使用Swing鼠标绘制(单色)数组的最简单方法是什么？

Question

我一直在寻找一种在屏幕上绘制黑白阵列的方法.这是一个简单的阵列,只有20x20.我打算用鼠标在数组上绘制,以便每个像素从黑色切换到白色并在单击时返回,然后将数组作为一组布尔(或整数)传递给另一个函数.目前我正在使用Swing.我记得在画布上使用Swing绘图,但我仍然无法找到实际用法.我应该使用画布,还是依靠JToggleButtons？

Answer 1

您可以简单地使用JFrame(或其他Swing组件)并覆盖该paint(Graphics)方法来绘制布尔矩阵的表示(请注意,在轻量级组件的情况下,JPanel您应该覆盖paintComponent(Graphics).这将为您提供单击并拖动功能你需要(使用单个Swing组件的网格很难实现).

正如其他人评论的那样,AWT Canvas并没有为你提供任何Swing组件所没有的功能,你会在下面的例子中看到我已经使用了createBufferStrategy同样存在的方法JFrame来确保显示非闪烁.

请注意,我的示例非常简单,因为它会切换您拖动的每个像素,而不是点击操作,确定您是处于"绘画"模式还是"擦除"模式,然后在拖动持续时间内专门应用黑色或白色像素.

public class Grid extends JFrame {
    private static final int SCALE = 10; // 1 boolean value == 10 x 10 pixels.
    private static final int SIZE = 20;

    private boolean[][] matrix = new boolean[SIZE][SIZE];
    private boolean painting;
    private int lastX = -1;
    private int lastY = -1;

    public Grid() throws HeadlessException {
        setPreferredSize(new Dimension(SIZE * SCALE, SIZE * SCALE));
        setResizable(false);
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setBackground(Color.WHITE);

        addMouseListener(new MouseAdapter() {
            public void mousePressed(MouseEvent e) {
                painting = true;
                tryAdjustValue(e.getPoint());
            }

            public void mouseReleased(MouseEvent e) {
                painting = false;
                lastX = -1;
                lastY = -1;
            }
        });

        addMouseMotionListener(new MouseMotionListener() {
            public void mouseDragged(MouseEvent e) {
                tryAdjustValue(e.getPoint());
            }

            public void mouseMoved(MouseEvent e) {
                tryAdjustValue(e.getPoint());
            }
        });
    }

    private void tryAdjustValue(Point pt) {
        int newX = pt.x / SCALE;
        int newY = pt.y / SCALE;

        if (painting && isInRange(newX) && isInRange(newY) && (newX != lastX || newY != lastY)) {
            // Only invert "pixel" if we're currently in painting mode, both array indices are valid
            // and we're not attempting to adjust the same "pixel" as before (important for drag operations).
            matrix[newX][newY] = !matrix[newX][newY];
            lastX = newX;
            lastY = newY;
            repaint();
        }
    }

    private boolean isInRange(int val) {
        return val >= 0 && val < SIZE;
    }

    public void paint(Graphics g) {
        super.paint(g);

        for (int x=0; x<SIZE; ++x) {
            for (int y=0; y<SIZE; ++y) {
                if (matrix[x][y]) {
                    g.fillRect(x * SCALE, y * SCALE, SCALE, SCALE);
                }
            }
        }
    }

    public static void main(String[] args) {
        Grid grid = new Grid();
        grid.pack();
        grid.setLocationRelativeTo(null);
        grid.createBufferStrategy(2);
        grid.setVisible(true);
    }
}