Saturday, December 24, 2011

JavaFX 2.0 Christmas Tree (JavaFX 2.0 Shapes)

The JavaFX 2.0 package javafx.scene.shape contains useful classes for drawing shapes in JavaFX. Given that today is Christmas Eve, it seems apropos to demonstrate some of the package's classes that can be used to draw a Christmas tree.

In my example for this post, I make heavy use of JavaFX 2.0's javafx.scene.shape.Path class, but I could have used javafx.scene.shape.Polyline, javafx.scene.shape.Polygon, or javafx.scene.shape.SVGPath to accomplish the same thing (and in arguably easier fashion). Because I use the Path approach, I also make heavy use of javafx.scene.shape.LineTo and javafx.scene.shape.MoveTo. I use the path approach to build the outline of the main portion of the tree and then again to build the outline of the stump. The main part of the tree is filled with green fill color and the stump similarly is filled with brown fill color.

The bulbs of the Christmas tree are circles created using JavaFX 2.0's javafx.scene.shape.Circle class. A MouseEvent handler is placed on each bulb such that clicking on a bulb leads to it increasing in size and showing the glow effect.

There is also some text added to the Christmas tree that makes use of the JavaFX 2.0 text APIs I discussed in my previous post Simple JavaFX 2.0 Text Example.

The code listing for ChristmasTreePath.java is shown next.

package dustin.examples;

import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.effect.Glow;
import javafx.scene.input.MouseEvent;
import javafx.scene.paint.Color;
import javafx.scene.paint.Paint;
import javafx.scene.shape.*;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
import javafx.stage.Stage;

/**
 * Simple example of using JavaFX 2.0's Path to create a simple Christmas tree.
 * 
 * @author Dustin
 */
public class ChristmasTreePath extends Application
{
   /** Number of branches on Christmas tree. */
   private final static int NUMBER_BRANCHES = 4;
   /** X-coordinate of very top of Christmas tree. */
   private final static int TOP_CENTER_X = 400;
   /** Y-coordinate of very top of Christmas tree. */
   private final static int TOP_CENTER_Y = 25;
   /** Horizontal distance to end of each branch. */
   private final static int DELTA_X = 125;
   /** Vertical distance to end of each branch. */
   private final static int DELTA_Y = 100;
   /** Length of each branch as measured on bottom of branch. */
   private final static int BRANCH_LENGTH = 75;
   /** Width of tree stump. */
   private final static int STUMP_WIDTH = 100;
   /** Height of tree stump. */
   private final static int STUMP_HEIGHT = 150;
   /** X-coordinate of top left corner of tree stump. */
   private final static int LEFT_STUMP_X = TOP_CENTER_X - STUMP_WIDTH/2;
   /** Y-coordinate of top left corner of tree stump. */
   private final static int LEFT_STUMP_Y = TOP_CENTER_Y + DELTA_Y * NUMBER_BRANCHES;
   /** Width of Christmas tree bottom. */
   private final static int TREE_BOTTOM_WIDTH = (DELTA_X-BRANCH_LENGTH) * NUMBER_BRANCHES * 2;

   /**
    * Simple representation of (x, y) coordinate.
    */
   private static class Coordinate
   {
      /** Horizontal portion of coordinate. */
      final private int x;

      /** Vertical portion of coordinate. */
      final private int y;

      /**
       * Create instance of me with 'x' and 'y' components.
       * 
       * @param newX The horizontal portion of the coordinate.
       * @param newY The vertical portion of the coordinate.
       */
      public Coordinate(final int newX, final int newY)
      {
         this.x = newX;
         this.y = newY; 
      }

      /**
       * Provide String representation of this coordinate.
       * 
       * @return String representation of this coordinate in form "(x, y)".
       */
      @Override
      public String toString()
      {
         return "(" + this.x + ", " + this.y + ")";
      }
   }

   /**
    * Draw left side of the Christmas tree from top to bottom.
    * 
    * @param path Path for left side of Christmas tree to be added to.
    * @param startingX X portion of the starting coordinate.
    * @param startingY Y portion of the starting coordinate.
    * @return Coordinate with x and y values.
    */
   private Coordinate drawLeftSide(
      final Path path, final int startingX, final int startingY)
   {
      int coordX = startingX - DELTA_X;
      int coordY = startingY + DELTA_Y;
      final LineTo topLeft = new LineTo(coordX, coordY);
      path.getElements().add(topLeft);

      coordX += BRANCH_LENGTH;
      final LineTo topLeftHorizontal = new LineTo(coordX, coordY);
      path.getElements().add(topLeftHorizontal);

      coordX -= DELTA_X;
      coordY += DELTA_Y;
      final LineTo secondLeft = new LineTo(coordX, coordY);
      path.getElements().add(secondLeft);

      coordX += BRANCH_LENGTH;
      final LineTo secondLeftHorizontal = new LineTo(coordX, coordY);
      path.getElements().add(secondLeftHorizontal);

      coordX -= DELTA_X;
      coordY += DELTA_Y;
      final LineTo thirdLeft = new LineTo(coordX, coordY);
      path.getElements().add(thirdLeft);

      coordX += BRANCH_LENGTH;
      final LineTo thirdLeftHorizontal = new LineTo(coordX, coordY);
      path.getElements().add(thirdLeftHorizontal);

      coordX -= DELTA_X;
      coordY += DELTA_Y;
      final LineTo fourthLeft = new LineTo(coordX, coordY);
      path.getElements().add(fourthLeft);

      coordX += BRANCH_LENGTH;
      final LineTo fourthLeftHorizontal = new LineTo(coordX, coordY);
      path.getElements().add(fourthLeftHorizontal);

      return new Coordinate(coordX, coordY);
   }

   /**
    * Draw right side of the Christmas tree from bottom to top.
    * 
    * @param path Path for right side of Christmas tree to be added to.
    * @param startingX X portion of the starting coordinate.
    * @param startingY Y portion of the starting coordinate.
    * @return Coordinate with x and y values.
    */
   private Coordinate drawRightSide(
      final Path path, final int startingX, final int startingY)
   {
      int coordX = startingX + BRANCH_LENGTH;
      int coordY = startingY;
      final LineTo bottomHorizontal = new LineTo(coordX, coordY);
      path.getElements().add(bottomHorizontal);

      coordX -= DELTA_X;
      coordY -= DELTA_Y;
      final LineTo bottomBranch = new LineTo(coordX, coordY);
      path.getElements().add(bottomBranch);

      coordX += BRANCH_LENGTH;
      final LineTo secondHorizontal = new LineTo(coordX, coordY);
      path.getElements().add(secondHorizontal);

      coordX -= DELTA_X;
      coordY -= DELTA_Y;
      final LineTo secondBottomBranch = new LineTo(coordX, coordY);
      path.getElements().add(secondBottomBranch);

      coordX += BRANCH_LENGTH;
      final LineTo thirdHorizontal = new LineTo(coordX, coordY);
      path.getElements().add(thirdHorizontal);

      coordX -= DELTA_X;
      coordY -= DELTA_Y;
      final LineTo thirdBottomBranch = new LineTo(coordX, coordY);
      path.getElements().add(thirdBottomBranch);

      coordX += BRANCH_LENGTH;
      final LineTo fourthHorizontal = new LineTo(coordX, coordY);
      path.getElements().add(fourthHorizontal);

      coordX -= DELTA_X;
      coordY -= DELTA_Y;
      final LineTo fourthBottomBranch = new LineTo(coordX, coordY);
      path.getElements().add(fourthBottomBranch);

      return new Coordinate(coordX, coordY);
   }

   /**
    * Draw stump of tree.
    * 
    * @return Path representing Christmas tree stump.
    */
   private Path buildStumpPath()
   {
      final Path path = new Path();

      int coordX = LEFT_STUMP_X;
      int coordY = LEFT_STUMP_Y;
      final MoveTo startingPoint = new MoveTo(coordX, coordY);
      path.getElements().add(startingPoint);

      coordY += STUMP_HEIGHT;
      final LineTo leftStumpSide = new LineTo(coordX, coordY);
      path.getElements().add(leftStumpSide);

      coordX += STUMP_WIDTH;
      final LineTo stumpBottom = new LineTo(coordX, coordY);
      path.getElements().add(stumpBottom);

      coordY -= STUMP_HEIGHT;
      final LineTo rightStumpSide = new LineTo(coordX, coordY);
      path.getElements().add(rightStumpSide);

      coordX -= STUMP_WIDTH;
      final LineTo topStump = new LineTo(coordX, coordY);
      path.getElements().add(topStump);

      path.setFill(Color.BROWN);

      return path;
   }

   /**
    * Build the exterior path of a Christmas Tree.
    * 
    * @return Path representing the exterior of a simple Christmas tree drawing.
    */
   private Path buildChristmasTreePath()
   {
      int coordX = TOP_CENTER_X;
      int coordY = TOP_CENTER_Y;
      final Path path = new Path();
      final MoveTo startingPoint = new MoveTo(coordX, coordY);
      path.getElements().add(startingPoint);

      final Coordinate bottomLeft = drawLeftSide(path, coordX, coordY);
      coordX = bottomLeft.x + TREE_BOTTOM_WIDTH;
      coordY = bottomLeft.y;

      final LineTo treeBottom = new LineTo(coordX, coordY);
      path.getElements().add(treeBottom);

      drawRightSide(path, coordX, coordY);

      path.setFill(Color.GREEN);

      return path;
   }

   /**
    * Create a bulb based on provided parameters and associate a MouseEvent to
    * it such that clicking on a bulb will increase its size and enable the glow
    * effect.
    * 
    * @param centerX X-coordinate of center of bulb.
    * @param centerY Y-coordinate of center of bulb.
    * @param radius Radius of bulb.
    * @param paint Paint/color instance to be used for bulb.
    * @return Christmas tree bulb with interactive support.
    */
   private Circle createInteractiveBulb(
      final int centerX, final int centerY, final int radius, final Paint paint)
   {
      final Circle bulb = new Circle(centerX, centerY, radius, paint);
      bulb.setOnMouseClicked(
         new EventHandler<MouseEvent>()  
         {
            @Override
            public void handle(MouseEvent mouseEvent)
            {
               bulb.setEffect(new Glow(1.0));
               bulb.setRadius(bulb.getRadius() + 5);
            }
         });
      return bulb;
   }

   /**
    * Add colored circles (bulbs) to the provided Group.
    * 
    * @param group Group to which 'bulbs' are to be added.
    */
   private void addBulbs(final Group group)
   {
      final Circle bulbOne = createInteractiveBulb(350,100,10, Color.RED);
      group.getChildren().add(bulbOne);
      final Circle bulbTwo = createInteractiveBulb(285,210,10, Color.YELLOW);
      group.getChildren().add(bulbTwo);
      final Circle bulbThree = createInteractiveBulb(325,300,10, Color.WHITE);
      group.getChildren().add(bulbThree);
      final Circle bulbFour = createInteractiveBulb(475,290,10, Color.BLUE);
      group.getChildren().add(bulbFour);
      final Circle bulbFive = createInteractiveBulb(380,150,10, Color.CADETBLUE);
      group.getChildren().add(bulbFive);
      final Circle bulbSix = createInteractiveBulb(550,390,10, Color.VIOLET);
      group.getChildren().add(bulbSix);
      final Circle bulbSeven = createInteractiveBulb(375,400,10, Color.GOLD);
      group.getChildren().add(bulbSeven);
      final Circle bulbEight = createInteractiveBulb(445,195,10, Color.SILVER);
      group.getChildren().add(bulbEight);
      final Circle bulbNine = createInteractiveBulb(220,385,10, Color.DARKSALMON);
      group.getChildren().add(bulbNine);
   }

   /**
    * Add text portions to Christmas Tree group.
    * 
    * @param group Group for text to be added to.
    */
   private void addText(final Group group)
   {
      final Text text1 = new Text(25, 125, "Merry\nChristmas!");  
      text1.setFill(Color.RED);  
      text1.setFont(Font.font(java.awt.Font.SERIF, 50));  
      group.getChildren().add(text1);
 
      final Text text2 = new Text(600, 150, "2011");
      text2.setFill(Color.DARKGREEN);
      text2.setFont(Font.font(java.awt.Font.SERIF, 75));
      group.getChildren().add(text2);
   }

   /**
    * Starting method of JavaFX application.
    * 
    * @param stage Primary stage.
    * @throws Exception Thrown for exceptional circumstances.
    */
   @Override
   public void start(final Stage stage) throws Exception
   {
      stage.setTitle("JavaFX 2.0: Christmas Tree 2011");
      final Group rootGroup = new Group();
      final Scene scene = new Scene(rootGroup, 800, 600, Color.WHITE);
      stage.setScene(scene);
      rootGroup.getChildren().add(buildChristmasTreePath());
      rootGroup.getChildren().add(buildStumpPath());
      addBulbs(rootGroup);
      addText(rootGroup);
      stage.show();
   }

   /**
    * Main function that kicks off this JavaFX demonstrative application.
    * 
    * @param arguments Command-line arguments; none expected.
    */
   public static void main(final String[] arguments)
   {
      Application.launch(arguments);
   }
}

This is no masterpiece, but the finished result is shown in the next two screen snapshots. The first image shows the application when it starts and the second image shows it after a few bulbs have been clicked on. I clicked on the bottom right bulb several times to make it much larger.

This blog post has demonstrated simple use of some of the classes in the javafx.scene.shape package. My drawing skills leaves something to be desired, but the example does illustrate use of these JavaFX 2.0 APIs. Although I did not show it here, use of SVGPath could be valuable for generating shapes generated with a tool like Inkscape.

2 comments:

Dustin said...

The blog post Merry Christmas features a Christmas tree drawn with ASCII art using Scala.

Dustin

Dustin said...

The blog post JavaFX 2 Custom Shapes provides another example of using JavaFX custom shapes.