使用平移校准坐标系后鼠标坐标停止工作-java

Question

我正在开发一个坐标系，点 (0,0) 将位于面板的中心，但在转换默认 (0,0) 坐标后，鼠标坐标停止 displaying.Without 这一行代码 "ga.translate(175.0, 125.0)"，程序运行正常。我该如何解决这个问题？谢谢。

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.event.MouseMotionListener;
import javax.swing.JLabel;

public class Main extends JPanel implements MouseMotionListener {
    public JLabel label;
    //@Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D ga = (Graphics2D) g;
        ga.translate(175.0, 125.0); //the mouse coordinates stop displaying with this code
        ga.drawLine(0, 0, 100, 100);
    }
    public static void main(String[] args) {
        Main m = new Main();
        GraphicsDraw D = new GraphicsDraw();
        JFrame frame = new JFrame();
        frame.setTitle("MouseCoordinates111");
        frame.setSize(400, 400);
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent we) {
                System.exit(0);
            }
        });
        Container contentPane = frame.getContentPane();
        contentPane.add(m);
        frame.setVisible(true);
    }
    public Main() {
        setSize(400, 400);
        label = new JLabel("No Mouse Event Captured", JLabel.CENTER);
        add(label);
        //super();
        addMouseMotionListener(this);

    }
    @Override
    public void mouseMoved(MouseEvent e) {
        //System.out.println(e.getX() + " / " + e.getY());
        label.setText("Mouse Cursor Coordinates => X:" + e.getX() + " |Y:" + e.getY());
    }
    @Override
    public void mouseDragged(MouseEvent e) {}
    public void mouseClicked(MouseEvent e) {
        int x = e.getX();
        int y = e.getY();

    }

}

Answer 1

当您操作 Graphics 对象的（某些）值（如翻译、转换）时，您应该始终将其恢复到其原始状态。

一个简单的方法是创建一个临时 Graphics 对象来处理您的绘画：

@Override
protected void paintComponent(Graphics g)
{
    super.paintComponent(g);

    //Graphics2D ga = (Graphics2D) g;
    Graphics2D ga =  (Graphics2D)g.create();

    ga.translate(175.0, 125.0); //the mouse coordinates stop displaying with this code
    ga.drawLine(0, 0, 100, 100);

    ga.dispose();
}

使用平移校准坐标系后鼠标坐标停止工作-java

Mouse Coordinates stop working after using translation to recallibrate the coordination system-java

java

swing

jpanel