Picture Lab A7: Mirroring Part of a Picture

Activity 4.68.1.

Picture Lab A7: Run to see mirrorTemple() working.

import java.awt.*;
import java.awt.font.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
import java.text.*;
import java.util.*;

/**
 * A class that represents a picture. This class inherits from SimplePicture and
 * allows the student to add functionality to the Picture class.
 *
 * @author Barbara Ericson ericson@cc.gatech.edu
 */
public class Picture extends SimplePicture
{
    ///////////////////// constructors //////////////////////////////////

/** Constructor that takes no arguments */
    public Picture()
    {
        /* not needed but use it to show students the implicit call to super()
         * child constructors always call a parent constructor
         */
        super();
    }

/**
     * Constructor that takes a file name and creates the picture
     *
     * @param fileName the name of the file to create the picture from
     */
    public Picture(String fileName)
    {
        // let the parent class handle this fileName
        super(fileName);
    }

/**
     * Constructor that takes the height and width
     *
     * @param height the height of the desired picture
     * @param width the width of the desired picture
     */
    public Picture(int height, int width)
    {
        // let the parent class handle this width and height
        super(width, height);
    }

/**
     * Constructor that takes a picture and creates a copy of that picture
     *
     * @param copyPicture the picture to copy
     */
    public Picture(Picture copyPicture)
    {
        // let the parent class do the copy
        super(copyPicture);
    }

/**
     * Constructor that takes a buffered image
     *
     * @param image the buffered image to use
     */
    public Picture(BufferedImage image)
    {
        super(image);
    }

////////////////////// methods ///////////////////////////////////////

/**
     * Method to return a string with information about this picture.
     *
     * @return a string with information about the picture such as fileName, height
     *     and width.
     */
    public String toString()
    {
        String output =
                "Picture, filename "
                        + getFileName()
                        + " height "
                        + getHeight()
                        + " width "
                        + getWidth();
        return output;
    }

/** Method mirrorTemple() fixes the temple.jpg picture */
    public void mirrorTemple()
    {
        int mirrorPoint = 276;
        Pixel leftPixel = null;
        Pixel rightPixel = null;
        Pixel[][] pixels = this.getPixels2D();

// loop through the rows
        for (int row = 27; row < 97; row++)
        {
            // loop from 13 to just before the mirror point
            for (int col = 13; col < mirrorPoint; col++)
            {
                leftPixel = pixels[row][col];
                rightPixel = pixels[row][mirrorPoint - col + mirrorPoint];
                rightPixel.setColor(leftPixel.getColor());
            }
        }
    }

/* Main method for testing
     */
    public static void main(String[] args)
    {
        Picture pict = new Picture("temple.jpg");
        pict.show();
        pict.mirrorTemple();
        pict.show();
    }
}
====
import static org.junit.Assert.*;

import org.junit.*;

import java.io.*;

public class RunestoneTests extends CodeTestHelper
{
    @Test
    public void test1()
    {
        String target = "public void mirrorTemple()";
        boolean passed = checkCodeContains("mirrorTemple() method", target);
        assertTrue(passed);
    }
}

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Activity 4.68.2.

How many times would the body of this nested for loop execute?

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for (int row = 7; row < 17; row++)
    for (int col = 6; col < 15; col++)

17
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Don’t forget the inner loop.
17 - 7 = 10
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Don’t forget the inner loop.
(17 - 7) * (15 - 6) = 90
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Correct
17 * 15 = 255
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The loops do not start at 0.

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Activity 4.68.3.

How many times would the body of this nested for loop execute?

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for (int row = 5; row <= 11; row++)
    for (int col = 3; col <= 18; col++)

11
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Don’t forget the inner loop.
11 - 5 = 6
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Don’t forget the inner loop.
(11 - 5) * (18 - 3) = 90
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Notice that these loops use <=
(11 - 5 + 1) * (18 - 3 + 1) = 112
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Yes, the loops do not start at 0 and use <=.

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Activity 4.68.4.

Picture Lab A7 Mirroring: Check the calculation of the number of times the body of the nested loop executes by adding an integer count variable to the mirrorTemple method that starts out at 0 and increments inside the body of the loop. Print the value of count after the nested loop ends which should be 18410.