如何在Java中旋转图形

Question

我在a中绘制了一些图形JPanel,如圆形,矩形等.

但我想绘制一些特定程度旋转的图形,如旋转的椭圆.我该怎么办？

Answer 1

如果你使用普通的Graphics,先铸造Graphics2D:

Graphics2D g2d = (Graphics2D)g;

要旋转整个Graphics2D:

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

要重置旋转(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

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
    }
}