We Keep Coding

Gradually incrementing stroke width in java

I have to draw the figure on the link in java as an assignment.The assignment
So far I have been able to draw the first arc using CubicCurve2D, as seen on the picture on the second link, but now I face the problem of incrementing the line width gradually.What I have achieved until now
Can anyone tell me if there is any way of achieving it. Thank you!
This is the code for the panel
import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.*;
import java.awt.geom.*;
import java.awt.image.*;
public class GraphicsDemo extends JPanel {
public void paintComponent(Graphics g){
super.paintComponent(g);
this.setBackground(Color.BLACK);
Graphics2D g2D = (Graphics2D) g;
g2D.setPaint(new Color(150,250, 187));
g2D.setStroke(new BasicStroke(1));
//g2D.drawArc(-50,50,300,300,0,90);
CubicCurve2D cubic = new CubicCurve2D.Double(0,230,80,90,130,220,80,190);
g2D.draw(cubic);
}
}
This is the code of the frame
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Test extends JFrame implements MouseListener, MouseMotionListener{
GraphicsDemo graphicDemo = new GraphicsDemo();
int x, y;
String str="";
public void mousePressed(MouseEvent e)
{
x = e.getX();
y = e.getY();
str = "Mouse Pressed";
System.out.println("Coordinates of x: " + x + " , coordinates of y :" +y);
repaint();
}
public void mouseReleased(MouseEvent e)
{
x = e.getX();
y = e.getY();
str = "Mouse Released";
repaint();
}
public void mouseClicked(MouseEvent e)
{
x = e.getX();
y = e.getY();
str = "Mouse Clicked";
repaint();
}
public void mouseEntered(MouseEvent e)
{
x = e.getX();
y = e.getY();
str = "Mouse Entered";
repaint();
}
public void mouseExited(MouseEvent e)
{
x = e.getX();
y = e.getY();
str = "Mouse Exited";
repaint();
}
// override MouseMotionListener two abstract methods
public void mouseMoved(MouseEvent e)
{
x = e.getX();
y = e.getY();
str = "Mouse Moved";
repaint();
}
public void mouseDragged(MouseEvent e)
{
x = e.getX();
y = e.getY();
str = "Mouse dragged";
repaint();
}
public Test()
{
this.setSize(420,420);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.add(graphicDemo);
this.setVisible(true);
this.addMouseListener(this);
this.addMouseMotionListener(this);
}
public static void main(String[] a){
new Test();
}
}

Java Awt & Swing

Pong.Java
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
public class Pong {
private static final int WIDTH = 900, HEIGHT = 700;
JFrame win = new JFrame();
Paddle paddleOne = new Paddle(1);
Paddle paddleTwo = new Paddle(2);
Graphics g;
Pong(){
init();
}
void init(){
win.setTitle("PONG");
win.setSize(WIDTH, HEIGHT);
win.addKeyListener(keyListener);
win.setLocationRelativeTo(null);
win.getContentPane().setBackground(Color.black);
win.setVisible(true);
win.getContentPane().validate();
win.repaint();
}
public void paintComponent(Graphics g){
g.setColor(Color.white);
g.fillRect(paddleOne.getX(), paddleOne.getY(), paddleOne.getHEIGHT(), paddleOne.getWIDTH());
System.out.println("drawn");
}
KeyListener keyListener = new KeyListener() {
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
switch(key){
case 87:
System.out.println("Player 1 Up");
break;
case 83:
System.out.println("Player 1 Down");
break;
case 38:
System.out.println("Player 2 Up");
break;
case 40:
System.out.println("Player 2 Down");
break;
}
win.getContentPane().validate();
win.repaint();
}
public void keyReleased(KeyEvent arg0) {
// TODO Auto-generated method stub
}
public void keyTyped(KeyEvent arg0) {
// TODO Auto-generated method stub
}
};
public static void main(String[] args) {
Pong p = new Pong();
}
}
Paddle.Java
public class Paddle{
private int WIDTH = 50, HEIGHT = 150, X, Y;
int playerNum;
Paddle(int playerNum){
if(playerNum == 1){
X = 10;
Y = 10;
}else if (playerNum == 2){
X = 500;
Y = 10;
}
}
public void setX(int x){
X = x;
}
public void setY(int y){
Y = y;
}
public int getWIDTH() {
return WIDTH;
}
public int getHEIGHT() {
return HEIGHT;
}
public int getX() {
return X;
}
public int getY() {
return Y;
}
}
I'm relatively new to Java programming, or more specifically Awt & Swing, what my question is, why isn't my rectangle drawing? Any help is appreciated. Thank you so much!

In order for something to be painted within in Swing, it first must extend from something Swing know's how to paint, this commonly means a JComponent (or more typically a JPanel).
Then you can override one of the paint methods, which is called by the painting subsystem, in this case, it's generally preferred to override paintComponent, but don't forget to call super.paintComponent before you do any custom painting, or you're setting yourself up for some weird and generally unpredictable painting issues.
Take a look at Painting in AWT and Swing and Performing Custom Painting for more details.
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Pongo {
public static void main(String[] args) {
new Pongo();
}
public Pongo() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new PongPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class PongPane extends JPanel {
private static final int WIDTH = 900, HEIGHT = 700;
Paddle paddleOne = new Paddle(1);
Paddle paddleTwo = new Paddle(2);
public PongPane() {
setBackground(Color.BLACK);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.white);
g.fillRect(paddleOne.getX(), paddleOne.getY(), paddleOne.getHEIGHT(), paddleOne.getWIDTH());
//System.out.println("drawn"); //Should not put something here which may overhead.
}
}
public class Paddle {
private int WIDTH = 50, HEIGHT = 150, X, Y;
int playerNum;
Paddle(int playerNum) {
if (playerNum == 1) {
X = 10;
Y = 10;
} else if (playerNum == 2) {
X = 500;
Y = 10;
}
}
public void setX(int x) {
X = x;
}
public void setY(int y) {
Y = y;
}
public int getWIDTH() {
return WIDTH;
}
public int getHEIGHT() {
return HEIGHT;
}
public int getX() {
return X;
}
public int getY() {
return Y;
}
}
}
I would also discourage the use of KeyListener within this context and inside advice the use of the key bindings API, it doesn't suffer from the same focus related issues that KeyListener does. See How to Use Key Bindings for more details

You need to overriding paintComponents to draw.
Here is your Pong.java
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
public class Pong {
private static final int WIDTH = 900, HEIGHT = 700;
JFrame win = new JFrame();
Paddle paddleOne = new Paddle(1);
Paddle paddleTwo = new Paddle(2);
Graphics g;
Pong() {
init();
}
void init() {
win.setTitle("PONG");
win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
win.setSize(WIDTH, HEIGHT);
win.addKeyListener(keyListener);
win.setLocationRelativeTo(null);
win.add(new Panel(paddleOne));
win.getContentPane().setBackground(Color.black);
win.setVisible(true);
win.getContentPane().validate();
win.repaint();
}
KeyListener keyListener = new KeyListener() {
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
switch (key) {
case 87:
System.out.println("Player 1 Up");
break;
case 83:
System.out.println("Player 1 Down");
break;
case 38:
System.out.println("Player 2 Up");
break;
case 40:
System.out.println("Player 2 Down");
break;
}
win.getContentPane().validate();
win.repaint();
}
public void keyReleased(KeyEvent arg0) {
// TODO Auto-generated method stub
}
public void keyTyped(KeyEvent arg0) {
// TODO Auto-generated method stub
}
};
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Pong();
}
});
}
}
Here Panel.java in where paintComponent overridden.
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JPanel;
public class Panel extends JPanel{
private Paddle paddleOne;
public Panel(Paddle pdl) {
paddleOne = pdl;
}
#Override
public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(Color.white);
g.fillRect(paddleOne.getX(), paddleOne.getY(), paddleOne.getHEIGHT(), paddleOne.getWIDTH());
//System.out.println("drawn"); //Should not put something here which may overhead.
}
}

Removing a rectangle with color on mouse release

I am developing a game and in some part of my game I want the rectangle to disappear on mouse release. I have placed 26 rectangles in an arrayList and remove the particular rectangle clicked as the mouse is released. So if I remove the fill methods, the rectangle disappears successfully but if the fill methods are there, it does not work anymore.
Here is my paint method:
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Image img = Toolkit.getDefaultToolkit().getImage(Rectangles2.class.getResource("background.jpg"));
g.drawImage(img, 0, 0, this.getWidth(), this.getHeight(), this);
Graphics2D g2 = (Graphics2D) g;
for (Rectangle s : rectanglesList) {
g2.draw(s);
}
g2.setColor(bColor);
g2.fill(box1);
g2.fill(box2);
g2.fill(box3);
g2.fill(box4);
g2.fill(box5);
g2.fill(box6);
g2.fill(box7);
g2.fill(box8);
g2.fill(box9);
g2.fill(box10);
g2.fill(box11);
g2.fill(box12);
g2.fill(box25);
g2.setColor(wColor);
g2.fill(box13);
g2.fill(box14);
g2.fill(box15);
g2.fill(box16);
g2.fill(box17);
g2.fill(box18);
g2.fill(box19);
g2.fill(box20);
g2.fill(box21);
g2.fill(box22);
g2.fill(box23);
g2.fill(box24);
g2.fill(box26);
}
Here is how I did the removing of the rectangle (Just an excerpt):
if (box1.getBounds().contains(x, y)) {
pickedPanelNum = 0;
rectanglesList.remove(box1);
panelsPane.repaint();
}
Here are the values of the bColor and wColor:
Color bColor = Color.BLACK;
Color wColor = Color.WHITE;
NOTE:
The pickedPanelNum is just for assigning an int value and has no connection to the problem.
I think it is because when I repaint, the fill methods are still there. However I have no idea for an alternate way of painting the rectangles.
I hope my problem is stated clearly. If you have ideas how I could solve this, please tell me. Thank you!
UPDATE:
Here is a shorter, runnable version of my program. (Background image isn't included though):
import java.awt.*;
import java.awt.Color.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
import java.awt.geom.Rectangle2D;
public class Rec extends JComponent
{
public ArrayList<Rectangle> rectanglesList = new ArrayList<Rectangle>();
public int arrx[] = new int[120];
public int arry[] = new int[120];
JFrame frame = new JFrame();
public int xSize = 2000;
public int ySize = 1000;
public int x;
public int y;
public int pickedPanelNum = 0;
public String pickedPanelDash = "";
public String pickedPanelColor = "";
Color bColor = Color.BLACK;
Color wColor = Color.WHITE;
boolean removedPanel = false;
public void launchFrame()
{
Random rand = new Random();
for(int x = 0;x<120;x++)
{
arrx[x] = rand.nextInt(640);
arry[x] = rand.nextInt(590);
}
Rectangle box1 = new Rectangle(arrx[103],arry[59],80,90);
Rectangle box2 = new Rectangle(arrx[105],arry[3],80,90);
rectanglesList.add(box1);
rectanglesList.add(box2);
JPanel mainPanel = new JPanel();
JPanel panelsPane = new JPanel()
{
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Image img = Toolkit.getDefaultToolkit().getImage(Rectangles2.class.getResource("background.jpg"));
g.drawImage(img, 0, 0, this.getWidth(), this.getHeight(), this);
Graphics2D g2 = (Graphics2D) g;
for (Rectangle s : rectanglesList) {
g2.draw(s);
}
g2.setColor(bColor);
g2.fill(box1);
g2.setColor(wColor);
g2.fill(box2);
}
};
JPanel rightPane = new JPanel();
panelsPane.addMouseListener (new MouseAdapter ()
{
public void mousePressed(MouseEvent event)
{
x = event.getX();
y = event.getY();
}
public void mouseReleased(MouseEvent event)
{
if (box1.getBounds().contains(x, y)) {
pickedPanelNum = 0;
rectanglesList.remove(box1);
panelsPane.repaint();
}
if (box2.getBounds().contains(x, y)) {
pickedPanelNum = 1;
rectanglesList.remove(box2);
panelsPane.repaint();
}
}
});
panelsPane.addMouseMotionListener (new MouseAdapter ()
{
public void mouseDragged(MouseEvent event)
{
Rec obj = new Rec();
int dx = event.getX() - x;
int dy = event.getY() - y;
if (box1.getBounds().contains(x, y)) {
box1.x += dx;
box1.y += dy;
panelsPane.repaint();
}
if (box2.getBounds().contains(x, y)) {
box2.x += dx;
box2.y += dy;
panelsPane.repaint();
}
x += dx;
y += dy;
}
public void mouseReleased(MouseEvent event) {}
public void mouseClicked(MouseEvent event) {}
public void mouseEntered(MouseEvent event) {}
public void mouseExited(MouseEvent event) {}
});
panelsPane.setPreferredSize(new Dimension (800, ySize-315));
rightPane.setPreferredSize(new Dimension (530, ySize-315));
mainPanel.setPreferredSize(new Dimension (xSize, ySize));
frame.setPreferredSize(new Dimension (xSize, ySize));
rightPane.setBackground(Color.gray);
mainPanel.add(panelsPane);
mainPanel.add(rightPane);
frame.add(mainPanel);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
}
public static void main(String args[])
{
Rec obj = new Rec();
obj.launchFrame();
}
}

Even if you remove box1 from the List, there is nothing stopping it from getting filled in your paintComponent method, the for-loop is only drawing the outline of the rectangles within the list, but you code implicitly fills them anyway.
So, first, get rid of all the box{n} variables. Next change the paintComponent method...
public void paintComponent(Graphics g) {
super.paintComponent(g);
//Image img = Toolkit.getDefaultToolkit().getImage(Rectangles2.class.getResource("background.jpg"));
//g.drawImage(img, 0, 0, this.getWidth(), this.getHeight(), this);
Graphics2D g2 = (Graphics2D) g;
for (Rectangle s : rectanglesList) {
g2.setColor(bColor);
g2.fill(s);
g2.setColor(wColor);
g2.draw(s);
}
}
So, this just uses the rectanglesList to first draw the rectangles and the fill them
Then, lets update the mouseReleased...
public void mouseReleased(MouseEvent event) {
// Because the rectangles are painted in order, the later
// rectangles are painted over the eailer ones, so, we reverse
// the list so we can check for the higher positioned
// rectangles
List<Rectangle> copy = new ArrayList<>(rectanglesList);
Collections.reverse(copy);
for (Rectangle r : copy) {
if (r.contains(event.getPoint())) {
rectanglesList.remove(r);
break;
}
}
event.getComponent().repaint();
}
Okay, this is little more funky, but basically, we reverse the list of rectangles (because those rectangles that appear later in the list are painted over those that appear before them) and checks to see if the mouse was clicked within any one of them. The moment we find a match, we break out of the loop and repaint the component which generated the event
And, because it's nice to see this stuff running, a complete example...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Random;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Rec extends JComponent {
public ArrayList<Rectangle> rectanglesList = new ArrayList<Rectangle>();
public int arrx[] = new int[120];
public int arry[] = new int[120];
JFrame frame = new JFrame();
public int xSize = 2000;
public int ySize = 1000;
public int x;
public int y;
public int pickedPanelNum = 0;
public String pickedPanelDash = "";
public String pickedPanelColor = "";
Color bColor = Color.BLACK;
Color wColor = Color.WHITE;
boolean removedPanel = false;
public void launchFrame() {
Random rand = new Random();
for (int x = 0; x < 10; x++) {
arrx[x] = rand.nextInt(640);
arry[x] = rand.nextInt(590);
rectanglesList.add(new Rectangle(arrx[x], arry[x], 80, 90));
}
JPanel mainPanel = new JPanel();
JPanel panelsPane = new JPanel() {
public void paintComponent(Graphics g) {
super.paintComponent(g);
// Image img = Toolkit.getDefaultToolkit().getImage(Rectangles2.class.getResource("background.jpg"));
// g.drawImage(img, 0, 0, this.getWidth(), this.getHeight(), this);
Graphics2D g2 = (Graphics2D) g;
for (Rectangle s : rectanglesList) {
g2.setColor(bColor);
g2.fill(s);
g2.setColor(wColor);
g2.draw(s);
}
}
};
JPanel rightPane = new JPanel();
panelsPane.addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent event) {
x = event.getX();
y = event.getY();
}
public void mouseReleased(MouseEvent event) {
// Because the rectangles are painted in order, the later
// rectangles are painted over the eailer ones, so, we reverse
// the list so we can check for the higher positioned
// rectangles
List<Rectangle> copy = new ArrayList<>(rectanglesList);
Collections.reverse(copy);
for (Rectangle r : copy) {
if (r.contains(event.getPoint())) {
rectanglesList.remove(r);
break;
}
}
event.getComponent().repaint();
}
});
panelsPane.addMouseMotionListener(new MouseAdapter() {
public void mouseDragged(MouseEvent event) {
}
public void mouseReleased(MouseEvent event) {
}
public void mouseClicked(MouseEvent event) {
}
public void mouseEntered(MouseEvent event) {
}
public void mouseExited(MouseEvent event) {
}
});
panelsPane.setPreferredSize(new Dimension(800, ySize - 315));
rightPane.setPreferredSize(new Dimension(530, ySize - 315));
mainPanel.setPreferredSize(new Dimension(xSize, ySize));
frame.setPreferredSize(new Dimension(xSize, ySize));
rightPane.setBackground(Color.gray);
mainPanel.add(panelsPane);
mainPanel.add(rightPane);
frame.add(mainPanel);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
}
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
Rec obj = new Rec();
obj.launchFrame();
}
});
}
}

how to add Mouselistener to line in graphics java

public Line2D line2d;
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g2 = (Graphics2D) g;
g2.setColor(Color.BLACK);
g2.setStroke(new BasicStroke(2.0F));
line2d = new Line2D.Double(40, 0, 400, 400);
g2.draw(line2d);
}
#Override
public void mouseClicked(MouseEvent e) {
if(line2d.contains(e.getX(), e.getY())) {
System.out.println("Line clicked");
}
}
This variant is not working. Is there any other way of adding MouseListener to the line?
I found solution. I think it is better add invisible Polygon there. and catching its
Mouseevents. because line doesn't have clickable area unlike polygons.See the code below:
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Polygon;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.geom.Line2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MyPanel extends JPanel implements MouseListener {
public Line2D line2d;
public Polygon pol;
public int x1 = 40;
public int y1 = 0;
public int x2 = 400;
public int y2 = 400;
public int margin = 3;
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setPreferredSize(new Dimension(500, 500));
frame.getContentPane().add(new MyPanel());
frame.pack();
frame.setVisible(true);
}
public MyPanel(){
setBackground(Color.WHITE);
addMouseListener(this);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setColor(Color.BLACK);
g2.setStroke(new BasicStroke(2.0F));
line2d = new Line2D.Double(x1, y1, x2, y2);
g2.draw(line2d);
int xPoints[] = { x1 - margin, x1 + margin, x2 + margin, x2 - margin };
int yPoints[] = { y1 + margin, y1 - margin, y2 - margin, y2 + margin };
pol = new Polygon(xPoints, yPoints, yPoints.length);
}
#Override
public void mouseClicked(MouseEvent e) {
if (pol.contains(e.getX(), e.getY())) {
System.out.println("Line clicked");
}
}
#Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
}

MouseListener can be add to a Component, for example: JPanel, JTextfield etc., or your self-defined class with extending Component. Please see the below example.
public class T extends JComponent {
public T(){
addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
// TODO: do your business.
}
});
}
public Line2D line2d;
Graphics2D g2;
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g2 = (Graphics2D) g;
g2.setColor(Color.BLACK);
g2.setStroke(new BasicStroke(2.0F));
line2d = new Line2D.Double(40, 0, 400, 400);
g2.draw(line2d);
}
}

you can use bessenheim (dunno how to properly pronounce) algorith to create a line...
then you merely have to check if you click into that line...
public class Line {
public static ArrayList<Point> getLine(Point start, Point target) {
ArrayList<Point> ret = new ArrayList<Point>();
int x0 = start.x;
int y0 = start.y;
int x1 = target.x;
int y1 = target.y;
int sx = 0;
int sy = 0;
int dx = Math.abs(x1-x0);
sx = x0<x1 ? 1 : -1;
int dy = -1*Math.abs(y1-y0);
sy = y0<y1 ? 1 : -1;
int err = dx+dy, e2; /* error value e_xy */
for(;;){ /* loop */
ret.add( new Point(x0,y0) );
if (x0==x1 && y0==y1) break;
e2 = 2*err;
if (e2 >= dy) { err += dy; x0 += sx; } /* e_xy+e_x > 0 */
if (e2 <= dx) { err += dx; y0 += sy; } /* e_xy+e_y < 0 */
}
return ret;
}
}
NOTE - this algorith is not my idea, it was developed by some guy named ?bessenheim? ^^ hehe much fun googeling ^^

How to drop a ball when clicked with mouse?

I'm working on a game project. The aim is clicking the balls and drop them into the basket which is below in the JPanel. I created some ways to do that but I can't achieve it. In my opinion, when the user click the ball's center with a margin of error (because the program can't catch the real point of balls), the program understands the action and runs the function of this issue. After clicking the ball it should be dropped down straight but the other balls should be continued. I use MouseListener#mousePressed method, but it doesn't work or I'm missing some parts. In addition, I made some changes in my source code, but I want to listen your advices so I am writing this topic.
I wrote a method which finds the mouse and ball coordinates. So when I make some changes to it, I can achieve my project goal. You can see the editing in the picture.
This is my source code ;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.ArrayList;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollBar;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Game {
public Game() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager
.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException
| IllegalAccessException
| UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("MultipleBallApp");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new BallControl());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class BallControl extends JPanel {
/**
*
*/
private static final long serialVersionUID = 1L;
private BallPanel ballPanel = new BallPanel();
private JButton Suspend = new JButton("Suspend");
private JButton Resume = new JButton("Resume");
private JButton Add = new JButton("+1");
private JButton Subtract = new JButton("-1");
private JScrollBar Delay = new JScrollBar();
public BallControl() {
// Group buttons in a panel
JPanel panel = new JPanel();
panel.add(Suspend);
panel.add(Resume);
panel.add(Add);
panel.add(Subtract);
// Add ball and buttons to the panel
ballPanel.setBorder(new javax.swing.border.LineBorder(Color.red));
Delay.setOrientation(JScrollBar.HORIZONTAL);
ballPanel.setDelay(Delay.getMaximum());
setLayout(new BorderLayout());
add(Delay, BorderLayout.NORTH);
add(ballPanel, BorderLayout.CENTER);
add(panel, BorderLayout.SOUTH);
this.addMouseListener(new MouseListener() {
#Override
public void mouseReleased(MouseEvent arg0) {
// TODO Auto-generated method stub
}
#Override
public void mousePressed(MouseEvent clickEvent) {
// TODO Auto-generated method stub
System.out.println("X coordinate =" + clickEvent.getX());
System.out.println("Y coordinate = " + clickEvent.getY());
double radius1;
int x = 0;
double y = 0;
int radius = 15;
double xM = clickEvent.getX();
double yM = clickEvent.getY();
radius1 = Math.sqrt((xM - x) * (xM - x) + (yM - y)
* (yM - y));
System.out.println("Radius1 =" + radius1);
// ballPanel.list.get(0).setD
}
#Override
public void mouseExited(MouseEvent arg0) {
// TODO Auto-generated method stub
}
#Override
public void mouseEntered(MouseEvent arg0) {
// TODO Auto-generated method stub
}
#Override
public void mouseClicked(MouseEvent arg0) {
// TODO Auto-generated method stub
}
});
// Register listeners
Suspend.addActionListener(new Listener());
Resume.addActionListener(new Listener());
Add.addActionListener(new Listener());
Subtract.addActionListener(new Listener());
Delay.addAdjustmentListener(new AdjustmentListener() {
public void adjustmentValueChanged(AdjustmentEvent e) {
ballPanel.setDelay(Delay.getMaximum() - e.getValue());
}
});
}
class Listener implements ActionListener {
public void actionPerformed(ActionEvent e) {
if (e.getSource() == Suspend) {
ballPanel.suspend();
} else if (e.getSource() == Resume) {
ballPanel.resume();
} else if (e.getSource() == Add) {
ballPanel.add();
} else if (e.getSource() == Subtract) {
ballPanel.subtract();
}
}
}
}
class BallPanel extends JPanel {
/**
*
*/
private static final long serialVersionUID = 1L;
private int delay = 30;
public ArrayList<AnimatedShape> list = new ArrayList<AnimatedShape>();
private AnimatedRectange rectangle;
public BallPanel() {
this.rectangle = new AnimatedRectange(-25, 373, 50, 25, Color.BLACK);
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
// Create a timer with the initial delay
protected Timer timer = new Timer(delay, new ActionListener() {
/**
* Handle the action event
*/
#Override
public void actionPerformed(ActionEvent e) {
for (AnimatedShape ball : list) {
ball.update(getBounds());
}
rectangle.update(getBounds());
repaint();
}
});
public void add() {
int radius = 15;
// Randomised position
int x = (int) (Math.random() * (getWidth() - (radius * 2)))
+ radius;
int y = (int) (Math.random() * (getHeight() - (radius * 2)))
+ radius;
Color color = new Color((int) (Math.random() * 256),
(int) (Math.random() * 256), (int) (Math.random() * 256));
AnimatedBall ball = new AnimatedBall(x, y, radius, color);
list.add(ball);
}
// public void formula(MouseEvent clickEvent) {
// double radius1;
// int x = 0;
// double y = 0;
// int radius = 15;
// double xM = clickEvent.getX();
// double yM = clickEvent.getY();
// radius1 = Math.sqrt((xM - x) * (xM - x) + (yM - y) * (yM - y));
// System.out.println("Radius1 =" + radius1);
// }
public void subtract() {
if (list.size() > 0) {
list.remove(list.size() - 1); // Remove the last ball
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
for (AnimatedShape ball : list) {
ball.paint(this, g2d);
}
rectangle.paint(this, g2d);
}
public void suspend() {
timer.stop();
}
public void resume() {
timer.start();
}
public void setDelay(int delay) {
this.delay = delay;
timer.setDelay(delay);
}
}
public interface AnimatedShape {
public void update(Rectangle bounds);
public void paint(JComponent parent, Graphics2D g2d);
}
public abstract class AbstractAnimatedShape implements AnimatedShape {
private Rectangle bounds;
private int dx, dy;
public AbstractAnimatedShape() {
}
public void setBounds(Rectangle bounds) {
this.bounds = bounds;
}
public Rectangle getBounds() {
return bounds;
}
public int getDx() {
return dx;
}
public int getDy() {
return dy;
}
public void setDx(int dx) {
this.dx = dx;
}
public void setDy(int dy) {
this.dy = dy;
}
#Override
public void update(Rectangle parentBounds) {// ball
Rectangle bounds = getBounds();
int dx = getDx();
int dy = getDy();
bounds.x += dx;
bounds.y += dy;
if (bounds.x < parentBounds.x) {
bounds.x = parentBounds.x;
setDx(dx *= -1);
} else if (bounds.x + bounds.width > parentBounds.x
+ parentBounds.width) {
bounds.x = parentBounds.x + (parentBounds.width - bounds.width);
setDx(dx *= -1);
}
if (bounds.y < parentBounds.y) {
bounds.y = parentBounds.y;
setDy(dy *= -1);
} else if (bounds.y + bounds.height > parentBounds.y
+ parentBounds.height) {
bounds.y = parentBounds.y
+ (parentBounds.height - bounds.height);
setDy(dy *= -1);
}
}
}
public class AnimatedBall extends AbstractAnimatedShape {
private Color color;
public AnimatedBall(int x, int y, int radius, Color color) {
setBounds(new Rectangle(x, y / 2, radius * 2, radius * 2));
this.color = color;
setDx(Math.random() > 0.5 ? 2 : -2);
// setDy(Math.random() > 0.5 ? 2 : -2);
}
public Color getColor() {
return color;
}
#Override
public void paint(JComponent parent, Graphics2D g2d) {
Rectangle bounds = getBounds();
g2d.setColor(getColor());
g2d.fillOval(bounds.x, bounds.y, bounds.width, bounds.height);
}
}
public class AnimatedRectange extends AbstractAnimatedShape {
private Color color;
public AnimatedRectange(int x, int y, int width, int height, Color color) {
setBounds(new Rectangle(x, y, width, height));
this.color = color;
setDx(2);
}
// Don't want to adjust the vertical speed
#Override
public void setDy(int dy) {
}
#Override
public void paint(JComponent parent, Graphics2D g2d) {
Rectangle bounds = getBounds();
g2d.setColor(color);
g2d.fill(bounds);
}
}
/**
* Main method
*/
public static void main(String[] args) {
new Game();
}
}

At the end of your mousePressed method, you can go though all AnimatedShape objects, check whether they are an AnimatedBall. When the object is a ball, you can test whether the mouse click hits the ball. The mouse click hits the ball when the distance between the center of the ball and the mouse position is smaller than the ball radius. When the ball is hit, you can set its horizontal speed to 0, and the vertical speed to 5 or so.
for (AnimatedShape as : ballPanel.list)
{
if (as instanceof AnimatedBall)
{
AnimatedBall ball = (AnimatedBall)as;
Rectangle b = ball.getBounds();
int ballCenterX = b.x + b.width / 2;
int ballCenterY = b.y + b.height / 2;
Point p = new Point(ballCenterX, ballCenterY);
double d = p.distance(clickEvent.getPoint());
if (d < radius)
{
ball.setDx(0);
ball.setDy(5);
}
}
}
Note
In order to make this work properly, you have to attach this listener to the ballPanel. Originally, you had the line
this.addMouseListener(new MouseListener() {
in your code. You have to change this to
ballPanel.addMouseListener(new MouseListener() {
Otherwise, the mouse coordinates will refer to the wrong component!
Concerning the question from the comment
how can I stop and disapper clickedball's when they crash the bound
You may probably insert method to check this, and call this method in the actionPerformed method of your timer. Further explainations are probably beyond the scope of an anser on a Q&A site. Stackoverflow is not a homework-solution-generator.