java - 使用 Java 小程序裁剪从网络摄像头拍摄的图像

Question

我的需求如下。

Take a photo using webcam and provide an edit button to crop and save the image using a re-sizable rectangle.

我已经完成了网络摄像头的编码，并使用小程序拍摄了照片并成功保存了图像。但是很难使用可调整大小的矩形启用编辑功能。我可以使用 Jcrop、jquery 进行裁剪，但问题是如何将图像从 applet 获取到 JSP。

或者有什么方法可以使用 Applet 本身使用矩形裁剪图像。

Answer 1

有点像...

public class ResizeCrop {

    public static void main(String[] args) {
        new ResizeCrop();
    }

    public ResizeCrop() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException ex) {
                } catch (InstantiationException ex) {
                } catch (IllegalAccessException ex) {
                } catch (UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new CropPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class CropPane extends JPanel {

        private BufferedImage background;
        private Rectangle cropBounds;

        public CropPane() {
            try {
                background = ImageIO.read(new File("/Users/swhitehead/Dropbox/MT008.gif"));
            } catch (IOException exp) {
                exp.printStackTrace();
            }

            MouseHandler handler = new MouseHandler();

            addMouseListener(handler);
            addMouseMotionListener(handler);
        }

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

        protected Rectangle getCropBounds() {
            Rectangle actualBounds = null;
            if (cropBounds != null) {
                int x = cropBounds.x;
                int y = cropBounds.y;
                int width = cropBounds.width;
                int height = cropBounds.height;

                if (width < 0) {
                    x += width;
                    width -= (width * 2);
                }
                if (height < 0) {
                    y += height;
                    height -= (height * 2);
                }

                actualBounds = new Rectangle(x, y, width, height);
                System.out.println(actualBounds);
            }
            return actualBounds;
        }

        @Override
        protected void paintComponent(Graphics g) {

            super.paintComponent(g);

            Graphics2D g2d = (Graphics2D) g.create();
            if (background != null) {
                int x = (getWidth() - background.getWidth()) / 2;
                int y = (getHeight() - background.getHeight()) / 2;
                g2d.drawImage(background, x, y, this);
            }

            Rectangle drawCrop = getCropBounds();
            if (drawCrop != null) {
                Color color = UIManager.getColor("List.selectionBackground");
                g2d.setColor(color);
                Composite composite = g2d.getComposite();
                g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f));
                g2d.fill(drawCrop);
                g2d.setComposite(composite);
                g2d.draw(drawCrop);
            }
        }

        public class MouseHandler extends MouseAdapter {

            @Override
            public void mouseReleased(MouseEvent e) {
                cropBounds = null;
                repaint();
            }

            @Override
            public void mousePressed(MouseEvent e) {
                cropBounds = new Rectangle();
                cropBounds.setLocation(e.getPoint());
                repaint();
            }

            @Override
            public void mouseDragged(MouseEvent e) {
                if (cropBounds != null) {
                    Point p = e.getPoint();
                    int width = p.x - cropBounds.x;
                    int height = p.y - cropBounds.y;
                    cropBounds.setSize(width, height);
                    repaint();
                }
            }
        }
    }
}

或者您可以进行反向选择...

只需将选择绘制代码(在 paintComponent 方法中)替换为...

Rectangle drawCrop = getCropBounds();
if (drawCrop != null) {

    Area area = new Area(new Rectangle(0, 0, getWidth() - 1, getHeight() - 1));
    area.subtract(new Area(drawCrop));

    Color color = UIManager.getColor("List.selectionBackground");
    g2d.setColor(color);
    Composite composite = g2d.getComposite();
    g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f));
    g2d.fill(area);
    g2d.setComposite(composite);
    g2d.draw(area);
}

这里的重要部分是不要使用 cropBounds 字段，您必须调用 getCropBounds 因为它会纠正负矩形 ;)

代码示例清除了 mouseRelease 上的裁剪，但您可以保留矩形直到用户执行其他操作，例如双击...