JPanel Fade 动画 java swing 不起作用

Question

我正在尝试制作适用于任何组件的淡入淡出动画
我覆盖了绘制组件 alphacomposite，但看起来它完全没有任何作用。

/*
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 * Click nbfs://nbhost/SystemFileSystem/Templates/Classes/Class.java to edit this template
 */

package JAnimator;

import java.awt.AlphaComposite;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JComponent;
import javax.swing.Timer;

public class JAnimator {
    public static class fade_animation extends JComponent{
        private float opacity;
        private Timer timer;
        private Component target;
        private int speed=100;
        private boolean isIn = true;
        public fade_animation(Component targetComponent, int SpeedMilisec) {
           this.target = targetComponent;
           this.speed = SpeedMilisec;
           timer = new Timer(speed, new ActionListener(){
               @Override
               public void actionPerformed(ActionEvent e) {
                   if(isIn){
                   opacity += 0.1f;
                   if(opacity>=1.0f){
                       opacity = 1.0f;
                      timer.stop();
                   }
                   target.repaint();
                   }else{
                       opacity -=0.1f;
                       if(opacity<=0.0f){
                           opacity = 0.0f;
                          timer.stop();
                       }
                       target.repaint();
                   } 
               }
           });
           
        }
        public void playIn(){
            opacity = 0.0f;
            target.repaint();
            isIn = true;
            try{
            timer.stop();
            }catch(Exception e){
            }
             timer.start();
        }
        public void playOut(){
        isIn = false;
        opacity = 1.0f;
        target.repaint();
        try{
            timer.stop();
        }catch(Exception e){
        }
        timer.start();
        }
          @Override
           protected void paintComponent(Graphics g){
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g;
            g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, this.opacity));
            super.paint(g2d);
            super.update(g);
          }
    }
}

在我的主程序中我试图这样称呼它

JAnimator.fade_animation ani1 = new JAnimator.fade_animation(JPanel1, 100); 
ani1.playOut();  

此面板由设计师 Netbeans 16 制作

我尝试了目标组件的重新验证和更新 ui 方法，但这根本没有效果

Answer 1

两种方式...

直接透明度设置：

  // without "extends"
static class fade_animation {

   int transparency = 0;
   private Timer timer;
   private Component target;
   private int speed = 100;
   private boolean isIn = true;

   public fade_animation( Component targetComponent, int SpeedMilisec ) {
      target = targetComponent;
      speed = SpeedMilisec;
      timer = new Timer( speed, new ActionListener() {
         @Override
         public void actionPerformed( ActionEvent e ) {
            if( isIn ) {
               transparency++;
               if( transparency > 255 ) {
                  transparency = 255;
                  timer.stop();
               }

                 // we change transparency
               target.setBackground( new Color( 100, 100, 100, transparency ) );
               target.repaint();
            }
            else {
               transparency--;
               if( transparency < 0 ) {
                  transparency = 0;
                  timer.stop();
               }

                 // we change transparency
               target.setBackground( new Color( 100, 100, 100, transparency ) );
               target.repaint();
            }
         }
      } );
   }

   public void playIn() {
      target.repaint();
      isIn = true;
      timer.start();
   }

   public void playOut() {
      isIn = false; 
      target.repaint();
      timer.start();
   }
}

通过 paintComponent() 覆盖设置透明度。