Wrap image to Jframe

Question

I'm trying to get my Jframe to match my image dimensions exactly, so that when i attempt to get the Rectangle2D co-ordinates of an area via drawing a rectangle, it's give me the true co-ordinates of where it would appear on the actual image.

The objective with this solution is to convert a PDF to a image, identify a particular area using the visual mapper and then use PDFBox (PDFTextStripperbyArea) to extract against this area.

The co-ordinates being given by the below code is not extracting the required area's.

This is the code:

    public class PDFVisualMapper extends JFrame {

    BufferedImage image = null;

    public static void main(String[] args) throws IOException {
        new PDFVisualMapper();
    }

    public PDFVisualMapper() throws IOException {
        this.setSize(1700, 2200);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.add(new PaintSurface(), BorderLayout.CENTER);
        this.setVisible(true);
    }

    private class PaintSurface extends JComponent {
        ArrayList<Shape> shapes = new ArrayList<Shape>();

        Point startDrag, endDrag;

        public PaintSurface() throws IOException {
            image = ImageIO.read(new File("C:\\Users\\Rusty\\Desktop\\temp\\Test_PDF-1.png"));
            if ( image != null ) {
                Dimension size = new Dimension(image.getWidth(null), image.getHeight(null));
                setPreferredSize(size);
                setMinimumSize(size);
                setMaximumSize(size);
                setSize(size);
                setLayout(null);
            }

            this.addMouseListener(new MouseAdapter() {
                public void mousePressed(MouseEvent e) {
                    startDrag = new Point(e.getX(), e.getY());
                    endDrag = startDrag;
                    repaint();
                }

                public void mouseReleased(MouseEvent e) {
                    Shape r = makeRectangle(startDrag.x, startDrag.y, e.getX(), e.getY());
                    shapes.add(r);
                    startDrag = null;
                    endDrag = null;
                    repaint();
                }
            });

            this.addMouseMotionListener(new MouseMotionAdapter() {
                public void mouseDragged(MouseEvent e) {
                    endDrag = new Point(e.getX(), e.getY());
                    repaint();
                }
            });
        }

        private void paintBackground(Graphics2D g2) {
            g2.setPaint(Color.LIGHT_GRAY);
            for (int i = 0; i < getSize().width; i += 10) {
                Shape line = new Line2D.Float(i, 0, i, getSize().height);
                g2.draw(line);
            }

            for (int i = 0; i < getSize().height; i += 10) {
                Shape line = new Line2D.Float(0, i, getSize().width, i);
                g2.draw(line);
            }

        }

        public void paint(Graphics g) {
            Graphics2D g2 = (Graphics2D) g;
            g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
             paintBackground(g2);
            Color[] colors = { Color.YELLOW, Color.MAGENTA, Color.CYAN, Color.RED, Color.BLUE, Color.PINK };
            int colorIndex = 0;
             g2.drawImage(image, null, 0, 0);

            g2.setStroke(new BasicStroke(2));
            g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.50f));

            for (Shape s : shapes) {
                g2.setPaint(Color.BLACK);
                g2.draw(s);
                g2.setPaint(colors[(colorIndex++) % 6]);
                g2.fill(s);
            }

            if (startDrag != null && endDrag != null) {
                g2.setPaint(Color.LIGHT_GRAY);
                Shape r = makeRectangle(startDrag.x, startDrag.y, endDrag.x, endDrag.y);
                g2.draw(r);
                System.out.println(r.getBounds2D());
            }
        }
    }

    private Rectangle2D.Float makeRectangle(int x1, int y1, int x2, int y2) {
        return new Rectangle2D.Float(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x1 - x2), Math.abs(y1 - y2));
    }

}

Can anybody help?

Answer 1

This might be simpler: using a JLabel within the contentpane, using FlowLayout:

import java.awt.FlowLayout;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class WarpImage {

    public static void main(String[] args) throws IOException {

        displayImage();
    }

    private static void displayImage() throws IOException{

        URL url = new URL("http://www.digitalphotoartistry.com/rose1.jpg");
        BufferedImage image = ImageIO.read(url);
        ImageIcon icon= new ImageIcon(image);
        JFrame frame=new JFrame(); 
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new FlowLayout());
        JLabel lbl= new JLabel();
        lbl.setIcon(icon);
        frame.add(lbl);
        frame.pack();
        //check size :
        Rectangle bounds = lbl.getBounds();
        System.out.println(bounds.getWidth() +"-"+ bounds.getHeight());
        frame.setVisible(true);
    }
}

Answer 2

I'm trying to get my Jframe to match my image dimensions exactly, so that when i attempt to get the Rectangle2D co-ordinates of an area via drawing a rectangle, it's give me the true co-ordinates of where it would appear on the actual image.

Then you paint the image yourself. Why? Because components like JLabel have their own internal layout mechanics which provide no way for you to determine the offset of the image within in, if the image is to large or to small for the component size.

Something like this, for example:

public class ImagePane extends JPanel {

    private BufferedImage img;

    public ImagePane(BufferedImage img) {
        this.img = img;
    }

    @Override
    public Dimension getPreferredSize() {
        return img == null ? new Dimension(0, 0) : new Dimension(img.getWidth(), img.getHeight());
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        if (img != null) {
            Graphics2D g2 = (Graphics2D) g.create();
            g2.drawImage(img, 0, 0, this);
            g2.dispose();
        }
    }
}

This places the image in the top left corner of the component, so if it's resized for some reason, the image will always be in the top left position. To be frank, it wouldn't be hard to generate an offset to allow the image to be centred, this could then be used by decedents of the component to calculate the offset required to adjust their own output as needed