2

I've been working on a program that involves the rotation of a partially transparent image over a transparent form. The drawing of the image originally worked fine, I also set my custom panel's background color to a transparent light blue this worked fine as well. My problems started when I tried rotating my image.

In order to rotate it I had to convert the panel.getGraphics() over to a Graphics2D. When I did this the transparency went away, So I finished up on my rotation code and then read up on transparency. I found that I could set the composite of the Graphics2D and that is exactly what I did as seen here:

@Override
public void paintComponent(Graphics g) 
{
    super.paintComponent(g);
    Graphics2D g2d = (Graphics2D)g;

    g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC));
    g2d.setColor(new Color(0, 0, 200, 90));
    g2d.fillRect(0, 0, this.getWidth(), this.getHeight());
    g2d.rotate(radians);
    g2d.drawImage(img, 0, 0, null);

    repaint();
}

When I run this I get the form as follows (Please note that this is not my normal image):

Before Rotation

This is almost what I want except for it doesn't show the transparent blue background. However if I rotate the image the blue shows:

After Rotation

4

2 に答える 2

2

問題は、指定したコンポジットに部分的にあります。AlphaComposite.SRC
何のために使用したのかはわかりませんが、ソースピクセルデータが上書きされます。そのため、パネルの背景に画像をペイントすると、パネルの背景が上書きされます。

まだ読んでいない場合は、グラフィックスのコンポジットについて読むことをお勧めします：http: //docs.oracle.com/javase/tutorial/2d/advanced/compositing.html

とにかく、似たようなことがどのように行われるかという例を参照してください:(
これは可能性の1つにすぎません-他の10の方法で行うことができます）

public class SmileyTest
{
    private static Color bg = new Color ( 0, 0, 255, 128 );
    private static float angle = 0f;

    public static void main ( String[] args )
    {
        final ImageIcon icon = new ImageIcon ( SmileyTest.class.getResource ( "icons/smiley.png" ) );

        JDialog frame = new JDialog ();
        frame.setLayout ( new BorderLayout () );

        // We should not use default background and opaque panel - that might cause repaint problems
        // This is why we use JPanel with transparent background painted and opacity set to false
        JPanel transparentPanel = new JPanel ( new BorderLayout () )
        {
            protected void paintComponent ( Graphics g )
            {
                super.paintComponent ( g );
                g.setColor ( bg );
                g.fillRect ( 0, 0, getWidth (), getHeight () );
            }
        };
        transparentPanel.setOpaque ( false );
        frame.add ( transparentPanel );

        // Image in another component
        final JComponent component = new JComponent ()
        {
            protected void paintComponent ( Graphics g )
            {
                super.paintComponent ( g );

                Graphics2D g2d = ( Graphics2D ) g;

                // For better image quality when it is rotated
                g2d.setRenderingHint ( RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR );

                // Rotating area using image middle as rotation center
                g2d.rotate ( angle * Math.PI / 180, getWidth () / 2, getHeight () / 2 );

                // Transparency for image
                g2d.setComposite ( AlphaComposite.getInstance ( AlphaComposite.SRC_OVER, 0.5f ) );

                // Draing image
                g2d.drawImage ( icon.getImage (), 0, 0, null );
            }
        };
        transparentPanel.add ( component );

        // Rotation animation (24 frames per second)
        new Timer ( 1000 / 48, new ActionListener ()
        {
            public void actionPerformed ( ActionEvent e )
            {
                angle += 0.5f;
                component.repaint ();
            }
        } ).start ();

        frame.setUndecorated ( true );
        AWTUtilities.setWindowOpaque ( frame, false );
        frame.setSize ( icon.getIconWidth (), icon.getIconHeight () );
        frame.setLocationRelativeTo ( null );
        frame.setVisible ( true );
    }
}

これを実行して結果を確認してください。 ここに画像の説明を入力してください

また、コードについて、何かをすべきかすべきでないかについてのコメントもいくつかあります。
必ずよくお読みください。

于 2013-02-25T10:39:18.150 に答える
0

それを行うさらに別の方法：

import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.geom.AffineTransform;
import java.awt.geom.NoninvertibleTransformException;
import java.net.MalformedURLException;
import java.net.URL;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.SwingUtilities;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class TestTransparentRotatedImage {

    private static class TransparentRotatedImage extends JPanel {
        private final Image image;
        private double rotation;

        public TransparentRotatedImage(Image image) {
            this.image = image;
            setOpaque(false);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2 = (Graphics2D) g;
            g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));
            g2.setColor(new Color(0, 0, 200, 90));
            g2.fillRect(0, 0, getWidth(), getHeight());
            g2.setTransform(getTransformation());
            g2.drawImage(image, 0, 0, this);
        }

        protected AffineTransform getTransformation() {
            try {
                AffineTransform translateInstance = AffineTransform.getTranslateInstance(+image.getWidth(this) / 2,
                        +image.getWidth(this) / 2);
                AffineTransform inverse = translateInstance.createInverse();
                AffineTransform rotateInstance = AffineTransform.getRotateInstance(Math.toRadians(rotation));
                AffineTransform at = translateInstance;
                at.concatenate(rotateInstance);
                at.concatenate(inverse);
                return at;
            } catch (NoninvertibleTransformException e) {
                e.printStackTrace();
                return null;
            }
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(image.getWidth(this), image.getHeight(this));
        }

        public void setRotation(double rotation) {
            this.rotation = rotation;
            repaint();
        }
    }

    protected void initUI() throws MalformedURLException {
        final JFrame frame = new JFrame(TestTransparentRotatedImage.class.getSimpleName());
        frame.setUndecorated(true);
        frame.setBackground(new Color(0, 0, 0, 0));
        frame.getContentPane().setBackground(new Color(0, 0, 0, 0));
        // com.sun.awt.AWTUtilities.setWindowOpacity(frame, 0);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        final TransparentRotatedImage rotatedImage = new TransparentRotatedImage(new ImageIcon(new URL(
                "http://files.myopera.com/supergreatChandu8/albums/5466862/smiley-transparent.png")).getImage());
        frame.add(rotatedImage);
        final JSlider slider1 = new JSlider(0, 360);
        slider1.setValue(0);
        slider1.addChangeListener(new ChangeListener() {

            @Override
            public void stateChanged(ChangeEvent e) {
                rotatedImage.setRotation(slider1.getValue());
            }
        });
        frame.add(slider1, BorderLayout.SOUTH);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException,
            UnsupportedLookAndFeelException {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                try {
                    new TestTransparentRotatedImage().initUI();
                } catch (MalformedURLException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        });
    }
}

ここに画像の説明を入力

于 2013-02-25T11:43:25.467 に答える