由于@justinzane说,你不能有一个真正的圆形图像。所有BufferedImage
s将是矩形的。
但是:您可以通过使用AlphaComposite
类和规则AlphaComposite.SrcIn
来达到您的效果。我已经添加了一个完全运行的示例,并在下面添加了屏幕截图,compose
方法是重要部分。
public class AlphaCompositeTest {
private static BufferedImage compose(final BufferedImage source, int w, int h) {
BufferedImage destination = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
Graphics2D graphics = destination.createGraphics();
try {
graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
graphics.setColor(Color.BLACK); // The color here doesn't really matter
graphics.fillOval(0, 0, destination.getWidth(), destination.getHeight());
if (source != null) {
graphics.setComposite(AlphaComposite.SrcIn); // Only paint inside the oval from now on
graphics.drawImage(source, 0, 0, null);
}
}
finally {
graphics.dispose();
}
return destination;
}
public static void main(String[] args) throws IOException {
final BufferedImage original = ImageIO.read(new File("lena.png"));
final BufferedImage template = compose(null, original.getWidth(), original.getHeight());
final BufferedImage composed = compose(original, original.getWidth(), original.getHeight());
SwingUtilities.invokeLater(new Runnable() {
@Override public void run() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
JPanel panel = new JPanel(new BorderLayout(10, 10));
panel.add(new JLabel("+", new ImageIcon(template), SwingConstants.LEFT), BorderLayout.WEST);
panel.add(new JLabel("=", new ImageIcon(original), SwingConstants.LEFT), BorderLayout.CENTER);
panel.add(new JLabel(new ImageIcon(composed)), BorderLayout.EAST);
frame.add(new JScrollPane(panel));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}
见例如the Compositing tutorial更多的信息和例子。