通过方法

Question

我想找到一种方法来定义一个方法，该方法在被调用时会在JPanel上绘制一条线。当重写PaintComponent时，我无法弄清楚如何解决这个问题。 看起来应该是这样......

class MyCanvas extends JPanel {
    My Canvas () {
    ...
    }
    public void drawLineOnCanvas(x1, y1, x2, y1) {
    ...code which draws a line
    }
}

Answer 1

从paintComponent调用该方法，您需要将Graphics上下文从paintComponent传递给此方法

protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    drawLine(g, fromX, fromY, toX, toY);
}

public void drawLineOnCanvas(Graphics g, x1, y1, x2, y1) {
...code which draws a line
}