Re: How do I paint on an existing Panel?

On 18/01/2012 16:55, A B wrote:


HI

I had the same problem! my solution is as follows

/*
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 * and open the template in the editor.
 */
package imagelibrary;

//~--- JDK
imports ------------------------------------------------------------
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.LayoutManager;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import javax.imageio.ImageIO;
import java.io.InputStream;
import javax.swing.JPanel;

/**
 *
 * @author NeilLewisMorris
 */
public class ImagePanel extends JPanel {

    private BufferedImage Bimage = null;
    private File imageFile = null;
    private InputStream imageInputStream = null;
    private Dimension size;
    private double panelWidth;
    private double panelHeight;
    private double BimageWidth;
    private double BimageHeight;
    private double scaledWidth;
    private double scaledHeight;
    private double scaled;
    private double startX = 0;
    private double startY = 0;

    public ImagePanel() {
        super();
    }

    public ImagePanel(LayoutManager layout) {
        super(layout);
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        if (Bimage != null) {
            BimageWidth = Bimage.getWidth();
            BimageHeight = Bimage.getHeight();
            panelWidth = getWidth();
            panelHeight = getHeight();
            scaledWidth = panelWidth / BimageWidth;
            scaledHeight = panelHeight / BimageHeight;

            if (scaledWidth > scaledHeight) {
                scaled = scaledHeight;
            } else {
                scaled = scaledWidth;
            }
            scaledWidth = scaled * BimageWidth;
            scaledHeight = scaled * BimageHeight;
            startX = (panelWidth - scaledWidth) / 2;
            startY = (panelHeight - scaledHeight) / 2;
        } else {
            scaledWidth = 0;
            scaledHeight = 0;
        }
        if (Bimage != null) {
            g.drawImage(Bimage, (int)startX, (int)startY, (int)
scaledWidth, (int) scaledHeight, this);
        }
    }

    public File getImageFile() {
        return imageFile;
    }

    public boolean setImageFile(File file) throws IOException {
        imageFile = file;
        return setImageInputStream(new FileInputStream(imageFile));
    }

    public boolean setImageInputStream(InputStream inputstream) {
        imageInputStream = inputstream;
        try {
            Bimage = ImageIO.read(imageInputStream);
        } catch (IOException e) {
            return false;
        }
        revalidate();
        repaint();
        return true;
    }
}

<>