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How to fix paint on existing draw

I have some problems with my DrawPanel. I want to make a grill—that should be drawn with the parameters—given by the user by defining the rows and colons.
For example, I enter 3 rows and 5 colons (:), Swing should draw it. The main problem is if I enter the numbers in the TextField and press the draw button, Swing draws the new grill over the old one. Furthermore, sometimes the program doesn't complete some rows or colons and I don't understand why. I already add some numbers such as rows-6 because swing draw a few pixels more than he should. Probably you know a solution for this problem too.
On the picture you can see the lines that are to much. I use a blue line to show how far the lines should go.
DrawPanel (JPanel)
import java.awt.Graphics;
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
/**
*
* #author Serge Junk
*/
public class DrawPanel extends javax.swing.JPanel {
/**
* Creates new form DrawPanel
*
*/
private int rows = 1;
private int cols = 2;
public DrawPanel() {
initComponents();
}
#Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
int width = getWidth();
int height = getHeight();
// draw the rows
int rowHt = (height / rows)-1;
for (int i = 0; i <= rows; i++){
g.drawLine(0, i * rowHt, width, i * rowHt);
}
// draw the columns
int rowWid = (width / cols)-1;
for (int i = 0; i <= cols; i++){
g.drawLine(i * rowWid, 0, i * rowWid, height);
}
}
public void setRows(int pRows){
rows = pRows;
}
public void setCols(int pCols){
cols = pCols;
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
#SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
setPreferredSize(new java.awt.Dimension(300, 200));
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
this.setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 400, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
);
}// </editor-fold>
// Variables declaration - do not modify
// End of variables declaration
}
MainFrame (JFrame)
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
/**
*
* #author Serge Junk
*/
public class MainFrame extends javax.swing.JFrame {
/**
* Creates new form MainFrame
*/
public MainFrame() {
initComponents();
}
public void updateView()
{
drawPanel1.repaint();
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
#SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
drawPanel1 = new DrawPanel();
jLabel1 = new javax.swing.JLabel();
rowTextField = new javax.swing.JTextField();
jLabel2 = new javax.swing.JLabel();
colsTextField = new javax.swing.JTextField();
drawButton = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
javax.swing.GroupLayout drawPanel1Layout = new javax.swing.GroupLayout(drawPanel1);
drawPanel1.setLayout(drawPanel1Layout);
drawPanel1Layout.setHorizontalGroup(
drawPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 600, Short.MAX_VALUE)
);
drawPanel1Layout.setVerticalGroup(
drawPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 200, Short.MAX_VALUE)
);
jLabel1.setText("Lignes");
jLabel2.setText("Colonnes");
drawButton.setText("Draw");
drawButton.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
drawButtonActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jLabel1)
.addGap(18, 18, 18)
.addComponent(rowTextField, javax.swing.GroupLayout.PREFERRED_SIZE, 95, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabel2)
.addGap(18, 18, 18)
.addComponent(colsTextField, javax.swing.GroupLayout.PREFERRED_SIZE, 95, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(25, 25, 25)
.addComponent(drawButton))
.addGroup(layout.createSequentialGroup()
.addGap(28, 28, 28)
.addComponent(drawPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, 600, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addContainerGap(26, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(41, 41, 41)
.addComponent(drawPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, 200, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 14, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel1)
.addComponent(rowTextField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel2)
.addComponent(colsTextField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(drawButton)))
.addContainerGap())
);
pack();
}// </editor-fold>
private void drawButtonActionPerformed(java.awt.event.ActionEvent evt) {
//E
int row = Integer.valueOf(rowTextField.getText());
int col = Integer.valueOf(colsTextField.getText());
//T
drawPanel1.setRows(row);
drawPanel1.setCols(col);
//S
updateView();
}
/**
* #param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(MainFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(MainFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(MainFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(MainFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new MainFrame().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JTextField colsTextField;
private javax.swing.JButton drawButton;
private DrawPanel drawPanel1;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JTextField rowTextField;
// End of variables declaration
}

Netbeans draw the new grill over the old one.
The first statement in the paintComponent() method should be:
super.paintComponent(g);
This will clear the background before you do your custom painting.
drawPanel1.setRows(row);
drawPanel1.setCols(col);
//S
updateView();
There is no need for the updateView() method. Instead both the setRows(...) and setCols(...) method should invoke repaint() directly. That is it is the responsibility of the component to repaint itself when a property of the component is changed.
sometimes the program doesn't complete some rows or colons and I don't understand why.
int rowHt = height / rows-1;
Be explicit when using formulas so we know exactly what you intend instead of relying in the compiler. So you should use:
int rowHt = (height / rows) - 1;
Don't be afraid to create variables for your parameters:
//g.drawLine(i * rowWid, 0, i * rowWid, height-5);
int xOffset = i * rowWidth;
int yEnd = height - 5;
g.drawLine(xOffset, 0, xOffset, yEnd);
This then allows you to add debug code easily to see exactly what values a being used to draw the line:
System.out.println(xOffset + " : " + yEnd);
Now you should be able to determine if your logic is correct.

So, as camickr suggested, you should not add any hidden variables to the division or rows / height or cols / width, because this is a maintenance nightmare. Stay away from magic values!
The DrawPanel.paintComponent must do a few things.
Don't forget to call super() !
You will need to determine line thickness so you know how much to offset.
Keep your units as floating-point values until you NEED to set them as integers.
Dispose afterwards.
Moreover, you do not want to set instance variables in their declaration, but through a constructor of some sorts.
Additionally, I added two more fields to control line width and color as seen below. I also redesigned the layout so that it is actually legible from a code maintenance standpoint.
Runner
package question58310987;
import javax.swing.*;
public class Runner {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new MainFrame();
setLookAndFeel(frame);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
});
}
private static void setLookAndFeel(JFrame frame) {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
SwingUtilities.updateComponentTreeUI(frame);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (UnsupportedLookAndFeelException e) {
e.printStackTrace();
}
}
}
DrawPanel
package question58310987;
import java.awt.*;
import javax.swing.JPanel;
public class DrawPanel extends JPanel {
private static final long serialVersionUID = 1889951852010548809L;
private int rows;
private int cols;
private int thickness;
private Color fgColor;
private Color bgColor;
private boolean dirty;
private Stroke strokeRef;
public DrawPanel() {
this(3, 3);
}
public DrawPanel(int rows, int cols) {
this(rows, cols, 1, Color.BLACK, null);
}
public DrawPanel(int rows, int cols, int thickness, Color fgColor, Color bgColor) {
super();
this.rows = rows;
this.cols = cols;
this.thickness = thickness;
this.fgColor = fgColor;
this.bgColor = bgColor;
this.dirty = true; // initialized as true
}
private float getStrokeThickness(Graphics2D g2d) {
Stroke stroke = g2d.getStroke();
if (stroke instanceof BasicStroke) {
return ((BasicStroke) stroke).getLineWidth();
}
return 1.0f;
}
/**
* Re-evaluates the state of the properties.
*/
protected void commitProperties(Graphics2D g2d) {
if (dirty) {
strokeRef = new BasicStroke(this.thickness);
dirty = false;
}
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
commitProperties(g2d);
g2d.setStroke(strokeRef);
float lineSize = getStrokeThickness(g2d); // Calculate line thickness
float halfStroke = lineSize > 2.0f ? lineSize / 2.0f : 1.0f;
int width = this.getWidth();
int height = this.getHeight();
int maxWidth = (int) (width - halfStroke);
int maxHeight = (int) (height - halfStroke);
float yOffset = (((float) maxHeight - halfStroke) / (rows));
float xOffset = (((float) maxWidth - halfStroke) / (cols));
if (bgColor != null) {
g2d.setColor(bgColor);
g2d.fillRect(0, 0, getWidth(), getHeight());
}
g2d.setColor(fgColor);
// Draw the horizontal lines
for (int row = 0; row < rows; row++) {
int y = (int) (row * yOffset + halfStroke);
g2d.drawLine((int) halfStroke, y, maxWidth, y);
}
g2d.drawLine((int) halfStroke, maxHeight, maxWidth, maxHeight); // Draw the final horizontal line
// Draw the vertical lines
for (int col = 0; col < cols; col++) {
int x = (int) (col * xOffset + halfStroke);
g2d.drawLine(x, (int) halfStroke, x, maxHeight);
}
g2d.drawLine(maxWidth, (int) halfStroke, maxWidth, maxHeight); // Draw the final vertical line
g2d.dispose(); // Clear changes
}
public String getFgColorHex() {
return String.format("#%02X%02X%02X", fgColor.getRed(), fgColor.getGreen(), fgColor.getBlue());
}
public int getRows() {
return rows;
}
public void setRows(int rows) {
this.rows = rows;
}
public int getCols() {
return cols;
}
public void setCols(int cols) {
this.cols = cols;
}
public int getThickness() {
return thickness;
}
public void setThickness(int thickness) {
this.thickness = thickness;
this.dirty = true;
}
public Color getFgColor() {
return fgColor;
}
public void setFgColor(Color fgColor) {
this.fgColor = fgColor;
}
public Color getBgColor() {
return bgColor;
}
public void setBgColor(Color bgColor) {
this.bgColor = bgColor;
}
}
MainFrame
package question58310987;
import java.awt.*;
import java.awt.event.ActionEvent;
import javax.swing.*;
public class MainFrame extends JFrame {
private static final long serialVersionUID = -2796976952328960949L;
private static final String DEFAULT_APP_TITLE = "Main Frame";
private DrawPanel drawPanel;
private JLabel rowLabel;
private JTextField rowTextField;
private JLabel colLabel;
private JTextField colTextField;
private JLabel thicknessLabel;
private JTextField thicknessTextField;
private JLabel colorLabel;
private JTextField colorTextField;
private JButton drawButton;
public MainFrame() {
this(DEFAULT_APP_TITLE);
}
public MainFrame(String title) {
super(title);
initialize();
addChildren();
}
protected void initialize() {
drawPanel = new DrawPanel();
drawPanel.setThickness(6);
drawPanel.setFgColor(Color.BLUE);
drawPanel.setPreferredSize(new Dimension(600, 200));
rowLabel = new JLabel("Rows");
rowTextField = new JTextField(Integer.toString(drawPanel.getRows()), 3);
colLabel = new JLabel("Columns");
colTextField = new JTextField(Integer.toString(drawPanel.getCols()), 3);
thicknessLabel = new JLabel("Thickness");
thicknessTextField = new JTextField(Integer.toString(drawPanel.getThickness()), 3);
colorLabel = new JLabel("Color");
colorTextField = new JTextField(drawPanel.getFgColorHex(), 6);
drawButton = new JButton("Draw");
drawButton.addActionListener(evt -> drawButtonActionPerformed(evt));
}
protected void addChildren() {
GridBagLayout verticalLayout = new GridBagLayout();
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
gbc.insets = new Insets(16, 16, 16, 16); // top, left, bottom, right
getContentPane().setLayout(verticalLayout);
getContentPane().add(drawPanel, gbc);
FlowLayout horizontalLayout = new FlowLayout();
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(horizontalLayout);
buttonPanel.add(rowLabel);
buttonPanel.add(rowTextField);
buttonPanel.add(Box.createHorizontalStrut(30));
buttonPanel.add(colLabel);
buttonPanel.add(colTextField);
buttonPanel.add(Box.createHorizontalStrut(30));
buttonPanel.add(thicknessLabel);
buttonPanel.add(thicknessTextField);
buttonPanel.add(Box.createHorizontalStrut(30));
buttonPanel.add(colorLabel);
buttonPanel.add(colorTextField);
buttonPanel.add(Box.createHorizontalStrut(30));
buttonPanel.add(drawButton);
gbc.gridx = 0;
gbc.gridy = 1;
gbc.insets = new Insets(0, 16, 16, 16); // top, left, bottom, right
getContentPane().add(buttonPanel, gbc);
}
private void drawButtonActionPerformed(ActionEvent evt) {
int row = Integer.valueOf(rowTextField.getText().trim());
int col = Integer.valueOf(colTextField.getText().trim());
int thickness = Integer.valueOf(thicknessTextField.getText().trim());
String colorHex = colorTextField.getText().trim();
drawPanel.setRows(row);
drawPanel.setCols(col);
drawPanel.setThickness(thickness);
drawPanel.setFgColor(hexToColor(colorHex));
this.updateView();
}
public void updateView() {
drawPanel.repaint();
}
/**
* Supports both #FF0000 and #F00 formats.
*
* #param hex a hexadecimal color value from #000000 -> #FFFFFF
* #return
*/
public static final Color hexToColor(String hex) {
if (hex.startsWith("#")) {
hex = hex.replace("#", "");
}
if (hex.length() == 3) {
hex = splicePad(hex, 2);
}
int v = Integer.parseInt(hex, 16);
int r = (v & 0xFF0000) >> 16;
int g = (v & 0xFF00) >> 8;
int b = (v & 0xFF);
return new Color(r, g, b);
}
/**
* Splices each character after itself n-number of times.
*/
public static final String splicePad(String str, final int repeat) {
StringBuffer buff = new StringBuffer();
for (char ch : str.toCharArray()) {
for (int i = 0; i < repeat; i++) {
buff.append(ch);
}
}
return buff.toString();
}
}

image wont move for scrolling background in java

import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.Timer;
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
/**
*
* #author kids
*/
public class background extends javax.swing.JFrame {
private PaintSurface canvas;
private BufferedImage image;
/**
* Creates new form background
*/
public background() {
try {
image = ImageIO.read(new File("C:\\Users\\kids\\Documents\\NetBeansProjects\\game\\src\\backgroundimage.png"));
} catch (IOException ex) {
// handle exception...
}
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // Handle the CLOSE button
pack(); // pack all the components in the JFrame
setVisible(true); // show it
requestFocus(); // set the focus to JFrame to receive KeyEvent
super.setTitle("Game");
this.setSize(1056, 540);
this.setDefaultCloseOperation(this.EXIT_ON_CLOSE);
this.add(new PaintSurface(), BorderLayout.CENTER);
this.setVisible(true);
canvas = new PaintSurface();
this.add(canvas, BorderLayout.CENTER);
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
#SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 400, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
);
pack();
}// </editor-fold>
class PaintSurface extends JComponent {
public void paint(Graphics g) {
int width = image.getWidth();
int height = image.getHeight();
int mapWidth = 1056; //Get map width
int mapHeight = 540; //Get map height
int tilesx = 1056/width;
int tilesy = 540/height;
int offsetx = 300;
int offsety = 300;
Graphics2D g2 = (Graphics2D) g;
for(int y=0; y<tilesy; y++)
{
for(int x=0; x<tilesx; x++)
{
g.drawImage(image, x*width-offsetx, y*height-offsety, null);
}
}
}
}
/**
*
* #param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(background.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(background.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(background.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(background.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new background();
}
});
}
// Variables declaration - do not modify
// End of variables declaration
}
It paints the image, but it does not move when I scroll, so I am confused where the error is. I have looked in various places for an explanation and eventually I tried one.
for(int y=0; y<tilesy; y++
{
for(int x=0; x<tilesx; x++)
{
g.drawImage(myimage, x*width, y*height, null);
}
}
This is how he first painted the image, but he later said that in order to make it scroll is simply a matter of adding an offsetx and offsety, where the offset is how much the map is scrolled. I was unsure of how to define these, so I gave them an integer value of 300. The image is now being drawn, but does not respond to scrolling of any kind. I know my code probably makes you gag but very new so please bear with me on this one. Thanks
I believe I followed the steps correctly, but when I came to the last step, using offset i was confused.

Putting an image in a Java GUI [duplicate]

This question already has answers here:
Adding images on Java JFrame - Netbeans
(3 answers)
Closed 6 years ago.
I'm creating a Java UI for a school project. I have 4 buttons and an image in the JFrame, I want to be able to perform a task on the Image with each button. Each time I press the button it will overwrite the Image using the buttons function. I have the buttons and functions working but I'm clueless at how to add the Image to the JFrame. Do I use a Jpanel or a canvas to put the image onto the frame. I used the netbeans GUI builder. Here is my code in a compressed form
//import static NewJFrame.plotWidth;
import ij.IJ;
import ij.ImagePlus;
import ij.WindowManager;
import ij.gui.GenericDialog;
import ij.process.ByteProcessor;
import ij.process.ColorProcessor;
import ij.process.ImageConverter;
import ij.process.ImageProcessor;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Polygon;
public class my_JframePlugin extends javax.swing.JFrame {
static int plotWidth =400;
static double angleInDegrees = 40;
static double angle = (angleInDegrees/360.0)*2.0*Math.PI;
static int polygonMultiplier = 100;
static boolean oneToOne;
double picsize;
ImagePlus img = IJ.openImage();
ImageProcessor imgP = img.getProcessor();
int[] x,y;
/**
* Creates new form NewJFrame
*/
public my_JframePlugin() {
initComponents();
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
#SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jFileChooser1 = new javax.swing.JFileChooser();
canvas1 = new java.awt.Canvas();
jPanel1 = new javax.swing.JPanel();
jButton1 = new javax.swing.JButton();
jButton2 = new javax.swing.JButton();
jButton3 = new javax.swing.JButton();
jButton4 = new javax.swing.JButton();
jButton5 = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 477, Short.MAX_VALUE)
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 310, Short.MAX_VALUE)
);
jButton1.setText("FFT");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
jButton2.setText("Inverse FFT");
jButton2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton2ActionPerformed(evt);
}
});
jButton3.setText("3D Plot");
jButton3.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton3ActionPerformed(evt);
}
});
jButton4.setText("Crop");
jButton4.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton4ActionPerformed(evt);
}
});
jButton5.setText("Add Image");
jButton5.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton5ActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addGap(36, 36, 36)
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 28, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jButton5, javax.swing.GroupLayout.DEFAULT_SIZE, 113, Short.MAX_VALUE)
.addComponent(jButton1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jButton2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jButton3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jButton4, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addGap(108, 108, 108))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(45, 45, 45)
.addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 55, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(31, 31, 31)
.addComponent(jButton2, javax.swing.GroupLayout.PREFERRED_SIZE, 55, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(33, 33, 33)
.addComponent(jButton3, javax.swing.GroupLayout.PREFERRED_SIZE, 55, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 42, Short.MAX_VALUE)
.addComponent(jButton4, javax.swing.GroupLayout.PREFERRED_SIZE, 53, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(38, 38, 38)
.addComponent(jButton5, javax.swing.GroupLayout.PREFERRED_SIZE, 55, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(56, 56, 56))
.addGroup(layout.createSequentialGroup()
.addGap(35, 35, 35)
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
pack();
}// </editor-fold>
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
IJ.log("FFT clicked");
}
private void jButton5ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
}
private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
//ImagePlus myimage = img;
img = WindowManager.getCurrentImage();
if (img==null)
{
//IJ.noImage();
IJ.log("No Image selected");
return;
}
if (!showDialog())
return;
if (img.getType()!=ImagePlus.GRAY8)
{
ImageProcessor ip = img.getProcessor();
ip = ip.crop(); // duplicate
img = new ImagePlus("temp", ip);
new ImageConverter(img).convertToGray8();
}
ImageProcessor plot = makeSurfacePlot(img.getProcessor());
new ImagePlus("Surface Plot", plot).show();
IJ.register(Surface_Plotter.class);
}
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
IJ.log("Inverse FFT clicked");
}
boolean showDialog()
{
GenericDialog gd = new GenericDialog("Surface Plotter");
gd.addNumericField("Width (pixels):", plotWidth, 0);
gd.addNumericField("Angle (-90-90 degrees):", angleInDegrees, 0);
gd.addNumericField("Polygon Multiplier (10-200%):", polygonMultiplier, 0);
gd.addCheckbox("One Polygon Per Line", oneToOne);
gd.showDialog();
if (gd.wasCanceled())
return false;
plotWidth = (int) gd.getNextNumber();
angleInDegrees = gd.getNextNumber();
polygonMultiplier = (int)gd.getNextNumber();
oneToOne = gd.getNextBoolean();
if (polygonMultiplier>400) polygonMultiplier = 400;
if (polygonMultiplier<10) polygonMultiplier = 10;
return true;
}
public ImageProcessor makeSurfacePlot(ImageProcessor ip)
{
double angle = (angleInDegrees/360.0)*2.0*Math.PI;
int polygons = (int)(plotWidth*(polygonMultiplier/100.0)/4);
if (oneToOne)
polygons = ip.getHeight();
double xinc = 0.8*plotWidth*Math.sin(angle)/polygons;
double yinc = 0.8*plotWidth*Math.cos(angle)/polygons;
boolean smooth = true;
IJ.showProgress(0.01);
ip.setInterpolate(true);
ip = ip.resize(plotWidth, polygons);
int width = ip.getWidth();
int height = ip.getHeight();
double min = ip.getMin();
double max = ip.getMax();
if (smooth)
ip.smooth();
//new ImagePlus("Image", ip).show();
int windowWidth =(int)(plotWidth+polygons*Math.abs(xinc) + 20.0);
int windowHeight = (int)(255+polygons*yinc + 10.0);
Image plot =IJ.getInstance().createImage(windowWidth, windowHeight);
Graphics g = plot.getGraphics();
g.setColor(Color.white);
g.fillRect(0, 0, windowWidth, windowHeight);
x = new int[width+2];
y = new int[width+2];
double xstart = 10.0;
if (xinc<0.0)
xstart += Math.abs(xinc)*polygons;
double ystart = 0.0;
for (int row=0; row<height; row++) {
double[] profile = ip.getLine(0, row, width-1, row);
Polygon p = makePolygon(profile, xstart, ystart);
g.setColor(Color.white);
g.fillPolygon(p);
g.setColor(Color.black);
g.drawPolygon(p);
xstart += xinc;
ystart += yinc;
if ((row%5)==0) IJ.showProgress((double)row/height);
}
IJ.showProgress(1.0);
ip = new ColorProcessor(plot);
byte[] bytes = new byte[windowWidth*windowHeight];
int[] ints =(int[]) ip.getPixels();
for (int i=0; i<windowWidth*windowHeight; i++)
bytes[i] = (byte)ints[i];
ip = new ByteProcessor(windowWidth,windowHeight, bytes, null);
return ip;
}
Polygon makePolygon(double[] profile, double xstart, double ystart) {
int width = profile.length;
for (int i=0; i<width; i++)
x[i] =(int)( xstart+i);
for (int i=0; i<width; i++)
y[i] =(int)(ystart+255.0-profile[i]);
x[width] =(int)xstart+width-1;
y[width] = (int)ystart+255;
x[width+1] =(int)xstart;
y[width+1] = (int)ystart+255;
//for (int i=0; i<width; i++)
// IJ.write("dbg: "+i+" "+profile[i]+" "+x[i]+" "+y[i]);
return new Polygon(x, y, width+2);
}
/**
* #param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(my_JframePlugin.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(my_JframePlugin.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(my_JframePlugin.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(my_JframePlugin.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
//new NewJFrame().setVisible(true);
}
});
}
// Variables declaration - do not modify
private java.awt.Canvas canvas1;
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton2;
private javax.swing.JButton jButton3;
private javax.swing.JButton jButton4;
private javax.swing.JButton jButton5;
private javax.swing.JFileChooser jFileChooser1;
private javax.swing.JPanel jPanel1;
// End of variables declaration
}
I just have no idea how to approach loading the image onto the frame

See the section from the Swing tutorial on How to Use Icons.
It shows you how to read an Image and use a JLabel to display the Image as an Icon.
The tutorial will also show you other Swing basics.

mouse Clicked event change colors

Well the goal of this program is to create a bullseye; and when you click on the panel, it will change the color of the bullseye from red to blue. When you click on mine nothing happens. What is causing this?
import java.awt.*;
public class TargetLogoPanel extends javax.swing.JPanel {
public Color ringColor = Color.RED;
public int size = 400;
public TargetLogoPanel() {
setBackground(Color.WHITE);
setPreferredSize(new Dimension(700,400 ));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
int width = getWidth();
int height = getHeight();
int radius = getHeight();
g.setColor(ringColor);
g.fillOval(
(int)((width/2 ) - (radius * 0.3)),
(int)((height/2) - (radius * 0.3)),
(int)(radius * .6),
(int)(radius * .6));
g.setColor(Color.WHITE);
g.fillOval(
(int)((width / 2) - (radius * 0.22)),
(int)((height / 2) - (radius * 0.22)),
(int)(radius * 0.44),
(int)(radius * 0.44));
g.setColor(ringColor);
g.fillOval(
(int)((width / 2) - (radius * 0.15)),
(int)((height / 2) - (radius * 0.15)),
(int)(radius * 0.3),
(int)(radius * 0.3));
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
#SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent evt) {
formMouseClicked(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
this.setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 400, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
);
}// </editor-fold>
private void formMouseClicked(java.awt.event.MouseEvent evt) {
if(ringColor == Color.RED){
ringColor = Color.BLUE;
repaint();
} else{
ringColor = Color.RED;
repaint();
}
}
// Variables declaration - do not modify
// End of variables declaration
}

Invoke initComponents() in your panel's constructor.
public TargetLogoPanel() {
initComponents();
setBackground(Color.WHITE);
setPreferredSize(new Dimension(700, 400));
}
As tested:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import javax.swing.JFrame;
/**
* #see http://stackoverflow.com/a/22548923/230513
*/
public class Test {
private void display() {
JFrame f = new JFrame("Test");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new TargetLogoPanel());
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
class TargetLogoPanel extends javax.swing.JPanel {
public Color ringColor = Color.RED;
public int size = 400;
public TargetLogoPanel() {
initComponents();
setBackground(Color.WHITE);
setPreferredSize(new Dimension(700, 400));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
int width = getWidth();
int height = getHeight();
int radius = getHeight();
g.setColor(ringColor);
g.fillOval(
(int) ((width / 2) - (radius * 0.3)),
(int) ((height / 2) - (radius * 0.3)),
(int) (radius * .6),
(int) (radius * .6));
g.setColor(Color.WHITE);
g.fillOval(
(int) ((width / 2) - (radius * 0.22)),
(int) ((height / 2) - (radius * 0.22)),
(int) (radius * 0.44),
(int) (radius * 0.44));
g.setColor(ringColor);
g.fillOval(
(int) ((width / 2) - (radius * 0.15)),
(int) ((height / 2) - (radius * 0.15)),
(int) (radius * 0.3),
(int) (radius * 0.3));
}
/**
* This method is called from within the constructor to initialize the
* form. WARNING: Do NOT modify this code. The content of this method is
* always regenerated by the Form Editor.
*/
#SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent evt) {
formMouseClicked(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
this.setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 400, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
);
}// </editor-fold>
private void formMouseClicked(java.awt.event.MouseEvent evt) {
if (ringColor == Color.RED) {
ringColor = Color.BLUE;
repaint();
} else {
ringColor = Color.RED;
repaint();
}
}
// Variables declaration - do not modify
// End of variables declaration
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new Test().display();
}
});
}
}

Essentially, you haven't registered a MouseListener to respond to mouse events.
The initComponents method that the Netbeans form editor created was used to register a MouseListener, but you stopped calling it.
Try calling initComponents within you component's constructor...

Jpanel resize on repaint

i am having a scaling operation performed in the below code. The two sliders in the form are X and Y parameters for an scaling affine transformation. My ask here is when i change the slider the image is getting scaled, how do i dynamically resize my jpanel in which this image is getting painted.
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package newpackage;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
/**
*
* #author ABC
*/
public class Swon extends javax.swing.JFrame {
final BufferedImage img;
/**
* Creates new form Swon
*/
public Swon() throws IOException{
BufferedImage im=ImageIO.read(new File("C:/Users/ABC/Desktop/I-RIX2012_Final_logo_out.jpg"));
this.img=new BufferedImage(im.getWidth(),im.getWidth(),BufferedImage.TYPE_BYTE_GRAY);
this.img.getGraphics().drawImage(im, 0, 0, null);
initComponents();
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
#SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jPanel1 = new javax.swing.JPanel(){
// #Override
// public void paint(Graphics g)
// {
// super.paint(g);
// g.drawImage(img.getScaledInstance(this.getWidth(), this.getHeight(), Image.SCALE_FAST),0,0,null);
// }
};
jSlider1 = new javax.swing.JSlider();
jSlider2 = new javax.swing.JSlider();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jPanel1.setBorder(new javax.swing.border.SoftBevelBorder(javax.swing.border.BevelBorder.RAISED));
jPanel1.addComponentListener(new java.awt.event.ComponentAdapter() {
public void componentResized(java.awt.event.ComponentEvent evt) {
jPanel1ComponentResized(evt);
}
});
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 268, Short.MAX_VALUE)
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 209, Short.MAX_VALUE)
);
jSlider1.setMaximum(5);
jSlider1.setValue(1);
jSlider1.addChangeListener(new javax.swing.event.ChangeListener() {
public void stateChanged(javax.swing.event.ChangeEvent evt) {
jSlider1StateChanged(evt);
}
});
jSlider2.setMaximum(5);
jSlider2.setValue(1);
jSlider2.addChangeListener(new javax.swing.event.ChangeListener() {
public void stateChanged(javax.swing.event.ChangeEvent evt) {
jSlider2StateChanged(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(45, 45, 45)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jSlider2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jSlider1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addContainerGap(242, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(36, 36, 36)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGap(33, 33, 33)
.addComponent(jSlider1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jSlider2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(38, Short.MAX_VALUE))
);
pack();
}// </editor-fold>
private void jPanel1ComponentResized(java.awt.event.ComponentEvent evt) {
// TODO add your handling code here:
// AffineTransform f=new AffineTransform();
}
private void jSlider1StateChanged(javax.swing.event.ChangeEvent evt) {
// TODO add your handling code here:
AffineTransform scale = AffineTransform.getScaleInstance(jSlider1.getValue(),jSlider2.getValue());
AffineTransformOp op3 = new AffineTransformOp(scale, AffineTransformOp.TYPE_BILINEAR);
BufferedImage scaling = new BufferedImage(this.img.getHeight(), this.img.getWidth(), this.img.getType());
BufferedImage img1=op3.filter(this.img, scaling);
jPanel1.getGraphics().drawImage(img1.getScaledInstance(jPanel1.getWidth(), jPanel1.getHeight(), Image.SCALE_FAST), 0, 0, null);
}
private void jSlider2StateChanged(javax.swing.event.ChangeEvent evt) {
// TODO add your handling code here:
AffineTransform scale = AffineTransform.getScaleInstance(jSlider1.getValue(),jSlider2.getValue());
AffineTransformOp op3 = new AffineTransformOp(scale, AffineTransformOp.TYPE_BILINEAR);
BufferedImage scaling = new BufferedImage(this.img.getHeight(), this.img.getWidth(), this.img.getType());
BufferedImage img1=op3.filter(this.img, scaling);
jPanel1.getGraphics().drawImage(img1.getScaledInstance(jPanel1.getWidth(), jPanel1.getHeight(), Image.SCALE_FAST), 0, 0, null);
}
/**
* #param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(Swon.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(Swon.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(Swon.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(Swon.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
try {
new Swon().setVisible(true);
} catch (IOException ex) {
Logger.getLogger(Swon.class.getName()).log(Level.SEVERE, null, ex);
}
}
});
}
// Variables declaration - do not modify
public javax.swing.JPanel jPanel1;
private javax.swing.JSlider jSlider1;
private javax.swing.JSlider jSlider2;
// End of variables declaration
}

Alright, firstly, don't do this.img.getGraphics().drawImage(im, 0, 0, null), when the panel is repainted, the image would not be updated. You need to override the paintComponent method of a JComponent (prefer JPanel) and repaint the image at the appropriate scale.
Secondly, you need to place the image panel onto a layout that is capable of actually caring about the size of the panel (such as GridBagLayout). To do this, override the getPreferredSize method and return the size of the scaled image...
public class ResizableImagePane {
public static void main(String[] args) {
new ResizableImagePane();
}
public ResizableImagePane() {
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 ScalerPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
protected class ScalerPane extends JPanel {
private JSlider slider;
private ImagePane imagePane;
public ScalerPane() {
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
imagePane = new ImagePane();
add(imagePane, gbc);
gbc.gridy = 1;
gbc.weightx = 0;
gbc.weighty = 0;
gbc.fill = GridBagConstraints.HORIZONTAL;
slider = new JSlider();
slider.setMinimum(1);
slider.setMaximum(100);
gbc.weightx = 1;
gbc.weighty = 1;
gbc.anchor = GridBagConstraints.SOUTH;
gbc.fill = GridBagConstraints.HORIZONTAL;
add(slider, gbc);
slider.addChangeListener(new ChangeListener() {
#Override
public void stateChanged(ChangeEvent ce) {
imagePane.setZoom(slider.getValue() / 100f);
}
});
slider.setValue(100);
}
}
protected class ImagePane extends JPanel {
private BufferedImage background;
private Image scaled;
private float zoom;
public ImagePane() {
try {
background = ImageIO.read(new File("path/to/your/image"));
} catch (IOException ex) {
ex.printStackTrace();
}
setZoom(1f);
setBorder(new LineBorder(Color.RED));
}
#Override
public Dimension getPreferredSize() {
return new Dimension(scaled.getWidth(this), scaled.getHeight(this));
}
public void setZoom(float zoom) {
this.zoom = zoom;
int width = Math.round(background.getWidth() * zoom);
scaled = background.getScaledInstance(width, -1, Image.SCALE_SMOOTH);
invalidate();
revalidate();
repaint();
}
public float getZoom() {
return zoom;
}
#Override
protected void paintComponent(Graphics grphcs) {
super.paintComponent(grphcs);
int x = (getWidth() - scaled.getWidth(this)) / 2;
int y = (getHeight() - scaled.getHeight(this)) / 2;
grphcs.drawImage(scaled, x, y, this);
}
}
}