add 27 + 31

README.md

@@ -158,7 +158,7 @@ Indicates 100% completion of all exercises for that chapter
 		<li><a href="https://github.com/HarryDulaney/intro-to-java-programming/tree/master/ch_15"><strong>Chapter 15
 </strong></a> - Event-Driven Programming and Animations
 <h6>
-Exercises Needed: 25,27,31,33,35
+Exercises Needed: 33,35
 </h6>
 </li><br>
 		<li><a href="https://github.com/HarryDulaney/intro-to-java-programming/tree/master/ch_16"><strong>Chapter

ch_15/Exercise15_27.java

@@ -0,0 +1,36 @@
+package ch_15;
+
+import javafx.animation.PathTransition;
+import javafx.animation.Timeline;
+import javafx.application.Application;
+import javafx.scene.Scene;
+import javafx.scene.layout.Pane;
+import javafx.scene.shape.Line;
+import javafx.scene.text.Text;
+import javafx.stage.Stage;
+import javafx.util.Duration;
+
+/**
+ * *15.27 (Control a moving text) Write a program that displays a moving text, as shown
+ * in Figure 15.33a and b. The text moves from left to right circularly. When it
+ * disappears in the right, it reappears from the left. The text freezes when the
+ * mouse is pressed and moves again when the button is released.
+ */
+public class Exercise15_27 extends Application {
+    @Override
+    public void start(Stage primaryStage) {
+        Pane pane = new Pane();
+        Text text = new Text("Programing is fun");
+        pane.getChildren().add(text);
+        PathTransition pt = new PathTransition(Duration.millis(10000),
+                new Line(-50, 50, 250, 50), text);
+        pt.setCycleCount(Timeline.INDEFINITE);
+        pt.play();
+        pane.setOnMousePressed(e -> pt.pause());
+        pane.setOnMouseReleased(e -> pt.play());
+        Scene scene = new Scene(pane, 200, 100);
+        primaryStage.setTitle("Exercise_15_27");
+        primaryStage.setScene(scene);
+        primaryStage.show();
+    }
+}

ch_15/Exercise15_31.java

@@ -0,0 +1,109 @@
+package ch_15;
+
+import javafx.animation.PathTransition;
+import javafx.application.Application;
+import javafx.scene.Scene;
+import javafx.scene.layout.Pane;
+import javafx.scene.paint.Color;
+import javafx.scene.shape.Arc;
+import javafx.scene.shape.Circle;
+import javafx.scene.shape.Line;
+import javafx.stage.Stage;
+import javafx.util.Duration;
+
+/**
+ * **15.31 (Geometry: pendulum) Write a program that animates a pendulum swinging,
+ * as shown in Figure 15.35. Press the UP arrow key to faster the speed and the
+ * DOWN key to slower it. Press the S key to stop animation and the R key to
+ * resume it.
+ */
+public class Exercise15_31 extends Application {
+    private final double sceneWidth = 400;
+
+    private final double sceneHeight = 400;
+
+    @Override
+    public void start(Stage primaryStage) throws Exception {
+        PendulumPane pendulumPane = new PendulumPane(sceneWidth, sceneHeight);
+        Scene scene = new Scene(pendulumPane, sceneWidth, sceneHeight);
+        primaryStage.setTitle(getClass().getName());
+        primaryStage.setScene(scene);
+        primaryStage.show();
+
+        pendulumPane.play();
+
+        scene.setOnKeyPressed(e -> {
+            switch (e.getCode()) {
+                case UP:
+                    pendulumPane.faster();
+                    break;
+                case DOWN:
+                    pendulumPane.slower();
+                    break;
+            }
+        });
+    }
+}
+
+class PendulumPane extends Pane {
+    PathTransition animationPath;
+    Circle referenceCircleTop;
+    Circle referenceCircleBottom;
+    Line shaft;
+    Arc pendulumSwingArc;
+
+    PendulumPane(double width, double height) {
+        setPrefWidth(width);
+        setPrefHeight(height);
+        pendulumSwingArc = new Arc(width / 2,
+                height * 0.8,
+                width * 0.15,
+                width * 0.15,
+                180,
+                180);
+        pendulumSwingArc.setFill(Color.TRANSPARENT);
+        pendulumSwingArc.setStroke(Color.BLACK);
+
+        referenceCircleBottom = new Circle(pendulumSwingArc.getCenterX() - pendulumSwingArc.getRadiusX(),
+                pendulumSwingArc.getCenterY(),
+                10);
+        referenceCircleTop = new Circle(pendulumSwingArc.getCenterX(),
+                pendulumSwingArc.getCenterY() - height / 2,
+                referenceCircleBottom.getRadius() / 2);
+        pendulumSwingArc = new Arc(referenceCircleTop.getCenterX(),
+                referenceCircleTop.getCenterY(),
+                width / 2,
+                height / 2,
+                240,
+                60);
+        shaft = new Line(
+                referenceCircleTop.getCenterX(), referenceCircleTop.getCenterY(),
+                referenceCircleBottom.getCenterX(), referenceCircleBottom.getCenterY());
+
+        shaft.endXProperty().bind(referenceCircleBottom.translateXProperty().add(referenceCircleBottom.getCenterX()));
+        shaft.endYProperty().bind(referenceCircleBottom.translateYProperty().add(referenceCircleBottom.getCenterY()));
+        animationPath = new PathTransition();
+        animationPath.setDuration(Duration.millis(4000));
+        animationPath.setPath(pendulumSwingArc);
+        animationPath.setNode(referenceCircleBottom);
+        animationPath.setOrientation(PathTransition.OrientationType.NONE);
+        animationPath.setCycleCount(PathTransition.INDEFINITE);
+        animationPath.setAutoReverse(true);
+
+        getChildren().addAll(referenceCircleBottom, referenceCircleTop, shaft);
+
+    }
+
+    public void play() {
+        animationPath.play();
+    }
+
+
+    public void faster() {
+        animationPath.rateProperty().set(animationPath.getRate() + 1);
+    }
+
+    public void slower() {
+        animationPath.rateProperty().set(animationPath.getRate() - 1);
+    }
+}