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Call the copyPictureWithCrop method again

Listing 9 begins by calling the copyPictureWithCrop method again. This time, however, the picture shown in Figure 5 is passed as the source image with the same picture as before being passed as thedestination image.

The offset coordinates

In this case, the offset coordinate values specify the upper-left corner of the right-most butterfly image in Figure 3 .

The cropping parameters

The final four parameters that are passed in Listing 9 specify that the entire source picture is to be copied into the destinationpicture.

Display the destination picture

When the copyPictureWithCrop method returns, Listing 9 calls the explore method to display the current state of the destination picture. The result is shown in Figure 3 .

A new array object

Finally, Listing 9 instantiates a new array object, populates it with references to three Picture objects, and returns control to the main method code in Listing 1 returning a reference to the array object in the process.

The code in Listing 1 saves the reference to the array object in the variable named pictures .

Pass Picture object references to println method

Then Listing 1 extracts and passes each of the three Picture object references to the println method causing the last three lines of text shown in Figure 4 to be displayed on the command-line screen.

The second line of output text ( picA ) describes the raw butterfly image shown in Figure 1 .

The third line of output text for ( picB ) describes the beach scene shown in Figure 2 and Figure 3 .

The last line of output text ( picC ) describes the cropped and flipped version of the butterfly image shown in Figure 5 .

Run the program

I encourage you to copy the code from Listing 10 . Compile the code and execute it. Experiment with the code, making changes, andobserving the results of your changes. Make certain that you can explain why your changes behave as they do.

Click here and here to download the two required input image files.

Summary

In this module, you learned how to:

  • Work directly with individual pixels and keep track of coordinate values.
  • Copy a portion of one picture into a specific location in another picture.
  • Crop and flip a picture.

What's next?

You will learn to write a program to do green-screen processing in the next module.

While not a requirement of the course, you can select the following links to view optional online video lectures on the material in thismodule.

Miscellaneous

This section contains a variety of miscellaneous information.

Housekeeping material
  • Module name: Java OOP: Cropping, Flipping, and Combining Pictures
  • File: Java3014.htm
  • Published: 08/01/12
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 shown in Listing 10 below.

Listing 10 . Complete program listing.
/*File Prob02 Copyright 2008 R.G.Baldwin Revised 12/16/08*********************************************************/ import java.awt.Color;public class Prob02{ public static void main(String[]args){ Picture[]pictures = new Prob02Runner().run(); System.out.println(pictures[0]); System.out.println(pictures[1]); System.out.println(pictures[2]); }//end main method}//end class Prob02 //======================================================//class Prob02Runner{ public Prob02Runner(){//constructorSystem.out.println("Display your name here."); }//end constructor//----------------------------------------------------// public Picture[]run(){ Picture picA = new Picture("Prob02a.jpg");picA.explore(); Picture picB = new Picture("Prob02b.jpg");picB.addMessage("Display your name here.",10,20); picB.explore();Picture picC = cropAndFlip(picA,4,5,80,105); copyPictureWithCrop(picA,picB,82,70,4,5,77,101);copyPictureWithCrop(picC,picB,161,70,0,0,77,101); picB.explore();Picture[] output = {picA,picB,picC};return output; }//end run//----------------------------------------------------// //Crops a picture to the specified coordinate values and// flips it around a vertical line at its center. private Picture cropAndFlip(Picture pic,int x1,int y1,int x2,int y2){ Picture output = new Picture(x2-x1+1,y2-y1+1);int width = output.getWidth(); Pixel pixel = null;Color color = null; for(int col = x1;col<(x2+1);col++){ for(int row = y1;row<(y2+1);row++){ color = pic.getPixel(col,row).getColor();pixel = output.getPixel(width-col+x1-1,row-y1); pixel.setColor(color);}//end inner loop }//end outer loopreturn output; }//end crop and flip//----------------------------------------------------// //Copies part of the source picture into the destination// picture with an offset on both axes after first // confirming that the part will fit. Does nothing if it// won't fit. private void copyPictureWithCrop(Picture source,Picture dest,int xOff, int yOff,int xCoor, int yCoor,int width, int height){//Confirm that source will fit in destination if(((width+xOff)<= dest.getWidth())&&((height+yOff)<= dest.getHeight())){ Pixel pixel = null;Color color = null; for(int col = 0;col<width;col++){ for(int row = 0;row<height;row++){ color = source.getPixel(col + xCoor,row + yCoor).getColor(); pixel = dest.getPixel(col+xOff,row+yOff);pixel.setColor(color); }//end inner loop}//end outer loop }//end if}//end copyPictureWithCrop method }//end class Prob02Runner

-end-

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