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Java2D: An Introduction and Tutorial

3. Paint Styles in Java2D

3.1 Paint Styles: Overview

3.2 Paint Classes

• Color
  Has the same constants (Color.red, Color.yellow, etc.) as the AWT version, plus some extra constructors.
• GradientPaint
  Constructors takes two points, two colors, and optionally a boolean flag that indicates that the color pattern should cycle. The first color is used at the first point, the second color at the second point, and points in between are colored based on how close they are to each of the points.
• TexturePaint
  Constructor takes a BufferedImage and a Rectangle2D, maps the image to the rectangle, then tiles the rectangle. Creating a BufferedImage from a GIF or JPEG file is a pain. First load an Image normally, get its size, create a BufferedImage that size with BufferedImage.TYPE_INT_ARGB as the image type, get the BufferedImage's Graphics object via createGraphics, then draw the Image into the BufferedImage using drawImage. An example of this process is shown later.

3.3 Transparency

3.4 Gradient Fills: Example Code

import java.awt.*;

/** An example of gradient fills with Java2D in Java 1.2.
 *  1998 Marty Hall, http://www.apl.jhu.edu/~hall/java/
 */

public class GradientPaintExample extends ShapeExample {
  // Red at (0,0), yellow at (175,175), changes gradually between.
  private GradientPaint gradient =
    new GradientPaint(0, 0, Color.red, 175, 175, Color.yellow,
                      true); // true means to repeat pattern

  public void paintComponent(Graphics g) {
    clear(g);
    Graphics2D g2d = (Graphics2D)g;
    drawGradientCircle(g2d);
  }

  protected void drawGradientCircle(Graphics2D g2d) {
    g2d.setPaint(gradient);
    g2d.fill(getCircle());
    g2d.setPaint(Color.black);
    g2d.draw(getCircle());
  }

  public static void main(String[] args) {
    WindowUtilities.openInJFrame(new GradientPaintExample(),
                                 380, 400);
  }
}

3.5 Gradient Fills: Example Output

3.6 Tiled Images as Fill Patterns -- Overview

Note, however, that as of JDK1.2beta4, tiled images fail when used in conjunction with rotation transformations.

3.7 Tiled Images as Fill Patterns: Example Code

TiledImages.java

import com.sun.java.swing.*;
import java.awt.*;
import java.awt.geom.*;
import java.awt.image.*;

/** An example of using TexturePaint to fill objects with tiled
 *  images. Uses the getBufferedImage method of ImageUtilitiesities to
 *  load an Image from a file and turn that into a BufferedImage.
 *  1998 Marty Hall, http://www.apl.jhu.edu/~hall/java/
 */

public class TiledImages extends JPanel {
  private String dir = System.getProperty("user.dir");
  private String imageFile1 = dir + "/images/marty.jpg";
  private TexturePaint imagePaint1;
  private Rectangle imageRect;
  private String imageFile2 = dir + "/images/bluedrop.gif";
  private TexturePaint imagePaint2;
  private int[] xPoints = { 30, 700, 400 };
  private int[] yPoints = { 30, 30, 600 };
  private Polygon imageTriangle = new Polygon(xPoints, yPoints, 3);

  public TiledImages() {
    BufferedImage image =
      ImageUtilitiesities.getBufferedImage(imageFile1, this);
    imageRect =
      new Rectangle(235, 70, image.getWidth(), image.getHeight());
    imagePaint1 =
	  new TexturePaint(image, imageRect);
    image = ImageUtilitiesities.getBufferedImage(imageFile2, this);
    imagePaint2 =
      new TexturePaint(image, new Rectangle(0, 0, 32, 32));
  }

  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2d = (Graphics2D)g;
    g2d.setPaint(imagePaint2);
    g2d.fill(imageTriangle);
    g2d.setPaint(Color.blue);
    g2d.setStroke(new BasicStroke(5));
    g2d.draw(imageTriangle);
    g2d.setPaint(imagePaint1);
    g2d.fill(imageRect);
    g2d.setPaint(Color.black);
    g2d.draw(imageRect);
  }

  public static void main(String[] args) {
    WindowUtilities.openInJFrame(new TiledImages(), 750, 650);
  }
}

ImageUtilities.java

import java.awt.*;
import java.awt.image.*;

/** A class that simplifies a few common image operations, in
 *  particular creating a BufferedImage from an image file, and
 *  using MediaTracker to wait until an image or several images are
 *  done loading. 1998 Marty Hall, http://www.apl.jhu.edu/~hall/java/
 */

public class ImageUtilities {

  /** Create Image from a file, then turn that into a BufferedImage.
   */

  public static BufferedImage getBufferedImage(String imageFile,
                                               Component c) {
    Image image = c.getToolkit().getImage(imageFile);
    waitForImage(image, c);
    BufferedImage bufferedImage =
      new BufferedImage(image.getWidth(c), image.getHeight(c),
                        BufferedImage.TYPE_INT_RGB);
    Graphics2D g2d = bufferedImage.createGraphics();
    g2d.drawImage(image, 0, 0, c);
    return(bufferedImage);
  }

  /** Take an Image associated with a file, and wait until it is
   *  done loading. Just a simple application of MediaTracker.
   *  If you are loading multiple images, don't use this
   *  consecutive times; instead use the version that takes
   *  an array of images.
   */

  public static boolean waitForImage(Image image, Component c) {
    MediaTracker tracker = new MediaTracker(c);
    tracker.addImage(image, 0);
    try {
      tracker.waitForAll();
    } catch(InterruptedException ie) {}
    return(!tracker.isErrorAny());
  }

  /** Take some Images associated with files, and wait until they
   *  are done loading. Just a simple application of MediaTracker.
   */

  public static boolean waitForImages(Image[] images, Component c) {
    MediaTracker tracker = new MediaTracker(c);
    for(int i=0; i<images.length; i++)
      tracker.addImage(images[i], 0);
    try {
      tracker.waitForAll();
    } catch(InterruptedException ie) {}
    return(!tracker.isErrorAny());
  }
}

3.8 Tiled Images as Fill Patterns: Example Output

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This article first appeared in November, 1998

Copyright 1998 Mecklermedia Corporation.
All Rights Reserved. Legal Notices.