java - JPanel 中的计时器未启动

Question

我正在尝试在 JPanel 中移动图像，静态变量 x 和 y 是使用 opencv 在其他类中更改的红色坐标。这里计时器没有启动。请告诉我哪里错了。

class ImageFollowingPanel extends JPanel
{

    private final BufferedImage image;
    private Point imagePosition = new Point(150, 150);
    private Point redPoint;
    private double imageAngleRad = 0;
    public static int x, y;
    public ImageFollowingPanel()
    {
        BufferedImage i = null;
        try
        {
            i = ImageIO.read(new File("forward.png"));
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        image = i;

        ActionListener taskPerformer = new ActionListener()
        {

            public void actionPerformed(ActionEvent evt)
            {
                if (redPoint != null)
                {

                    int centerX = imagePosition.x + (image.getWidth() / 2);
                    int centerY = imagePosition.y + (image.getHeight() / 2);

                    if (redPoint.x != centerX)
                    {
                        imagePosition.x += redPoint.x < centerX ? -1 : 1;
                    }
                    if (redPoint.y != centerY)
                    {
                        imagePosition.y += redPoint.y < centerY ? -1 : 1;
                    }
                    System.out.println("mouse:::  x : " + x + "y :" + y);
                    redPoint.x = x;
                    redPoint.y = y;
                    double dx = x - imagePosition.getX();
                    double dy = y - imagePosition.getY();
                    imageAngleRad = Math.atan2(dy, dx);
                    repaint();
                }
            }
        };
        Timer timer = new Timer(1000, taskPerformer);
        timer.start();
    }

    protected void paintComponent(Graphics gr)
    {
        super.paintComponent(gr);
        Graphics2D g = (Graphics2D) gr;
        g.setRenderingHint(RenderingHints.KEY_RENDERING,
                RenderingHints.VALUE_RENDER_QUALITY);

        int cx = image.getWidth() / 2;
        int cy = image.getHeight() / 2;
        AffineTransform oldAT = g.getTransform();
        g.translate(cx + imagePosition.x, cy + imagePosition.y);
        g.rotate(imageAngleRad);
        g.translate(-cx, -cy);
        g.drawImage(image, 0, 0, null);
        g.setTransform(oldAT);

    }
}

Answer 1

每次计时器触发操作事件时，您都会检查 redPoint 是否不为 null，如果为 null，则什么都不做。但在您的代码中 redPoint 始终为 null，这就是为什么什么也没有发生。