Matrizes...para que afinal?

Matrizes durante o ensino básico pode parecer inútil além de resolver sistemas lineares. Acontece que sistemas lineares são extremamente úteis para resolver problemas de otimização em sistemas industriais resolvidos por Engenheiros de Produção. Mas Matrizes são a base para muitas aplicações na computação. Um delas que agora cito é a reflexão de uma imagem no seu eixo x ou y. Encontrei um código perfeito (cortesia de Byron Kiourtzoglou) exemplificando um método empregado em java para refletir tanto em x quanto em y, contudo, esse código só está fazendo reflexão em x. Para testar o código, basta usar basta montar o projeto com uma IDE como netbeans ou eclipse e por a imagem de teste no diretório "c:/" com nome de "image.png"

 


/*
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 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

package raizgeom;

/**
 *
 * @author Byron Kiourtzoglou
 */
import java.awt.Component;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.Transparency;
import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import java.awt.image.ImageObserver;

public class BufferedImageFlipps {

    static BufferedImage image;
    static boolean imageLoaded = false;

    public static void main(String[] args) {

  // The ImageObserver implementation to observe loading of the image

  ImageObserver myImageObserver = new ImageObserver() {

    public boolean imageUpdate(Image image, int flags, int x, int y, int width, int height) {

if ((flags & ALLBITS) != 0) {

  imageLoaded = true;

  System.out.println("Image loading finished!");

  return false;

}

return true;

    }

  };

  // The image URL - change to where your image file is located!

  String imageURL = "c:/image.png";

  /**

   * This call returns immediately and pixels are loaded in the background

   * We use an ImageObserver to be notified when the loading of the image

   * is complete

   */

  Image sourceImage = Toolkit.getDefaultToolkit().getImage(imageURL);

  sourceImage.getWidth(myImageObserver);

  // We wait until the image is fully loaded

  while (!imageLoaded) {

try {

    Thread.sleep(100);

} catch (InterruptedException e) {

}

  }

  // Create a buffered image from the source image with a format that's compatible with the screen

  GraphicsEnvironment graphicsEnvironment = GraphicsEnvironment.getLocalGraphicsEnvironment();

  GraphicsDevice graphicsDevice = graphicsEnvironment.getDefaultScreenDevice();

  GraphicsConfiguration graphicsConfiguration = graphicsDevice.getDefaultConfiguration();

  // If the source image has no alpha info use Transparency.OPAQUE instead

  image = graphicsConfiguration.createCompatibleImage(sourceImage.getWidth(null), sourceImage.getHeight(null), Transparency.BITMASK);

  // Copy image to buffered image

  Graphics graphics = image.createGraphics();

  // Paint the image onto the buffered image

  graphics.drawImage(sourceImage, 0, 0, null);

  graphics.dispose();

  // Flip the image vertically

  //AffineTransform tx = AffineTransform.getScaleInstance(1, -1);

 // tx.translate(0, -image.getHeight(null));

  //AffineTransformOp op = new AffineTransformOp(tx, AffineTransformOp.TYPE_NEAREST_NEIGHBOR);

  //image = op.filter(image, null);

  // Flip the image horizontally

  AffineTransform tx = AffineTransform.getScaleInstance(-1, 1);

  tx.translate(-image.getWidth(null), 0);

  AffineTransformOp op = new AffineTransformOp(tx, AffineTransformOp.TYPE_NEAREST_NEIGHBOR);

  image = op.filter(image, null);

  /* Flip the image vertically and horizontally; equivalent to rotating the image 180 degrees

  tx = AffineTransform.getScaleInstance(-1, -1);

  tx.translate(-image.getWidth(null), -image.getHeight(null));

  op = new AffineTransformOp(tx, AffineTransformOp.TYPE_NEAREST_NEIGHBOR);

  image = op.filter(image, null); */

  // Create frame with specific title

  Frame frame = new Frame("Example Frame");

  // Add a component with a custom paint method

  frame.add(new CustomPaintComponent());

  // Display the frame

  int frameWidth = 300;

  int frameHeight = 300;

  frame.setSize(frameWidth, frameHeight);

  frame.setVisible(true);

    }

    /**
     * To draw on the screen, it is first necessary to subclass a Component and
     * override its paint() method. The paint() method is automatically called
     * by the windowing system whenever component's area needs to be repainted.
     */
    static class CustomPaintComponent extends Component {

  public void paint(Graphics g) {

// Retrieve the graphics context; this object is used to paint

// shapes

Graphics2D g2d = (Graphics2D) g;

/**

 * Draw an Image object The coordinate system of a graphics context

 * is such that the origin is at the northwest corner and x-axis

 * increases toward the right while the y-axis increases toward the

 * bottom.

 */

int x = 0;

int y = 0;

g2d.drawImage(image, x, y, this);

  }

    }

}