: A gray color box appeare d when loading an image on JPanel

[Nikhil V G]

posted June 01, 2006 01:32 AM
--------------------------------------------------------------------------------
Hai All,

I m nikhil. I have a Problem that when I load an image in to jpanel using drawImage method of Graphics class(G.drawImage(Image img,int width,int higth))...It take more time to load. When loading firts a gray color box will be appear on Frame. Then image loaded.How to avaoid this gray color. How to make it fast.
I m attaching part of my program with this

import javax.swing.*;
import java.awt.*;

public class wbDisplay extends JPanel
{
Image WB=null;
int widthOfWB, heightOfWB;

wbDisplay()
{

}

public void createWB()
{
// This method is responsible for creating the off-screen image.
// It should be called before using the WB. It will make a new WB if
// the size of the panel changes.

if(WB == null || widthOfWB != getSize().width || heightOfWB != getSize().height)
{
// Create the WB, or make a new one if panel size has changed.
WB = null; // (If WB already exists, this frees up the memory.)
WB = createImage(getSize().width, getSize().height);
widthOfWB = getSize().width;
heightOfWB = getSize().height;
Graphics OSG = WB.getGraphics(); // Graphics context for drawing to WB.
OSG.setColor(getBackground());
OSG.fillRect(0, 0, widthOfWB, heightOfWB);
OSG.dispose();
}
}



public void paintComponent(Graphics G)
{
// Copy the off-screen image to the screen,
// after checking to make sure it exists. Then,
// if a shsape other than CURVE is being drawn,
// draw it on top of the image from the WB.

createWB();
G.drawImage(WB, 0, 0, this);

if (dragging && figure != CURVE )
{
G.setColor(foreColor);

drawFigure(G,figure,startX,startY,mouseX,mouseY);
}

}//paintComponent

//insert picture is calling from another class that extends JFrame
//File f stored image

public void insertPicture(File F, int Mx, int My,mainScreenPart ms)
{

createWB();
Graphics G = WB.getGraphics();
System.out.println("inside insert picture");
try
{
ImageIcon img=new ImageIcon(F.getPath());
int WID=img.getIconWidth();
int HEI=img.getIconHeight();
setPreferredSize(new java.awt.Dimension(WID,HEI));
G.drawImage(img.getImage(), Mx, My,WID,HEI, img.getImageObserver());

}
catch(Exception e)
{System.out.println(e);}
}
}


I think i will get a solution from javaranch.Thanks in advance.

Regards,
NIKHIL

[Campbell Ritchie]

When you were asked for code, you ought to have posted it as a reply, with code tags, not started a new thread.
And change your display name; the Ranch requires a full last name.

[Craig Wood]

import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.Hashtable;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.event.MouseInputAdapter;
 
public class AddingImages extends JPanel
{
    BufferedImage image;
    Rectangle r;
    JSlider widthSlider;
    JSlider heightSlider;
 
    public AddingImages()
    {
        r = new Rectangle();
        addComponentListener(sizer);
    }
 
    protected void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        if(image == null)
            initImage();
        g2.drawImage(image, 0, 0, this);
        g2.setPaint(Color.red);
        g2.draw(r);
    }
 
    public void setRect(Point p1, Point p2)
    {
        r.setFrameFromDiagonal(p1, p2);
        repaint();
    }
 
    private void insertImage(BufferedImage bi, int x, int y)
    {
        Graphics2D g2 = image.createGraphics();
        g2.drawImage(bi, x, y, this);
        g2.dispose();
        repaint();
    }
 
    private void initImage()
    {
        int w = getWidth();
        int h = getHeight();
        image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        Graphics2D g2 = image.createGraphics();
        g2.setBackground(getBackground());
        g2.clearRect(0,0,w,h);
        g2.dispose();
    }
 
    private void calibrateSliders()
    {
        int maxW = getWidth()-20;
        int maxH = getHeight()-20;
        widthSlider.setMaximum(maxW);
        widthSlider.setLabelTable(getLabels("width", maxW));
        heightSlider.setMaximum(maxH);
        heightSlider.setLabelTable(getLabels("height", maxH));
        widthSlider.revalidate();
        heightSlider.revalidate();
    }
 
    public static void main(String[] args) throws IOException
    {
        File file = new File("images/Bird.gif");
        BufferedImage bi = ImageIO.read(file);
        AddingImages addingImages = new AddingImages();
        RectanglePositioner positioner = new RectanglePositioner(addingImages);
        addingImages.addMouseListener(positioner);
        addingImages.addMouseMotionListener(positioner);
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(addingImages);
        f.getContentPane().add(addingImages.getSouthPanel(bi), "South");
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
    }
 
    private JPanel getSouthPanel(final BufferedImage bi)
    {
        widthSlider = getSlider("width");
        heightSlider = getSlider("height");
        final JButton addImage = new JButton("add image");
        final JButton clear = new JButton("clear");
        ActionListener l = new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                JButton button = (JButton)e.getSource();
                if(button == addImage)
                {
                    int x = widthSlider.getValue();
                    int y = heightSlider.getValue();
                    insertImage(bi, x, y);
                }
                if(button == clear)
                {
                    image = null;
                    repaint();
                }
            }
        };
        addImage.addActionListener(l);
        clear.addActionListener(l);
        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.weightx = 1.0;
        gbc.insets = new Insets(2,0,2,0);
        gbc.fill = GridBagConstraints.HORIZONTAL;
        gbc.gridwidth = GridBagConstraints.RELATIVE;
        panel.add(widthSlider, gbc);
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        panel.add(heightSlider, gbc);
        gbc.fill = GridBagConstraints.NONE;
        gbc.gridwidth = GridBagConstraints.RELATIVE;
        panel.add(addImage, gbc);
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        panel.add(clear, gbc);
        return panel;
    }
 
    private JSlider getSlider(String id)
    {
        int max = 100;
        JSlider slider = new JSlider(JSlider.HORIZONTAL, 0, max, max/3);
        slider.setLabelTable(getLabels(id, max));
        slider.setPaintLabels(true);
        return slider;
    }
 
    private Hashtable getLabels(String id, int max)
    {
        // generics declaration for j2se 1.5+
        //Hashtable<Integer,JComponent> ht = new Hashtable<Integer,JComponent>();
        Hashtable ht = new Hashtable();    // non-generic for j2se 1.4-
        ht.put(new Integer(0), new JLabel("0"));
        int w = getFontMetrics(getFont()).stringWidth(id);
        ht.put(new Integer((max-w)/2), new JLabel(id));
        ht.put(new Integer(max), new JLabel(String.valueOf(max)));
        return ht;
    }
 
    private ComponentListener sizer = new ComponentAdapter()
    {
        public void componentResized(ComponentEvent e)
        {
            image = null;
            calibrateSliders();
            repaint();
        }
    };
}
 
class RectanglePositioner extends MouseInputAdapter
{
    AddingImages addingImages;
    Point start;
    boolean dragging;
 
    public RectanglePositioner(AddingImages ai)
    {
        addingImages = ai;
        dragging = false;
    }
 
    public void mousePressed(MouseEvent e)
    {
        start = e.getPoint();
        dragging = true;
    }
 
    public void mouseReleased(MouseEvent e)
    {
        dragging = false;
    }
 
    public void mouseDragged(MouseEvent e)
    {
        if(dragging)
            addingImages.setRect(start, e.getPoint());
    }
}