按指定的角度在java中旋转图像 [英] Rotate an image in java by the specified angle

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添加一个名为'angle'的变量，这样图像也会旋转指定的角度（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).

更新为示例

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，这实际上没有做任何事情。：/

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

推荐答案

优先权很重要......

Precedence matters...

在你的第二个例子中，你在绘制完所有东西之后应用了一个旋转。这不是图形的工作方式。你需要先应用变换，然后是后面的所有内容使用该转换。

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();

        }

    }

}

您可能想看看转换形状，文本和图像了解更多信息

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

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