3.26 Java3026: gradientpaint and other java2d classes

Revised: Mon Apr 04 10:05:32 CDT 2016

This page is included in the following Books:

• ITSE 2321 - Object-Oriented Programming (Java)
• Object-Oriented Programming (OOP) with Java

Table of contents

• Preface
  • Viewing tip
    • Figures
    • Listings
• Preview
• Discussion and sample code
• Run the program
• Summary
• What's next?
• Online video link
• Miscellaneous
• Complete program listing

Preface

This module is one of a series of modules designed to teach you about Object-Oriented Programming (OOP) using Java.

The program described in this module requires the use of the Guzdial-Ericson multimedia class library. You will find download, installation, and usageinstructions for the library at Java OOP: The Guzdial-Ericson Multimedia Class Library .

Viewing tip

I recommend that you open another copy of this document in a separate browser window and use the following links to easily find and view the Figures and Listings while you are reading about them.

Figures

• Figure 1 . Required graphic output.
• Figure 2 . Required text output.
• Figure 3 . A drawing of an ellipse.

Listings

• Listing 1 . The driver class named Prob03.
• Listing 2 . Beginning of the class named Prob03Runner.
• Listing 3 . Beginning of the method named process.
• Listing 4 . Translate the origin to the center of the image.
• Listing 5 . Draw the black horizontal and vertical axes.
• Listing 6 . Draw the solid green filled ellipse in the upper-left quadrant.
• Listing 7 . Draw a circle with a gradient fill in the upper-right quadrant.
• Listing 8 . Code for the remaining two quadrants..
• Listing 9 . Complete program listing.

Preview

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

Program specifications

Write a program named Prob03 that uses the class definition shown in Listing 1 and Ericson's media library along with the image file named Prob03.jpg to produce the graphic output image shown in Figure 1 . (Note that the image in the file named Prob03.jpg is a blank white image. You could also create thisblank image using one of the constructors for the Picture class.)

Figure 1 - Required graphic output.

Circles with gradient paint

The program draws four circles in the quadrants of a Cartesian coordinate system. One is filled with solid green. The other three are filled with cyclicgradient paint from green to blue.

The number of cycles varies in each circle, as do the axes along which the gradient occurs.

The background is set to Color.RED.

New classes

You may define new classes as necessary to cause your program to behave as required, but you may not modify the class definition for the class named Prob03 shown in Listing 1 .

Required text output

In addition to the output image mentioned above, your program must display your name and the other line of text shown in Figure 2 .

Discussion and sample code

Will discuss in fragments

I will discuss and explain this program in fragments. A complete listing of the program is provided in Listing 9 near the end of the module.