调用paintComponent后Java Swing绘制图像

Question

我对如何在 Swing 中扩展 JPanel 来制作 Canvas 样式对象有点困惑，如果我想在创建新对象后创建新图像或文本，我该怎么办？因为我假设那就是调用paintComponent的时候。

Answer 1

除了 ControlAltDel 的出色建议(有关如何以编程方式重绘的信息，请参阅 step 3 of the tutorial)和 Andrew Thompson ，这可以作为一个非常简单的示例来帮助您入门:

public class Main {
    public static void main(final String[] args) throws InterruptedException {
        final JFrame frame = new JFrame("Swing canvas");
        frame.setBounds(100, 100, 640, 480);
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        final CanvasPanel canvasPanel = new CanvasPanel();
        frame.getContentPane().add(canvasPanel);
        frame.setVisible(true);
        final List<String> words = Arrays.asList("one", "ein", "une", "uno", "jeden", "een");
        for (final String word : words) {
            canvasPanel.addWord(word);
            // Dirty way to simulate some heavy translation work...
            Thread.sleep(246);
        }
    }
}

class CanvasPanel extends JPanel {
    private final List<String> words = new ArrayList<>();

    public void addWord(final String word) {
        words.add(word);
        repaint();
    }

    @Override
    protected void paintComponent(final Graphics graphics) {
        super.paintComponent(graphics);
        for (int wordIndex = 0; wordIndex < words.size(); wordIndex++)
            graphics.drawString(words.get(wordIndex), 42, 64 + 28 * wordIndex);
    }
}

在此示例中， Canvas 面板调用其自身的 repaint 方法，但也可以从外部调用它。祝您的项目顺利!