Class CurveTo

java.lang.Object
com.itextpdf.svg.renderers.path.impl.AbstractPathShape
com.itextpdf.svg.renderers.path.impl.CurveTo
All Implemented Interfaces:
IControlPointCurve, IPathShape
Direct Known Subclasses:
SmoothSCurveTo
public class CurveTo extends AbstractPathShape implements IControlPointCurve
Implements curveTo(C) attribute of SVG's path element.

  • Field Details

  • Constructor Details

    • CurveTo

      public CurveTo()
      Creates new CurveTo instance.

    • CurveTo

      public CurveTo(boolean relative)
      Creates new CurveTo instance.
      Parameters:
      relative - true in case it is a relative operator, false if it is an absolute operator

    • CurveTo

      public CurveTo(boolean relative, IOperatorConverter copier)
      Creates new CurveTo instance.
      Parameters:
      relative - true in case it is a relative operator, false if it is an absolute operator
      copier - IOperatorConverter copier for converting relative coordinates to absolute coordinates

  • Method Details

    • draw

      public void draw()
      Description copied from class: AbstractPathShape
      Draws this instruction to a canvas object.
      Specified by:
      draw in class AbstractPathShape

    • setCoordinates

      public void setCoordinates(String[] inputCoordinates, Point startPoint)
      Description copied from interface: IPathShape
      This method sets the coordinates for the path painting operator and does internal preprocessing, if necessary
      Specified by:
      setCoordinates in interface IPathShape
      Parameters:
      inputCoordinates - an array containing point values for path coordinates
      startPoint - the ending point of the previous operator, or, in broader terms, the point that the coordinates should be absolutized against, for relative operators

    • getLastControlPoint

      public Point getLastControlPoint()
      Description copied from interface: IControlPointCurve
      Returns coordinates of the last control point (the one closest to the ending point) in the Bezier curve, in SVG space coordinates
      Specified by:
      getLastControlPoint in interface IControlPointCurve
      Returns:
      coordinates of the last control point in SVG space coordinates

    • getPathShapeRectangle

      public Rectangle getPathShapeRectangle(Point lastPoint)
      Description copied from class: AbstractPathShape
      Get bounding rectangle of the current path shape.
      Specified by:
      getPathShapeRectangle in interface IPathShape
      Overrides:
      getPathShapeRectangle in class AbstractPathShape
      Parameters:
      lastPoint - start point for this shape
      Returns:
      calculated rectangle

    • getFirstControlPoint

      private Point getFirstControlPoint()

    • getBezierMinMaxPoints

      private static double[] getBezierMinMaxPoints(double x0, double y0, double x1, double y1, double x2, double y2, double x3, double y3)
      Initial function of cubic bezier is f(t) = (t-1)^3*P0 + 3*(1-t)^2*t*P1 + 3*(1-t)*t^2*P2 + t^3*P3, where 0 invalid input: '<'= t invalid input: '<'= 1 After opening brackets it can be reduced to f(t) = a*t^3 + b*t^2 + c*t + d, where a = P3-3*P2+3*P1-P0 b = 3*P2-6*P1+3*P0 c = 3*P1-3*P0 d = P0 First we must find the values of t at which the function reaches its extreme points. This happens in the method getTValuesInExtremePoints(double, double, double, double, double, double, double, double). Next we get x and y values in extremes and compare it with the start and ending points coordinates to get the borders of the bounding box.
      Parameters:
      x0 - x coordinate of the starting point
      y0 - y coordinate of the starting point
      x1 - x coordinate of the first control point
      y1 - y coordinate of the first control point
      x2 - x coordinate of the second control point
      y2 - y coordinate of the second control point
      x3 - x coordinate of the ending point
      y3 - y coordinate of the ending point
      Returns:
      array of {xMin, yMin, xMax, yMax} values

    • getTValuesInExtremePoints

      private static double[] getTValuesInExtremePoints(double x0, double y0, double x1, double y1, double x2, double y2, double x3, double y3)
      Calculate values of t at which the function reaches its extreme points. To do this, we get the derivative of the function and equate it to 0: f'(t) = 3a*t^2 + 2b*t + c. This is parabola and for finding we calculate the discriminant. t can only be in the range [0, 1] and it discarded otherwise.
      Parameters:
      x0 - x coordinate of the starting point
      y0 - y coordinate of the starting point
      x1 - x coordinate of the first control point
      y1 - y coordinate of the first control point
      x2 - x coordinate of the second control point
      y2 - y coordinate of the second control point
      x3 - x coordinate of the ending point
      y3 - y coordinate of the ending point
      Returns:
      array of theta values corresponding to extreme points

    • calculateTValues

      private static List<Double> calculateTValues(double p0, double p1, double p2, double p3)
      Calculate the quadratic function 3a*t^2 + 2b*t + c = 0 to obtain the values of t
      Parameters:
      p0 - coordinate of the starting point
      p1 - coordinate of the first control point
      p2 - coordinate of the second control point
      p3 - coordinate of the ending point
      Returns:
      list of t values. t should be in range [0, 1]

    • addTValueToList

      private static void addTValueToList(double t, List<Double> tValuesList)
      Check that t is in the range [0, 1] and add it to list
      Parameters:
      t - value of t
      tValuesList - list storing t values

    • calculateExtremeCoordinate

      private static double calculateExtremeCoordinate(double t, double p0, double p1, double p2, double p3)