557,7 @@ void InsetMathHull::metrics(MetricsInfo & mi, Dimension & dim) const
 	if (numberedType()) {
 		BufferParams::MathNumber const math_number = buffer().params().getMathNumber();
 		int extra_offset = 0;
+		int max_nlwid = 0;
 		for (row_type row = 0; row < nrows(); ++row) {
 			rowinfo(row).offset[mi.base.bv] += extra_offset;
 			docstring const nl = nicelabel(row);
@@ -561,7 +565,6 @@ void InsetMathHull::metrics(MetricsInfo & mi, Dimension & dim) const
 				continue;
 			Dimension dimnl;
 			mathed_string_dim(mi.base.font, nl, dimnl);
-			int const ind = indent(*mi.base.bv);
 			int const x = ind ? ind : (mi.base.textwidth - dim.wid) / 2;
 			// for some reason metrics does not trigger at the
 			// same point as draw, and therefore we use >= instead of >
@@ -569,8 +572,10 @@ void InsetMathHull::metrics(MetricsInfo & mi, Dimension & dim) const
 			    || (math_number == BufferParams::RIGHT
 			        && dimnl.wid >= mi.base.textwidth - x - dim.wid)) {
 				extra_offset += dimnl.height();
+			} else if (dimnl.wid > max_nlwid)
+				max_nlwid = dimnl.wid;
 		}
-		}
+		mi.extrawidth += max_nlwid;
 		dim.des += extra_offset;
 	}