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How to fix chess board squares not moving to middle

at the moment I try to make a chessboard with fix sizes. I successfully make that the chessboard will be painted in the corner (coordinate 0,0,400,400). However, now I want that the chessboard will always be in the middle also if I move the window.
The background of the chessboard moves always and is always in the middle but the squares are fixed.
To make you understand my problem, I upload some pics where you can see my main issue.
First Start:
Moving the window to the left
Background in the middle but without the white squares
JPanel
import java.awt.Color;
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
*/
public DrawPanel() {
initComponents();
}
#Override
public void paintComponent(Graphics g)
{
int width = (getWidth() - 400)/2;
int height = (getHeight()- 400)/2;
g.setColor(Color.white);
g.fillRect(0, 0, getWidth(), getHeight());
g.setColor(Color.gray);
g.fillRect(width, height, 400, 400);
g.setColor(Color.black);
g.drawRect(width, height, 400, 400);
for(int i=width;i<400;i+=100)
{
for(int j=height;j<400;j+=100)
{
g.setColor(Color.white);
g.fillRect(i, j, 50, 50);
g.setColor(Color.black);
g.drawRect(i, j, 50, 50);
}
}
for(int i=width+50;i<400;i+=100)
{
for(int j=height+50;j<400;j+=100)
{
g.setColor(Color.white);
g.fillRect(i, j, 50, 50);
g.setColor(Color.black);
g.drawRect(i, j, 50, 50);
}
}
}
/**
*
*/
/**
* 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() {
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
}
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();
}
/**
* 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();
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, 652, Short.MAX_VALUE)
);
drawPanel1Layout.setVerticalGroup(
drawPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 473, Short.MAX_VALUE)
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(drawPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(drawPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
pack();
}// </editor-fold>
/**
* #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 DrawPanel drawPanel1;
// End of variables declaration
}

Here is the "correct" way to draw your squares.
for (int i = width; i < 400 + width; i += 100) {
for (int j = height; j < 400 + height; j += 100) {
g.setColor(Color.white);
g.fillRect(i, j, 50, 50);
g.setColor(Color.black);
g.drawRect(i, j, 50, 50);
}
}
for (int i = width + 50; i < 400 + width; i += 100) {
for (int j = height + 50; j < 400 + height; j += 100) {
g.setColor(Color.white);
g.fillRect(i, j, 50, 50);
g.setColor(Color.black);
g.drawRect(i, j, 50, 50);
}
}

You can achieve it with a twice smaller code:
for (int i = width; i < 400 + width; i += 100) {
for (int j = height; j < 400 + height; j += 100) {
g.setColor(Color.white);
g.fillRect(i, j, 50, 50);
g.fillRect(i+50, j+50, 50, 50);
g.setColor(Color.black);
g.drawRect(i, j, 50, 50);
g.drawRect(i+50, j+50, 50, 50);
}
}

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();
}
}

Run a WindowBuilder GUI from another class which also contains a JFrame

So I am working on a project that needs a GUI; currently, I have a class which creates a JFrame with a flock of agents in it and these agents fly around the environment. I need to add a GUI to this JFrme so I can control the size of the flock as well as other items.
I am using WindowBuilder in eclipse to create the GUI and I need to now 'attach' this GUI to the frame in the other class or, at the very least, have this GUI window running simultaneously with the other class so that when I run the application in eclipse, I can use the sliders to control the flock size then run the flock simulation, taking in the variable from the GUI.
I have been searching around online for quite some time trying to figure out how on earth to do this but I haven't been able to find an answer.
Code for Emre -> Thanks for the help so far! I have managed to get everything working regarding the JPanel but I am still having issues regarding the actionlistener for the "Run" button...I have included the amended code which contains an actionlistener for btnRun in the main class "Boids" - to me it looks like everything is correct and when run is pressed it should perform as expected but for whatever reason this button still isn't functional and I can't figure out why...
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.*;
import static java.lang.Math.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.*;
import javax.swing.Timer;
import java.util.Random;
import javax.swing.JButton;
public class Boids extends JPanel {
Flock flock;
Flock flock2;
final int w, h;
public Boids() {
w = 1200;
h = 600;
setPreferredSize(new Dimension(w, h));
setBackground(Color.black);
spawnFlock();
spawnFlock2();
new Timer(17, (ActionEvent e) -> {
if (flock.hasLeftTheBuilding(w))
spawnFlock();
repaint();
}).start();
new Timer(18, (ActionEvent e) -> {
if (flock2.hasLeftTheBuilding(w) && (flock.hasLeftTheBuilding(w)))
spawnFlock2();
repaint();
}).start();
//need to wait for the rest of the flock to leavebuilding before respawning leader, spawning is out of sync
}
public void spawnFlock() {
Random rand = new Random();
int n = rand.nextInt(599) + 1;
//implement random for width as well as height
flock = Flock.spawn(100, h - n, 20);
flock2 = Flock.spawn(100, h - n, 1);
}
public void spawnFlock2() {
Random rand = new Random();
int n = rand.nextInt(599) + 1;
//implement random for width as well as height
// flock2 = Flock.spawn(100, h - n, 1);
}
#Override
public void paintComponent(Graphics gg) {
super.paintComponent(gg);
Graphics2D g = (Graphics2D) gg;
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
SimGUI buttonx = new SimGUI();
buttonx.btnRun.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event1) {
flock.run(g, w, h);
}
});
// flock.
// flock2.run(g, w, h);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setTitle("Simulator v0.6");
f.setResizable(false);
f.add(new Boids(), BorderLayout.CENTER);
// f.add(new Boids(), BorderLayout.CENTER); to add another flock to environment
//leaders will also be added in this fashion
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
// SimGUI.getFrames();
// SimGUI test = new SimGUI();
// test.panel.setVisible(true);
SimGUI test = new SimGUI();
f.getContentPane().add(test, BorderLayout.EAST); //just positions a slither to the right, dont understand why it wont display jpanel -->
//COULD THIS BE BECAUSE OF ME SETTING PREFERRED SIZE AND WIDTH/HEIGHT OUTSIDE OF MAIN? SEE "public Boids"...
//SimGUI tempt = new SimGUI();
// tempt.setVisible(true);
});
}
// private void printPanelCompPoints(JPanel f) {
// f.getComponentAt(600, 500);
//currently working on this = voting system
//see psuedocode!
}
//}
class Boid {
static final Random r = new Random();
static final Vec migrate = new Vec(0.02, 0);
static final int size = 3;
static final Path2D shape = new Path2D.Double();
static {
shape.moveTo(0, -size * 2);
shape.lineTo(-size, size * 2);
shape.lineTo(size, size * 2);
shape.closePath();
}
final double maxForce, maxSpeed;
Vec location, velocity, acceleration;
private boolean included = true;
Boid(double x, double y) {
acceleration = new Vec();
velocity = new Vec(r.nextInt(3) + 1, r.nextInt(3) - 1);
location = new Vec(x, y);
maxSpeed = 3.0;
maxForce = 0.05;
}
void update() {
velocity.add(acceleration);
velocity.limit(maxSpeed);
location.add(velocity);
acceleration.mult(0);
}
void applyForce(Vec force) {
acceleration.add(force);
}
Vec seek(Vec target) {
Vec steer = Vec.sub(target, location);
steer.normalize();
steer.mult(maxSpeed);
steer.sub(velocity);
steer.limit(maxForce);
return steer;
}
void flock(Graphics2D g, List<Boid> boids) {
view(g, boids);
Vec rule1 = separation(boids);
Vec rule2 = alignment(boids);
Vec rule3 = cohesion(boids);
rule1.mult(2.5);
rule2.mult(1.5);
rule3.mult(1.3);
applyForce(rule1);
applyForce(rule2);
applyForce(rule3);
applyForce(migrate);
}
void view(Graphics2D g, List<Boid> boids) {
double sightDistance = 100;
double peripheryAngle = PI * 0.85;
for (Boid b : boids) {
b.included = false;
if (b == this)
continue;
double d = Vec.dist(location, b.location);
if (d <= 0 || d > sightDistance)
continue;
Vec lineOfSight = Vec.sub(b.location, location);
double angle = Vec.angleBetween(lineOfSight, velocity);
if (angle < peripheryAngle)
b.included = true;
}
}
Vec separation(List<Boid> boids) {
double desiredSeparation = 25;
Vec steer = new Vec(0, 0);
int count = 0;
for (Boid b : boids) {
if (!b.included)
continue;
double d = Vec.dist(location, b.location);
if ((d > 0) && (d < desiredSeparation)) {
Vec diff = Vec.sub(location, b.location);
diff.normalize();
diff.div(d); // weight by distance
steer.add(diff);
count++;
}
}
if (count > 0) {
steer.div(count);
}
if (steer.mag() > 0) {
steer.normalize();
steer.mult(maxSpeed);
steer.sub(velocity);
steer.limit(maxForce);
return steer;
}
return new Vec(0, 0);
}
Vec alignment(List<Boid> boids) {
double preferredDist = 50;
Vec steer = new Vec(0, 0);
int count = 0;
for (Boid b : boids) {
if (!b.included)
continue;
double d = Vec.dist(location, b.location);
if ((d > 0) && (d < preferredDist)) {
steer.add(b.velocity);
count++;
}
}
if (count > 0) {
steer.div(count);
steer.normalize();
steer.mult(maxSpeed);
steer.sub(velocity);
steer.limit(maxForce);
}
return steer;
}
Vec cohesion(List<Boid> boids) {
double preferredDist = 50;
Vec target = new Vec(0, 0);
int count = 0;
for (Boid b : boids) {
if (!b.included)
continue;
double d = Vec.dist(location, b.location);
if ((d > 0) && (d < preferredDist)) {
target.add(b.location);
count++;
}
}
if (count > 0) {
target.div(count);
return seek(target);
}
return target;
}
/* Vec avoid(List<Boid> boids) {
int up = 0;
int down = 0;
for (Boid b : boids) {
if (b.location.x + 100 > 600 ) {
up = 1;
}
}
return velocity = new Vec (0,1);
} */
void draw(Graphics2D g) {
AffineTransform save = g.getTransform();
g.translate(location.x, location.y);
g.rotate(velocity.heading() + PI / 2);
g.setColor(Color.green);
g.fill(shape);
g.setColor(Color.green);
g.draw(shape);
g.setTransform(save);
g.drawOval(600, 500, 75, 75);
}
void run(Graphics2D g, List<Boid> boids, int w, int h) { //similair method to run leader
flock(g, boids);
update();
draw(g);
//may need additional run method for leader
}
}
class Flock {
List<Boid> boids;
Flock() {
boids = new ArrayList<>();
}
void run(Graphics2D g, int w, int h) {
for (Boid b : boids) {
b.run(g, boids, w, h);
}
}
boolean hasLeftTheBuilding(int w) {
int count = 0;
for (Boid b : boids) {
if (b.location.x + Boid.size > w) //will also be used to calculate votes based on whether boids is near food
count++;
}
return boids.size() == count;
}
void addBoid(Boid b) {
boids.add(b);
}
static Flock spawn(double w, double h, int numBoids) {
Flock flock = new Flock();
for (int i = 0; i < numBoids; i++)
flock.addBoid(new Boid(w, h));
return flock;
}
}
class Vec {
double x, y;
Vec() {
}
Vec(double x, double y) {
this.x = x;
this.y = y;
}
void add(Vec v) {
x += v.x;
y += v.y;
}
void sub(Vec v) {
x -= v.x;
y -= v.y;
}
void div(double val) {
x /= val;
y /= val;
}
void mult(double val) {
x *= val;
y *= val;
}
double mag() {
return sqrt(pow(x, 2) + pow(y, 2));
}
double dot(Vec v) {
return x * v.x + y * v.y;
}
void normalize() {
double mag = mag();
if (mag != 0) {
x /= mag;
y /= mag;
}
}
void limit(double lim) {
double mag = mag();
if (mag != 0 && mag > lim) {
x *= lim / mag;
y *= lim / mag;
}
}
double heading() {
return atan2(y, x);
}
static Vec sub(Vec v, Vec v2) {
return new Vec(v.x - v2.x, v.y - v2.y);
}
static double dist(Vec v, Vec v2) {
return sqrt(pow(v.x - v2.x, 2) + pow(v.y - v2.y, 2));
}
static double angleBetween(Vec v, Vec v2) {
return acos(v.dot(v2) / (v.mag() * v2.mag()));
}
Working JPanel! ->
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.util.Dictionary;
import java.util.Hashtable;
import javax.swing.JPanel;
import javax.swing.BoxLayout;
import javax.swing.JToolBar;
import com.jgoodies.forms.layout.FormLayout;
import com.jgoodies.forms.layout.ColumnSpec;
import com.jgoodies.forms.layout.RowSpec;
import javax.swing.GroupLayout;
import javax.swing.GroupLayout.Alignment;
import javax.swing.JSlider;
import javax.swing.JLabel;
import javax.swing.JButton;
import java.awt.Color;
import com.jgoodies.forms.layout.FormSpecs;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.ActionEvent;
import javax.swing.LayoutStyle.ComponentPlacement;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import java.awt.Font;
import javax.swing.JCheckBox;
import javax.swing.JTextField;
public class SimGUI extends JPanel {
/**
* Create the panel.
*/
//JPanel panel = new JPanel();
public JPanel panel_1 = new JPanel();
private JTextField textField;
private JTextField textField_1;
public JButton btnRun = new JButton("Run");
public SimGUI() {
JSlider sizeOfFlock = new JSlider();
sizeOfFlock.setValue(10);
sizeOfFlock.setMaximum(20);
sizeOfFlock.setMinimum(1);
JLabel lblNewLabel = new JLabel("Settings");
lblNewLabel.setFont(new Font("Sitka Banner", Font.BOLD, 18));
JLabel lblFlockSize = new JLabel("Flock Size");
lblFlockSize.setFont(new Font("Sitka Heading", Font.BOLD, 16));
JLabel label = new JLabel("1");
label.setFont(new Font("Sitka Display", Font.PLAIN, 14));
JLabel label_1 = new JLabel("20");
label_1.setFont(new Font("Sitka Display", Font.PLAIN, 14));
JLabel lblTypesOfLeader = new JLabel("Types of Leader:");
lblTypesOfLeader.setFont(new Font("Sitka Heading", Font.BOLD, 16));
JLabel lblNewLabel_1 = new JLabel("Spawn a leader inside the Flock");
lblNewLabel_1.setFont(new Font("Sitka Subheading", Font.PLAIN, 14));
JLabel lblSpawnAPersistant = new JLabel("Spawn a persistant leader");
lblSpawnAPersistant.setFont(new Font("Sitka Subheading", Font.PLAIN, 14));
JCheckBox checkBox = new JCheckBox("");
JCheckBox checkBox_1 = new JCheckBox("");
JSlider noOfRuns = new JSlider();
textField = new JTextField();
textField.setColumns(10);
textField.setText("" + noOfRuns.getValue());
textField_1 = new JTextField();
textField_1.setColumns(10);
textField_1.setText("" + sizeOfFlock.getValue());
/**
* Handle change event for sizeOfFlock slider.
*/
sizeOfFlock.addChangeListener(new ChangeListener(){
#Override
public void stateChanged(ChangeEvent e) {
textField_1.setText(String.valueOf(sizeOfFlock.getValue()));
}
});
textField_1.addKeyListener(new KeyAdapter(){
#Override
public void keyReleased(KeyEvent ke) {
String typed = textField_1.getText();
sizeOfFlock.setValue(0);
if(!typed.matches("\\d+") || typed.length() > 3) {
return;
}
int value = Integer.parseInt(typed);
sizeOfFlock.setValue(value);
}
});
/**
* Handle change event for noOfRuns slider.
*/
noOfRuns.addChangeListener(new ChangeListener(){
#Override
public void stateChanged(ChangeEvent e) {
textField.setText(String.valueOf(noOfRuns.getValue()));
}
});
textField.addKeyListener(new KeyAdapter(){
#Override
public void keyReleased(KeyEvent ke) {
String typed = textField.getText();
noOfRuns.setValue(0);
if(!typed.matches("\\d+") || typed.length() > 3) {
return;
}
int value = Integer.parseInt(typed);
noOfRuns.setValue(value);
}
});
JLabel label_2 = new JLabel("1");
label_2.setFont(new Font("Sitka Display", Font.PLAIN, 14));
JLabel label_3 = new JLabel("100");
label_3.setFont(new Font("Sitka Display", Font.PLAIN, 14));
JLabel lblNoOfSimulation = new JLabel("No. of runs");
lblNoOfSimulation.setFont(new Font("Sitka Heading", Font.BOLD, 16));
GroupLayout groupLayout = new GroupLayout(this);
groupLayout.setHorizontalGroup(
groupLayout.createParallelGroup(Alignment.LEADING)
.addGroup(groupLayout.createSequentialGroup()
.addGroup(groupLayout.createParallelGroup(Alignment.LEADING)
.addGroup(groupLayout.createSequentialGroup()
.addGap(83)
.addComponent(lblNewLabel)
.addGap(82)
.addComponent(panel_1, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
.addGroup(groupLayout.createSequentialGroup()
.addContainerGap()
.addComponent(label, GroupLayout.PREFERRED_SIZE, 11, GroupLayout.PREFERRED_SIZE)
.addPreferredGap(ComponentPlacement.RELATED)
.addComponent(sizeOfFlock, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
.addPreferredGap(ComponentPlacement.RELATED)
.addComponent(label_1, GroupLayout.PREFERRED_SIZE, 22, GroupLayout.PREFERRED_SIZE)
.addPreferredGap(ComponentPlacement.RELATED, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(textField_1, GroupLayout.PREFERRED_SIZE, 33, GroupLayout.PREFERRED_SIZE))
.addGroup(groupLayout.createSequentialGroup()
.addContainerGap()
.addComponent(lblFlockSize)))
.addContainerGap())
.addGroup(groupLayout.createSequentialGroup()
.addContainerGap()
.addComponent(lblNoOfSimulation)
.addContainerGap(207, Short.MAX_VALUE))
.addGroup(groupLayout.createSequentialGroup()
.addContainerGap()
.addComponent(label_2, GroupLayout.PREFERRED_SIZE, 11, GroupLayout.PREFERRED_SIZE)
.addGap(2)
.addComponent(noOfRuns, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
.addPreferredGap(ComponentPlacement.RELATED)
.addComponent(label_3, GroupLayout.PREFERRED_SIZE, 22, GroupLayout.PREFERRED_SIZE)
.addPreferredGap(ComponentPlacement.RELATED, 10, Short.MAX_VALUE)
.addComponent(textField, GroupLayout.PREFERRED_SIZE, 33, GroupLayout.PREFERRED_SIZE)
.addGap(6))
.addGroup(groupLayout.createSequentialGroup()
.addContainerGap()
.addGroup(groupLayout.createParallelGroup(Alignment.LEADING)
.addComponent(lblTypesOfLeader)
.addGroup(groupLayout.createSequentialGroup()
.addComponent(lblNewLabel_1)
.addGap(18)
.addGroup(groupLayout.createParallelGroup(Alignment.LEADING)
.addComponent(checkBox_1, GroupLayout.PREFERRED_SIZE, 21, GroupLayout.PREFERRED_SIZE)
.addComponent(checkBox)))
.addComponent(lblSpawnAPersistant, GroupLayout.PREFERRED_SIZE, 178, GroupLayout.PREFERRED_SIZE))
.addContainerGap(53, Short.MAX_VALUE))
.addGroup(groupLayout.createSequentialGroup()
.addGap(86)
.addComponent(btnRun, GroupLayout.PREFERRED_SIZE, 76, GroupLayout.PREFERRED_SIZE)
.addContainerGap(136, Short.MAX_VALUE))
);
groupLayout.setVerticalGroup(
groupLayout.createParallelGroup(Alignment.TRAILING)
.addGroup(groupLayout.createSequentialGroup()
.addGap(5)
.addGroup(groupLayout.createParallelGroup(Alignment.LEADING)
.addGroup(groupLayout.createSequentialGroup()
.addGap(5)
.addComponent(panel_1, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
.addGroup(groupLayout.createSequentialGroup()
.addPreferredGap(ComponentPlacement.RELATED)
.addComponent(lblNewLabel)))
.addPreferredGap(ComponentPlacement.RELATED, 8, Short.MAX_VALUE)
.addComponent(lblFlockSize)
.addPreferredGap(ComponentPlacement.RELATED)
.addGroup(groupLayout.createParallelGroup(Alignment.TRAILING)
.addComponent(label, GroupLayout.PREFERRED_SIZE, 34, GroupLayout.PREFERRED_SIZE)
.addComponent(sizeOfFlock, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
.addGroup(groupLayout.createParallelGroup(Alignment.BASELINE)
.addComponent(label_1, GroupLayout.PREFERRED_SIZE, 34, GroupLayout.PREFERRED_SIZE)
.addComponent(textField_1, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)))
.addGap(28)
.addGroup(groupLayout.createParallelGroup(Alignment.TRAILING)
.addGroup(groupLayout.createSequentialGroup()
.addComponent(lblTypesOfLeader)
.addPreferredGap(ComponentPlacement.RELATED)
.addComponent(lblNewLabel_1))
.addComponent(checkBox))
.addGap(11)
.addGroup(groupLayout.createParallelGroup(Alignment.BASELINE)
.addComponent(lblSpawnAPersistant, GroupLayout.PREFERRED_SIZE, 19, GroupLayout.PREFERRED_SIZE)
.addComponent(checkBox_1, GroupLayout.PREFERRED_SIZE, 21, GroupLayout.PREFERRED_SIZE))
.addGap(30)
.addComponent(lblNoOfSimulation, GroupLayout.PREFERRED_SIZE, 21, GroupLayout.PREFERRED_SIZE)
.addPreferredGap(ComponentPlacement.RELATED)
.addGroup(groupLayout.createParallelGroup(Alignment.TRAILING)
.addComponent(noOfRuns, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
.addComponent(label_2, GroupLayout.PREFERRED_SIZE, 34, GroupLayout.PREFERRED_SIZE)
.addGroup(groupLayout.createParallelGroup(Alignment.BASELINE)
.addComponent(label_3, GroupLayout.PREFERRED_SIZE, 34, GroupLayout.PREFERRED_SIZE)
.addComponent(textField, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)))
.addGap(18)
.addComponent(btnRun, GroupLayout.PREFERRED_SIZE, 38, GroupLayout.PREFERRED_SIZE)
.addGap(225))
);
setLayout(groupLayout);
};
}
When the "Run" button is pressed it should execute flock.run(x,x,x) but despite my efforts this still wont perform as expected. I'm hoping you may be able to figure out why this is as I have been playing around with this for quite some time but have yet to get it working as expected

Make the GUI which you want to add to the JFrame a JPanel. Use it as a container to hold components you want to add to the GUI (buttons, labels, text areas etc.) After that call
frame.getContentPane().add(panel);
JFrame's default layout is border layout. So JPanel will be placed center by deafult if you do not modify default behaviour.
If you want to add more than one JPanel to the same JFrame, then you should explicitly specify which panel goes to which area like
frame.getContentPane().add(panel1, BorderLayout.CENTER);
frame.getContentPane().add(panel2, BorderLayout.LEFT);
If you do not specify layout area, only the last panel added will be visible at the center.
For more than one container, I suggest to use one JPanel as main container and set its layout accordingly. Next add other components to main JPanel and then add only that JPanel to JFrame.

smooth rounded corners in swing

I want to make smooth rounded corners for my swing application, but I can't get my desired result...
here's the screenshots:
1.setShape() for JFrame :
2.overriding paintComponent() method for JPanel instead of using setShape() :
3.setBackground(new Color(0, 0, 0, 0)) for JFrame :
well, but there's a problem with text quality:
before step 3 :
after step 3 :
guys I'm confused, I've searched many times but nothing helped me...
what should I do? please help me
here's the full code :
public class WelcomePage extends JFrame {
private Point initialClick;
private boolean end = false;
private JLabel jLabelAppTitle;
private JPanel jPanelExit;
private JLabel jLabelHint;
private int r = 220, g = 0, b = 0;
private int r2 = 10, g2 = 10, b2 = 10;
private boolean flag = false;
public WelcomePage() {
initComponents();
// setShape(new RoundRectangle2D.Double(0, 0, getWidth(), getHeight(), 15, 15));
centerLocation();
refreshPage();
}
public static void main(String args[]) {
try {
for (UIManager.LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException e) {
e.printStackTrace();
}
EventQueue.invokeLater(() -> FadeTransitions.fadeIn(new WelcomePage(), FadeTransitions.NORMAL_FADE, true));
}
private void refreshPage() {
Timer timer = new Timer(20, e -> {
if (!end) {
if (r == 220 && b == 0 && g < 220) {
g++;
} else if (g == 220 && b == 0 && r > 0) {
r--;
} else if (g == 220 && r == 0 && b < 220) {
b++;
} else if (b == 220 && r == 0 && g > 0) {
g--;
} else if (b == 220 && g == 0 && r < 220) {
r++;
} else if (r == 220 && g == 0 && b > 0) {
b--;
}
if (!flag) {
r2 += 5;
g2 += 5;
b2 += 5;
if (r2 == 250) {
flag = true;
}
} else {
r2 -= 5;
g2 -= 5;
b2 -= 5;
if (r2 == 10) {
flag = false;
}
}
jLabelAppTitle.setForeground(new Color(r, g, b));
jLabelHint.setForeground(new Color(r2, g2, b2));
} else {
((Timer) e.getSource()).stop();
}
});
timer.setCoalesce(true);
timer.setRepeats(true);
timer.start();
}
private void centerLocation() throws HeadlessException {
final Toolkit toolkit = Toolkit.getDefaultToolkit();
final Dimension screenSize = toolkit.getScreenSize();
final int x = (screenSize.width - this.getWidth()) / 2;
final int y = (screenSize.height - this.getHeight()) / 2;
this.setLocation(x, y);
}
#SuppressWarnings("unchecked")
private void initComponents() {
JPanel jPanelMain = new JPanel() {
#Override
protected void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g.create();
RenderingHints qualityHints = new RenderingHints(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
qualityHints.put(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
g2.setRenderingHints(qualityHints);
g2.setPaint(Color.WHITE);
g2.fillRoundRect(0, 0, getWidth(), getHeight(), 25, 25);
g2.dispose();
}
};
jPanelExit = new JPanel();
JLabel jLabelExit = new JLabel();
JLabel jLabelWelcome = new JLabel();
jLabelAppTitle = new JLabel();
jLabelHint = new JLabel();
JButton jButtonGo = new JButton();
setDefaultCloseOperation(WindowConstants.DO_NOTHING_ON_CLOSE);
setTitle("welcome to My App!");
setUndecorated(true);
setBackground(new Color(0, 0, 0, 0));
addWindowListener(new WindowAdapter() {
#Override
public void windowClosing(WindowEvent e) {
close();
}
});
addMouseMotionListener(new java.awt.event.MouseMotionAdapter() {
public void mouseDragged(MouseEvent evt) {
thisMouseDragged(evt);
}
});
addMouseListener(new java.awt.event.MouseAdapter() {
public void mousePressed(MouseEvent evt) {
thisMousePressed(evt);
}
});
jPanelMain.setBackground(Color.WHITE);
jPanelExit.setBackground(new Color(160, 0, 20));
jLabelExit.setFont(new Font("Tahoma", Font.BOLD, 13));
jLabelExit.setForeground(new Color(255, 255, 255));
jLabelExit.setHorizontalAlignment(SwingConstants.CENTER);
jLabelExit.setText("X");
jLabelExit.setCursor(new Cursor(Cursor.HAND_CURSOR));
jLabelExit.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(MouseEvent evt) {
jLabelExitMouseClicked();
}
public void mouseEntered(MouseEvent evt) {
jLabelExitMouseEntered();
}
public void mouseExited(MouseEvent evt) {
jLabelExitMouseExited();
}
});
GroupLayout jPanelExitLayout = new GroupLayout(jPanelExit);
jPanelExit.setLayout(jPanelExitLayout);
jPanelExitLayout.setHorizontalGroup(
jPanelExitLayout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(GroupLayout.Alignment.TRAILING, jPanelExitLayout.createSequentialGroup()
.addGap(0, 0, Short.MAX_VALUE)
.addComponent(jLabelExit, GroupLayout.PREFERRED_SIZE, 45, GroupLayout.PREFERRED_SIZE))
);
jPanelExitLayout.setVerticalGroup(
jPanelExitLayout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(GroupLayout.Alignment.TRAILING, jPanelExitLayout.createSequentialGroup()
.addGap(0, 0, Short.MAX_VALUE)
.addComponent(jLabelExit, GroupLayout.PREFERRED_SIZE, 22, GroupLayout.PREFERRED_SIZE))
);
jLabelWelcome.setFont(new Font("Tahoma", 0, 25));
jLabelWelcome.setForeground(new Color(0, 0, 100));
jLabelWelcome.setHorizontalAlignment(SwingConstants.CENTER);
jLabelWelcome.setText("Welcome");
jLabelAppTitle.setFont(new Font("MV Boli", 0, 29));
jLabelAppTitle.setHorizontalAlignment(SwingConstants.CENTER);
jLabelAppTitle.setText("My Swing App");
jButtonGo.setBackground(new Color(100, 20, 80));
jButtonGo.setFont(new Font("Tahoma", 0, 15));
jButtonGo.setForeground(new Color(255, 255, 255));
jButtonGo.setText("GO");
jButtonGo.addActionListener(evt -> jButtonGoActionPerformed());
jLabelHint.setFont(new Font("Tahoma", 0, 11));
jLabelHint.setHorizontalAlignment(SwingConstants.CENTER);
jLabelHint.setText("press GO button");
javax.swing.GroupLayout jPanelMainLayout = new javax.swing.GroupLayout(jPanelMain);
jPanelMain.setLayout(jPanelMainLayout);
jPanelMainLayout.setHorizontalGroup(
jPanelMainLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanelMainLayout.createSequentialGroup()
.addContainerGap(48, Short.MAX_VALUE)
.addGroup(jPanelMainLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanelMainLayout.createSequentialGroup()
.addGap(0, 0, Short.MAX_VALUE)
.addComponent(jPanelExit, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(15, 15, 15))
.addGroup(jPanelMainLayout.createSequentialGroup()
.addGroup(jPanelMainLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
.addComponent(jLabelWelcome, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jLabelAppTitle, javax.swing.GroupLayout.DEFAULT_SIZE, 220, Short.MAX_VALUE)
.addComponent(jLabelHint, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jButtonGo, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addContainerGap(48, Short.MAX_VALUE))))
);
jPanelMainLayout.setVerticalGroup(
jPanelMainLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanelMainLayout.createSequentialGroup()
.addComponent(jPanelExit, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(64, 64, 64)
.addComponent(jLabelWelcome, javax.swing.GroupLayout.PREFERRED_SIZE, 28, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(98, 98, 98)
.addComponent(jLabelAppTitle)
.addGap(86, 86, 86)
.addComponent(jLabelHint)
.addGap(24, 24, 24)
.addComponent(jButtonGo, javax.swing.GroupLayout.PREFERRED_SIZE, 40, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(86, 86, 86))
);
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(0, 0, 0)
.addComponent(jPanelMain, javax.swing.GroupLayout.DEFAULT_SIZE, 316, Short.MAX_VALUE)
.addGap(0, 0, 0))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(0, 0, 0)
.addComponent(jPanelMain, javax.swing.GroupLayout.DEFAULT_SIZE, 473, Short.MAX_VALUE)
.addGap(0, 0, 0))
);
pack();
}
private void thisMousePressed(MouseEvent evt) {
initialClick = evt.getPoint();
}
private void thisMouseDragged(MouseEvent evt) {
int thisX = this.getLocation().x;
int thisY = this.getLocation().y;
int xMoved = (thisX + evt.getX()) - (thisX + initialClick.x);
int yMoved = (thisY + evt.getY()) - (thisY + initialClick.y);
int x = thisX + xMoved;
int y = thisY + yMoved;
this.setLocation(x, y);
}
private void jLabelExitMouseClicked() {
close();
}
private void close() {
end = true;
FadeTransitions.fadeOut(this, FadeTransitions.FAST_FADE, FadeTransitions.EXIT_ON_CLOSE);
}
private void jLabelExitMouseEntered() {
jPanelExit.setBackground(new Color(200, 0, 20));
}
private void jLabelExitMouseExited() {
jPanelExit.setBackground(new Color(160, 0, 20));
}
private void jButtonGoActionPerformed() {
end = true;
FadeTransitions.run(this, new ServerManager(this), FadeTransitions.NORMAL_FADE, FadeTransitions.DISPOSE_ON_CLOSE);
}
}
thanks.

Sorry, not an answer, but hopefully at least one step towards an acceptable answer: From my analysis so far, it might be that this is simply a bug somewhere deep (deeeep!) inside the rendering pipeline.
The following MVCE shows two (undecorated) frames, each containing a button. They are equal, except for the background of the frames. For one frame, the color is transparent, and for the other one, it is opaque.
import java.awt.Color;
import java.awt.Font;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
public class TextRenderBug extends JFrame {
public static void main(String[] args)
{
setLookAndFeel();
SwingUtilities.invokeLater(new Runnable()
{
#Override
public void run()
{
createAndShowGUI(new Color(0,0,0 ), 400);
createAndShowGUI(new Color(0,0,0,0), 600);
}
});
}
private static void setLookAndFeel()
{
try
{
for (UIManager.LookAndFeelInfo info :
UIManager.getInstalledLookAndFeels())
{
if ("Nimbus".equals(info.getName()))
{
UIManager.setLookAndFeel(info.getClassName());
break;
}
}
}
catch (Exception e)
{
e.printStackTrace();
}
}
private static void createAndShowGUI(Color background, int x)
{
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setUndecorated(true);
f.setBackground(background);
JButton b = new JButton("Text");
b.setFont(new Font("Tahoma", 0, 15));
f.getContentPane().add(b);
f.setBounds(x, 400, 200, 50);
f.setVisible(true);
}
}
It clearly shows that the text is rendered differently, solely depending on the background being transparent - and of course, this should not be the case.
(This is not Nimbus-specific, by the way: It also applies to other LookAndFeels. Just remove the line where the LaF is set).
What I found out so far:
The behavior is somehow caused by the drawString method of the sun.swing.SwingUtilities2 class
It does not appear in all components. It can be observed on JButton and JLabel, but not on a normal JComponent
Update: It also does not depend on the font (although with other fonts, the effect is not so noticable). When rendered correctly, the font looks a little bit more bold, but of course, it is not simply the same font as a Font.BOLD.
The painting process is rather complicated.
(OK, some of you might already have known the latter).
Here is an example that shows the last observations, maybe it can serve as a starting point for further research of others:
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.lang.reflect.Method;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
public class TextRenderBugTest
{
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
#Override
public void run()
{
createAndShowGUI(new Color(0,0,0 ), 400);
createAndShowGUI(new Color(0,0,0,0), 600);
}
});
}
private static void createAndShowGUI(Color background, int x)
{
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setUndecorated(true);
f.setBackground(background);
JButton b = new JButton("Text");
b.setFont(new Font("Tahoma", 0, 15));
JComponent c = new ExampleComponent();
c.setFont(new Font("Tahoma", 0, 15));
f.getContentPane().setLayout(new GridLayout(0,1));
f.getContentPane().add(b);
f.getContentPane().add(c);
f.setBounds(x, 400, 200, 100);
f.setVisible(true);
}
static class ExampleComponent
//extends JComponent
extends JButton
{
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
g.setColor(getBackground());
g.fillRect(0, 0, getWidth(), getHeight());
g.setColor(getForeground());
g.drawString("Text", 10, 20);
drawStringWithSwingUtilities(g, 60, 20);
}
private void drawStringWithSwingUtilities(Graphics g, int x, int y)
{
try
{
Class<?> c = Class.forName("sun.swing.SwingUtilities2");
Method m = c.getMethod("drawString", JComponent.class,
Graphics.class, String.class, int.class, int.class);
m.invoke(null, this, g, "Text", x, y);
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
}
I already tried to analyze this further, and played around with RenderingHints like KEY_TEXT_ANTIALIASING and KEY_TEXT_LCD_CONTRAST and other settings that are changed in the painting pipeline while it is heading towards the pixels that are finally placed on the screen, but no further insights until now.
(If you want to, you can add this information to your original question, then I'll delete this (not-)answer)

The only chance you have is working with regions. You will need to hardcode a bit and play with subtract, but eventually it will look fine. You can take a look at how it's done in mylyn's notification class: http://grepcode.com/file/repository.grepcode.com/java/eclipse.org/3.6/org.eclipse.mylyn.commons/ui/3.4.0/org/eclipse/mylyn/internal/provisional/commons/ui/AbstractNotificationPopup.java
Hope it helps, best of luck!
Edit: Just remembered this little tutorial which might help: http://www.java2s.com/Code/Java/SWT-JFace-Eclipse/SWTShellcreateanonrectangularwindow.htm

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);
}
}
}