Develop Reference

rotate an Ellipse2D object

I'm trying to rotate one whole Ellipse2D object based on user key input. If the user presses the right key, rotate right and left key means rotate left. The rotAngle is set to 25. I made a separate drawRotEllipse because otherwise it would have always drawn the original one. I think my confusion is happening with the Graphics and Shapes Objects. Tried the AffineTransform business but that didn't work out either. I just want it to rotate about the center. Thanks for any help!
class Canvas extends JPanel implements java.io.Serializable{
int x1 = (int) (this.getWidth()/2)+100;
int y1 = (int) (this.getHeight()/2)+20;
int x2 = (int) this.getWidth()+100;
int y2 = (int) this.getHeight()+200;
#Override
public void paintComponent(Graphics g){
g.setColor(Color.WHITE);
g.fillRect(0, 0, this.getWidth(), this.getHeight());
g.setColor(Color.RED);
drawEllipse(g);
}
public void drawEllipse (Graphics g){
Graphics2D g2d = (Graphics2D) g;
myShape = new Ellipse2D.Double(x1,y1,x2,y2);
g2d.draw(myShape);
this.repaint();
}
public void drawRotEllipse (Graphics g){
g2d.draw(myShape);
this.repaint();
}
}
private void jPanel1KeyPressed(java.awt.event.KeyEvent evt) {
if (evt.getKeyCode()==39){
g2d.rotate(Math.toDegrees(rotAngle));
myCanvas.drawRotEllipse(g2d);
}
else if (evt.getKeyCode()==37){
g2d.rotate(Math.toDegrees(-rotAngle));
myCanvas.drawRotEllipse(g2d);
}
}

if (evt.getKeyCode()==39)
Don't use magic numbers. People don't know that means by just looking at the code.
Instead use variable provided by the API:
if (evt.getKeyCode() == KeyEvent.VK_RIGHT)
You KeyEvent code should not do the actual painting. All the code should do is set the "degrees" property of your class. The setDegrees(...) method will then be responsible for invoking repaint(). Now whenever the component is repainted the shape will be painted at its current degrees of rotation.
Here is an example that uses a JSlider to change the rotation degrees of the class.
It rotates an image. You should be able to change the code rotation the image to just draw your shape:
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.event.*;
public class Rotation2 extends JPanel
{
BufferedImage image;
int degrees;
int point = 250;
public Rotation2(BufferedImage image)
{
this.image = image;
setDegrees( 0 );
setPreferredSize( new Dimension(600, 600) );
}
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g.create();
double radians = Math.toRadians( degrees );
g2.translate(point, point);
g2.rotate(radians);
g2.translate(-image.getWidth(this) / 2, -image.getHeight(this) / 2);
g2.drawImage(image, 0, 0, null);
g2.dispose();
g.setColor(Color.RED);
g.fillOval(point - 5, point - 5, 10, 10);
}
public void setDegrees(int degrees)
{
this.degrees = degrees;
repaint();
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
try
{
// String path = "mong.jpg";
String path = "dukewavered.gif";
ClassLoader cl = Rotation2.class.getClassLoader();
BufferedImage bi = ImageIO.read(cl.getResourceAsStream(path));
final Rotation2 r = new Rotation2(bi);
final JSlider slider = new JSlider(JSlider.HORIZONTAL, 0, 360, 0);
slider.addChangeListener(new ChangeListener()
{
public void stateChanged(ChangeEvent e)
{
int value = slider.getValue();
r.setDegrees( value );
}
});
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new JScrollPane(r));
f.add(slider, BorderLayout.SOUTH);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
catch(IOException e)
{
System.out.println(e);
}
}
});
}
}

change size rounded button in java

Hi I am programming a game and i thought a rounded button would look nice but i am curious how do i change the size of said button to something bigger? here is my code
public JavaApplication3(String label) {
super(label);
Dimension size = getPreferredSize();
size.width = size.height = Math.max(size.width,size.height);
setPreferredSize(size);
setContentAreaFilled(false);
}
protected void paintComponent(Graphics g) {
if (getModel().isArmed()) {
g.setColor(Color.RED);
} else {
g.setColor(Color.yellow);
}
g.fillOval(0, 0, getSize().width-1,getSize().height-1);
super.paintComponent(g);
}
protected void paintBorder(Graphics g) {
g.setColor(getForeground());
g.drawOval(0, 0, getSize().width-1, getSize().height-1);
}
Shape shape;
public boolean contains(int x, int y) {
if (shape == null ||
!shape.getBounds().equals(getBounds())) {
shape = new Ellipse2D.Float(0, 0, getWidth(), getHeight());
}
return shape.contains(x, y);
}
Hope someone can help :)

this changes the size of your button with every time you click on it.
addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("klick");
setSize(new Dimension(newSizeWidth, newSizeHeight));
}
});
}
just call the
setSize(new Dimension(newSizeWidth, newSizeHeight));
method.
here is some working code:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Shape;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import javax.swing.JButton;
import javax.swing.JFrame;
public class test2 extends JButton {
int width = 100;
int height = 100;
public test2(String label) {
super(label);
setSize(width, height);
setContentAreaFilled(false);
addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("klick");
setSize(new Dimension(width--, height--));
}
});
}
protected void paintComponent(Graphics g) {
if (getModel().isArmed()) {
System.out.println(width + " " + height);
g.setColor(Color.RED);
} else {
g.setColor(Color.yellow);
}
g.fillOval(0, 0, getSize().width - 1, getSize().height - 1);
super.paintComponent(g);
}
protected void paintBorder(Graphics g) {
g.setColor(getForeground());
g.drawOval(0, 0, getSize().width - 1, getSize().height - 1);
}
Shape shape;
public boolean contains(int x, int y) {
if (shape == null || !shape.getBounds().equals(getBounds())) {
shape = new Ellipse2D.Float(0, 0, getWidth(), getHeight());
}
return shape.contains(x, y);
}
static JFrame f;
public static void main(String[] args) {
f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLocationRelativeTo(null);
f.setSize(200, 200);
f.add(new test2("label"));
f.setLayout(new BorderLayout());
f.setVisible(true);
}
}

Java simple paint code not working

I have this simple paint code that should draw but instead it moves the oval around the panel.
When I remove super.paintComponent(g) line the program works it paints and not just move the oval, but I keep reading that we should not remove this line, so what can I do to leave the line in but still get the desired results?
class OraclePaint extends JFrame {
public static void main(String[] args) {
OraclePaint ss = new OraclePaint();
ss.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ss.add(new MyPanel());
ss.setSize(250, 200);
ss.setVisible(true);
}
}
class MyPanel extends JPanel {
private int x = -10, y = -10;
public MyPanel() {
addMouseMotionListener(new MouseMotionAdapter() {
public void mouseDragged(MouseEvent event) {
x = event.getX();
y = event.getY();
repaint();
}
}); // end call to addMouseMotionListener
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.fillOval(x, y, 22, 22);
}
}

Based on the description, I assume that you want something like "a simple paint program".
It is correct to invoke super.paintComponent(g) as the first line of an overridden paintComponent. And it is true that this erases the background (that is, everything that was painted before will be deleted).
In Swing, everything that you want to paint has to be painted in the paintComponent method (or in any method that is called from there, and receives the same Graphics object).
If you want to "save" everything that you have painted, you have to paint everything into an image (that is, into a BufferedImage), and paint this image in your paintComponent method.
There are some other issues with the code, but without changing too much of the remaining code, this could roughly (!) be achieved like this:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
import javax.swing.JPanel;
class OraclePaint extends JFrame {
public static void main(String[] args) {
OraclePaint ss = new OraclePaint();
ss.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ss.add(new MyPanel());
ss.setSize(250, 200);
ss.setVisible(true);
}
}
class MyPanel extends JPanel {
private BufferedImage image = null;
public MyPanel() {
addMouseMotionListener(new MouseMotionAdapter() {
#Override
public void mouseDragged(MouseEvent event) {
if (image != null) {
// Paint into the image
Graphics g = image.getGraphics();
g.setColor(Color.BLACK);
g.fillOval(event.getX(), event.getY(), 22, 22);
g.dispose();
repaint();
}
}
}); // end call to addMouseMotionListener
}
// Make sure that the image is not 'null' and that
// it has the same size as this panel
private void validateImage()
{
if (image == null)
{
image = new BufferedImage(getWidth(), getHeight(),
BufferedImage.TYPE_INT_ARGB);
}
if (image.getWidth() != getWidth() || image.getHeight() != getHeight())
{
BufferedImage newImage = new BufferedImage(getWidth(), getHeight(),
BufferedImage.TYPE_INT_ARGB);
Graphics g = newImage.getGraphics();
g.drawImage(image, 0, 0, null);
g.dispose();
image = newImage;
}
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
validateImage();
g.drawImage(image, 0, 0, null);
}
}

change your MyPanel to this:
class MyPanel extends JPanel
{
private int x2 = 0, y2 = 0;
private int x1 = 0, y1 = 0;
public MyPanel()
{
addMouseMotionListener(new MouseMotionAdapter()
{
public void mouseDragged( MouseEvent event )
{
x2 = event.getX();
y2 = event.getY();
repaint();
}
}
); // end call to addMouseMotionListener
addMouseListener(new MouseListener() {
#Override
public void mousePressed(MouseEvent e) {
x1 = e.getX();
y1 = e.getY();
}
});
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
g.fillOval(x1, y1, x2, y2);
}
}

Rotation with Graphics2D

I am currently experimenting with the Graphics2D and the KeyListener, and I am currently testing out rotating objects (in this case a pentagon). Now, it's working in the sense that it rotates, except it is supposed to rotate by 1 radian each time VK_RIGHT or VK_LEFT are pressed.
However, currently it does that for the first key press only. From then on, it creates a pattern of rotating it by 1, 2, 3, 4, 5... and so on radians each time (the nth keypress rotates it by nth radians) instead of just 1 radian per keypress.
Creating the JFrame:
import javax.swing.JFrame;
public class Main {
public Main() {
JFrame window = new JFrame("Rotating Hexagons");
window.setSize(800,600);
window.setLocationRelativeTo(null);
window.setResizable(false);
window.setContentPane(new RotatingHexagon());
window.pack();
window.setVisible(true);
}
public static void main(String[]args) {
new Main();
}
}
RotatingHexagon Class:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Polygon;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JPanel;
public class RotatingHexagon extends JPanel implements KeyListener {
private Polygon poly;
private int[] xpoints = { 0, -10, -7, 7, 10 };
private int[] ypoints = { -10, -2, 10, 10, -2 };
private int rotation = 0;
public RotatingHexagon() {
setPreferredSize(new Dimension(800,600));
setFocusable(true);
requestFocus();
}
public void init() {
poly = new Polygon(xpoints, ypoints, xpoints.length);
addKeyListener(this);
}
public void paint(Graphics g) {
init();
Graphics2D g2d = (Graphics2D) g;
int width = getSize().width;
int height = getSize().height;
g2d.setColor(Color.BLACK);
g2d.fillRect(0, 0, width, height);
g2d.setColor(Color.WHITE);
g2d.drawString(rotation + " radians", 10, 20);
g2d.translate(width / 2, height / 2);
g2d.scale(20, 20);
g2d.rotate(Math.toRadians(rotation));
g2d.setColor(new Color(255, 100, 100));
g2d.fill(poly);
g2d.setColor(Color.WHITE);
g2d.draw(poly);
}
public void keyPressed(KeyEvent k) {
switch(k.getKeyCode()) {
case KeyEvent.VK_LEFT:
rotation--;
if (rotation < 0) rotation = 359;
repaint();
break;
case KeyEvent.VK_RIGHT:
rotation++;
if (rotation > 360) rotation = 0;
repaint();
break;
}
}
public void keyReleased(KeyEvent k) {}
public void keyTyped(KeyEvent k) {}
}
I really don't have any idea why it isn't just rotating 1 radian each time, so any help is appreciated.
Thanks.

the reason is calling the init() function in the paint() method again and again. So the KeyListener is added multiple times, causing that it is called multiple times, incrementing your counter more every time you press the key.
Move it to the constructor:
public RotatingHexagon() {
setPreferredSize(new Dimension(800,600));
setFocusable(true);
requestFocus();
addKeyListener(this);
}
public void init() {
poly = new Polygon(xpoints, ypoints, xpoints.length);
}
Andy

You should probally just use a persistant AffineTransform to do the rotation. They are a lot more powerfull.
I also saw several issues in your code, you are calling the init method each frame - this could be 60 times per second. In this you are adding a new keylistener each frame. You are also creating a new polygon which would slow down performance.
I've made some changes to your code and and i've used AffineTransforms as an example. Have a look and see if this helps.
package com.joey.testing;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Polygon;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.geom.AffineTransform;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class AffineTransformTest extends JPanel implements KeyListener {
private Polygon poly;
private int[] xpoints = { 0, -10, -7, 7, 10 };
private int[] ypoints = { -10, -2, 10, 10, -2 };
private int rotation = 0;
AffineTransform transform;
AffineTransform rotationTransform;
AffineTransform translateTransform;
public AffineTransformTest() {
setPreferredSize(new Dimension(800,600));
setFocusable(true);
requestFocus();
//Do Init here - no point in creating new polygon each frame.
//It also adds the key listener each time
init();
updateTransforms();
}
public void init() {
poly = new Polygon(xpoints, ypoints, xpoints.length);
transform = new AffineTransform();
rotationTransform = new AffineTransform();
translateTransform = new AffineTransform();
addKeyListener(this);
}
//Use Paint Compoent
#Override
public void paintComponent(Graphics g) {
//Always call super to clear the screen
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
int width = getSize().width;
int height = getSize().height;
g2d.setColor(Color.BLACK);
g2d.fillRect(0, 0, width, height);
g2d.setColor(Color.WHITE);
g2d.drawString(rotation + " radians", 10, 20);
//Store old transform so we can apply it
AffineTransform old = g2d.getTransform();
//Add Transform and move polygon
g2d.setTransform(transform);
g2d.setColor(new Color(255, 100, 100));
g2d.fill(poly);
g2d.setColor(Color.WHITE);
g2d.draw(poly);
g2d.setTransform(old);
}
public void keyPressed(KeyEvent k) {
switch(k.getKeyCode()) {
case KeyEvent.VK_LEFT:
rotation--;
if (rotation < 0) rotation = 359;
repaint();
break;
case KeyEvent.VK_RIGHT:
rotation++;
if (rotation > 360) rotation = 0;
repaint();
break;
}
updateTransforms();
}
public void updateTransforms(){
//Resets transform to rotation
rotationTransform.setToRotation(Math.toRadians(rotation));
translateTransform.setToTranslation(getWidth()/2, getHeight()/2);
//Chain the transforms (Note order matters)
transform.setToIdentity();
transform.concatenate(translateTransform);
transform.concatenate(rotationTransform);
}
public void keyReleased(KeyEvent k) {}
public void keyTyped(KeyEvent k) {}
public static void main(String input[]){
JFrame f= new JFrame("AffineTransform");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setSize(100, 100);
f.setResizable(true);
f.getContentPane().setLayout(new BorderLayout());
f.getContentPane().add(new AffineTransformTest());
f.show();
}
}

Need help to create a custom button in swing

I am trying to create a button which looks as shown below and continuously fades in and fades out .It looks like :-
Now i have done till the looks with gradient paint but what should i do to make the button text appear.Inspite of calling 'super(s)' it doesn't appear as i have painted it with GradientPaint.What should i do make the text appear over paint.My code is shown below :-
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
public class Fader extends JFrame{
Fader()
{
super("A fading button");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new FlowLayout());
setSize(400,400);
add(new CustomButton("Submit"));
setVisible(true);
}
public static void main(String args[])
{
SwingUtilities.invokeLater(new Runnable(){public void run(){new Fader();}});
}
}
class CustomButton extends JButton
{
public CustomButton(String s) {
super(s);
// TODO Auto-generated constructor stub
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2=(Graphics2D)g.create();
GradientPaint gp=new GradientPaint(0, 0, Color.RED, 200, 100, Color.YELLOW);
g2.setPaint(gp);
g2.fillRect(0, 0, getWidth(), getHeight());
}
public Dimension getPreferredSize()
{
return new Dimension(200,100);
}
}
Secondly,an advice to implement the fade in and out effect is also requested.

You can use this option, that paints a transparent color gradient on a component:
#Override
public void paintComponent(Graphics g){
super.paintComponent( g );
Graphics2D g2=(Graphics2D)g.create();
int h = getHeight();
int w = getWidth();
g2.setComposite(AlphaComposite.getInstance(
AlphaComposite.SRC_OVER, .5f));
g2.setPaint(new GradientPaint(0, 0, Color.yellow, 0, h, Color.red));
g2.fillRect(0, 0, w, h);
g2.dispose();
}
Other pretty good example with fading in (as requested). I used RadialGradientPaint. You can play with AlphaComposite
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, .4f));
where 4f represent transparent level 40%
#Override
public void paintComponent(Graphics g){
super.paintComponent( g );
Graphics2D g2=(Graphics2D)g.create();
int h = getHeight();
int w = getWidth();
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, .5f));
Point2D center = new Point2D.Float(100, 50);
float radius = 150;
float[] dist = {0.0f, 1.0f};
Color[] colors = {Color.yellow, Color.red};
RadialGradientPaint p = new RadialGradientPaint(center, radius, dist, colors);
g2.setPaint(p);
g2.fillRect(0, 0, w, h);
g2.dispose();
}
Finally we can play with alpha dynamically. Her is the full code. I created simple thread that change me alpha from 0 to 9 and vise versa. Here we go:
public class Fader extends JFrame{
private static final long serialVersionUID = 1L;
static JButton button;
public static float mTransparent = .0f;
Fader(){
super("A fading button");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new FlowLayout());
setSize(400,400);
JButton button = new CustomButton("Submit");
add(button);
setVisible(true);
Blink blink = new Blink(this);
blink.start();
}
public static void main(String args[]){
SwingUtilities.invokeLater(new Runnable(){public void run(){new Fader();}});
}
public static float getTransparentLevel() {
return mTransparent;
}
public void setTransparentLevel(float newVal) {
mTransparent = newVal;
if(button != null){
button.repaint();
}
repaint();
}
}
class Blink extends Thread{
Fader fader;
public Blink(Fader fader) {
this.fader = fader;
}
#Override
public void run(){
while(true){
if(Fader.getTransparentLevel() == 0.0f){
//increase to 1f
for(int i=1; i<10; i++){
fader.setTransparentLevel((float)i/10);
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
else if(Fader.getTransparentLevel() == 0.9f){
//increase to 1f
for(int i=10; i>=0; i--){
fader.setTransparentLevel((float)i/10);
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
}
class CustomButton extends JButton {
private static final long serialVersionUID = 1L;
public CustomButton(String s) {
super(s);
}
#Override
public void paintComponent(Graphics g){
super.paintComponent( g );
Graphics2D g2=(Graphics2D)g.create();
int h = getHeight();
int w = getWidth();
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, Fader.getTransparentLevel()));
Point2D center = new Point2D.Float(100, 50);
float radius = 150;
float[] dist = {0.0f, 1.0f};
Color[] colors = {Color.yellow, Color.red};
RadialGradientPaint p = new RadialGradientPaint(center, radius, dist, colors);
g2.setPaint(p);
g2.fillRect(0, 0, w, h);
g2.dispose();
}
public Dimension getPreferredSize(){
return new Dimension(200,100);
}
}
It blinks with sleep 300 ms from .0 to .9 of transparent and back from .9 to .0:
-->

Once you override the paintComponent() method, you are on your own with drawing the button. So, you will have to draw the text yourself. Something like this will help:
g2.setColor(Color.GREEN);
g2.drawString(getText(), 0, 10);
The above code must be added after the fillRect method. However, you will have to use FontMetrics in order to position the text according to the text alignment preferences.

To fadeIn and fadeOut you will need to implement your own Animation Sequencer that runs in a different thread, that will constantly vary the alpha value with a TimerTask. Once the value of alpha reaches 0, it should be incremented back to 100%.
Also check out the book by Romain Guy: Filthy Rich Java Clients