GalleryPictureTableCell.java

/*
 * Copyright 2014 michael-simons.eu.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package ac.simons.bikingFX.gallery;

import ac.simons.bikingFX.api.JsonRetrievalTask;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Node;
import javafx.scene.control.ProgressIndicator;
import javafx.scene.control.TableCell;
import javafx.scene.control.TableColumn;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.VBox;

/** 
 * @author Michael J. Simons, 2014-10-19
 */
public class GalleryPictureTableCell extends TableCell<GalleryPicture, Integer> {
    /** Those table cells are created twice, so we keep track of images used here... Very trivial solution using global state. */
    private static final Map<Integer, Image> images = new ConcurrentHashMap<>();
    
    private final VBox container;
    /** The current image that is or should be displayed */
    private Image image;
    
    /**
     * Watches the progress of the given image to load. If the progress its 1.0
     * it checks wether the image that is set for the given cell is still the
     * same that was loaded.
     */
    private class ImageLoadedListener implements ChangeListener<Number> {
	private final Image imageToLoad;

	public ImageLoadedListener(Image imageToLoad) {
	    this.imageToLoad = imageToLoad;
	}
	
	@Override
	public void changed(ObservableValue<? extends Number> observable, Number oldValue, Number newValue) {
	    if(newValue.intValue() == 1 && imageToLoad == GalleryPictureTableCell.this.image) {
		displayImage(imageToLoad);
	    }
	}	
    }
        
    public GalleryPictureTableCell(TableColumn<GalleryPicture, Integer> column) {	
	this.container = new VBox(new ProgressIndicator());
	this.container.setFillWidth(true);
	this.container.setAlignment(Pos.CENTER);
	this.container.setMinWidth(400);
	this.container.setMaxWidth(800);
	this.container.setMinHeight(300);
	this.container.setMaxHeight(600);
      
	setPadding(Insets.EMPTY);
	setMaxWidth(800);
	setMaxHeight(600);
	setAlignment(Pos.CENTER);
	setGraphic(container);		
    }
   
    @Override
    protected void updateItem(final Integer item, boolean empty) {
	super.updateItem(item, empty);
	if (item == null || empty) {
	    setText(null);
	    setGraphic(null);
	} else {	    	  	     
	    this.image = images.computeIfAbsent(item, id -> new Image(String.format("%s/galleryPictures/%d.jpg", JsonRetrievalTask.BASE_URL, id), 800, 600, true, true, true));
	    if(image.getProgress() == 1.0) {		   
		displayImage(image);
	    } else {
		final ProgressIndicator progressIndicator = new ProgressIndicator();		
		container.getChildren().set(0, progressIndicator);
		progressIndicator.progressProperty().bind(image.progressProperty());		
		image.progressProperty().addListener(new ImageLoadedListener(this.image));		
	    }		    
	    setGraphic(container);
	}
    }
    
    void displayImage(final Image image) {
	final Node currentContent = this.container.getChildren().get(0);
	if(!(currentContent instanceof ProgressIndicator)) {
	    final ImageView imageView = (ImageView) currentContent;						    
	    imageView.setImage(image);	    
	} else {
	    final ImageView imageView = new ImageView(image);
	    imageView.fitWidthProperty().bind(this.container.widthProperty());	   
	    imageView.setPreserveRatio(true);
	    imageView.setCache(true);
	    this.container.getChildren().set(0, imageView);
	}
    }
}