Java AWT | Ellipse2D

Ellipse2D class is present in java.awt.geom package and it is used to define an ellipse by stating its framing rectangle. This class is only the abstract superclass for all objects which store a 2D ellipse.

• Ellipse2D.Double defines an ellipse with double precision.
• Ellipse2D.Float defines an ellipse with float precision.

Constructor of the class are:

1. Ellipse2D.Double() : creates an ellipse at location 0, 0 and size 0, 0.
2. Ellipse2D.Double(double x, double y, double w, double h) : creates an ellipse at location x, y and width w and height h.
3. Ellipse2D.Float() : creates an ellipse at location 0, 0 and size 0, 0.
4. Ellipse2D.Float(Float x, Float y, Float w, Float h) : creates an ellipse at location x, y and width w and height h.

Commonly used methods:

method	explanation
contains(double x, double y)	returns whether the point is inside the ellipse or not
contains(double x, double y, double w, double h)	returns whether the rectangle is inside the ellipse or not
equals(Object o)	Determines whether or not the specified Object is equal to this Ellipse2D.
intersects(double x, double y, double w, double h)	returns whether the rectangle intersects the ellipse or not
setFrame(double x, double y, double w, double h)	Sets the location and size of the framing rectangle of this Shape to the specified rectangular values.

Below programs illustrate the Ellipse2D class:

1. Java program to create two ellipses and draw them to a java applet: To create ellipse shape on Java applet, we will initialize Ellipse2d class objects named “ed” and “ed1”. The 4 parameters passed in the constructor of the “ed” object are the X coordinate of the upper-left corner of the framing rectangle, the Y coordinate of the upper-left corner of the framing rectangle, the width of the framing rectangle and the height of the framing rectangle. In the constructor of “ed”, we pass nothing, which means the ellipse is initialized to location (0, 0) and size (0, 0). To show them on screen, we create an object of Graphics2d class “g1” and call g1.draw() method.

   // java program to create two ellipse and
   // draw them to a java applet
   import java.awt.*;
   import javax.swing.*;
   import java.awt.geom.*;
   public class solve1 extends JApplet {
       public void init()
       {
           setSize(300, 300);
       }
   
       // paint the applet
       public void paint(Graphics g)
       {
           // create a ellipse2d
           Ellipse2D ed = new Ellipse2D.Double(100.0d, 100.0d,
                                                120.0d, 80.0d);
   
           // create another ellipse2d
           Ellipse2D ed1 = new Ellipse2D.Double();
   
           // set framing rectangle of ellipse
           ed1.setFrame(100.0d, 100.0d, 80.0d, 120.0d);
   
           Graphics2D g1 = (Graphics2D)g;
   
           g1.setColor(Color.red);
   
           // draw the first ellipse
           g1.draw(ed);
   
           g1.setColor(Color.blue);
   
           // draw the first ellipse
           g1.draw(ed1);
       }
   }

   Output:
   

2. Java program to create two ellipse and check whether a point or a rectangle is contained in that ellipse or intersected by it: To check whether a point or a rectangle is contained in that ellipse or intersected by the 2 ellipses, we first create the 2 ellipses in the similar way we created above. Then we create 2 rectangles, by calling the method drawRect() on Graphics2d object “g1”. The parameters in drawRect() method specify the x coordinate of the rectangle to be drawn, the y coordinate of the rectangle to be drawn, the width of the rectangle to be drawn and the height of the rectangle to be drawn. To check whether they contain it or not, we call ed.contains() method and pass the coordinate of the point or rectangle in it, and show the results on a message dialog.

   // java program to create two ellipse and check whether
   // a point or a rectangle is contained in that ellipse
   // or intersected by it
   import java.awt.*;
   import javax.swing.*;
   import java.awt.geom.*;
   public class solve2 extends JApplet {
       public void init()
       {
           setSize(300, 300);
       }
   
       // paint the applet
       public void paint(Graphics g)
       {
           // create a ellipse2d
           Ellipse2D ed = new Ellipse2D.Double(100.0d, 100.0d,
                                                120.0d, 80.0d);
   
           // create another ellipse2d
           Ellipse2D ed1 = new Ellipse2D.Double();
   
           // set framing rectangle of ellipse
           ed1.setFrame(100.0d, 100.0d, 80.0d, 120.0d);
   
           Graphics2D g1 = (Graphics2D)g;
   
           g1.setColor(Color.red);
   
           // draw the first ellipse
           g1.draw(ed);
   
           g1.setColor(Color.blue);
   
           // draw the first ellipse
           g1.draw(ed1);
   
           g1.setColor(Color.black);
   
           // draw a rectangle
           g.drawRect(100, 100, 80, 100);
   
           g1.setColor(Color.orange);
   
           // draw a rectangle
           g.drawRect(150, 150, 10, 10);
   
           // does it contain point
           JOptionPane.showMessageDialog(this, "ellipse 1 contains point 150, 150  "
                                                           + ed.contains(150, 150));
   
           // does it contain rectangle
           JOptionPane.showMessageDialog(this, "ellipse 1 contains rectangle at" +
           "  150, 150 of width 10 and height 10 " + ed.contains(150, 150, 10, 10));
   
           // does it contain rectangle
           JOptionPane.showMessageDialog(this, "ellipse 1 contains rectangle at "+
            " 150, 150 of width 80 and height 100 " + ed.contains(150, 150, 80, 100));
   
           // does it  intersect rectangle
           JOptionPane.showMessageDialog(this, "ellipse 1 intersect rectangle at "+
           " 150, 150 of width 80 and height 100 " + ed.intersects(150, 150, 80, 100));
       }
   }

   Output:
   

   

   

   

   

Note: The above programs might not run in an online IDE please use an Offline compiler.

Reference: https://docs.oracle.com/javase/7/docs/api/java/awt/geom/Ellipse2D.html