如何在Java中旋转图形

Question

我在JPanel中绘制了一些图形，如圆形，矩形等。

但我想绘制一些旋转特定度数的图形，如旋转的椭圆。我该怎么办？

Answer 1

如果您使用普通Graphics，请先转发至Graphics2D：

Graphics2D g2d = (Graphics2D)g;

旋转整个Graphics2D：

g2d.rotate(Math.toRadians(degrees));
//draw shape/image (will be rotated)

重置旋转（所以你只旋转一件事）：

AffineTransform old = g2d.getTransform();
g2d.rotate(Math.toRadians(degrees));
//draw shape/image (will be rotated)
g2d.setTransform(old);
//things you draw after here will not be rotated

示例：

class MyPanel extends JPanel {
    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D)g;
        AffineTransform old = g2d.getTransform();
        g2d.rotate(Math.toRadians(degrees));
        //draw shape/image (will be rotated)
        g2d.setTransform(old);
        //things you draw after here will not be rotated
    }
}

Answer 2

在paintComponent()重写方法中，将Graphics参数强制转换为Graphics2D，在此Graphics2D上调用rotate()，然后绘制椭圆。