java repaint()问题

Question

我在使用任何类型的转换调用repaint时遇到了一些问题，例如: g2D.scale(1.1,1.1)参见代码示例repaint()没有问题，但是如果你调用repaint(x，y，w，h)，重绘就会完全变成梨形，不起作用。你如何解决这个问题？

import javax.swing.SwingUtilities;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.BorderFactory;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseMotionAdapter;

public class RepaintDemo {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI(); 
            }
        });
    }

    private static void createAndShowGUI() {
        JFrame f = new JFrame("Swing Paint Demo");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
        f.add(new MyPanel());
        f.setSize(400,400);
        f.setVisible(true);
    } 
}

class MyPanel extends JPanel {

    private int squareX = 50;
    private int squareY = 50;
    private int squareW = 20;
    private int squareH = 20;

    public MyPanel() {

        setBorder(BorderFactory.createLineBorder(Color.black));

        addMouseListener(new MouseAdapter() {
            public void mousePressed(MouseEvent e) {
                moveSquare(e.getX(),e.getY());
            }
        });

        addMouseMotionListener(new MouseAdapter() {
            public void mouseDragged(MouseEvent e) {
                moveSquare(e.getX(),e.getY());
            }
        });

    }

    private void moveSquare(int x, int y) {
        int OFFSET = 1;
        if ((squareX!=x) || (squareY!=y)) {
          repaint(squareX,squareY,squareW+OFFSET,squareH+OFFSET);
            squareX=x;
            squareY=y;
            repaint(squareX,squareY,squareW+OFFSET,squareH+OFFSET);
        } 
    }


    protected void paintComponent(Graphics g) {
        super.paintComponent(g);       
       Graphics2D g2D = (Graphics2D)g; 
       g2D.scale(1.1,1.1);
        g.setColor(Color.RED);
        g.fillRect(squareX,squareY,squareW,squareH);
        g.setColor(Color.BLACK);
        g.drawRect(squareX,squareY,squareW,squareH);
    }  
}

Answer 1

这样怎么样？

 if ((squareX!=x) || (squareY!=y)) {
        repaint(squareX,squareY,squareW+OFFSET,squareH+OFFSET);
        squareX=x;
        squareY=y;
        repaint(squareX+x,squareY+y,squareW+x+OFFSET,squareH+y+OFFSET);
 }

显然，您可以根据自己的特定需求修改和改进行为