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Where is the line segment positioned?

One end of the line segment is at the center of the circle. The other end of the line segment is at the point where the 45-degree line intersects the edge ofthe circle closest to the origin.

You can take it from there

You should be able to take it from there and explain the color gradient in the circle in the lower-right quadrant. Recall that the diameter of the circleis 128 pixels. The length of the line segment is 64 pixels or one-half the diameter.

The end of the class

Listing 8 signals the end of the class named Prob03Runner and the end of the program.

Run the program

I encourage you to copy the code from Listing 9 . Compile the code and execute it. Experiment with the code, making changes, andobserving the results of your changes. For example, try setting the cyclic constructor parameter to false and observe the effect. Make certain that you canexplain why your changes behave as they do.

Click Prob03.jpg to download the input image file if you elect to use it.

Summary

In this module, you learned to use the GradientPaint class along with a variety of other Java2D classes.

What's next?

In the next module, you will Learn how to use shapes to clip images during the drawing process.

While not a requirement of the course, you can select the following link to view an optional online video lecture on the material in this module.

Miscellaneous

This section contains a variety of miscellaneous information.

Housekeeping material
  • Module name: Java OOP: GradientPaint and other Java2D Classes
  • File: Java3026.htm
  • Published: 08/04/12
Disclaimers:

Financial : Although the Connexions site makes it possible for you to download a PDF file for thismodule at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should beaware that some of the HTML elements in this module may not translate well into PDF.

I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version of the module.

In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale on Amazon.com showing me as the author. Ineither receive compensation for those sales nor do I know who does receive compensation. If you purchase such a book, please beaware that it is a copy of a module that is freely available on cnx.org and that it was made and published withoutmy prior knowledge.

Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.

Complete program listing

A complete listing of the program discussed in this module is provided in Listing 9 below.

Listing 9 . Complete program listing .
/*File Prob03 Copyright 2008 R.G.Baldwin *********************************************************/import java.awt.geom.Line2D; import java.awt.geom.Ellipse2D;import java.awt.Color; import java.awt.Graphics;import java.awt.Graphics2D; import java.awt.GradientPaint;public class Prob03{ //DO NOT MODIFY THE CODE IN THIS CLASS DEFINITION.public static void main(String[] args){new Prob03Runner().run(); }//end main method}//end class Prob03 //======================================================//class Prob03Runner{ public Prob03Runner(){System.out.println("Display your name here."); }//end constructor//----------------------------------------------------// public void run(){Picture pic = new Picture("Prob03.jpg"); pic.setAllPixelsToAColor(Color.RED);process(pic); //Add your name and display the output picture.pic.addMessage("Display your name here.",10,20); pic.explore();System.out.println(pic); }//end run//----------------------------------------------------// private void process(Picture pic){Graphics2D g2 = (Graphics2D)(pic.getGraphics()); int width = pic.getWidth();int height = pic.getHeight(); //Translate origin to center of Frameg2.translate(width/2,height/2); g2.setColor(Color.BLACK);//Draw x-axis g2.draw(new Line2D.Double(-width/2,0.0,width/2,0.0));//Draw y-axis g2.draw(new Line2D.Double(0.0,-width/2,0.0,height/2));//Upper left quadrant, Solid GREEN fill Ellipse2D.Double circle1 =new Ellipse2D.Double(-128,-128,128,128); g2.setPaint(Color.GREEN);g2.fill(circle1); g2.draw(circle1);//Upper right quadrant //Gradient GREEN to BLUE, cyclic along horizontal// axis. Ellipse2D.Double circle2 =new Ellipse2D.Double(0.0,-128,128,128); g2.setPaint(new GradientPaint(64,0,Color.GREEN, 64,-32,Color.BLUE,true));g2.fill(circle2); g2.draw(circle2);//Lower left quadrant //Gradient GREEN to BLUE, cyclic along vertical axis.//horizontal axis Ellipse2D.Double circle3 =new Ellipse2D.Double(-128,0.0,128,128); g2.setPaint(new GradientPaint( -128,-64,Color.GREEN,-107,-64,Color.BLUE,true)); g2.fill(circle3);g2.draw(circle3); //Lower right quadrant//Gradient GREEN to BLUE, cyclic along // 45 degree angleEllipse2D.Double circle4 = new Ellipse2D.Double(0,0,128,128);g2.setPaint( new GradientPaint(19,19,Color.GREEN, 64,64,Color.BLUE,true));g2.fill(circle4); g2.draw(circle4);}//end process }//end class Prob03Runner

-end-

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Source:  OpenStax, Object-oriented programming (oop) with java. OpenStax CNX. Jun 29, 2016 Download for free at https://legacy.cnx.org/content/col11441/1.201
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