Java标签中gif的问题

Question

我尝试放入 JPanel 的 gif 在单击触发它的按钮后没有显示，直到我调整窗口大小。当它确实出现时，它不适合 JPanel 并且没有动画。我查看了几篇涉及此问题的帖子，但我不明白如何在我的案例中使用它们。

/*
 * Author: Raymo111
 * Date: 13/04/2018
 * Description: Wishes happy birthday to a special someone
 */

//Imports java GUI classes
import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

// Main class with JFrame and ActionListener enabled
public class Happy_Birthday_GUI extends JFrame implements ActionListener {

    // Class variables
    private static JButton startButton = new JButton("CLICK TO START");
    private static JPanel startPanel = new JPanel(), gifPanel = new JPanel();
    private static Color blue = new Color(126, 192, 238), pink = new Color(255, 192, 203);
    private static GridLayout grid1 = new GridLayout(1, 1);

    // Constructor
    public Happy_Birthday_GUI() {

        // Initial screen
        startButton.addActionListener(this);
        startButton.setFont(new Font("Comic Sans MS", Font.PLAIN, 50));
        startPanel.setLayout(grid1);
        startPanel.add(startButton);
        startPanel.setBorder(BorderFactory.createLineBorder(blue, 100));
        startButton.setBackground(pink);
        getContentPane().add(startPanel);

        // Sets title, size, layout (grid 1x1), and location of GUI window (center)
        setTitle("Happy Birthday from Dolphin");
        setSize(840, 840);
        setLayout(grid1);
        setLocationRelativeTo(null);
        setVisible(true);

    }

    // Main method
    public static void main(String[] args) {
        new Happy_Birthday_GUI();
    }

    // Action Performed method
    public void actionPerformed(ActionEvent event) {

        // Proceed to gif and song
        if (startButton == event.getSource()) {
            getContentPane().removeAll();
            BufferedImage dolphin;
            gifPanel.setLayout(grid1);
            gifPanel.setBorder(BorderFactory.createLineBorder(pink, 100));
            try {
                dolphin = ImageIO.read(new File("C:\\Users\\raymo\\Pictures\\dolphin.gif"));
                JLabel gifLabel = new JLabel(new ImageIcon(dolphin));
                gifPanel.add(gifLabel);
            } catch (IOException e) {
                e.printStackTrace();
            }
            getContentPane().add(gifPanel);
        }
    }

}

<小时/>

这是 dolphin.gif。很可爱。

<小时/>

如何让它在单击开始按钮后立即显示为适合 JPanel 的动画 gif？提前致谢。

Answer 1

BufferedImage 不支持绘制动画 Gif，相反，您需要使用 Image(或者最好使用 ImageIcon) .

然后可以将其直接应用于 JLabel，后者将自行执行动画操作。

animated gif that fits he JPanel?

好吧，这是一个更复杂的问题。一种方法是将 Gif 转换为所需的大小，但不用说，这非常非常复杂。

更简单的解决方案可能是使用 AffineTransform 并缩放图像以满足组件本身的要求。这需要一个自定义组件，能够计算比例并绘制图像的每一帧。

幸运的是，JPanel 是一个 ImageObserver，这意味着它能够绘制 gif 动画

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

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

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private ImageIcon image;

        public TestPane() {
            image = new ImageIcon("/Users/swhitehead/Downloads/NbENe.gif");
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(600, 600);
        }

        @Override
        protected void paintComponent(Graphics g) {
            int imageWidth = image.getIconWidth();
            int imageHeight = image.getIconHeight();

            if (imageWidth == 0 || imageHeight == 0) {
                return;
            }
            double widthScale = (double)getWidth() / (double)imageWidth;
            double heightScale = (double)getHeight() / (double)imageHeight;
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.drawImage(image.getImage(), AffineTransform.getScaleInstance(widthScale, heightScale), this);
            g2d.dispose();
        }

    }

}