public override Box CreateBox(TexEnvironment environment)
{
var texFont = environment.TexFont;
var style = environment.Style;
// set thickness to default if default value should be used
double lineHeight;
var defaultLineThickness = texFont.GetDefaultLineThickness(style);
if (useDefaultThickness)
{
lineHeight = lineRelativeThickness * defaultLineThickness ?? defaultLineThickness;
}
else
{
lineHeight = new SpaceAtom(lineThicknessUnit, 0, lineThickness, 0).CreateBox(environment).Height;
}
// Create boxes for numerator and demoninator atoms, and make them of equal width.
var numeratorBox = Numerator is null ? StrutBox.Empty :
Numerator.CreateBox(environment.GetNumeratorStyle());
var denominatorBox = Denominator is null ? StrutBox.Empty :
Denominator.CreateBox(environment.GetDenominatorStyle());
if (numeratorBox.Width < denominatorBox.Width)
{
numeratorBox = new HorizontalBox(numeratorBox, denominatorBox.Width, numeratorAlignment);
}
else
{
denominatorBox = new HorizontalBox(denominatorBox, numeratorBox.Width, denominatorAlignment);
}
// Calculate preliminary shift-up and shift-down amounts.
double shiftUp, shiftDown;
if (style < TexStyle.Text)
{
shiftUp = texFont.GetNum1(style);
shiftDown = texFont.GetDenom1(style);
}
else
{
shiftDown = texFont.GetDenom2(style);
shiftUp = lineHeight > 0 ? texFont.GetNum2(style) : texFont.GetNum3(style);
}
// Create result box.
var resultBox = new VerticalBox();
// add box for numerator.
resultBox.Add(numeratorBox);
// Calculate clearance and adjust shift amounts.
var axis = texFont.GetAxisHeight(style);
if (lineHeight > 0)
{
// Draw fraction line.
// Calculate clearance amount.
double clearance;
if (style < TexStyle.Text)
{
clearance = 3 * lineHeight;
}
else
{
clearance = lineHeight;
}
// Adjust shift amounts.
var delta = lineHeight / 2;
var kern1 = shiftUp - numeratorBox.Depth - (axis + delta);
var kern2 = axis - delta - (denominatorBox.Height - shiftDown);
var delta1 = clearance - kern1;
var delta2 = clearance - kern2;
if (delta1 > 0)
{
shiftUp += delta1;
kern1 += delta1;
}
if (delta2 > 0)
{
shiftDown += delta2;
kern2 += delta2;
}
resultBox.Add(new StrutBox(0, kern1, 0, 0));
resultBox.Add(new HorizontalRule(lineHeight, numeratorBox.Width, 0));
resultBox.Add(new StrutBox(0, kern2, 0, 0));
}
else
{
// Do not draw fraction line.
// Calculate clearance amount.
double clearance;
if (style < TexStyle.Text)
{
clearance = 7 * defaultLineThickness;
}
else
{
clearance = 3 * defaultLineThickness;
}
// Adjust shift amounts.
var kern = shiftUp - numeratorBox.Depth - (denominatorBox.Height - shiftDown);
var delta = (clearance - kern) / 2;
if (delta > 0)
{
shiftUp += delta;
shiftDown += delta;
kern += 2 * delta;
}
resultBox.Add(new StrutBox(0, kern, 0, 0));
}
// add box for denominator.
resultBox.Add(denominatorBox);
// Adjust height and depth of result box.
resultBox.Height = shiftUp + numeratorBox.Height;
resultBox.Depth = shiftDown + denominatorBox.Depth;
return(resultBox);
}
