Custom Strokes : Stroke « 2D Graphics GUI « Java






Custom Strokes

Custom Strokes
      
/*
 * Copyright (c) 2000 David Flanagan.  All rights reserved.
 * This code is from the book Java Examples in a Nutshell, 2nd Edition.
 * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
 * You may study, use, and modify it for any non-commercial purpose.
 * You may distribute it non-commercially as long as you retain this notice.
 * For a commercial use license, or to purchase the book (recommended),
 * visit http://www.davidflanagan.com/javaexamples2.
 */

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.Stroke;
import java.awt.font.GlyphVector;
import java.awt.geom.GeneralPath;
import java.awt.geom.PathIterator;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;

/** A demonstration of writing custom Stroke classes */
public class CustomStrokes extends JPanel{
  static final int WIDTH = 750, HEIGHT = 200; // Size of our example

  public String getName() {
    return "Custom Strokes";
  }

  public int getWidth() {
    return WIDTH;
  }

  public int getHeight() {
    return HEIGHT;
  }

  // These are the various stroke objects we'll demonstrate
  Stroke[] strokes = new Stroke[] { new BasicStroke(4.0f), // The standard,
      // predefined
      // stroke
      new NullStroke(), // A Stroke that does nothing
      new DoubleStroke(8.0f, 2.0f), // A Stroke that strokes twice
      new ControlPointsStroke(2.0f), // Shows the vertices & control
      // points
      new SloppyStroke(2.0f, 3.0f) // Perturbs the shape before stroking
  };

  /** Draw the example */
  public void paint(Graphics g1) {
    Graphics2D g = (Graphics2D)g1;
    // Get a shape to work with. Here we'll use the letter B
    Font f = new Font("Serif", Font.BOLD, 200);
    GlyphVector gv = f.createGlyphVector(g.getFontRenderContext(), "B");
    Shape shape = gv.getOutline();

    // Set drawing attributes and starting position
    g.setColor(Color.black);
    g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
        RenderingHints.VALUE_ANTIALIAS_ON);
    g.translate(10, 175);

    // Draw the shape once with each stroke
    for (int i = 0; i < strokes.length; i++) {
      g.setStroke(strokes[i]); // set the stroke
      g.draw(shape); // draw the shape
      g.translate(140, 0); // move to the right
    }
  }

  public static void main(String[] a) {
    JFrame f = new JFrame();
    f.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
    f.setContentPane(new CustomStrokes());
    f.setSize(750,200);
    f.setVisible(true);
  }

}

/**
 * This Stroke implementation does nothing. Its createStrokedShape() method
 * returns an unmodified shape. Thus, drawing a shape with this Stroke is the
 * same as filling that shape!
 */

class NullStroke implements Stroke {
  public Shape createStrokedShape(Shape s) {
    return s;
  }
}

/**
 * This Stroke implementation applies a BasicStroke to a shape twice. If you
 * draw with this Stroke, then instead of outlining the shape, you're outlining
 * the outline of the shape.
 */

class DoubleStroke implements Stroke {
  BasicStroke stroke1, stroke2; // the two strokes to use

  public DoubleStroke(float width1, float width2) {
    stroke1 = new BasicStroke(width1); // Constructor arguments specify
    stroke2 = new BasicStroke(width2); // the line widths for the strokes
  }

  public Shape createStrokedShape(Shape s) {
    // Use the first stroke to create an outline of the shape
    Shape outline = stroke1.createStrokedShape(s);
    // Use the second stroke to create an outline of that outline.
    // It is this outline of the outline that will be filled in
    return stroke2.createStrokedShape(outline);
  }
}

/**
 * This Stroke implementation strokes the shape using a thin line, and also
 * displays the end points and Bezier curve control points of all the line and
 * curve segments that make up the shape. The radius argument to the constructor
 * specifies the size of the control point markers. Note the use of PathIterator
 * to break the shape down into its segments, and of GeneralPath to build up the
 * stroked shape.
 */

class ControlPointsStroke implements Stroke {
  float radius; // how big the control point markers should be

  public ControlPointsStroke(float radius) {
    this.radius = radius;
  }

  public Shape createStrokedShape(Shape shape) {
    // Start off by stroking the shape with a thin line. Store the
    // resulting shape in a GeneralPath object so we can add to it.
    GeneralPath strokedShape = new GeneralPath(new BasicStroke(1.0f)
        .createStrokedShape(shape));

    // Use a PathIterator object to iterate through each of the line and
    // curve segments of the shape. For each one, mark the endpoint and
    // control points (if any) by adding a rectangle to the GeneralPath
    float[] coords = new float[6];
    for (PathIterator i = shape.getPathIterator(null); !i.isDone(); i
        .next()) {
      int type = i.currentSegment(coords);
      Shape s = null, s2 = null, s3 = null;
      switch (type) {
      case PathIterator.SEG_CUBICTO:
        markPoint(strokedShape, coords[4], coords[5]); // falls through
      case PathIterator.SEG_QUADTO:
        markPoint(strokedShape, coords[2], coords[3]); // falls through
      case PathIterator.SEG_MOVETO:
      case PathIterator.SEG_LINETO:
        markPoint(strokedShape, coords[0], coords[1]); // falls through
      case PathIterator.SEG_CLOSE:
        break;
      }
    }

    return strokedShape;
  }

  /** Add a small square centered at (x,y) to the specified path */
  void markPoint(GeneralPath path, float x, float y) {
    path.moveTo(x - radius, y - radius); // Begin a new sub-path
    path.lineTo(x + radius, y - radius); // Add a line segment to it
    path.lineTo(x + radius, y + radius); // Add a second line segment
    path.lineTo(x - radius, y + radius); // And a third
    path.closePath(); // Go back to last moveTo position
  }
}

/**
 * This Stroke implementation randomly perturbs the line and curve segments that
 * make up a Shape, and then strokes that perturbed shape. It uses PathIterator
 * to loop through the Shape and GeneralPath to build up the modified shape.
 * Finally, it uses a BasicStroke to stroke the modified shape. The result is a
 * "sloppy" looking shape.
 */

class SloppyStroke implements Stroke {
  BasicStroke stroke;

  float sloppiness;

  public SloppyStroke(float width, float sloppiness) {
    this.stroke = new BasicStroke(width); // Used to stroke modified shape
    this.sloppiness = sloppiness; // How sloppy should we be?
  }

  public Shape createStrokedShape(Shape shape) {
    GeneralPath newshape = new GeneralPath(); // Start with an empty shape

    // Iterate through the specified shape, perturb its coordinates, and
    // use them to build up the new shape.
    float[] coords = new float[6];
    for (PathIterator i = shape.getPathIterator(null); !i.isDone(); i
        .next()) {
      int type = i.currentSegment(coords);
      switch (type) {
      case PathIterator.SEG_MOVETO:
        perturb(coords, 2);
        newshape.moveTo(coords[0], coords[1]);
        break;
      case PathIterator.SEG_LINETO:
        perturb(coords, 2);
        newshape.lineTo(coords[0], coords[1]);
        break;
      case PathIterator.SEG_QUADTO:
        perturb(coords, 4);
        newshape.quadTo(coords[0], coords[1], coords[2], coords[3]);
        break;
      case PathIterator.SEG_CUBICTO:
        perturb(coords, 6);
        newshape.curveTo(coords[0], coords[1], coords[2], coords[3],
            coords[4], coords[5]);
        break;
      case PathIterator.SEG_CLOSE:
        newshape.closePath();
        break;
      }
    }

    // Finally, stroke the perturbed shape and return the result
    return stroke.createStrokedShape(newshape);
  }

  // Randomly modify the specified number of coordinates, by an amount
  // specified by the sloppiness field.
  void perturb(float[] coords, int numCoords) {
    for (int i = 0; i < numCoords; i++)
      coords[i] += (float) ((Math.random() * 2 - 1.0) * sloppiness);
  }
}

           
         
    
    
    
    
    
  








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