将java中的图像旋转指定角度

问题描述

这是在给定坐标处绘制形状的函数:

Here's the function which draws a shape at the given coordinates:

public void drawTank(int x,int y){
   int h = 50;
   int w = 50;

   graphic.setColor(Color.darkGray);
   graphic.drawRect(x, y, h, w);
   graphic.fillRect(x, y, h, w);
   graphic.setColor(Color.GRAY);
   graphic.drawRect(x+50, y+20, 35, 10);
   graphic.fillRect(x+50, y+20, 35, 10);
}

我想在上面的函数中再添加一个名为'angle'的变量，这样图像也可以旋转指定的角度(drawTank(int x,int y,int angle).

I want to add one more variable to the above function called 'angle', so that the image is also rotated by the angle specified (drawTank(int x,int y,int angle).

更新示例

我试图做的是我初始化了 Graphics2D 并分别更改了我的代码:

What I tried to do is that I initialized Graphics2D and changed my code respectively:

g2D.setColor(Color.darkGray);
g2D.drawRect(x, y, h, w);
g2D.fillRect(x, y, h, w);
g2D.setColor(Color.red);
g2D.drawRect(x+50, y+20, 35, 10);
g2D.fillRect(x+50, y+20, 35, 10);
g2D.rotate((Math.toRadians(angle)));

但是，这实际上并没有做任何事情.:/

But, this doesn't actually do anything. :/

推荐答案

优先级很重要...

在您的第二个示例中，您将在绘制完所有内容后应用旋转.这不是图形的工作方式.您需要先应用转换，然后后面的所有内容都将使用该转换.

In your second example, you're apply a rotation AFTER you've drawn everything. This is not how graphics works. You need to apply the transformation first, then everything that follows will use that transformation.

public class TestRotateImage {

    public static void main(String[] args) {
        new TestRotateImage();
    }

    public TestRotateImage() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (Exception ex) {
                }

                JFrame frame = new JFrame("Test");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private JSlider slider;
        private Rectangle rectangle;

        public TestPane() {
            setLayout(new BorderLayout());
            rectangle = new Rectangle(0, 0, 100, 100);
            slider = new JSlider();
            slider.setMinimum(0);
            slider.setMaximum(360);
            slider.setMinorTickSpacing(5);
            slider.setMajorTickSpacing(10);
            slider.setValue(0);
            add(slider, BorderLayout.SOUTH);
            slider.addChangeListener(new ChangeListener() {
                @Override
                public void stateChanged(ChangeEvent e) {
                    repaint();
                }
            });
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        public double getAngle() {

            return Math.toRadians(slider.getValue());

        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);

            Graphics2D g2d = (Graphics2D) g.create();

            g2d.setColor(Color.RED);
            g2d.drawLine(getWidth() / 2, 0, getWidth() / 2, getHeight());
            g2d.drawLine(0, getHeight() / 2, getWidth(), getHeight() / 2);

            g2d.setColor(Color.BLACK);
            int x = (getWidth() - rectangle.width) / 2;
            int y = (getHeight() - rectangle.height) / 2;
            AffineTransform at = new AffineTransform();
            at.setToRotation(getAngle(), x + (rectangle.width / 2), y + (rectangle.height / 2));
            at.translate(x, y);
            g2d.setTransform(at);
            g2d.draw(rectangle);
            g2d.dispose();

        }

    }

}

您可能想看看 Transforming Shapes, Text and图片了解更多信息

You might like to take a look at Transforming Shapes, Text and Images for more information

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