Fix the display of column spacing in AMS environments

AMS align environment should have some spacing between odd and even columns.

Add a new virtual method displayColSpace() to InsetMathGrid, InsetMathHull and
InsetMathSplit.

src/mathed/InsetMathGrid.cpp

@@ -486,7 +486,7 @@ void InsetMathGrid::metrics(MetricsInfo & mi, Dimension & dim) const
 		colinfo_[col].offset_ =
 			colinfo_[col - 1].offset_ +
 			colinfo_[col - 1].width_ +
-			colinfo_[col - 1].skip_ +
+			displayColSpace(col - 1) +
 			colsep() +
 			colinfo_[col].lines_ * vlinesep();
 	}
@@ -508,7 +508,7 @@ void InsetMathGrid::metrics(MetricsInfo & mi, Dimension & dim) const
 			int const nextoffset =
 				colinfo_[first].offset_ +
 				wid +
-				colinfo_[last].skip_ +
+				displayColSpace(last) +
 				colsep() +
 				colinfo_[last+1].lines_ * vlinesep();
 			int const dx = nextoffset - colinfo_[last+1].offset_;
@@ -741,7 +741,7 @@ void InsetMathGrid::metricsT(TextMetricsInfo const & mi, Dimension & dim) const
 		colinfo_[col].offset_ =
 			colinfo_[col - 1].offset_ +
 			colinfo_[col - 1].width_ +
-			colinfo_[col - 1].skip_ +
+			displayColSpace(col - 1) +
 			1 ; //colsep() +
 			//colinfo_[col].lines_ * vlinesep();
 	}
@@ -953,7 +953,7 @@ int InsetMathGrid::cellWidth(idx_type idx) const
 		col_type c2 = c1 + ncellcols(idx);
 		return colinfo_[c2].offset_
 			- colinfo_[c1].offset_
-			- colinfo_[c2].skip_
+			- displayColSpace(c2)
 			- colsep()
 			- colinfo_[c2].lines_ * vlinesep();
 	}
@@ -1378,6 +1378,11 @@ char InsetMathGrid::displayColAlign(idx_type idx) const
 }
 
 
+int InsetMathGrid::displayColSpace(col_type col) const
+{
+	return colinfo_[col].skip_;
+}
+
 void InsetMathGrid::doDispatch(Cursor & cur, FuncRequest & cmd)
 {
 	//lyxerr << "*** InsetMathGrid: request: " << cmd << endl;
@@ -1862,5 +1867,32 @@ char InsetMathGrid::colAlign(HullType type, col_type col)
 }
 
 
+//static
+int InsetMathGrid::colSpace(HullType type, col_type col)
+{
+	int alignInterSpace;
+	switch (type) {
+	case hullEqnArray:
+		return 5;
+	
+	case hullAlign:
+		alignInterSpace = 20;
+		break;
+	case hullAlignAt:
+		alignInterSpace = 0;
+		break;
+	case hullXAlignAt:
+		alignInterSpace = 40;
+		break;
+	case hullXXAlignAt:
+	case hullFlAlign:
+		alignInterSpace = 60;
+		break;
+	default:
+		return 0;
+	}
+	return (col % 2) ? alignInterSpace : 0;
+}
+
 
 } // namespace lyx

src/mathed/InsetMathGrid.h

@@ -261,8 +261,16 @@ protected:
 	/// Column alignment for display of cell \p idx.
 	/// Must not be written to file!
 	virtual char displayColAlign(idx_type idx) const;
+	/// Column spacing for display of column \p col.
+	/// Must not be written to file!
+	virtual int displayColSpace(col_type col) const;
+
+	// The following two functions are used in InsetMathHull and
+	// InsetMathSplit.
 	/// The value of a fixed col align for a certain hull type 
 	static char colAlign(HullType type, col_type col);
+	/// The value of a fixed col spacing for a certain hull type
+	static int colSpace(HullType type, col_type col);
 
 	/// row info.
 	/// rowinfo_[nrows()] is a dummy row used only for hlines.

src/mathed/InsetMathHull.cpp

@@ -382,6 +382,13 @@ char InsetMathHull::displayColAlign(idx_type idx) const
 }
 
 
+int InsetMathHull::displayColSpace(col_type col) const
+{
+	return colSpace(type_, col);
+}
+
+
+//FIXME: This has probably no effect and can be removed.
 int InsetMathHull::defaultColSpace(col_type col)
 {
 	if (type_ == hullAlign || type_ == hullAlignAt)

src/mathed/InsetMathHull.h

@@ -111,6 +111,8 @@ public:
 	///
 	int defaultColSpace(col_type col);
 	///
+	int displayColSpace(col_type col) const;
+	///
 	char defaultColAlign(col_type col);
 	///
 	char displayColAlign(idx_type idx) const;

src/mathed/InsetMathSplit.cpp

@@ -83,6 +83,17 @@ char InsetMathSplit::displayColAlign(idx_type idx) const
 }
 
 
+int InsetMathSplit::displayColSpace(col_type col) const
+{
+	if (name_ == "split" || name_ == "aligned" || name_ == "align")
+		return colSpace(hullAlign, col);
+	if (name_ == "alignedat")
+		return colSpace(hullAlignAt, col);
+	return 0;
+}
+
+
+
 void InsetMathSplit::draw(PainterInfo & pi, int x, int y) const
 {
 	InsetMathGrid::draw(pi, x, y);

src/mathed/InsetMathSplit.h

@@ -41,6 +41,8 @@ public:
 	///
 	int defaultColSpace(col_type) { return 0; }
 	///
+	int displayColSpace(col_type col) const;
+	///
 	char defaultColAlign(col_type);
 	///
 	char displayColAlign(idx_type idx) const;