MouseMotionListener 不会将坐标传输到 Canvas

Question

我希望鼠标 class 的坐标转到绘画方法中的绘画 class。并且正方形随着鼠标的移动而移动。但是坐标传不出来

g.drawRect(mouse.getX(), mouse.getY(), 10, 10);

mouse.getX(), mouse.getY() 只从头开始。之后不变。

Class 画点数

public class DrawPoints
{
    Frame f;
    KeyBoard key;
    Mouse mouse;
    Paint c;

    public void GUI()
    {
        f = new Frame("DrawPoints");
        f.setSize(300, 300);

        mouse = new Mouse(); // edit

        c = new Paint(mouse); // edit
        c.setSize(300, 300);
        c.setBackground(Color.WHITE);

        c.addMouseListener(mouse);
        c.addMouseMotionListener(mouse);

        key = new KeyBoard();
        c.addKeyListener(key);

        f.add(c);
        f.pack();
        f.setVisible(true);

        f.addWindowListener(new WindowAdapter()
        {
            @Override
            public void windowClosing(WindowEvent e)
            {
                System.exit(0);
            }
        });
    }
}

Class 绘画

class Paint extends Canvas
{
    Mouse mouse; // edit

    public Paint() // added
    {
        mouse = new Mouse();
    }

    @Override
    public void paint(Graphics g)
    {
        g.drawRect(mouse.getX(), mouse.getY(), 10, 10);
        repaint(); // added
    }
}

Class鼠标

class Mouse implements MouseListener, MouseMotionListener
{   
    private int x;
    private int y;

    public int getX()
    {
        return this.x;
    }

    public int getY()
    {
        return this.y;
    }

    // MouseMotionListener
    @Override
    public void mouseMoved(MouseEvent e)
    {
        x = e.getX();
        y = e.getY();
        //System.out.println(e.getX() + " " + e.getY());
    }

    @Override
    public void mouseDragged(MouseEvent e)
    {
        System.out.println("mouseDragged");
    }

Answer 1

忘记您不应该使用 AWT 库进行编码，因为这个 GUI 库已经过时 20 多年了，这不是您进行事件驱动编程的方式，因为您需要通知程序鼠标状态的变化，你的代码不会做的事情。您的鼠标侦听器方法需要更改绘图 Paint 对象中的 x 和 y 属性，然后在同一对象上调用 repaint()。

Answer 2

我不知道其他 classes 但我认为问题是您创建了不同的鼠标对象。将 new Mouse() 移动到 new Paint() 之前，并将 new Paint 更改为 Paint(mouse)。抽签点 class：

public class DrawPoints
{
    Frame f;
    KeyBoard key;
    Mouse mouse;
    Paint c;

    public void GUI()
    {
        f = new Frame("DrawPoints");
        f.setSize(300, 300);

        mouse = new Mouse();


        c = new Paint(mouse);
        c.setSize(300, 300);
        c.setBackground(Color.WHITE);
        c.addMouseListener(mouse);
        c.addMouseMotionListener(mouse);

        key = new KeyBoard();
        c.addKeyListener(key);



        f.add(c);
        f.pack();
        f.setVisible(true);

        f.addWindowListener(new WindowAdapter()
        {
            @Override
            public void windowClosing(WindowEvent e)
            {
                System.exit(0);
            }
        });
    }
}}

Paint class：将 Paint() 更改为 Paint(Mouse mouse) 并将新的 Mouses() 行更改为 this.mouse = mouse;

class Paint extends Canvas
{
    Mouse mouse;

    public Paint(Mouse mouse)
    {
        this.mouse = mouse;
    }

    @Override
    public void paint(Graphics g)
    {
        g.drawRect(mouse.getX(), mouse.getY(), 10, 10);
    }
}

MouseMotionListener 不会将坐标传输到 Canvas

MouseMotionListener does not transfer coordinates to the Canvas

java

canvas

awt

mousemotionlistener