Fade Transition Opacity Adjuster

Question

The point of this code is to choose an image from filechooser, load that image into an ImageView, and have a slider able to adjust the opacity of that image.

I'm currently trying to figure out what is wrong with my code. I'm trying to get this program done for an assignment for school but I think I'm missing a line of code. If anyone could explain what my mistake is, it would be very appreciated.

package opacityadjuster;

import javafx.application.Application;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.animation.FadeTransition;
import javafx.embed.swing.SwingFXUtils;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Slider;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.VBox;
import javafx.stage.FileChooser;
import javafx.stage.Stage;

public class OpacityAdjuster extends Application{   

ImageView myImageView;

public static void main(String[] args){
    launch(args);
}     

@Override
public void start(Stage primaryStage){

  final double MIN = 0.0, MAX = 1.0, INITIAL = .50;
  final double MAJOR_TICK_UNIT = .1;
  final int MINOR_TICK_COUNT = 1;
  final double SLIDER_WIDTH = 300.0;

  Button button = new Button("Search for Image");
  Slider slider = new Slider(MIN, MAX, INITIAL);
  slider.setMajorTickUnit(MAJOR_TICK_UNIT);
  slider.setMinorTickCount(MINOR_TICK_COUNT);
  slider.setShowTickMarks(true);
  slider.setShowTickLabels(true);
  slider.setSnapToTicks(true);
  slider.setPrefWidth(SLIDER_WIDTH);

  button.setOnAction(e ->
  {
    FileChooser fileChooser = new FileChooser();

    FileChooser.ExtensionFilter extFilterJPG = 
        new FileChooser.ExtensionFilter("JPG files (*.JPG)", "*.JPG");
    FileChooser.ExtensionFilter extFilterjpg = 
        new FileChooser.ExtensionFilter("jpg files (*.jpg)", "*.jpg");
    FileChooser.ExtensionFilter extFilterPNG = 
        new FileChooser.ExtensionFilter("PNG files (*.PNG)", "*.PNG");
    FileChooser.ExtensionFilter extFilterpng = 
        new FileChooser.ExtensionFilter("png files (*.png)", "*.png");
    fileChooser.getExtensionFilters()
        .addAll(extFilterJPG, extFilterjpg, extFilterPNG, extFilterpng);

    File file = fileChooser.showOpenDialog(null);


       try {BufferedImage bufferedImage = ImageIO.read(file);
            Image image = SwingFXUtils.toFXImage(bufferedImage, null);
            myImageView.setImage(image);
       } 
       catch (IOException ex) {

        Logger.getLogger(OpacityAdjuster.class.getName()).log(Level.SEVERE, null, ex);
        }
    });

    FadeTransition ft = new FadeTransition();


    slider.valueProperty().addListener((observable, oldvalue, newvalue) ->{
           ft.setFromValue(oldvalue.doubleValue());
           ft.setToValue(newvalue.doubleValue());
           ft.play();
    });

    myImageView = new ImageView();  
    myImageView.setFitWidth(500);
    myImageView.setPreserveRatio(true);

    VBox vBox = new VBox(10);
    vBox.getChildren().addAll(button, slider, myImageView);
    vBox.setAlignment(Pos.TOP_CENTER);
    Scene scene = new Scene(vBox, 800, 800);

    primaryStage.setTitle("Opacity Adjuster");
    primaryStage.setScene(scene);
    primaryStage.show();

    }
 }

This is what I've done. I have read my book, asked classmates, my professor, Reddit, and even googled the question out right looking for that last part I'm missing.

Answer 1

Your codes are almost perfect. You have to build a "relationship" between ImageView and FadeTransition then the codes become perfect. Change your codes as following and they'll work perfectly

...
myImageView = new ImageView();  
myImageView.setFitWidth(500);
myImageView.setPreserveRatio(true);

button.setOnAction(e ->
{
  ...
});

FadeTransition ft = new FadeTransition(Duration.millis(1000), myImageView);