Question

我很好奇两个摆动BufferedImage从给定和可见组件中获取方法。在某种程度上，我将（Component.paintAll）组件绘制到BufferedImage，在第二种方式中绘制图像（Graphics.drawImage）。

它的行为方式有趣：

在绘制时会产生空灰色图像（方法saveBufferedImageByDraw）
在绘画上会产生适当的组件图像（方法saveBufferedImageByPaint）

对于简短的解释，我将不胜感激。

以下是示例源代码（要运行，您需要设置正确的OUTPUT_DIRECTORY）：

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.GraphicsEnvironment;
import java.awt.HeadlessException;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.BorderFactory;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class SaveTest extends JFrame {

    private static final String PAINT_STATUS = "Paint status : ";

    private static final String DRAW_STATUS = "Draw status : ";

    private static final File OUTPUT_DIRECTORY = new File(".....");

    private JLabel messageDraw;

    private JLabel messagePaint;

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new SaveTest();
            }
        });
    }


    public SaveTest() throws HeadlessException {
        super();
        initialize();
    }

    private void initialize() {
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        messageDraw = new JLabel(DRAW_STATUS);
        messagePaint = new JLabel(PAINT_STATUS);
        JButton button = new JButton("Create images");
        button.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                create(SaveTest.this);
            }
        });

        JPanel messagesPane = new JPanel();
        messagesPane.setBorder(BorderFactory.createTitledBorder("Save statuses"));
        messagesPane.setPreferredSize(new Dimension(400, 100));

        messagesPane.setLayout(new BoxLayout(messagesPane, BoxLayout.PAGE_AXIS));
        messagesPane.add(Box.createHorizontalGlue());
        messagesPane.add(messageDraw);
        messagesPane.add(messagePaint);

        JPanel buttonsPane = new JPanel();
        buttonsPane.setLayout(new BoxLayout(buttonsPane, BoxLayout.LINE_AXIS));
        buttonsPane.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
        buttonsPane.add(button);


        Container contentPane = getContentPane();
        contentPane.add(messagesPane, BorderLayout.CENTER);
        contentPane.add(buttonsPane, BorderLayout.PAGE_END);

        this.pack();
        this.setVisible(true);
    }


    /**
     * Creates the image of current component.
     *
     * @param component the component
     */
    public void create(Component component) {
        if (component != null && component.isVisible()
                && !GraphicsEnvironment.isHeadless()) {

            try {
                saveBufferedImageByPaint(component);
                messagePaint.setText(PAINT_STATUS + "OK");
            } catch (Exception e) {
                messagePaint.setText(PAINT_STATUS + "ERROR : " + e.getMessage());
            }
            try {
                saveBufferedImageByDraw(component);
                messageDraw.setText(DRAW_STATUS + "OK");
            } catch (Exception e) {
                messageDraw.setText(DRAW_STATUS + "ERROR : " + e.getMessage());
            }
        } else {
            messagePaint.setText(PAINT_STATUS + "ERROR : invalid component state");
            messageDraw.setText(DRAW_STATUS + "ERROR : invalid component state");
        }
    }

    private void saveBufferedImageByDraw(Component component) {
        BufferedImage image = (BufferedImage) component.createImage(component.getWidth(), component.getHeight());
        Graphics2D g2 = image.createGraphics();
        g2.drawImage(image, 0, 0, component);
        g2.dispose();
        saveImage(image, "DRAW");
    }

    private void saveBufferedImageByPaint(Component component) {
        BufferedImage image = new BufferedImage(component.getWidth(), component.getHeight(), BufferedImage.TYPE_INT_RGB);
        Graphics2D g2 = image.createGraphics();     
        component.printAll(g2);
        g2.dispose();

        saveImage(image, "PAINT");
    }


    public static void saveImage(BufferedImage image, String prefix) {
        try {
            File f = new File(OUTPUT_DIRECTORY, prefix + ".png");
            ImageIO.write(image, "PNG", f);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

以两种方式获取BufferedImage

0 个答案: