/// <summary>This method use derivative of function defined on interval: [xMin, xMax] to find its local minimum and maximum.
/// </summary>
/// <remarks>
/// This method use derivative of function defined on interval: [xMin, xMax] to find its local minimum and maximum.
/// It also calculate other handy values needed for the creation of
/// <see cref="RotationMinMaxWidth"/>.
/// </remarks>
/// <param name="func">
/// the
/// <see cref="WidthFunction.GetRotatedWidth(double)"/>
/// of this instance is used as analysed function
/// </param>
/// <param name="xMin">the smallest possible value of function argument</param>
/// <param name="xMax">the biggest possible value of function argument</param>
/// <returns>
/// the calculated
/// <see cref="RotationMinMaxWidth"/>
/// </returns>
private static iText.Layout.Minmaxwidth.RotationMinMaxWidth Calculate(RotationMinMaxWidth.WidthFunction func
, double xMin, double xMax)
{
double minWidthOrigin;
double maxWidthOrigin;
//Derivative sign change point
double x0 = func.GetWidthDerivativeZeroPoint();
//The point x0 may be in three different positions in relation to function interval.
if (x0 < xMin)
{
//The function is decreasing in this case on whole interval so the local mim and max are on interval borders
minWidthOrigin = xMin;
maxWidthOrigin = xMax;
}
else
{
if (x0 > xMax)
{
//The function is increasing in this case on whole interval so the local mim and max are on interval borders
minWidthOrigin = xMax;
maxWidthOrigin = xMin;
}
else
{
//The function derivative changes its sign from negative to positive on function interval in point x0,
//so its local min is x0, and its local maximum is on one of interval borders
minWidthOrigin = x0;
maxWidthOrigin = func.GetRotatedWidth(xMax) > func.GetRotatedWidth(xMin) ? xMax : xMin;
}
}
return(new iText.Layout.Minmaxwidth.RotationMinMaxWidth(func.GetRotatedWidth(minWidthOrigin), func.GetRotatedWidth
(maxWidthOrigin), minWidthOrigin, maxWidthOrigin, func.GetRotatedHeight(minWidthOrigin), func.GetRotatedHeight
(maxWidthOrigin)));
}
/// <summary>
/// Heuristic method, based on the assumption that area of element stays the same, when we try to
/// layout it with different available width (available width is between min-width and max-width).
/// </summary>
/// <param name="angle">rotation angle in radians</param>
/// <param name="area">the constant area</param>
/// <param name="elementMinMaxWidth">NOT rotated element min-max-width</param>
/// <param name="availableWidth">the maximum width of area the element will occupy after rotation.</param>
/// <returns>possible min-max-width of element after rotation</returns>
public static iText.Layout.Minmaxwidth.RotationMinMaxWidth Calculate(double angle, double area, MinMaxWidth
elementMinMaxWidth, double availableWidth)
{
RotationMinMaxWidth.WidthFunction function = new RotationMinMaxWidth.WidthFunction(angle, area);
RotationMinMaxWidth.WidthFunction.Interval validArguments = function.GetValidOriginalWidths(availableWidth
);
if (validArguments == null)
{
return(null);
}
double xMin = Math.Max(elementMinMaxWidth.GetMinWidth(), validArguments.GetMin());
double xMax = Math.Min(elementMinMaxWidth.GetMaxWidth(), validArguments.GetMax());
if (xMax < xMin)
{
//Initially the null was returned in this case, but this result in old layout logic that looks worse in most cases.
//The difference between min and max is not that big and not critical.
double rotatedWidth = function.GetRotatedWidth(xMin);
double rotatedHeight = function.GetRotatedHeight(xMin);
return(new iText.Layout.Minmaxwidth.RotationMinMaxWidth(rotatedWidth, rotatedWidth, xMin, xMin, rotatedHeight
, rotatedHeight));
}
return(Calculate(function, xMin, xMax));
}
/// <summary>
/// Heuristic method, based on the assumption that area of element stays the same, when we try to
/// layout it with different available width (available width is between min-width and max-width).
/// </summary>
/// <param name="angle">rotation angle in radians</param>
/// <param name="area">the constant area</param>
/// <param name="elementMinMaxWidth">NOT rotated element min-max-width</param>
/// <returns>possible min-max-width of element after rotation</returns>
public static iText.Layout.Minmaxwidth.RotationMinMaxWidth Calculate(double angle, double area, MinMaxWidth
elementMinMaxWidth)
{
RotationMinMaxWidth.WidthFunction function = new RotationMinMaxWidth.WidthFunction(angle, area);
return(Calculate(function, elementMinMaxWidth.GetMinWidth(), elementMinMaxWidth.GetMaxWidth()));
}