java - 在 Java 中绘制到后台缓冲区的问题

Question

我想绘制到后备缓冲区，然后将其显示在 JPanel 上，但我无法应用我的绘图，它只会显示为全黑屏幕。

有什么想法吗？

我当前的代码:

public class Game extends JPanel {

    int screenWidth = 1280;
    int screenHeight = 720;
    BufferedImage backbuffer;
    Graphics2D g2d;
    AffineTransform at = new AffineTransform();
    Polys polygon = new Polys();

    public void init() {
        backbuffer = new BufferedImage(screenWidth, screenHeight, BufferedImage.TYPE_INT_RGB);
        g2d = backbuffer.createGraphics();
    }

    public void update(Graphics g) {
        g2d.setColor(Color.PINK);
        g2d.fillRect(0, 0, screenWidth, screenHeight);
        drawStuff();
        paint(g);
    }

    public void drawStuff() {
        g2d.setTransform(at);
        g2d.translate(10, 10);
        g2d.setColor(Color.BLACK);
        g2d.drawPolygon(polygon.getPoly());
    }

    public void paint(Graphics g) {
        g.drawImage(backbuffer, 0, 0, this);
    }

    Game() {
        setPreferredSize(new Dimension(screenWidth, screenHeight));
        init();
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Game Test");
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setResizable(false);
        frame.getContentPane().add(new Game());
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

Answer 1

Got it to work with a Canvas but not with JPanel (with paintComponent) for some reason. update() does not get called with paintComponent maybe?

不要重写 update() 方法。这是旧的 AWT 代码，Swing 中没有完成。当您创建 BufferedImage 时，可以在构造函数中完成对 BufferedImage 的绘制。但一般来说，当图像是静态时，您只会使用 BufferedImage。

就您而言，我建议您不需要 BufferedImage。只需在 paintComponent(...) 方法中完成所有自定义绘制即可。