FlingPane.java

package at.bestsolution.efxclipse.runtime.panels;

import java.util.concurrent.atomic.AtomicReference;

import javafx.animation.Interpolator;
import javafx.animation.TranslateTransition;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Bounds;
import javafx.scene.Node;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.Region;
import javafx.scene.shape.Rectangle;
import javafx.util.Duration;
import at.bestsolution.efxclipse.runtime.panels.internal.VelocityTracker;

/**
 * Fling pane is a scrollable list container like
 * you have it on mobile devices
 * 
 * @author Tom Schindl
 */
public class FlingPane extends Region {
	private ObjectProperty<Node> content;
	private Rectangle clipRect = new Rectangle();

	private ObjectProperty<FlingDirection> flingDirection = new SimpleObjectProperty<FlingDirection>(FlingDirection.BOTH, "flingDirection");

	private VelocityTracker tracker = new VelocityTracker();

	public enum FlingDirection {
		BOTH, HORIZONTAL, VERTICAL
	}

	public FlingPane() {
		setFocusTraversable(false);
		setClip(clipRect);
		contentProperty().addListener(new ChangeListener<Node>() {

			@Override
			public void changed(ObservableValue<? extends Node> observable, Node oldValue, Node newValue) {
				getChildren().clear();
				if (newValue != null) {
					getChildren().add(newValue);
				}
				layout();
			}
		});

		final AtomicReference<MouseEvent> deltaEvent = new AtomicReference<MouseEvent>();
		final AtomicReference<TranslateTransition> currentTransition = new AtomicReference<TranslateTransition>();
		setOnMousePressed(new EventHandler<MouseEvent>() {

			@Override
			public void handle(MouseEvent event) {
				tracker.addMovement(event);
				deltaEvent.set(event);
				if( currentTransition.get() != null ) {
					currentTransition.get().stop();
				}
			}
		});
		setOnMouseDragged(new EventHandler<MouseEvent>() {

			@Override
			public void handle(MouseEvent event) {
				tracker.addMovement(event);
				if (flingDirection.get() == FlingDirection.HORIZONTAL || flingDirection.get() == FlingDirection.BOTH) {
					double delta = event.getX() - deltaEvent.get().getX();
					content.get().setTranslateX(content.get().getTranslateX() + delta);
				}
				
				if (flingDirection.get() == FlingDirection.VERTICAL || flingDirection.get() == FlingDirection.BOTH) {
					double delta = event.getY() - deltaEvent.get().getY();
					double targetY = content.get().getTranslateY() + delta;
					
					content.get().setTranslateY(targetY);
				}
				
				deltaEvent.set(event);
			}
		});
		setOnMouseReleased(new EventHandler<MouseEvent>() {

			@Override
			public void handle(MouseEvent event) {
				tracker.addMovement(event);
				tracker.computeCurrentVelocity(500);
				float velocityX = tracker.getXVelocity();
				float velocityY = tracker.getYVelocity();
				
				if (content != null && content.get() != null) {
					TranslateTransition translate = new TranslateTransition(new Duration(1000), content.get());
					translate.setInterpolator(Interpolator.EASE_OUT);

					final Bounds b = content.get().getLayoutBounds();

					Double backBouncingX = null;
					Double backBouncingY = null;
					Double targetX = null;
					Double targetY = null;
					
					if( Math.abs(velocityX) < 10 ) {
						velocityX = 0;
					}
					
					if( Math.abs(velocityY) < 10 ) {
						velocityY = 0;
					}
					
					if (flingDirection.get() == FlingDirection.HORIZONTAL || flingDirection.get() == FlingDirection.BOTH) {
						targetX = content.get().getTranslateX();
						
						double controlWidth = b.getWidth();
						double viewWith = getWidth();

						if (controlWidth < viewWith && targetX < controlWidth) {
							targetX = 0.0;
						} else if (targetX > 0) {
							targetX = 0.0;
						} else if( (targetX < (controlWidth - viewWith) * -1) ) {
							targetX = (controlWidth - viewWith) * -1;
						} else {
							targetX += velocityX;
							
							if (controlWidth < viewWith && targetX < controlWidth) {
								targetX = -100.0;
								backBouncingX = 0.0;
							} else if (targetX > 0) {
								targetX = 100.0;
								backBouncingX = 0.0;
							} else if (targetX < (controlWidth - viewWith) * -1) {
								targetX = (controlWidth - viewWith) * -1 - 100;
								backBouncingX = (controlWidth - viewWith) * -1;
							}
						}
					}

					if (flingDirection.get() == FlingDirection.VERTICAL || flingDirection.get() == FlingDirection.BOTH) {
						targetY = content.get().getTranslateY();
						
						double controlHeight = b.getHeight();
						double viewHeight = getHeight();

						if (controlHeight < viewHeight && targetY < controlHeight) {
							targetY = 0.0;
						} else if (targetY > 0) {
							targetY = 0.0;
						} else if(targetY < (controlHeight - viewHeight) * -1) {
							targetY = (controlHeight - viewHeight) * -1;
						} else {
							targetY += velocityY;
							
							if (controlHeight < viewHeight && targetY < controlHeight) {
								targetY = -100.0;
								backBouncingY = 0.0;
							} else if (targetY > 0) {
								targetY = 100.0;
								backBouncingY = 0.0;
							} else if (targetY < (controlHeight - viewHeight) * -1) {
								targetY = (controlHeight - viewHeight) * -1 - 100;
								backBouncingY = (controlHeight - viewHeight) * -1;
							}
						}
					}

					if (targetX != null) {
						translate.setFromX(content.get().getTranslateX());
						translate.setToX(targetX);
					}

					if (targetY != null) {
						translate.setFromY(content.get().getTranslateY());
						translate.setToY(targetY);
					}

					if (backBouncingX != null || backBouncingY != null) {
						final Double fbackFlingX = backBouncingX;
						final Double fbackFlingY = backBouncingY;
						translate.setOnFinished(new EventHandler<ActionEvent>() {

							@Override
							public void handle(ActionEvent event) {
								currentTransition.set(null);
								TranslateTransition translate = new TranslateTransition(new Duration(300), content.get());
								if (fbackFlingX != null) {
									translate.setFromX(content.get().getTranslateX());
									translate.setToX(fbackFlingX);
								}

								if (fbackFlingY != null) {
									translate.setFromY(content.get().getTranslateY());
									translate.setToY(fbackFlingY);
								}

								translate.play();
								currentTransition.set(translate);
							}
						});
					} else {
						translate.setOnFinished(new EventHandler<ActionEvent>() {

							@Override
							public void handle(ActionEvent event) {
								currentTransition.set(null);
							}
						});
					}

					translate.play();
					currentTransition.set(translate);
				}
			}
		});
	}

	public final void setContent(Node value) {
		contentProperty().set(value);
	}

	public final Node getContent() {
		return content == null ? null : content.get();
	}

	public final ObjectProperty<Node> contentProperty() {
		if (content == null) {
			content = new SimpleObjectProperty<Node>(this, "content");
		}
		return content;
	}

	public final ObjectProperty<FlingDirection> flingDirection() {
		return flingDirection;
	}

	public void setFlingDirection(FlingDirection value) {
		flingDirection.set(value);
	}

	public FlingDirection getFlingDirection() {
		return flingDirection.get();
	}

	@Override
	protected void layoutChildren() {
		super.layoutChildren();
		clipRect.setWidth(getWidth());
		clipRect.setHeight(getHeight());
	}

//	@Override
//	protected double computeMaxHeight(double width) {
//		return Double.MAX_VALUE;
//	}
//
//	@Override
//	protected double computeMinWidth(double height) {
//		return 0;
//	}
//
//	@Override
//	protected double computeMaxWidth(double height) {
//		return Double.MAX_VALUE;
//	}
//
//	@Override
//	protected double computeMinHeight(double width) {
//		return 0;
//	}
//
//	@Override
//	protected double computePrefHeight(double width) {
//		return Double.MAX_VALUE;
//	}
//
//	@Override
//	protected double computePrefWidth(double height) {
//		return Double.MAX_VALUE;
//	}
}