an怎么做淡入_使圖像淡入淡出？ - Making an image fade in and fade out? - 开发者知识库...

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Use an AlphaComposite when painting the image:

繪制圖像時使用AlphaComposite:

import java.awt.AlphaComposite;

import java.awt.Graphics;

import java.awt.Graphics2D;

import java.awt.Image;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import javax.swing.ImageIcon;

import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.Timer;

public class FadeIn extends JPanel implements ActionListener {

Image imagem;

Timer timer;

private float alpha = 0f;

public FadeIn() {

imagem = new ImageIcon("???.jpg").getImage();

timer = new Timer(100, this);

timer.start();

}

// here you define alpha 0f to 1f

public FadeIn(float alpha) {

imagem = new ImageIcon("???.jpg").getImage();

this.alpha = alpha;

}

public void paintComponent(Graphics g) {

super.paintComponent(g);

Graphics2D g2d = (Graphics2D) g;

g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,

alpha));

g2d.drawImage(imagem, 0, 0, null);

}

public static void main(String[] args) {

JFrame frame = new JFrame("Fade out");

frame.add(new FadeIn());

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

frame.setSize(420, 330);

// frame.pack();

frame.setLocationRelativeTo(null);

frame.setVisible(true);

}

public void actionPerformed(ActionEvent e) {

alpha += 0.05f;

if (alpha >1) {

alpha = 1;

timer.stop();

}

repaint();

}

}