James Weaver on Quantum Computing and Java

Game Over: Improving upon the Compiled JavaFX Tetris Program

In the Knowing the State of a JavaFX Script Animation post I showed you the more succinct syntax for controlling animations.  Now I'd like to show you some improvements to the TetrisJFX program that I've been developing in this blog, including switching to the new animation syntax.  Here is a screenshot of the TetrisJFX game after the blocks stacked up to the top and the game is over.

By the way, Bruno Ghisi (a fellow Java Champion) and Lucas Torri have developed a Java Bluetooth Framework called Marge.  Using that framework they developed a mobile phone game controller for this TetrisJFX program.  You can see a video of this in action in one of Bruno's blog posts.

As you can see, I've added some functionality since the previous post, but here are some highlights:

• A preview area in the upper right corner that shows the next tetromino shape that will drop.
• Scoring is more Tetris-like, in that each tetromino is worth 25 points when it is finished dropping, and each row that fills up is worth 100 points.  Full rows are removed from the playing field and the tetrominoes above are moved down.
• The button on the left toggles between Play and Stop.  If you choose to Stop the game, "Game Over" will appear in the background, followed by which pressing Play will start a new game.
• When the tetrominoes stack up to the top, as shown in the sceenshot above,  "Game Over" appears in the background and the game stops.

Here is the code for this version of TetrisJFX.  Note that I've added a new class named TetrisNextShapeNode that shows the next tetromino shape to drop.

TetrisMain.fx:

/*
 *  TetrisMain.fx - The main program for a compiled JavaFX Script Tetris game 
 *
 *  Developed 2008 by James L. Weaver (jim.weaver at lat-inc.com)
 *  to serve as a compiled JavaFX Script example.
 */
package tetris_ui;

import javafx.ui.*;
import javafx.ui.canvas.*;
import java.lang.System;
import tetris_model.*;

Frame {
  var model = TetrisModel {}
  var canvas:Canvas
  width: 350
  height: 500
  title: "TetrisJFX"
  background: Color.LIGHTGREY
  content: 
    StackPanel {
      content: [
        Canvas {
          content: [
            ImageView {
              image:
                Image {
                  url: "{__DIR__}images/background.jpg"
                }
            },
            Text {
              transform: bind [
                Translate.translate(30, 350),
                Rotate.rotate(290, 0, 0),
              ]
              content: "Game Over"
              fill: Color.WHITE
              opacity: bind if (model.timeline.running) 0
                            else 1
              font:
                Font {
                  face: FontFace.SANSSERIF
                  size: 60
                  style: FontStyle.BOLD
                }
            }
          ]
        },
        BorderPanel {
          center:
            FlowPanel {
              alignment: Alignment.LEADING
              vgap: 10
              hgap: 10
              content: [
                Canvas {
                  content:
                    TetrisPlayingField {
                      model: model
                    }
                }
              ]
            }
          right:
            GridPanel {
            var sansSerif24 = 
              Font {
                face: FontFace.SANSSERIF
                size: 24
                style: FontStyle.BOLD
              }
              rows: 2
              columns: 1
              cells: [
                BorderPanel {
                  top:
                    FlowPanel {
                      vgap: 10
                      alignment: Alignment.LEADING
                      content:
                        Label {
                          foreground: Color.LIGHTBLUE
                          text: "NEXT:"
                          font: sansSerif24
                        }
                    }
                  center:  
                    Canvas {
                      content:
                        TetrisNextShapeNode {
                          model: model
                        }
                    }
                },
                BorderPanel {
                  top:
                    Label {
                      foreground: Color.LIGHTBLUE
                      text: "SCORE:"
                      font: sansSerif24
                    }
                  center:
                    FlowPanel {
                      alignment: Alignment.TRAILING
                      content:
                        Label {
                          foreground: Color.LIGHTBLUE
                          text: bind "{model.score}"
                          font: sansSerif24
                        }
                    }
                }
              ]
            } 
          bottom:
            FlowPanel {
              alignment: Alignment.CENTER
              content: [
                Button {
                  text: bind 
                    if (model.timeline.running) 
                      "Stop" 
                    else 
                      "Play"
                  action:
                    function():Void {
                      if (model.timeline.running) {
                        model.stopGame();
                      }
                      else {
                        model.startGame();
                      }
                    }
                },
                Button {
                  text: "Rotate"
                  enabled: bind not model.stopDropping
                  action:
                    function():Void {
                      model.rotate90();
                    }
                },
                Button {
                  text: "Left"
                  enabled: bind not model.stopDropping
                  action:
                    function():Void {
                      model.moveLeft();
                    }
                },
                Button {
                  text: "Right"
                  enabled: bind not model.stopDropping
                  action:
                    function():Void {
                      model.moveRight();
                    }
                }
              ]
            }
        }
      ]
    }
  visible: true
  onClose:
    function():Void {
      System.exit(0);
    }
}

TetrisPlayingField.fx: 

/*
 *  TetrisPlayingField.fx -
 *  A custom graphical component that is the UI for the
 *  playing field.
 *
 *  Developed 2008 by James L. Weaver (jim.weaver at lat-inc.com)
 *  to serve as a compiled JavaFX Script example.
 *  
 */
package tetris_ui;

import javafx.ui.*;
import javafx.ui.canvas.*;
import java.lang.System;
import tetris_model.*;

class TetrisPlayingField extends CompositeNode {
  private static attribute squareOutlineColor = Color.BLACK;
  private static attribute squareOutlineWidth = 1;
  public attribute model:TetrisModel;
  private attribute numHiddenTopRows = 2;
  public function composeNode():Node {
    Group {
      content: bind [
        Rect {
          x: 0
          y: 0
          width: model.NUM_COLS * model.SQUARE_SIZE
          height: (model.NUM_ROWS - numHiddenTopRows) * model.SQUARE_SIZE
          strokeWidth: 1
          stroke: Color.BLACK
          fill: Color.BLUE
          opacity: bind if (model.timeline.running) .5
                        else .2
        },
        for (cell in model.fieldCells
               where cell <> TetrisShapeType.NONE) {
          Rect {
            var yPos:Integer = indexof cell / model.NUM_COLS
            //x: (indexof cell % model.NUM_COLS).intValue() * model.SQUARE_SIZE
            x: indexof cell % model.NUM_COLS * model.SQUARE_SIZE
            y: (yPos - numHiddenTopRows) * model.SQUARE_SIZE
            width: model.SQUARE_SIZE
            height: model.SQUARE_SIZE
            fill: cell.squareColor
            stroke: squareOutlineColor
            strokeWidth: squareOutlineWidth
          }
        }
      ]
    }
  }
}

TetrisNextShapeNode.fx: 

/*
 *  TetrisNextShapeNode.fx -
 *  A custom graphical component that shows the next shape to fall
 *
 *  Developed 2008 by James L. Weaver (jim.weaver at lat-inc.com)
 *  to serve as a compiled JavaFX Script example.
 *  
 */
package tetris_ui;

import javafx.ui.*;
import javafx.ui.canvas.*;
import java.lang.System;
import tetris_model.*;

class TetrisNextShapeNode extends CompositeNode {
  private static attribute squareOutlineColor = Color.BLACK;
  private static attribute squareOutlineWidth = 1;
  public attribute model:TetrisModel;
  public function composeNode():Node {
    Group {
      content: bind [
        Rect {
          x: 0
          y: 0
          width: model.PREVIEW_NUM_COLS * model.SQUARE_SIZE
          height: model.PREVIEW_NUM_ROWS * model.SQUARE_SIZE
          strokeWidth: 1
          stroke: Color.BLACK
          fill: Color.BLUE
          opacity: bind if (model.timeline.running) .7
                        else .2
        },
        for (cell in model.nextShapePreviewCells
               where cell <> TetrisShapeType.NONE) {
          Rect {
            var yPos:Integer = indexof cell / model.PREVIEW_NUM_COLS
            x: indexof cell % model.PREVIEW_NUM_COLS * model.SQUARE_SIZE
            y: yPos * model.SQUARE_SIZE
            width: model.SQUARE_SIZE
            height: model.SQUARE_SIZE
            fill: cell.squareColor
            stroke: squareOutlineColor
            strokeWidth: squareOutlineWidth
          }
        }
      ]
    }
  }
}

TetrisModel.fx: 

/*
 *  TetrisModel.fx - The model behind the Tetris UI
 *
 *  Developed 2008 by James L. Weaver (jim.weaver at lat-inc.com)
 *  to serve as a compiled JavaFX Script example.
 *  
 */
package tetris_model;

import javafx.animation.*;
import javafx.lang.*;
import java.lang.System;

public class TetrisModel {
  /** Size of each tetromino in pixels */
  public static attribute SQUARE_SIZE = 19;
  
  /** Number of rows in the playing field */
  public static attribute NUM_ROWS = 23;
  
  /** Number of columns in the playing field */
  public static attribute NUM_COLS = 10;
  
  /** Number of rows in the next shape viewing area */
  public static attribute PREVIEW_NUM_ROWS = 4;
  
  /** Number of columns in the next shape viewing area  */
  public static attribute PREVIEW_NUM_COLS = 6;
  
  public attribute stopDropping:Boolean;

  /** 
   * Sequence of objects that represent the
   * type of shapes (including no shape) in each playing field cell 
   */
  public attribute fieldCells:TetrisShapeType[];

  /** 
   * Sequence of objects that represent the
   * type of shapes (including no shape) in each next shape preview cell 
   */
  public attribute nextShapePreviewCells:TetrisShapeType[];
    
  /**
   * The active tetromino shape type.
   */
  public attribute activeShapeType:TetrisShapeType;
  public attribute nextShapeType:TetrisShapeType;
  
  public attribute score:Integer = 0;
  private attribute pieceScore = 25;
  private attribute rowScore = 100;
  
  private attribute startDropRow = 2;
  private attribute stopDropRow = NUM_ROWS;
  private attribute pieceAppearRow = 3;
  private attribute fieldFullRow = 5;
  
  /**
   * This value is incremented via the KeyFrame animation mechanism,
   * and represents the row in which the pivotal block is currently residing.
   */
  public attribute a:Integer on replace oldVal {
    if (a == pieceAppearRow) {
      activeShapeType = nextShapeType;
      
      // Remove the current "next shape type" from the preview area
      updateNextShapePreviewCells(true);
      
      nextShapeType = TetrisShapeType.randomShapeType();
      // Load the new "next shape type" into the preview area
      updateNextShapePreviewCells(false);
      
      tetrominoHorzPos = NUM_COLS / 2 - 1 as Integer;
      stopDropping = false;
    }
    if (not stopDropping) {
      // Remove the tetromino from the playing field
      updateFieldCells(tetrominoHorzPos, oldVal, tetrominoAngle, true);

      if (canMoveDown(tetrominoHorzPos, a, tetrominoAngle)) {    
        // Was able to move down, so place the tetromino accordingly
        updateFieldCells(tetrominoHorzPos, a, tetrominoAngle, false);
      }
      else {
        score += pieceScore;
        updateFieldCells(tetrominoHorzPos, oldVal, tetrominoAngle, false);
        stopDropping = true;
        if (a <= fieldFullRow) {
          // The blocks have stacked up too high, and game is over
          timeline.stop();
        }
      }
      removeFilledRows();
    }
  };
  public attribute timeline = 
    Timeline {
      keyFrames: [
        KeyFrame {
          time: 0s
          values: a => startDropRow tween Interpolator.LINEAR 
        },
        KeyFrame {
          time: 10s
          values: a => stopDropRow tween Interpolator.LINEAR 
        }
      ]
      repeatCount: Timeline.INDEFINITE
    };
  public attribute tetrominoAngle:Number;
  public attribute tetrominoHorzPos:Number;

  public function startGame():Void {
    fieldCells = for (i in [1..(NUM_ROWS * NUM_COLS)]) {
      TetrisShapeType.NONE
    };
    nextShapePreviewCells = for (i in [1..(PREVIEW_NUM_ROWS * PREVIEW_NUM_COLS)]) {
      TetrisShapeType.NONE
    }; 
    nextShapeType = TetrisShapeType.randomShapeType(); 
    activeShapeType = null;
    score = 0;
    timeline.start();
  }

  public function stopGame():Void {
    timeline.stop();
    stopDropping = true;
  }

  public function rotate90():Void {
    if (stopDropping) {return;} // Don't try to process if a piece isn't falling
    updateFieldCells(tetrominoHorzPos, a, tetrominoAngle, true);
    for (oldCell in TetrisShapeType.squarePositionsForRotatedShape(activeShapeType, 
                                              computeNewAngle(tetrominoAngle, 90))) {
      // First check to see if the rotated tetromino is past the 
      // left side of the playing field
      if (tetrominoHorzPos + oldCell.x < 0) {
        updateFieldCells(tetrominoHorzPos, a, tetrominoAngle, false);
        return;
      }
      // Then check to see if the tetromino is at the right of
      // the playing field
      if (tetrominoHorzPos + oldCell.x > NUM_COLS - 1) {
        updateFieldCells(tetrominoHorzPos, a, tetrominoAngle, false);
        return;
      }
      // Now check to see if another tetromino is preventing it from rotating
      if (fieldCells[((a + oldCell.y) * NUM_COLS + tetrominoHorzPos - 1 + oldCell.x) as Integer] <>
                TetrisShapeType.NONE) {
        updateFieldCells(tetrominoHorzPos, a, tetrominoAngle, false);
        return;
      }
    }
    tetrominoAngle = computeNewAngle(tetrominoAngle, 90);
    updateFieldCells(tetrominoHorzPos, a, tetrominoAngle, false);
  }

  public function computeNewAngle(originalRotationAngle:Integer, degreesToRotate):Integer {
    ((originalRotationAngle + degreesToRotate) % (activeShapeType.rotateStates * 90)) as Integer;
  }

  public function moveLeft():Void {
    if (stopDropping) {return;} // Don't try to process if a piece isn't falling
    updateFieldCells(tetrominoHorzPos, a, tetrominoAngle, true);
    for (oldCell in TetrisShapeType.squarePositionsForRotatedShape(activeShapeType, 
                                                                   tetrominoAngle)) {
      // First check to see if the tetromino is at the left of
      // the playing field
      if (tetrominoHorzPos + oldCell.x <= 0) {
        updateFieldCells(tetrominoHorzPos, a, tetrominoAngle, false);
        return;
      }
      // Now check to see if another tetromino is preventing it from moving left
      if (fieldCells[((a + oldCell.y) * NUM_COLS + tetrominoHorzPos - 1 + oldCell.x) as Integer] <>
                TetrisShapeType.NONE) {
        updateFieldCells(tetrominoHorzPos, a, tetrominoAngle, false);
        return;
      }
    }
    tetrominoHorzPos--;
    updateFieldCells(tetrominoHorzPos, a, tetrominoAngle, false);
  }
  // TODO: Refactor with moveLeft method
  public function moveRight():Void {
    if (stopDropping) {return;} // Don't try to process if a piece isn't falling
    updateFieldCells(tetrominoHorzPos, a, tetrominoAngle, true);
    for (oldCell in TetrisShapeType.squarePositionsForRotatedShape(activeShapeType, 
                                                                   tetrominoAngle)) {
      // First check to see if the tetromino is at the left of
      // the playing field
      if (tetrominoHorzPos + oldCell.x >= NUM_COLS - 1) {
        updateFieldCells(tetrominoHorzPos, a, tetrominoAngle, false);
        return;
      }
      // Now check to see if another tetromino is preventing it from moving left
      if (fieldCells[((a + oldCell.y) * NUM_COLS + tetrominoHorzPos + 1 + oldCell.x) as Integer] <>
                TetrisShapeType.NONE) {
        updateFieldCells(tetrominoHorzPos, a, tetrominoAngle, false);
        return;
      }
    }
    tetrominoHorzPos++;
    updateFieldCells(tetrominoHorzPos, a, tetrominoAngle, false);
  }

  /**
   * Keeps the fieldCells sequence (that represents the
   * cells in the playing field) updated to reflect reality.
   * pass in the row and column that the pivotal block was
   * located, as well as the former angle of the tetromino.
   * The new row, column, angle, as well as the shape type, is
   * held in the model, so don't have to be passed in.  
   */
  public function updateFieldCells(oldX:Integer, oldY:Integer, oldAngle:Integer, remove:Boolean):Void {
    // Place (or remove) the shape on the playing field
    for (oldCell in TetrisShapeType.squarePositionsForRotatedShape(activeShapeType, 
                                                                   oldAngle)) {
      fieldCells[(oldY + oldCell.y) * NUM_COLS + oldX + oldCell.x] = 
        if (remove) TetrisShapeType.NONE else activeShapeType;
    }
  }

  /**
   * Keeps the nextShapePreviewCells sequence (that represents the
   * cells in the next shape preview area) updated to reflect reality.
   */
  public function updateNextShapePreviewCells(remove:Boolean):Void {
    // Place (or remove) the shape on the next shape preview field
    var pivotPosX = 2;
    var pivotPosY = 1;
    
    for (oldCell in TetrisShapeType.squarePositionsForRotatedShape(nextShapeType, 0)) {
      nextShapePreviewCells[(pivotPosY + oldCell.y) * PREVIEW_NUM_COLS + pivotPosX + oldCell.x] = 
        if (remove) TetrisShapeType.NONE else nextShapeType;
    }
  }

  public function canMoveDown(oldX:Integer, oldY:Integer, oldAngle:Integer):Boolean {
    var retVal = true;
    for (oldCell in TetrisShapeType.squarePositionsForRotatedShape(activeShapeType, 
                                                                   oldAngle)) {
      // First check to see if the tetromino is at the bottom of
      // the playing field
      if (oldY + oldCell.y >= NUM_ROWS) {
        return false;
      }
      // Now check to see if another tetromino is preventing it from moving down
      if (fieldCells[(oldY + oldCell.y) * NUM_COLS + oldX + oldCell.x] <>
                TetrisShapeType.NONE) {
        return false;
      }
    }
    return true;
  }
  
  private function removeFilledRows():Void {
    if (not stopDropping) {
      return;
    }
    for (row in [0..NUM_ROWS - 1]) {
      // First see if the beginning of the row is empty
      // before doing the more expensive check of the whole row
      //TODO: Consider not doing this, as perhaps the indexOf isn't expensive
      if (fieldCells[row * NUM_COLS] <> TetrisShapeType.NONE) {
        var fieldRowSlice = fieldCells[row * NUM_COLS .. (row + 1) * NUM_COLS -1];
        if (Sequences.indexOf(fieldRowSlice, TetrisShapeType.NONE) < 0) {
          score += rowScore;
          stopDropping = true;
          //TODO: Use fieldRowSlice in delete statement
          delete fieldCells[row * NUM_COLS .. (row + 1) * NUM_COLS -1];
          insert 
            for (i in [1..NUM_COLS]) {
              TetrisShapeType.NONE
            }
            before fieldCells[0];
        }
      }
    }
  }
}

TetrisShapeType.fx:

/*
 *  TetrisShapeType.fx - A Tetris shape type, which are
 *                       I, J, L, O, S, T, and Z
 *
 *  Developed 2008 by James L. Weaver (jim.weaver at lat-inc.com)
 *  to serve as a compiled JavaFX Script example.
 *  
 */
package tetris_model;

import javafx.ui.*;
import java.awt.Point;
import java.lang.Math;
import java.lang.System;

/**
 * This class contains the model information for each type
 * of tetromino (Tetris piece).
 */
public class TetrisShapeType {
  public attribute id: Integer;
  public attribute name: String;
  
  /** 
   * A sequence containing positions of each square in a 
   * tetromino type.  The first element in the sequence is
   * the one around which the tetromino will rotate.
   * Note that the "O" tetromino type doesn't rotate.
   */
  public attribute squarePositions:Point[];
  
  //public attribute allowRotate:Boolean = true;
  
  /** 
   * Valid values are 1 (for "O" shape, 2 (for "S", "Z", and "I" shapes)
   * and 4 (for "L", "J", and "T" shapes)
   */
  public attribute rotateStates:Integer =  4;
  
  public attribute squareColor:Color;
 
  /** The "NONE" shape (represents the absence of a shape) */
  public static attribute NONE = 
    TetrisShapeType {
      id: 0 
      name: "."
      squarePositions: [
        new Point(0, 0),
        new Point(0, 0),
        new Point(0, 0),
        new Point(0, 0)
      ]
      squareColor: Color.SILVER
    };

  /** The "I" shape (four squares in a straight line) */
  public static attribute I = 
    TetrisShapeType {
      id: 1 
      name: "I"
      squarePositions: [
        new Point(0, 0),
        new Point(-1, 0),
        new Point(1, 0),
        new Point(2, 0)
      ]
      squareColor: Color.SILVER
      rotateStates: 2
    };

  /** The "T" shape (looks like a stout "T") */
  public static attribute T = 
    TetrisShapeType {
      id: 2 
      name: "T"
      squarePositions: [
        new Point(0, 0),
        new Point(-1, 0),
        new Point(1, 0),
        new Point(0, 1)
      ]
      squareColor: Color.HOTPINK
    };

  /** The "L" shape (looks like an "L") */
  public static attribute L = 
    TetrisShapeType {
      id: 3
      name: "L"
      squarePositions: [
        new Point(0, 0),
        new Point(-1, 0),
        new Point(1, 0),
        new Point(-1, 1)
      ]
      squareColor: Color.LIGHTBLUE
    };

  /** The "J" shape (looks sort of like a "J", but
   *  more like a backwards "L") */
  public static attribute J = 
    TetrisShapeType {
      id: 4
      name: "J"
      squarePositions: [
        new Point(0, 0),
        new Point(-1, 0),
        new Point(1, 0),
        new Point(1, 1)
      ]
      squareColor: Color.YELLOW 
    };

  /** The "S" shape (looks sort of like an "S") */
  public static attribute S = 
    TetrisShapeType {
      id: 5 
      name: "S"
      squarePositions: [
        new Point(0, 0),
        new Point(1, 0),
        new Point(-1, 1),
        new Point(0, 1)
      ]
      squareColor: Color.LIGHTGREEN
      rotateStates: 2
    };

  public static attribute Z = 
    TetrisShapeType {
      id: 6
      name: "Z"
      squarePositions: [
        new Point(0, 0),
        new Point(-1, 0),
        new Point(0, 1),
        new Point(1, 1)
      ]
      squareColor: Color.ORANGE
      rotateStates: 2
    };

  /** The "O" shape (looks sort of like an "O", but
   *  more like a square) */
  public static attribute O = 
    TetrisShapeType {
      id: 7
      name: "O"
      squarePositions: [
        new Point(0, 0),
        new Point(0, 1),
        new Point(1, 0),
        new Point(1, 1)
      ]
      squareColor: Color.RED
      rotateStates: 1
    };
    
  /** 
   * A sequence of the shape types for use in generating a
   * random shape type.
   */
  private static attribute allShapeTypes:TetrisShapeType[];
  
  /**
   * A function that returns a random TetrisShapeType
   */
  public static function randomShapeType():TetrisShapeType {
    if (sizeof allShapeTypes <= 0) {
      insert I into allShapeTypes;
      insert T into allShapeTypes;
      insert L into allShapeTypes;
      insert J into allShapeTypes;
      insert S into allShapeTypes;
      insert Z into allShapeTypes;
      insert O into allShapeTypes;
    }
    allShapeTypes[(Math.random() * sizeof allShapeTypes) as Integer] 
  }

  /**
   * A function that returns the squarePositions of a given TetrisShapeType
   * at a given angle of rotation.  This could have used trig functions,
   * but the cases are simple enough to use if/else expressions.
   */
  public static function 
      squarePositionsForRotatedShape(shapeType:TetrisShapeType, rotAngle:Integer):Point[] {
    for (position in shapeType.squarePositions) {
      var newX = position.x;
      var newY = position.y;
      if (rotAngle == 90) {
        newX = if (position.y == 0) 0 else position.y * -1;
        newY = if (position.x == 0) 0 else position.x;
      }
      else if (rotAngle == 180) {
        newX = position.x * -1;
        newY = position.y * -1;
      }
      else if (rotAngle == 270) {
        newX = if (position.y == 0) 0 else position.y;
        newY = if (position.x == 0) 0 else position.x * -1;
      }
      new Point(newX, newY);
    }
  }
}

You may have noticed some TODO comments in the code, which will remind me to do some refactoring and add some enhacements (like create a button that will accelerate a tetromino's rate of decent).

 

If you have any question, please post a comment.  Also, if you'll be at JavaOne 2008, please attend my JavaFX Script Progamming Language Tutorial session and introduce yourself afterward!

 

Regards,
Jim Weaver
JavaFX Script: Dynamic Java Scripting for Rich Internet/Client-side Applications
Immediate eBook (PDF) download available at the book's Apress site

Knowing the State of a JavaFX Script Animation

In the Reading 'tween the Lines - Simplified JavaFX Script Animation Syntax post, I showed you how to start, stop, pause and resume an animation.  In this post I'm going to show you how to read the state of the animation (i.e. whether is it running, and whether it is paused).  To demonstrate this, I modified the metronome-like example from the previous post.  Here's a screenshot of today's example when it first starts up:

Notice that only the Start button is enabled.  As shown in the screenshot below, when you click the Start button the animation starts, and the enabled state of some of the buttons change:

When you click the Pause button, it becomes enabled and the Resume button is disabled:

Clicking the Stop button causes the animation to stop and for the buttons to have the same states shown in the first screenshot.  In the code for this example, notice that the buttons' enabled attributes are bound to the running and paused attributes of the Timeline instance:

/*
 *  Metronome.fx
 *
 *  Developed 2008 by James L. Weaver (jim.weaver at lat-inc.com)
 *  to serve as a compiled JavaFX Script example.
 */

import javafx.ui.*;
import javafx.ui.canvas.*;
import javafx.animation.*;

class MetronomeModel {
  public attribute x2Val = 100;
  public attribute anim =
    Timeline {
      autoReverse: true
      keyFrames: [
        KeyFrame {
          time: 0s
          values: x2Val => 100
        },
        KeyFrame {
          time: 1s
          values: x2Val => 300 tween Interpolator.LINEAR 
        }
      ]
      repeatCount: Timeline.INDEFINITE
    };
}

Frame {
  var metroModel = 
    MetronomeModel {}
  title: "Animation Example"
  width: 400
  height: 500
  visible: true
  content:
    BorderPanel {
      center:
        Canvas {
          content:
            Line {
              x1: 200
              y1: 400
              x2: bind metroModel.x2Val
              y2: 100
              strokeWidth: 5
              stroke: Color.RED
            }
        }
      bottom:
        FlowPanel {
          content: [
            Button {
              text: "Start"
              enabled: bind not metroModel.anim.running
              action:
                function():Void {
                  metroModel.anim.start();
                }
            },
            Button {
              text: "Pause"
              enabled: bind not metroModel.anim.paused and
                                metroModel.anim.running 
              action:
                function():Void {
                  metroModel.anim.pause();
                }
            },
            Button {
              text: "Resume"
              enabled: bind metroModel.anim.paused
              action:
                function():Void {
                  metroModel.anim.resume();
                }
            },
            Button {
              text: "Stop"
              enabled: bind metroModel.anim.running
              action:
                function():Void {
                  metroModel.anim.stop();
                }
            }
          ]
        }
    }
}

If you have any question, please post a comment.  Also, if you'll be at JavaOne 2008, please attend my JavaFX Script Progamming Language Tutorial session and introduce yourself afterward!

 

Regards,
Jim Weaver
JavaFX Script: Dynamic Java Scripting for Rich Internet/Client-side Applications
Immediate eBook (PDF) download available at the book's Apress site

Reading 'tween the Lines - Simplified JavaFX Script Animation Syntax

As mentioned in the first Tetris post, the JavaFX Script animation syntax is undergoing simplification.  Today, I'd like to show you a very basic example of this simplified syntax.  As shown in the screenshot below, this example consists of a line that moves back and forth like a metronome:

When you click the Start button, the top of the line will move from one side to the other in one second, and then travel back to its starting place in one second, repeating this indefinitely.  Clicking the Pause button causes the animation to pause, and clicking Resume causes a paused animation to resume.  Clicking the Stop button stops the animation, requiring it to be started again.  Take a look at the code for this example to see the animation-related syntax and functions:

/*
 *  AnimationExample.fx
 *
 *  Developed 2008 by James L. Weaver (jim.weaver at lat-inc.com)
 *  to serve as a compiled JavaFX Script example.
 */

import javafx.ui.*;
import javafx.ui.canvas.*;
import javafx.animation.*;

class MetronomeModel {
  public attribute x2Val = 100;
  public attribute anim =
    Timeline {
      autoReverse: true
      keyFrames: [
        KeyFrame {
          time: 0s
          values: x2Val => 100
        },
        KeyFrame {
          time: 1s
          values: x2Val => 300 tween Interpolator.LINEAR 
        }
      ]
      repeatCount: Timeline.INDEFINITE
    };
}

Frame {
  var metroModel = 
    MetronomeModel {}
  title: "Animation Example"
  width: 400
  height: 500
  visible: true
  content:
    BorderPanel {
      center:
        Canvas {
          content:
            Line {
              x1: 200
              y1: 400
              x2: bind metroModel.x2Val
              y2: 100
              strokeWidth: 5
              stroke: Color.BLUE
            }
        }
      bottom:
        FlowPanel {
          content: [
            Button {
              text: "Start"
              action:
                function():Void {
                  metroModel.anim.start();
                }
            },
            Button {
              text: "Pause"
              action:
                function():Void {
                  metroModel.anim.pause();
                }
            },
            Button {
              text: "Resume"
              action:
                function():Void {
                  metroModel.anim.resume();
                }
            },
            Button {
              text: "Stop"
              action:
                function():Void {
                  metroModel.anim.stop();
                }
            }
          ]
        }
    }
}

Animation related concepts in this example

The Timeline class allows you to articulate the "key frames" that will be in the animation.  You can have as many as you need, but in this simple case we have two:

• One KeyFrame that occurs at the beginning of the animation.  Note the use of the new literal syntax for durations, in this case 0s, which means 0 seconds.  100ms would be 100 milliseconds, and 3m would represent 3 minutes.
• One KeyFrame that occurs 1 second after the animation starts.

The autoReverse attribute allows you to specify that the animation should run in reverse when it reaches the last KeyFrame.  The repeatCount attribute allows you to control how many times the animation will run, in this case, indefinitely.

The values attribute of the KeyFrame uses the new, more concise, animation syntax.  The values attribute in the first KeyFrame sets the inital value of the x2Val variable to 100. The values attribute in the second KeyFrame causes the x2Val variable to change in value between its previous value to 300, 1 second after the animation started.  Because of the Interpolator.LINEAR constant, this change of value will be linear (as opposed to, for example, slowing down at the end, which is what Interpolator.EASEOUT would do).  The x2 attribute of the Line is bound to this changing x2Val variable, which is what causes the line to move on the screen.

By the way, I'm furiously preparing JavaFX presentations and demos (as are lots of other folks) for JavaOne, so please excuse the lapse of a few days here and there between posts.  I'll be blogging daily from JavaOne, as there will be lots to tell you ;-)

Regards,
Jim Weaver
JavaFX Script: Dynamic Java Scripting for Rich Internet/Client-side Applications
Immediate eBook (PDF) download available at the book's Apress site

Compiled JavaFX Script Tutorial - Lesson #2 is Ready

A few weeks ago, the first lesson in a compiled JavaFX Script tutorial series was made available.  Today, the second lesson is ready for you to take, and is currently available on the Java home page (java.sun.com).

Have fun!
Jim Weaver
JavaFX Script: Dynamic Java Scripting for Rich Internet/Client-side Applications
Immediate eBook (PDF) download available at the book's Apress site

Powerful good time talking 'bout JavaFX at the Java Ranch

Just wanted to give a hardy "thanks y'all" to the friendly folks at JavaRanch for hosting me in one of their weekly book giveaways. 

The JavaRanch family and community had lots of good questions, to which I tried to supply good answers, on the HTML and JavaScript forum in the Big Moose Salon.

Also, sheriff (and gunslinger) Gregg Bolinger had a JavaFX vs Plain Old Java shootout with me (actually with a code example on one of my blog posts).

Thanks again, JavaRanch!
Jim Weaver
JavaFX Script: Dynamic Java Scripting for Rich Internet/Client-side Applications
Immediate eBook (PDF) download available at the book's Apress site

Video from the JavaPolis "Intro to JavaFX" Presentation

In a previous post, I provided a link to the slides from the JavaPolis 2007 "Intro to JavaFX" Presentation.  The video of that presentation is now available at this link on the Parleys classic website, or at this link on the Parleys RIA beta website.

Regards,
Jim Weaver
JavaFX Script: Dynamic Java Scripting for Rich Internet/Client-side Applications
Immediate eBook (PDF) download available at the book's Apress site