QuadCurve2D類指出二次參數曲線段（X，Y）坐標空間。

類的聲明

以下是聲明java.awt.geom.QuadCurve2D類：

public abstract class QuadCurve2D
   extends Object
      implements Shape, Cloneable

類的構造函數

S.N.	構造函數與說明
1	protected QuadCurve2D() ()  This is an abstract class that cannot be instantiated directly.

類方法

S.N.	方法和說明
1	Object clone()  Creates a new object of the same class and with the same contents as this object.
2	boolean contains(double x, double y)  Tests if the specified coordinates are inside the boundary of the Shape.
3	boolean contains(double x, double y, double w, double h)  Tests if the interior of the Shape entirely contains the specified rectangular area.
4	boolean contains(Point2D p)  Tests if a specified Point2D is inside the boundary of the Shape.
5	boolean contains(Rectangle2D r)  Tests if the interior of the Shape entirely contains the specified Rectangle2D.
6	Rectangle getBounds()  Returns an integer Rectangle that completely encloses the Shape.
7	abstract Point2D getCtrlPt()  Returns the control point.
8	abstract double getCtrlX()  Returns the X coordinate of the control point in double precision.
9	abstract double getCtrlY()  Returns the Y coordinate of the control point in double precision.
10	doublegetFlatness()  Returns the flatness, or maximum distance of a control point from the line connecting the end points, of this QuadCurve2D.
11	static double getFlatness(double[] coords, int offset)  Returns the flatness, or maximum distance of a control point from the line connecting the end points, of the quadratic curve specified by the control points stored in the indicated array at the indicated index.
12	static double getFlatness(double x1, double y1, double ctrlx, double ctrly, double x2, double y2)  Returns the flatness, or maximum distance of a control point from the line connecting the end points, of the quadratic curve specified by the indicated control points.
13	double getFlatnessSq()  Returns the square of the flatness, or maximum distance of a control point from the line connecting the end points, of this QuadCurve2D.
14	static double getFlatnessSq(double[] coords, int offset)  Returns the square of the flatness, or maximum distance of a control point from the line connecting the end points, of the quadratic curve specified by the control points stored in the indicated array at the indicated index.
15	static double getFlatnessSq(double x1, double y1, double ctrlx, double ctrly, double x2, double y2)  Returns the square of the flatness, or maximum distance of a control point from the line connecting the end points, of the quadratic curve specified by the indicated control points.
16	abstract Point2D getP1()  Returns the start point.
17	abstract Point2D getP2()  Returns the end point.
18	PathIterator getPathIterator(AffineTransform at)  Returns an iteration object that defines the boundary of the shape of this QuadCurve2D.
19	PathIterator getPathIterator(AffineTransform at, double flatness)  Returns an iteration object that defines the boundary of the flattened shape of this QuadCurve2D.
20	abstract double getX1()  Returns the X coordinate of the start point in double in precision.
21	abstract double getX2()  Returns the X coordinate of the end point in double precision.
22	abstract double getY1()  Returns the Y coordinate of the start point in double precision.
23	abstract double getY2()  Returns the Y coordinate of the end point in double precision.
24	boolean intersects(double x, double y, double w, double h)  Tests if the interior of the Shape intersects the interior of a specified rectangular area.
25	boolean intersects(Rectangle2D r)  Tests if the interior of the Shape intersects the interior of a specified Rectangle2D.
26	void setCurve(double[] coords, int offset)  Sets the location of the end points and control points of this QuadCurve2D to the double coordinates at the specified offset in the specified array.
27	abstract void setCurve(double x1, double y1, double ctrlx, double ctrly, double x2, double y2)  Sets the location of the end points and control point of this curve to the specified double coordinates.
28	void setCurve(Point2D[] pts, int offset)  Sets the location of the end points and control points of this QuadCurve2D to the coordinates of the Point2D objects at the specified offset in the specified array.
29	void setCurve(Point2D p1, Point2D cp, Point2D p2)  Sets the location of the end points and control point of this QuadCurve2D to the specified Point2D coordinates.
30	void setCurve(QuadCurve2D c)  Sets the location of the end points and control point of this QuadCurve2D to the same as those in the specified QuadCurve2D.
31	static int solveQuadratic(double[] eqn)  Solves the quadratic whose coefficients are in the eqn array and places the non-complex roots back into the same array, returning the number of roots.
32	static int solveQuadratic(double[] eqn, double[] res)  Solves the quadratic whose coefficients are in the eqn array and places the non-complex roots into the res array, returning the number of roots.
33	static void subdivide(double[] src, int srcoff, double[] left, int leftoff, double[] right, int rightoff)  Subdivides the quadratic curve specified by the coordinates stored in the src array at indices srcoff through srcoff + 5 and stores the resulting two subdivided curves into the two result arrays at the corresponding indices.
34	void subdivide(QuadCurve2D left, QuadCurve2D right)  Subdivides this QuadCurve2D and stores the resulting two subdivided curves into the left and right curve parameters.
35	static void subdivide(QuadCurve2D src, QuadCurve2D left, QuadCurve2D right)  Subdivides the quadratic curve specified by the src parameter and stores the resulting two subdivided curves into the left and right curve parameters.

繼承的方法

這個類繼承的方法從以下類：

• java.lang.Object

QuadCurve2D 實例

選擇使用任何編輯器創建以下java程序 D:/ > AWT > com > yiibai > gui >

AWTGraphicsDemo

package com.yiibai.gui;

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;

public class AWTGraphicsDemo extends Frame {
       
   public AWTGraphicsDemo(){
      super("Java AWT Examples");
      prepareGUI();
   }

   public static void main(String[] args){
      AWTGraphicsDemo  awtGraphicsDemo = new AWTGraphicsDemo();  
      awtGraphicsDemo.setVisible(true);
   }

   private void prepareGUI(){
      setSize(400,400);
      addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent windowEvent){
            System.exit(0);
         }        
      }); 
   }    

   @Override
   public void paint(Graphics g) {
      QuadCurve2D shape = new QuadCurve2D.Double();
      shape.setCurve(250D,250D,100D,100D,200D,150D);  
      Graphics2D g2 = (Graphics2D) g; 
      g2.draw (shape);
      Font font = new Font("Serif", Font.PLAIN, 24);
      g2.setFont(font);
      g.drawString("Welcome to TutorialsPoint", 50, 70);
      g2.drawString("QuadCurve2D.Curve", 100, 120);  
   }
}

編譯程序，使用命令提示符。進入到D:/> AWT，然後鍵入以下命令。

D:AWT>javac comyiibaiguiAWTGraphicsDemo.java

如果冇有錯誤出現，這意味著編譯成功。使用下麵的命令來運行程序。

D:AWT>java com.yiibai.gui.AWTGraphicsDemo

驗證下麵的輸出