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
Implements curveTo(C) attribute of SVG's path element
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Field Summary
FieldsModifier and TypeFieldDescription(package private) static final int
private static double
Fields inherited from class com.itextpdf.svg.renderers.path.impl.AbstractPathShape
coordinates, copier, properties, relative
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Constructor Summary
ConstructorsConstructorDescriptionCurveTo()
CurveTo
(boolean relative) CurveTo
(boolean relative, IOperatorConverter copier) -
Method Summary
Modifier and TypeMethodDescriptionprivate static void
addTValueToList
(double t, List<Double> tValuesList) Check that t is in the range [0, 1] and add it to listprivate static double
calculateExtremeCoordinate
(double t, double p0, double p1, double p2, double p3) 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 tvoid
Draws this instruction to a canvas object.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.private Point
Returns coordinates of the last control point (the one closest to the ending point) in the Bezier curve, in SVG space coordinatesgetPathShapeRectangle
(Point lastPoint) Get bounding rectangle of the current path shape.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.void
setCoordinates
(String[] inputCoordinates, Point startPoint) This method sets the coordinates for the path painting operator and does internal preprocessing, if necessaryMethods inherited from class com.itextpdf.svg.renderers.path.impl.AbstractPathShape
createPoint, getEndingPoint, isRelative
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Field Details
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ARGUMENT_SIZE
static final int ARGUMENT_SIZE- See Also:
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ZERO_EPSILON
private static double ZERO_EPSILON
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Constructor Details
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CurveTo
public CurveTo() -
CurveTo
public CurveTo(boolean relative) -
CurveTo
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Method Details
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draw
Description copied from interface:IPathShape
Draws this instruction to a canvas object.- Specified by:
draw
in interfaceIPathShape
- Parameters:
canvas
- to which this instruction is drawn
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setCoordinates
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 interfaceIPathShape
- Parameters:
inputCoordinates
- an array containing point values for path coordinatesstartPoint
- the ending point of the previous operator, or, in broader terms, the point that the coordinates should be absolutized against, for relative operators
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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 interfaceIControlPointCurve
- Returns:
- coordinates of the last control point in SVG space coordinates
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getPathShapeRectangle
Description copied from class:AbstractPathShape
Get bounding rectangle of the current path shape.- Specified by:
getPathShapeRectangle
in interfaceIPathShape
- Overrides:
getPathShapeRectangle
in classAbstractPathShape
- Parameters:
lastPoint
- start point for this shape- Returns:
- calculated rectangle
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getFirstControlPoint
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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 methodgetTValuesInExtremePoints(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 pointy0
- y coordinate of the starting pointx1
- x coordinate of the first control pointy1
- y coordinate of the first control pointx2
- x coordinate of the second control pointy2
- y coordinate of the second control pointx3
- x coordinate of the ending pointy3
- y coordinate of the ending point- Returns:
- array of {xMin, yMin, xMax, yMax} values
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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 pointy0
- y coordinate of the starting pointx1
- x coordinate of the first control pointy1
- y coordinate of the first control pointx2
- x coordinate of the second control pointy2
- y coordinate of the second control pointx3
- x coordinate of the ending pointy3
- y coordinate of the ending point- Returns:
- array of theta values corresponding to extreme points
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calculateTValues
Calculate the quadratic function 3a*t^2 + 2b*t + c = 0 to obtain the values of t- Parameters:
p0
- coordinate of the starting pointp1
- coordinate of the first control pointp2
- coordinate of the second control pointp3
- coordinate of the ending point- Returns:
- list of t values. t should be in range [0, 1]
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addTValueToList
Check that t is in the range [0, 1] and add it to list- Parameters:
t
- value of ttValuesList
- list storing t values
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calculateExtremeCoordinate
private static double calculateExtremeCoordinate(double t, double p0, double p1, double p2, double p3)
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