截图程序

Question

我正在制作截图程序，所以当你按下屏幕截图按钮时，会弹出一个JMessageDial并提示你你的图像，它会告诉你拖动鼠标并在你要拍摄的区域周围做一个方框截图。当用户点击“OK”时，我似乎无法找到如何在框内获取图像。

所以我需要帮助的是让用户用鼠标“绘制”矩形内部的图像，并将其存储在变量中。

以下是具体代码：

public void selectArea(final BufferedImage screen) throws Exception {
    final BufferedImage screenCopy = new BufferedImage(screen.getWidth(), screen.getHeight(), screen.getType());
    final JLabel screenLabel = new JLabel(new ImageIcon(screenCopy));
    JScrollPane screenScroll = new JScrollPane(screenLabel);

    screenScroll.setPreferredSize(new Dimension((int)(screen.getWidth()/2), (int)(screen.getHeight()/2)));

    JPanel panel = new JPanel(new BorderLayout());
    panel.add(screenScroll, BorderLayout.CENTER);

    final JLabel selectionLabel = new JLabel("Draw a rectangle");
    panel.add(selectionLabel, BorderLayout.SOUTH);
    repaint(screen, screenCopy);
    screenLabel.repaint();

    screenLabel.addMouseMotionListener(new MouseMotionAdapter() {

        @Override
        public void mouseMoved(MouseEvent me) {
            start = me.getPoint();
            repaint(screen, screenCopy);
            selectionLabel.setText("Start Point: " + start);
            screenLabel.repaint();
        }

        @Override
        public void mouseDragged(MouseEvent me) {
            end = me.getPoint();
            captureRect = new Rectangle(start, new Dimension(end.x-start.x, end.y-start.y));
            try {
                paintFinalImage(new BufferedImage((int)screenCopy.getGraphics().getClipBounds(captureRect).getWidth()+1,
                        (int)screenCopy.getGraphics().getClipBounds(captureRect).getHeight()+1, screen.getType()));
            } catch (Exception e) {
                e.printStackTrace();
            }
            repaint(screen, screenCopy);
            screenLabel.repaint();
            selectionLabel.setText("Rectangle: " + captureRect);
        }
    });
    JOptionPane.showMessageDialog(null, panel, "Select your image", JOptionPane.OK_OPTION, new ImageIcon(""));
    uploadImage(screenShot);
    System.out.println("Final rectangle: " + screenCopy.getGraphics().getClipBounds(captureRect));
}

如果你需要，这是完整的课程：

package com.screencapture;


import java.awt.*;

public class Main implements ActionListener, ItemListener, KeyListener, NativeKeyListener {

    private final Image icon = Toolkit.getDefaultToolkit().getImage("./data/icon.gif");
    private final TrayIcon trayIcon = new TrayIcon(icon, "Screen Snapper");
    private JFrame frame;
    private Rectangle captureRect;
    private JComboBox<String> imageType;
    private boolean hideWhenMinimized = false;
    private final String API_KEY = "b84e430b4a65d16a6955358141f21a61";
    private static Robot robot;
    private BufferedImage screenShot;
    private Point end;
    private Point start;

    public static void main(String[] args) throws Exception {
        robot = new Robot();
        new Main().start();
    }

    public void start() throws Exception {
        GlobalScreen.getInstance().registerNativeHook();
        GlobalScreen.getInstance().addNativeKeyListener(this);
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        frame = new JFrame("White power!");
        frame.setPreferredSize(new Dimension(250, 250));
        frame.getContentPane().setLayout(null);
        frame.setIconImage(icon);
        frame.addKeyListener(this);
        frame.addWindowListener(new WindowListener() {

            @Override
            public void windowOpened(WindowEvent e) {}

            @Override
            public void windowClosing(WindowEvent e) {}

            @Override
            public void windowClosed(WindowEvent e) {}

            @Override
            public void windowIconified(WindowEvent e) {
                if (hideWhenMinimized)
                    frame.setVisible(false);
            }

            @Override
            public void windowDeiconified(WindowEvent e) {}

            @Override
            public void windowActivated(WindowEvent e) {}

            @Override
            public void windowDeactivated(WindowEvent e)  {}

        });

        JLabel lblImageType = new JLabel("Image Format:");
        lblImageType.setBounds(10, 11, 90, 14);
        frame.getContentPane().add(lblImageType);

        String[] imageTypes = {"PNG", "JPG"};
        imageType = new JComboBox<String>(imageTypes);
        imageType.setBounds(106, 8, 51, 20);
        frame.getContentPane().add(imageType);

        JButton btnTakeScreenShot = new JButton("ScreenShot");
        btnTakeScreenShot.setBounds(24, 69, 115, 23);
        frame.getContentPane().add(btnTakeScreenShot);
        btnTakeScreenShot.addActionListener(this);

        setTrayIcon();
        frame.pack();
        frame.setVisible(true);
    }

    public void setTrayIcon() throws AWTException {
        CheckboxMenuItem startup = new CheckboxMenuItem("Run on start-up");
        CheckboxMenuItem hide = new CheckboxMenuItem("Hide when minimized");
        String[] popupMenuOptions = {"Open", "Exit"};
        if (SystemTray.isSupported()) {
            SystemTray tray = SystemTray.getSystemTray();
            trayIcon.setImageAutoSize(true);
            PopupMenu popupMenu = new PopupMenu();
            for (String option : popupMenuOptions) {
                if (option == "Exit") {
                    popupMenu.add(startup);
                    popupMenu.add(hide);
                    popupMenu.add(option);
                } else {
                    popupMenu.add(option);
                }
            }
            trayIcon.setPopupMenu(popupMenu);
            popupMenu.addActionListener(this);
            startup.addItemListener(this);
            hide.addItemListener(this);
            trayIcon.addActionListener(new ActionListener() {

                @Override
                public void actionPerformed(ActionEvent e) {
                    frame.setVisible(true);
                }

            });
            tray.add(trayIcon);
        }
    }

    public void selectArea(final BufferedImage screen) throws Exception {
        final BufferedImage screenCopy = new BufferedImage(screen.getWidth(), screen.getHeight(), screen.getType());
        final JLabel screenLabel = new JLabel(new ImageIcon(screenCopy));
        JScrollPane screenScroll = new JScrollPane(screenLabel);

        screenScroll.setPreferredSize(new Dimension((int)(screen.getWidth()/2), (int)(screen.getHeight()/2)));

        JPanel panel = new JPanel(new BorderLayout());
        panel.add(screenScroll, BorderLayout.CENTER);

        final JLabel selectionLabel = new JLabel("Draw a rectangle");
        panel.add(selectionLabel, BorderLayout.SOUTH);
        repaint(screen, screenCopy);
        screenLabel.repaint();

        screenLabel.addMouseMotionListener(new MouseMotionAdapter() {

            @Override
            public void mouseMoved(MouseEvent me) {
                start = me.getPoint();
                repaint(screen, screenCopy);
                selectionLabel.setText("Start Point: " + start);
                screenLabel.repaint();
            }

            @Override
            public void mouseDragged(MouseEvent me) {
                end = me.getPoint();
                captureRect = new Rectangle(start, new Dimension(end.x-start.x, end.y-start.y));
                try {
                    paintFinalImage(new BufferedImage((int)screenCopy.getGraphics().getClipBounds(captureRect).getWidth()+1,
                            (int)screenCopy.getGraphics().getClipBounds(captureRect).getHeight()+1, screen.getType()));
                } catch (Exception e) {
                    e.printStackTrace();
                }
                repaint(screen, screenCopy);
                screenLabel.repaint();
                selectionLabel.setText("Rectangle: " + captureRect);
            }
        });
        JOptionPane.showMessageDialog(null, panel, "Select your image", JOptionPane.OK_OPTION, new ImageIcon(""));
        uploadImage(screenShot);
        System.out.println("Final rectangle: " + screenCopy.getGraphics().getClipBounds(captureRect));
    }

    public void paintFinalImage(BufferedImage image) throws Exception {
        screenShot = new BufferedImage(image.getWidth(), image.getHeight(), image.getType());
        Graphics2D g = screenShot.createGraphics();
        g.drawImage(image, 0, 0, null);
        g.dispose();
    }

    public void repaint(BufferedImage orig, BufferedImage copy) {
        Graphics2D g = copy.createGraphics();
        g.drawImage(orig, 0, 0, null);
        if (captureRect != null) {
            g.setColor(Color.BLACK);
            g.draw(captureRect);
        }
        g.dispose();
    }

    public void uploadImage(BufferedImage image) throws Exception {
        String IMGUR_POST_URI = "http://api.imgur.com/2/upload.xml";
        String IMGUR_API_KEY = API_KEY;
        String readLine = null;
        try {
            ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
            ImageIO.write(image, imageType.getSelectedItem().toString(), outputStream);
            URL url = new URL(IMGUR_POST_URI);

            String data = URLEncoder.encode("image", "UTF-8") + "=" + URLEncoder.encode(Base64.encodeBase64String(outputStream.toByteArray()).toString(), "UTF-8");
            data += "&" + URLEncoder.encode("key", "UTF-8") + "=" + URLEncoder.encode(IMGUR_API_KEY, "UTF-8");

            URLConnection urlConnection = url.openConnection();
            urlConnection.setDoOutput(true);
            OutputStreamWriter wr = new OutputStreamWriter(urlConnection.getOutputStream());
            wr.write(data);
            wr.flush();
            InputStream inputStream;
            if (((HttpURLConnection) urlConnection).getResponseCode() == 400) {
                inputStream = ((HttpURLConnection) urlConnection).getErrorStream();
            } else {
                inputStream = urlConnection.getInputStream();
            }
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
            String line;
            while ((line = reader.readLine()) != null) {
                readLine = line;
            }
            wr.close();
            reader.close();
        } catch(Exception e){
            e.printStackTrace();
        }
        String URL = readLine.substring(readLine.indexOf("<original>") + 10, readLine.indexOf("</original>"));
        System.out.println(URL);
        Toolkit.getDefaultToolkit().beep();
        StringSelection stringSelection = new StringSelection(URL);
        Toolkit.getDefaultToolkit().getSystemClipboard().setContents(stringSelection, null);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        String command = e.getActionCommand();
        System.out.println(command);
        if (command.equalsIgnoreCase("open")) {
            frame.setVisible(true);
        } else if (command.equalsIgnoreCase("exit")) {
            System.exit(-1);
        } else if (command.equalsIgnoreCase("screenshot")) {
            try {
                final Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
                final BufferedImage screen = robot.createScreenCapture(new Rectangle(screenSize));
                selectArea(screen);
            } catch (Exception e1) {
                e1.printStackTrace();
            }
        }
    }

    @Override
    public void itemStateChanged(ItemEvent e) {
        System.out.println(e.getItem() + ", " +e.getStateChange());
        String itemChanged = e.getItem().toString();
        if (itemChanged.equalsIgnoreCase("run on start-up")) {
            //TODO
        } else if (itemChanged.equalsIgnoreCase("hide when minimized")) {
            if (e.getStateChange() == ItemEvent.DESELECTED) {
                hideWhenMinimized = false;
            } else if (e.getStateChange() == ItemEvent.SELECTED) {
                hideWhenMinimized = true;
            }
        }
    }

    @Override
    public void keyTyped(KeyEvent e) {
        System.out.println("KeyTyped: "+e.getKeyCode());
    }

    @Override
    public void keyPressed(KeyEvent e) {
    }

    @Override
    public void keyReleased(KeyEvent e) {
    }

    @Override
    public void nativeKeyPressed(NativeKeyEvent e) {
    }

    @Override
    public void nativeKeyReleased(NativeKeyEvent e) {
        System.out.println("KeyReleased: "+e.getKeyCode());
        System.out.println(KeyEvent.getKeyText(e.getKeyCode()));
        if (e.getKeyCode() == 154) {
            try {
                final Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
                final BufferedImage screen = robot.createScreenCapture(new Rectangle(screenSize));
                selectArea(screen);
                frame.setVisible(true);
            } catch(Exception e1) {
                e1.printStackTrace();
            }
        }
    }

    @Override
    public void nativeKeyTyped(NativeKeyEvent e) {
    }
}

Answer 1

我建议您简化问题以解决问题。创建一个小的可编译和可运行程序，它没有当前代码的所有包袱，但其唯一目标是显示图像，并让用户选择该图像的子部分。然后，如果您的尝试失败，您可以在此处发布您的尝试，我们实际上可以运行它并理解它，并希望能够解决它。

例如，这里有一小部分可编译和可运行的代码，它使用MouseListener来选择图像的一小部分。也许你可以从中得到一些想法：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;

import javax.imageio.ImageIO;
import javax.swing.*;

@SuppressWarnings("serial")
public class ImagePlay extends JPanel {
   public static final String IMAGE_PATH = "http://upload.wikimedia.org/wikipedia/" +
        "commons/thumb/3/39/European_Common_Frog_Rana_temporaria.jpg/" +
        "800px-European_Common_Frog_Rana_temporaria.jpg";
   private static final Color RECT_COLOR = new Color(180, 180, 255);
   private BufferedImage img = null;
   Point p1 = null;
   Point p2 = null;

   public ImagePlay() {
      URL imgUrl;
      try {
         imgUrl = new URL(IMAGE_PATH);
         img = ImageIO.read(imgUrl );
         ImageIcon icon = new ImageIcon(img);
         JLabel label = new JLabel(icon) {
            @Override
            protected void paintComponent(Graphics g) {
               super.paintComponent(g);
               myLabelPaint(g);
            }
         };

         setLayout(new BorderLayout());
         add(new JScrollPane(label));

         MouseAdapter mAdapter = new MyMouseAdapter();
         label.addMouseListener(mAdapter);
         label.addMouseMotionListener(mAdapter);

      } catch (MalformedURLException e) {
         e.printStackTrace();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }

   private void myLabelPaint(Graphics g) {
      if (p1 != null && p2 != null) {
         int x = Math.min(p1.x, p2.x);
         int y = Math.min(p1.y, p2.y);
         int width = Math.abs(p1.x - p2.x);
         int height = Math.abs(p1.y - p2.y);
         g.setXORMode(Color.DARK_GRAY);
         g.setColor(RECT_COLOR);
         g.drawRect(x, y, width, height);
      }
   }

   private class MyMouseAdapter extends MouseAdapter {

      @Override
      public void mousePressed(MouseEvent e) {
         p1 = e.getPoint();
         p2 = null;
         repaint();
      }

      @Override
      public void mouseDragged(MouseEvent e) {
         p2 = e.getPoint();
         repaint();
      }

      @Override
      public void mouseReleased(MouseEvent e) {
         p2 = e.getPoint();
         repaint();

         int x = Math.min(p1.x, p2.x);
         int y = Math.min(p1.y, p2.y);
         int width = Math.abs(p1.x - p2.x);
         int height = Math.abs(p1.y - p2.y);
         BufferedImage smlImg = img.getSubimage(x, y, width, height);
         ImageIcon icon = new ImageIcon(smlImg);
         JLabel label = new JLabel(icon);
         JOptionPane.showMessageDialog(ImagePlay.this, label, "Selected Image", 
               JOptionPane.PLAIN_MESSAGE);         
      }
   }


   private static void createAndShowGui() {
      ImagePlay mainPanel = new ImagePlay();

      JFrame frame = new JFrame("ImagePlay");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

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

它使用在线获取的公开图像，添加到JLabel的MouseListener，以及JLabel覆盖其paintComponent(...)方法，以显示MouseListener / Adapter的引导线。它通过BufferedImage的getSubimage(...)方法创建子图像，然后将其显示在JOptionPane中，但如果需要，保存图像将是微不足道的。