如何通过命令 JPanel、其组件及其颜色淡出或淡入

Question

I wanted to make a Glass Panel that contain a JPanel with white background, border and the msg "please wait".

Here is the code example:

JLabel glassLabel = new JLabel("Please wait");
FadingPanel msg = new FadingPanel();
glassLabel.setFont(new Font("Dialog", Font.BOLD, 26));
msg.setLayout(new BorderLayout());
msg.add(glassLabel,BorderLayout.NORTH);
msg.setBackground(Color.white);
msg.setFont(UIManager.getFont("Table.font").deriveFont(24f));   
msg.setBorder(new CompoundBorder(new TitledBorder(""),
  new EmptyBorder(20,20,20,20)));

It will fade in and out while waiting for the query. the problem is that I am getting a bad result.

need help

Answer 1

the other is that none of them show it with glass panel

Animating the opacity state of a glassPane is no different from animating the state of any Swing component, after all, the glassPane is just another component.

one is that the Timer system doesn't know if the start function started and it keeps the panel hanging on because it closing it before fading the panel and then before it shows it and then it dont try to close it again

This is more about your own internal state management. The panel shouldn't care, it should just be responding to the request to change opacity level, forward or backwards

What you should have, is some kind of "engine" which can provide events when certain states are achieved, at which time, you make decisions about what should be done, removing the functionality from the "panel" itself.

Theory TL;DR

Okay, first, some theory.

Animation...

Animation is the illusion of change over time. In your case, you're moving from 0 to 1 and back again over a specified period of time. This is commonly known as "linear progression/animation". Most naive animation implementations will simple add a constant delta to a value and keep doing so until a desired state is reached. This is naive because not all systems are equal. Some will be able to achieve the desired state faster than others, making the animation uneven and providing a poor user experience.

Instead, you should be focused on perform a operation over a fixed period of time, calculating the required value as fast as the system will allow. This allows the animation to "drop" frames as required based on the system's capabilities. This is commonly known as "duration based animation".

This approach is much more powerful, as it allows you to play around with the speed of the animation in a very simply way. It also allows you do some very advanced operations, like easement, which wouldn't be easily achievable through a linear progression.

Swing and animation...

Swing is SINGLE threaded. This means you can't perform blocking or long running operations within the context of the Event Dispatching Thread.

Swing is also NOT thread safe. This means you shouldn't update the UI (or any state the UI depends on) from outside the context of the EDT.

For animation, what you need is some way to post, fast, repetitive, events onto the EDT, which will allow you to make changes to the UI safely. For this, the most common tool is a Swing Timer ...

The Framework

So based on that, what we need is some kind of "engine", which given a "range" and a "duration" can notify us of "ticks" on a regular bases from which we can calculate the progression that the animation has played, and calculate the value we should use based on our inputs ... simple ...

I, personally, prefer to use an animation library, but the simple framework presented in the examples basically abstracts all these concepts into a re-usable framework.

Make it so...

nb: I ran out of room, so the underlying framework is included in the main example

Okay, that's all nice and fluffy, but how does this actually help us. Essentially, the idea of the above is to abstract common functionality out and make it re-usable (and yes, I actually do use it, a lot)

What we now need, is a component which can actually use it, something like...

public interface FaderListener {
    public void fadeDidComplete(FadePane pane);
}

public class FadePane extends JPanel {

    private double alpha = 1;
    private boolean fadingIn = true;
    private DoubleAnimatable animatable;
    private Duration duration = Duration.ofSeconds(5);
    private List<FaderListener> listeners = new ArrayList<>(5);

    public FadePane() {
        setOpaque(false);
    }
    
    public void addFadeListener(FaderListener listener) {
        listeners.add(listener);
    }

    public void removeFadeListener(FaderListener listener) {
        listeners.remove(listener);
    }
    
    public boolean isFadingIn() {
        return fadingIn;
    }
    
    public double getAlpha() {
        return alpha;
    }

    @Override
    public void paint(Graphics g) {
        Graphics2D g2d = (Graphics2D) g.create();
        g2d.setComposite(AlphaComposite.SrcOver.derive((float)getAlpha()));
        g2d.setColor(getBackground());
        g2d.fillRect(0, 0, getWidth(), getHeight());
        super.paint(g2d);
        g2d.dispose();
    }
    
    protected void fadeTo(double to) {
        double currentAlpha = getAlpha();
        if (animatable != null) {
            animatable.stop();
            animatable = null;
        }
        
        if (currentAlpha == to) {
            fadeDidComplete();
            return;
        }
        
        DoubleRange animationRange = new DoubleRange(currentAlpha, to);
        double maxFrom = to == 1 ? 1 : 0;
        double maxTo = to == 1 ? 0 : 1;
        DoubleRange maxRange = new DoubleRange(maxFrom, maxTo);
        
        animatable = new DoubleAnimatable(animationRange, maxRange, duration, new AnimatableListener<Double>() {
            @Override
            public void animationChanged(Animatable<Double> animatable) {
                alpha = animatable.getValue();
                repaint();
            }
        }, new AnimatableLifeCycleListenerAdapter<Double>() {
            @Override
            public void animationCompleted(Animatable<Double> animatable) {
                fadeDidComplete();
            }
        });
        
        Animator.INSTANCE.add(animatable);
    }
    
    public void fadeIn() {
        fadingIn = true;
        fadeTo(1);
    }
    
    public void fadeOut() {
        fadingIn = false;
        fadeTo(0);
    }
    
    protected void fadeDidComplete() {            
        for (FaderListener listener : listeners) {
            listener.fadeDidComplete(this);
        }
    }

}

Okay, this is a pretty simple concept. It's a JPanel which has a alpha property which changes the opacity level of the component - basically, this is all faked, as Swing only support opaque and transparent components, not translucent components. So we set the component to be transparent and manually paint the background ourselves.

The component exposes two methods, fadeIn and fadeOut and supports a FaderListener which can be used to notify interested parties that the fade operation has been completed

Runnable example...

import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.time.Duration;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;

public class Test {

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

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
            setBackground(Color.RED);
            setLayout(new BorderLayout());

            FadePane pane = new FadePane();
            pane.setLayout(new GridBagLayout());
            pane.add(new JLabel("Look ma, no hands"));

            add(pane);

            JButton btn = new JButton("Switch");
            btn.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    btn.setEnabled(false);
                    if (pane.isFadingIn()) {
                        pane.fadeOut();
                    } else {
                        pane.fadeIn();
                    }
                }
            });
            add(btn, BorderLayout.SOUTH);

            pane.addFadeListener(new FaderListener() {
                @Override
                public void fadeDidComplete(FadePane pane) {
                    btn.setEnabled(true);
                }
            });
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

    }

    public interface FaderListener {
        public void fadeDidComplete(FadePane pane);
    }

    public class FadePane extends JPanel {

        private double alpha = 1;
        private boolean fadingIn = true;
        private DoubleAnimatable animatable;
        private Duration duration = Duration.ofSeconds(5);
        private List<FaderListener> listeners = new ArrayList<>(5);

        public FadePane() {
            setOpaque(false);
        }

        public void addFadeListener(FaderListener listener) {
            listeners.add(listener);
        }

        public void removeFadeListener(FaderListener listener) {
            listeners.remove(listener);
        }

        public boolean isFadingIn() {
            return fadingIn;
        }

        public double getAlpha() {
            return alpha;
        }

        public void setFaddedOut() {
            alpha = 0;
            fadingIn = false;
        }

        public void setFaddedIn() {
            alpha = 1;
            fadingIn = true;
        }

        @Override
        public void paint(Graphics g) {
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.setComposite(AlphaComposite.SrcOver.derive((float)getAlpha()));
            g2d.setColor(getBackground());
            g2d.fillRect(0, 0, getWidth(), getHeight());
            super.paint(g2d);
            g2d.dispose();
        }

        protected void fadeTo(double to) {
            double currentAlpha = getAlpha();
            if (animatable != null) {
                animatable.stop();
                animatable = null;
            }

            if (currentAlpha == to) {
                fadeDidComplete();
                return;
            }

            DoubleRange animationRange = new DoubleRange(currentAlpha, to);
            double maxFrom = to == 1 ? 1 : 0;
            double maxTo = to == 1 ? 0 : 1;
            DoubleRange maxRange = new DoubleRange(maxFrom, maxTo);

            animatable = new DoubleAnimatable(animationRange, maxRange, duration, new AnimatableListener<Double>() {
                @Override
                public void animationChanged(Animatable<Double> animatable) {
                    alpha = animatable.getValue();
                    repaint();
                }
            }, new AnimatableLifeCycleListenerAdapter<Double>() {
                @Override
                public void animationCompleted(Animatable<Double> animatable) {
                    fadeDidComplete();
                }
            });

            Animator.INSTANCE.add(animatable);
        }

        public void fadeIn() {
            fadingIn = true;
            fadeTo(1);
        }

        public void fadeOut() {
            fadingIn = false;
            fadeTo(0);
        }

        protected void fadeDidComplete() {            
            for (FaderListener listener : listeners) {
                listener.fadeDidComplete(this);
            }
        }

    }

    public class DoubleAnimatable extends AbstractAnimatable<Double> {

        public DoubleAnimatable(DoubleRange animationRange, DoubleRange maxRange, Duration duration, AnimatableListener<Double> listener, AnimatableLifeCycleListener<Double> lifeCycleListener) {
            super(animationRange, duration, listener, lifeCycleListener);

            double maxDistance = maxRange.getDistance();
            double aniDistance = animationRange.getDistance();

            double progress = Math.min(100, Math.max(0, Math.abs(aniDistance / maxDistance)));
            Duration remainingDuration = Duration.ofMillis((long) (duration.toMillis() * progress));
            setDuration(remainingDuration);
        }

    }

    public interface AnimatableListener<T> {
        public void animationChanged(Animatable<T> animatable);
    }

    public interface AnimatableLifeCycleListener<T> {
        public void animationStopped(Animatable<T> animatable);
        public void animationCompleted(Animatable<T> animatable);
        public void animationStarted(Animatable<T> animatable);
        public void animationPaused(Animatable<T> animatable);        
    }

    public class AnimatableLifeCycleListenerAdapter<T> implements AnimatableLifeCycleListener<T> {

        @Override
        public void animationStopped(Animatable<T> animatable) {
        }

        @Override
        public void animationCompleted(Animatable<T> animatable) {
        }

        @Override
        public void animationStarted(Animatable<T> animatable) {
        }

        @Override
        public void animationPaused(Animatable<T> animatable) {
        }

    }

    public abstract class AbstractAnimatable<T> implements Animatable<T> {

        private Range<T> range;
        private LocalDateTime startTime;
        private Duration duration = Duration.ofSeconds(5);
        private T value;
        private AnimatableListener<T> animatableListener;
        private AnimatableLifeCycleListener<T> lifeCycleListener;
//        private Easement easement;
        private double rawOffset;

        public AbstractAnimatable(Range<T> range, Duration duration, AnimatableListener<T> listener) {
            this.range = range;
            this.value = range.getFrom();
            this.animatableListener = listener;
        }

        public AbstractAnimatable(Range<T> range, Duration duration, AnimatableListener<T> listener, AnimatableLifeCycleListener<T> lifeCycleListener) {
            this(range, duration, listener);
            this.lifeCycleListener = lifeCycleListener;
        }

//        public AbstractAnimatable(Range<T> range, Duration duration, Easement easement, AnimatableListener<T> listener) {
//            this(range, duration, listener);
//            this.easement = easement;
//        }
//
//        public AbstractAnimatable(Range<T> range, Duration duration, Easement easement, AnimatableListener<T> listener, AnimatableLifeCycleListener<T> lifeCycleListener) {
//            this(range, duration, easement, listener);
//            this.lifeCycleListener = lifeCycleListener;
//        }
//
//        public void setEasement(Easement easement) {
//            this.easement = easement;
//        }
//
//        @Override
//        public Easement getEasement() {
//            return easement;
//        }

        public Duration getDuration() {
            return duration;
        }

        public Range<T> getRange() {
            return range;
        }

        public void setRange(Range<T> range) {
            this.range = range;
        }

        @Override
        public T getValue() {
            return value;
        }

        protected void setDuration(Duration duration) {
            this.duration = duration;
        }

        public double getCurrentProgress(double rawProgress) {
            double progress = Math.min(1.0, Math.max(0.0, getRawProgress()));
//            Easement easement = getEasement();
//            if (easement != null) {
//                progress = easement.interpolate(progress);
//            }
            return Math.min(1.0, Math.max(0.0, progress));
        }

        public double getRawProgress() {
            if (startTime == null) {
                return 0.0;
            }
            Duration duration = getDuration();
            Duration runningTime = Duration.between(startTime, LocalDateTime.now());
            double progress = rawOffset + (runningTime.toMillis() / (double) duration.toMillis());

            return Math.min(1.0, Math.max(0.0, progress));
        }

        @Override
        public void tick() {
            if (startTime == null) {
                startTime = LocalDateTime.now();
                fireAnimationStarted();
            }
            double rawProgress = getRawProgress();
            double progress = getCurrentProgress(rawProgress);
            if (rawProgress >= 1.0) {
                progress = 1.0;
            }
            value = getRange().valueAt(progress);
            fireAnimationChanged();
            if (rawProgress >= 1.0) {
                fireAnimationCompleted();
            }
        }

        @Override
        public void start() {
            if (startTime != null) {
                // Restart?
                return;
            }
            Animator.INSTANCE.add(this);
        }

        @Override
        public void stop() {
            stopWithNotification(true);
        }

        @Override
        public void pause() {
            rawOffset += getRawProgress();
            stopWithNotification(false);

            double remainingProgress = 1.0 - rawOffset;
            Duration remainingTime = getDuration().minusMillis((long) remainingProgress);
            setDuration(remainingTime);

            lifeCycleListener.animationStopped(this);
        }

        protected void fireAnimationChanged() {
            if (animatableListener == null) {
                return;
            }
            animatableListener.animationChanged(this);
        }

        protected void fireAnimationCompleted() {
            stopWithNotification(false);
            if (lifeCycleListener == null) {
                return;
            }
            lifeCycleListener.animationCompleted(this);
        }

        protected void fireAnimationStarted() {
            if (lifeCycleListener == null) {
                return;
            }
            lifeCycleListener.animationStarted(this);
        }

        protected void fireAnimationPaused() {
            if (lifeCycleListener == null) {
                return;
            }
            lifeCycleListener.animationPaused(this);
        }

        protected void stopWithNotification(boolean notify) {
            Animator.INSTANCE.remove(this);
            startTime = null;
            if (notify) {
                if (lifeCycleListener == null) {
                    return;
                }
                lifeCycleListener.animationStopped(this);
            }
        }

    }

    public interface Animatable<T> {

        public Range<T> getRange();

        public T getValue();

        public void tick();

        public Duration getDuration();

        //public Easement getEasement();

        // Wondering if these should be part of a secondary interface
        // Provide a "self managed" unit of work
        public void start();

        public void stop();

        public void pause();
    }

    public abstract class Range<T> {

        private T from;
        private T to;

        public Range(T from, T to) {
            this.from = from;
            this.to = to;
        }

        public T getFrom() {
            return from;
        }

        public T getTo() {
            return to;
        }

        @Override
        public String toString() {
            return "From " + getFrom() + " to " + getTo();
        }

        public abstract T valueAt(double progress);

    }

    public class DoubleRange extends Range<Double> {

        public DoubleRange(Double from, Double to) {
            super(from, to);
        }

        public Double getDistance() {
            return getTo() - getFrom();
        }

        @Override
        public Double valueAt(double progress) {
            double distance = getDistance();
            double value = distance * progress;
            value += getFrom();
            return value;
        }
    }

    public enum Animator {
        INSTANCE;
        private Timer timer;
        private List<Animatable> properies;

        private Animator() {
            properies = new ArrayList<>(5);
            timer = new Timer(5, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    List<Animatable> copy = new ArrayList<>(properies);
                    Iterator<Animatable> it = copy.iterator();
                    while (it.hasNext()) {
                        Animatable ap = it.next();
                        ap.tick();
                    }
                    if (properies.isEmpty()) {
                        timer.stop();
                    }
                }
            });
        }

        public void add(Animatable ap) {
            properies.add(ap);
            timer.start();
        }

        protected void removeAll(List<Animatable> completed) {
            properies.removeAll(completed);
        }

        public void remove(Animatable ap) {
            properies.remove(ap);
            if (properies.isEmpty()) {
                timer.stop();
            }
        }

    }

}

But it's not a glassPane

... ok, as I said, a glassPane is just another component

This is a simple example which makes use of the frame's glassPane and will, when the panel is faded out, reset the glassPane to a default component

import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.time.Duration;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;

public class Test {

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

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
            setLayout(new GridBagLayout());

            JButton btn = new JButton("Switch");
            btn.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    Window window = SwingUtilities.getWindowAncestor(TestPane.this);
                    if (!(window instanceof JFrame)) {
                        System.out.println("Not out frame");
                        return;
                    }
                    JFrame frame = (JFrame) window;
                    FadePane pane = new FadePane();
                    pane.setLayout(new BorderLayout());
                    pane.add(new JLabel("All your base are belong to us"));
                    pane.setFaddedOut();
                    pane.addFadeListener(new FaderListener() {
                        @Override
                        public void fadeDidComplete(FadePane pane) {
                            System.out.println("Completed");
                            if (pane.getAlpha() == 1) {
                                System.out.println("Fade out");
                                pane.fadeOut();
                            } else {
                                System.out.println("Remove glasspane");
                                frame.setGlassPane(new JPanel());
                            }
                        }
                    });
                    frame.setGlassPane(pane);
                    System.out.println("Fade in");
                    pane.setVisible(true);
                    pane.fadeIn();
                }
            });
            add(btn);
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

    }

}

nb: The required classes are in the previous example

Answer 2

Consider using JDialog container. When it is undecorated , you can change its opacity :

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Point;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.WindowConstants;


public class FadeDialog extends JDialog  {

    private float alfa = 1;
    private JLabel label;
    private boolean isFadeIn = true;
    private JButton fadeIn, fadeOut;

    FadeDialog() {

        setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
        setLocation(new Point(300, 300));
        getContentPane().setLayout(new BorderLayout(5,0));
        setUndecorated(true); //opacity supported for undecorated JDialogs

        JButton close = new JButton("Close");
        close.addActionListener(e -> dispose());
        getContentPane().add(close, BorderLayout.PAGE_END);
        getContentPane().add(new ContentPane(), BorderLayout.CENTER);
        pack();
        setVisible(true);

        Timer timer = new Timer(2000,  e -> fade());//endless fade-in-out loop
        timer.setInitialDelay(100);
        timer.start();
    }

    void fade() {

        alfa = isFadeIn ? alfa + 0.1f : alfa -0.1f;
        if(alfa <=0 ) {
            alfa = 0; isFadeIn = true;
        }else if(alfa >= 1) {
            alfa = 1; isFadeIn = false;
        }

        fadeIn.setEnabled(! isFadeIn); fadeOut.setEnabled(isFadeIn);
        label.setText("Alfa is " + alfa);
        setOpacity(alfa); //set JDialog opacity
    }

    class ContentPane extends JPanel {

        ContentPane() {
            setPreferredSize(new Dimension(200, 100));
            setLayout(new BorderLayout());
            fadeIn = new JButton("Fade In");
            fadeIn.addActionListener(e -> isFadeIn = true);
            add(fadeIn, BorderLayout.PAGE_START);

            label = new JLabel("Alfa is " + alfa);
            add(label, BorderLayout.CENTER);

            fadeOut = new JButton("Fade Out");
            fadeOut.addActionListener(e -> isFadeIn = false);
            add(fadeOut, BorderLayout.PAGE_END);
        }
    }

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