Java利用AlphaComposite类合并图像

package com.hdwang.test;

import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Map;

/**
 * Created by hdwang on 2018/10/11.
 */
public class TestDrawing {

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

  /**
   * 合成测试
   */
  public static void testComposite() {
    //创建背景图片（带透明分量的）
    BufferedImage bg = new BufferedImage(300, 300, BufferedImage.TYPE_INT_ARGB);
    Graphics2D bgGraphics = (Graphics2D) bg.getGraphics();
    bgGraphics.setColor(Color.yellow); //设置颜色
    bgGraphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); //边缘抗锯齿
    bgGraphics.fillRect(0, 0, bg.getWidth(), bg.getHeight()); //填充矩形
    bgGraphics.setColor(Color.BLACK);
    bgGraphics.setFont(new Font("楷体", Font.ITALIC, 50));
    bgGraphics.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON); //文本抗锯齿
    bgGraphics.drawString("背景黄色", 50, 150); //画文本
    bgGraphics.dispose();

    //创建第二张图片
    BufferedImage image = new BufferedImage(300, 300, BufferedImage.TYPE_INT_ARGB);
    Graphics2D imageGraphics = (Graphics2D) image.getGraphics();
    imageGraphics.setColor(Color.GREEN);
    imageGraphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    imageGraphics.fillRoundRect(0, 0, image.getWidth(), image.getHeight(), image.getWidth(), image.getHeight());
    imageGraphics.setColor(Color.BLACK);
    imageGraphics.setFont(new Font("楷体", Font.ITALIC, 50));
    imageGraphics.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
    imageGraphics.drawString("前景绿色", 50, 200);
    imageGraphics.dispose();

    JFrame jf = new JFrame(); //窗体
    JPanel contentPanel = new JPanel(); //内容面板
    contentPanel.setBorder(BorderFactory.createLineBorder(Color.blue)); //设置边框
    //contentPanel.setLayout(new BorderLayout());

    //添加标签
    JLabel label = new JLabel();
    label.setText("组合模式：");
    contentPanel.add(label);

    //添加下拉框
    JComboBox comboBox = new JComboBox();
    comboBox.addItem("默认");
    comboBox.addItem("CLEAR");
    comboBox.addItem("SRC");
    comboBox.addItem("DST");
    comboBox.addItem("SRC_OVER");
    comboBox.addItem("DST_OVER");
    comboBox.addItem("SRC_IN");
    comboBox.addItem("DST_IN");
    comboBox.addItem("SRC_OUT");
    comboBox.addItem("DST_OUT");
    comboBox.addItem("SRC_ATOP");
    comboBox.addItem("DST_ATOP");
    comboBox.addItem("XOR");
    contentPanel.add(comboBox);

    JLabel label2 = new JLabel();
    label2.setText("源图非透明度：");
    contentPanel.add(label2);

    //添加滑动条([0-10]=>[0,0.1,0.2,.... 1.0])
    JSlider jSlider = new JSlider(0,10,10);
    jSlider.setMajorTickSpacing(5); // 设置主刻度间隔
    jSlider.setMinorTickSpacing(1); // 设置次刻度间隔
    jSlider.setPaintTicks(true); // 绘制刻度
    jSlider.setPaintLabels(true); // 绘制标签
    jSlider.setSnapToTicks(true); // 对其到刻度取值
     /*
     * 给指定的刻度值显示自定义标签
     */
    Hashtable<Integer, JComponent> hashtable = new Hashtable<Integer, JComponent>();
    hashtable.put(0, new JLabel("0"));   // 0 刻度位置，显示 "0"
    hashtable.put(5, new JLabel("0.5"));  // 5 刻度位置，显示 "0.5"
    hashtable.put(10, new JLabel("1"));    // 10 刻度位置，显示 "1"
    jSlider.setLabelTable(hashtable); //将刻度值和自定义标签的对应关系设置到滑块（设置后不再显示默认的刻度值）

    contentPanel.add(jSlider);


    jf.setContentPane(contentPanel); //窗体设置内容面板为jp
    jf.setBounds(200, 200, 500, 500);
    jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    jf.setVisible(true); //窗体可见


    DrawingPanel drawPanel = new DrawingPanel();
    drawPanel.setBounds(0,60,500,415);
    drawPanel.setPreferredSize(new Dimension(500,415));
    drawPanel.setBorder(BorderFactory.createLineBorder(Color.red)); //设置边框
    drawPanel.setBg(bg);
    drawPanel.setImage(image);
    // drawPanel.setAlphaComposite(AlphaComposite.SrcAtop);
    contentPanel.add(drawPanel);

    Map<String,AlphaComposite> compositeMap = new HashMap<>();
    compositeMap.put("CLEAR",AlphaComposite.Clear);
    compositeMap.put("SRC",AlphaComposite.Src);
    compositeMap.put("DST",AlphaComposite.Dst);
    compositeMap.put("SRC_OVER",AlphaComposite.SrcOver);
    compositeMap.put("DST_OVER",AlphaComposite.DstOver);
    compositeMap.put("SRC_IN",AlphaComposite.SrcIn);
    compositeMap.put("DST_IN",AlphaComposite.DstIn);
    compositeMap.put("SRC_OUT",AlphaComposite.SrcOut);
    compositeMap.put("DST_OUT",AlphaComposite.DstOut);
    compositeMap.put("SRC_ATOP",AlphaComposite.SrcAtop);
    compositeMap.put("DST_ATOP",AlphaComposite.DstAtop);
    compositeMap.put("XOR",AlphaComposite.Xor);
    //下拉框选中事件
    comboBox.addItemListener(new ItemListener() {
      @Override
      public void itemStateChanged(ItemEvent e) {
        if(e.getStateChange() == ItemEvent.SELECTED){
          String selected = e.getItem().toString();
          System.out.println(selected);
          drawPanel.setAlphaComposite(compositeMap.get(selected));
          drawPanel.repaint(); //重画
        }
      }
    });

    //滑动条改变事件
    jSlider.addChangeListener(new ChangeListener() {
      @Override
      public void stateChanged(ChangeEvent e) {
        int val = jSlider.getValue();
        float alpha = (float) (val / 10.0);
        System.out.println("alpha:"+alpha);
        drawPanel.setAlpha(alpha);
        drawPanel.repaint(); //重画
      }
    });

    //窗体改变事件
    jf.addWindowStateListener(new WindowStateListener() {

      @Override
      public void windowStateChanged(WindowEvent e) {
        System.out.println("window state:"+e.paramString());
      }
    });
  }


  static class DrawingPanel extends JPanel{

    BufferedImage bg;
    BufferedImage image;
    AlphaComposite alphaComposite;
    float alpha = 1.0f; //源图非透明度（新加的图）

    public BufferedImage getBg() {
      return bg;
    }

    public void setBg(BufferedImage bg) {
      this.bg = bg;
    }

    public BufferedImage getImage() {
      return image;
    }

    public void setImage(BufferedImage image) {
      this.image = image;
    }

    public AlphaComposite getAlphaComposite() {
      return alphaComposite;
    }

    public void setAlphaComposite(AlphaComposite alphaComposite) {
      this.alphaComposite = alphaComposite;
    }

    public float getAlpha() {
      return alpha;
    }

    public void setAlpha(float alpha) {
      this.alpha = alpha;
    }

    /**
     * 重写paint方法
     * @param g
     */
    @Override
    public void paint(Graphics g){
      //调用的super.paint(g),让父类做一些事前的工作，如刷新屏幕
      super.paint(g);

      //在面板上画画
      Graphics2D g2d = (Graphics2D)g;
      g2d.setComposite(AlphaComposite.Src);
      g2d.drawImage(bg,100,100,null); //背景图
      if(alphaComposite!=null) {
        g2d.setComposite(alphaComposite.derive(alpha));
      }else{
        //默认SrcOver
        g2d.setComposite(AlphaComposite.SrcOver.derive(alpha));
      }
      g2d.drawImage(image,100,100,null); //叠加图

      //g2d.setColor(Color.GREEN);
      //g2d.fillRoundRect(100,100,image.getWidth(),image.getHeight(),image.getWidth(),image.getHeight()); //叠加图层
      g2d.dispose();
    }
  }
}