如何在paintComponent方法中为图像添加颜色图层？

Question

我用Java编写了我的第一个游戏.所以我有Board类扩展JPanel,在这个类里面我有paintComponent方法.卡片图像是BufferedImages.

现在......我刚刚完成方法,计算可能的球员动作.为了澄清,我有敌人卡片场,并且每当敌人的CardField在玩家移动时我想向敌人的cardField图像添加一些图层.

我在paintComponent方法中的代码是这样的:

if(!field.isWithinMove()){
//draw normal state card
  g.drawImage(field.getLoadedCard().getCardImage(),
  field.getX(), field.getY(), Card.cardWidth, Card.cardHeight, null);
}
else{
 //there should be a card picture with layer of color 
}

我的目标是:

正常:

精彩推荐:

我将非常感谢你的帮助:)

干杯!

Answer 1

您可以使用a AlphaComposite来改变图形的渲染方式,例如......

import java.awt.AlphaComposite;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
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 BufferedImage img;

        public TestPane() {
            try {
                img = ImageIO.read(source of your image here);
            } catch (IOException ex) {
                Logger.getLogger(JavaApplication393.class.getName()).log(Level.SEVERE, null, ex);
            }
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(189 * 2, 270);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            // Normal
            g2d.drawImage(img, 0, 0, this);
            // Highlighted
            g2d.drawImage(img, img.getWidth(), 0, this);
            g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f));
            g2d.setColor(UIManager.getColor("List.selectionBackground"));
            g2d.fillRect(img.getWidth(), 0, img.getWidth(), img.getHeight());
            g2d.dispose();
        }

    }

}

现在,您可以实际预渲染(具有"正常"和"突出显示"图像),但这取决于您的需求

nb:我使用了List.selectionBackground当前外观和颜色的填充颜色,你可以用你想要的颜色替换它

有关详细信息,请查看Trail:2D图​​形和合成图形