如何为 JSlider 的每个变量更改重新绘制图像？

Question

我希望每次更改滑块位置时都重新绘制显示的图像。

我已经将来自 JSlider 的变量的每次更改添加到像素中。但我就是不知道怎么重绘它。

package training;
import javax.swing.*;
import java.io.*;
import java.awt.*;
import java.awt.image.*;
import javax.imageio.*;
import javax.swing.plaf.SliderUI;
import java.awt.Color;
import java.util.Arrays;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;


public class Training extends JPanel {
  public BufferedImage image;
  double maxw, maxh;
  double w, h, ratio;
  int warna, red, green, blue, abu, value;
  int forT1, forT2;
  int[][] bmpR;
  int[][] bmpG;
  int[][] bmpB;
  int[][] alpha;

  public Training () {

    super();
    try {               
      image = ImageIO.read(new File("src/training/V.jpg"));
    }
    catch (IOException e)   {
      //Not handled.
    }

    maxw = 750;
    maxh = 600;
    w = image.getWidth();
    h = image.getHeight();
    bmpR = new int[(int)w][(int)h]; 
    bmpG = new int[(int)w][(int)h];
    bmpB = new int[(int)w][(int)h];


    if (w > h) {
    if (w > maxw) {
        ratio = maxw / w;
        h = h * ratio;    // Reset height to match scaled image
        w = w * ratio;   
    }

    }
    if (w <= h) {
    if (h > maxh) {
        ratio = maxh / h;
        w = w * ratio;    // Reset height to match scaled image
        h = h * ratio;   
    }

    } 
    try {
        for( int i = 0; i < w; i++ ) {
         for( int j = 0; j < h; j++ ) {
             Color c = new Color(image.getRGB(i, j));
             bmpR [i][j] = c.getRed();
             bmpG [i][j] = c.getGreen();
             bmpB [i][j] = c.getBlue();
            // alpha = c.getAlpha();
           }
        }
        System.out.println(bmpB[40][40]);

    }
    catch (Exception e) {
    System.out.println("Terjadi kesalahan saat mengambil data pixel");
    e.printStackTrace();
    return;
    }

  }


  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Image i = image.getScaledInstance((int)w, (int)h,Image.SCALE_SMOOTH);
    g.drawImage(i, 20, 20, null);

  }



    public static void main(String[] args) {
       final Training ns = new Training();

        System.out.println("User dir: " + System.getProperty("user.dir"));
        JFrame f = new JFrame("Window");
        JPanel p = new Training();
        f.setSize(1100, 600);
        p.setSize(750, 600); 
        f.add(p);

        JSlider Temp = new JSlider(-50, 50, 0);

        Temp.setMajorTickSpacing(10);
        Temp.setMinorTickSpacing(1);

        Temp.addChangeListener(new ChangeListener () {
            public void stateChanged(ChangeEvent evt) {
                JSlider Temp = (JSlider) evt.getSource();
                if (Temp.getValueIsAdjusting()) {
                    ns.value = Temp.getValue();

                    for(ns.forT1 = 0; ns.forT1 < ns.w; ns.forT1++ ) {
                        for(ns.forT2 = 0; ns.forT2 < ns.h; ns.forT2++ ) {
                            ns.bmpB[ns.forT1][ns.forT2] = ns.bmpB[ns.forT1][ns.forT2] - ns.value;
                            if (ns.bmpB[ns.forT1][ns.forT2] > 255) {
                                ns.bmpB[ns.forT1][ns.forT2] = 255;
                            }
                            if (ns.bmpB[ns.forT1][ns.forT2] < 0) {
                                ns.bmpB[ns.forT1][ns.forT2] = 0;
                            }
                            ns.bmpR[ns.forT1][ns.forT2] = ns.bmpR[ns.forT1][ns.forT2] + ns.value;
                            if (ns.bmpR[ns.forT1][ns.forT2] > 255) {
                                ns.bmpR[ns.forT1][ns.forT2] = 255;
                            }
                            if (ns.bmpR[ns.forT1][ns.forT2] < 0) {
                                ns.bmpR[ns.forT1][ns.forT2] = 0;
                            } 
                        }  
                    }
                }
               ns.repaint();
            }
        });

        f.add(Temp, BorderLayout.EAST);

        f.setVisible(true);       
    }  
}

是我放错了 ChangeListener 还是应该在更改侦听器发生后放置 paintComponent 方法？

Answer 1

您的代码的随机缩进使您很难确切地弄清楚发生了什么，但我在您的ChangeListener 中的任何地方都看不到repaint()。您需要使用repaint() 来触发组件的重绘。