有沒有簡單的方法可以將淡入淡出/動畫從JButton圖標更改為翻轉圖標？

Question

波紋管是我的按鈕代碼之一

    continueGame = new JButton("");
    continueGame.setIcon(new ImageIcon("resources/buttonUI/continueGame.png"));
    continueGame.setRolloverEnabled(true);
    continueGame.setRolloverIcon(new ImageIcon("resources/buttonUI/continueGameOnHover.png"));
    continueGame.setBorderPainted(false);
    continueGame.setContentAreaFilled(false);
    continueGame.setBounds(frameSize.x/2-343/2, (int)((frameSize.y)*0.28), 343, 85);
    continueGame.addActionListener(this);

效果很好，但是當我將按鈕懸停時，它立即從基本圖標更改為RolloverIcon。 有沒有辦法讓它們之間變淡或變化緩慢？

Answer 1

“簡單”是主觀的

“最大”的問題是試圖找出繪畫應該出現的“位置”。

該圖標和滾動圖標由UI委托繪制。 這確實很痛苦，因為您確實不想為可能要使用的每種外觀設計UI委托。

因此，您需要自己接管很多功能。

以下方法基本上使用委托模式來減輕“普通”和“翻轉”圖標的混合，並相應地設置按鈕的icon屬性（這是一種作弊行為）

基本功能是由Swing Timer控制的，有關更多詳細信息，請參見如何使用Swing計時器 。

它是基於時間的，也就是說，它是在指定的時間段內運行，而不是一直運行直到獲得一個值。 通常這會產生更好的動畫效果。

import java.awt.AlphaComposite;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ButtonModel;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class JavaApplication155 {

    public static void main(String[] args) {
        new JavaApplication155();
    }

    public JavaApplication155() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    JFrame frame = new JFrame();
                    frame.add(new TestPane());
                    frame.pack();
                    frame.setLocationRelativeTo(null);
                    frame.setVisible(true);
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() throws IOException {
            JButton btn = new JButton();
            BufferedImage cat = ImageIO.read(getClass().getResource("cat.png"));
            BufferedImage dog = ImageIO.read(getClass().getResource("dog.png"));

            btn.setIcon(new ImageIcon(cat));
            btn.setRolloverEnabled(true);

            RolloverAnimator animator = new RolloverAnimator(btn, cat, dog);

            setLayout(new GridBagLayout());
            add(btn);
        }

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

    }

    public class RolloverAnimator {

        private JButton btn;
        private BufferedImage normalImage;
        private BufferedImage rolloverImage;

        private double progress;

        private Timer timer;

        private int totalAnimationTime = 300;
        private int animationTime = totalAnimationTime;
        private Long startedAt = null;

        private boolean wasRolledOver = false;

        public RolloverAnimator(JButton btn, BufferedImage normalImage, BufferedImage rolloverImage) {
            this.btn = btn;
            this.normalImage = normalImage;
            this.rolloverImage = rolloverImage;
            ButtonModel model = btn.getModel();
            model.addChangeListener(new ChangeListener() {
                @Override
                public void stateChanged(ChangeEvent e) {
                    if (model.isArmed()) {
                        return;
                    }
                    if (model.isRollover() && !wasRolledOver) {
                        wasRolledOver = true;
                        prepare();
                    } else if (!model.isRollover() && wasRolledOver) {
                        wasRolledOver = false;
                        prepare();
                    }
                }
            });

            timer = new Timer(5, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    if (startedAt == null) {
                        startedAt = System.currentTimeMillis();
                    }
                    long duration = System.currentTimeMillis() - startedAt;
                    progress = (double) duration / (double) animationTime;
                    if (progress > 1.0) {
                        progress = 1.0;
                        startedAt = null;
                        timer.stop();
                    }
                    BufferedImage target = transition(normalImage, rolloverImage, progress);
                    btn.setIcon(new ImageIcon(target));

                    if (!timer.isRunning()) {
                        progress = 0.0;
                    }
                }
            });
        }

        protected void prepare() {
            if (timer.isRunning()) {
                timer.stop();
                animationTime = (int) ((double) totalAnimationTime * progress);
                startedAt = System.currentTimeMillis() - (totalAnimationTime - (long)animationTime);
            } else {
                animationTime = totalAnimationTime;
                startedAt = null;
            }
            progress = 0.0;

            timer.start();
        }

        public BufferedImage transition(BufferedImage from, BufferedImage to, double progress) {
            int width = Math.max(from.getWidth(), to.getWidth());
            int height = Math.max(from.getHeight(), to.getHeight());
            BufferedImage target = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
            Graphics2D g2d = target.createGraphics();

            float normalAlpha = wasRolledOver ? 1.0f - (float) progress : (float) progress;
            float rollOverAlpha = wasRolledOver ? (float) progress : 1.0f - (float) progress;

            g2d.setComposite(AlphaComposite.SrcOver.derive(normalAlpha));
            draw(from, target, g2d);
            g2d.setComposite(AlphaComposite.SrcOver.derive(rollOverAlpha));
            draw(to, target, g2d);
            g2d.dispose();
            return target;
        }

        protected void draw(BufferedImage img, BufferedImage on, Graphics2D g2d) {
            int xPos = (img.getWidth() - on.getWidth()) / 2;
            int yPos = (img.getHeight() - on.getHeight()) / 2;
            g2d.drawImage(img, xPos, yPos, btn);
        }
    }

}