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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();
}
});
}
}

Java moving a circle in a gui with arrow keys

I am trying to move a circle left with a keyEvent. So far, the circle is drawn on the window but it does not move left! I feel like the problem is where I add the Window() constructor to the container. The is no output on the console to tell me that it is working. So I dont think it even reaches the KeyEvent class. Here is my code:
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.Ellipse2D;
import javax.swing.*;
public class Window extends JPanel {
private static Ellipse2D.Double circle;
public Window() {
super();
int width = 400;
int height = 400;
circle = new Ellipse2D.Double(0.5 * width, 0.9 * height,
0.1 * width, 0.05 * height);
addKeyListener(new MoveCircle());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponents(g);
Graphics2D brush = (Graphics2D) g;
int width = getWidth();
int height = getHeight();
g.clearRect(0, 0, width, height);
brush.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
brush.draw(circle);
}
public class MoveCircle implements KeyListener {
#Override
public void keyPressed(KeyEvent e) {
System.out.println("Working on top!");
if (e.getKeyCode() == KeyEvent.VK_LEFT) {
System.out.println("Working on bottom!");
circle.x++;
repaint();
}
}
#Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub
}
#Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
}
public static void main(String[] args) {
Window window = new Window();
JFrame frame = new JFrame();
Container container = frame.getContentPane();
container.add(new Window());
frame.addKeyEvent(window.new MoveCircle());
frame.setSize(800, 700);
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setVisible(true);
}
}

Actually what is happening is this, you are adding Window to the JFrame, but the focus lies with the JFrame, so when you type on your Keyboard that thing goes to the JFrame not the KeyListener attached to the Window class. So in order to get over it, you simply have to call requestFocusInWindow() on the Window class's Object. Try this code, I had done some modification regarding EDT and stuff.
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.Ellipse2D;
import javax.swing.*;
public class Window extends JPanel {
private static Ellipse2D.Double circle;
private JFrame frame;
public Window() {
super();
int width = 400;
int height = 400;
circle = new Ellipse2D.Double(0.5 * width, 0.9 * height,
0.1 * width, 0.05 * height);
}
public Dimension getPreferredSize()
{
return (new Dimension(frame.getWidth(), frame.getHeight()));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponents(g);
Graphics2D brush = (Graphics2D) g;
int width = getWidth();
int height = getHeight();
g.clearRect(0, 0, width, height);
brush.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
brush.draw(circle);
}
public class MoveCircle implements KeyListener {
#Override
public void keyPressed(KeyEvent e) {
System.out.println("Working on top!");
if (e.getKeyCode() == Event.ENTER) {
System.out.println("Working on bottom!");
double newX = circle.x - 1;
circle.x = newX;
repaint();
}
}
#Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub
}
#Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
}
private void createAndDisplayGUI(Window window)
{
frame = new JFrame();
Container container = frame.getContentPane();
container.add(window);
window.addKeyListener(new MoveCircle());
frame.setSize(800, 700);
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setVisible(true);
window.requestFocusInWindow();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
Window window = new Window();
window.createAndDisplayGUI(window);
}
});
}
}

Only the focussed component will get key events. You need to call requestFocus() at some point.

A solution would be, to add the KeyListener to the JFrame. This way all the key strokes will throw an event, when the JFrame has the focus.

Changing JPanel Graphics g color drawing line

i have a program similar to paint. and that i am trying to implement a change pen color however when i change the color, everything currently drawn is changed to the color RED for example in my program,how can i make it such that it will not repaint everything currently drawn to the currently changed color?Below code will compile and run
Class for the JPanel drawing area
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import javax.swing.BorderFactory;
import javax.swing.JPanel;
//refer to http://jkost.ergoway.gr/jnkjavaconnection/freedraw.html for the algorithm.
public class STDrawingArea extends JPanel {
/**
*
*/
private static final long serialVersionUID = 1L;
ArrayList<Rectangle> dPoint = new ArrayList<Rectangle>();
Point point = new Point(-1,-1);
private Color currentColor;
public STDrawingArea()
{
setBorder(BorderFactory.createLineBorder(Color.black));
setBackground(Color.WHITE);
addMouseMotionListener(new MouseAdapter() {
public void mouseDragged(MouseEvent e)
{
dPoint.add(new Rectangle(point.x,point.y,e.getX(),e.getY()));
point.x = e.getX();
point.y = e.getY();
repaint();
}
});
addMouseListener(new MouseAdapter(){
public void mousePressed(MouseEvent e)
{
System.out.println("mousePressed X: "+e.getX()+"mousePressed Y: "+e.getY());
dPoint.add(new Rectangle(e.getX(),e.getY(),-1,-1));
point.x = e.getX();
point.y = e.getY();
}
});
addMouseListener(new MouseAdapter(){
public void mouseReleased(MouseEvent e)
{
System.out.println("mouseReleased X: "+e.getX()+"mouseReleased Y: "+e.getY());
repaint();
}
});
}
#Override
public Dimension getPreferredSize() {
return new Dimension(700,500);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(getCurrentColor());
for (int i=0; i < dPoint.size(); i++) {
Rectangle r = dPoint.get(i);
if (r.width != -1)
{
g.drawLine(r.x, r.y, r.width, r.height);
}
}
/* Draw current point.*/
g.drawLine(point.x, point.y, point.x, point.y);
}
//set current drawing color
public void changePenColor(Color color)
{
if (color == null)
setCurrentColor(Color.BLACK);
else
setCurrentColor(color);
}
//clear drawings method
public void clearDrawings()
{
if(!(dPoint==null))
{
dPoint.clear();
repaint();
}
}
private void setCurrentColor(Color currentColor) {
this.currentColor = currentColor;
}
private Color getCurrentColor() {
return currentColor;
}
}
Test main class.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class STTestMain extends JFrame {
STDrawingArea drawingArea = new STDrawingArea();
public STTestMain()
{
//JFrame settings
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Spelling Trainer");
setResizable(false);
setVisible(true);
//Panel of buttons
JPanel buttonContainer = new JPanel();
JButton btnPenColor = new JButton("Red Pen");
buttonContainer.add(btnPenColor);
//Drawing Area instantiation
//Adding things to JFrame
getContentPane().add(drawingArea);
getContentPane().add(buttonContainer,BorderLayout.PAGE_END);
pack();
//button listener
btnPenColor.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
drawingArea.changePenColor(Color.RED);
}
});
}
public static void main(String args[])
{
STTestMain test = new STTestMain();
}
}

One way:
Use your ArrayList to draw the current curve as it is being drawn, but
Use a BufferedImage to draw your completed curves
You would do this on mouseReleased and would draw the current curve to the BufferedImage using the current color.
You'll also need to re-initialize your ArrayList of points after drawing to the BufferedImage.
Don't forget to dispose of the BufferedImage's Graphics object after you're done using it.
Draw the BufferedImage in your paintComponent method after super.paintComponent but before drawing your current curve.
This way when you change the color of your drawing, only the current curve is effected.
EDIT
You've mentioned in a comment that you're not familiar with BufferedImage, and are looking for another way. I suppose you could create a class that holds an ArrayList of Points together with a Color, and then on each mouseReleased create an object of this class and add it to an ArrayList in your drawing panel. Then your paintComponent method could iterate through that ArrayList, drawing the list of Points with their associated color, but my gut tells me that you're an intelligent guy and that you'd pick up on how to use a BufferedImage in no time. I really think it's the best solution. And if you try it and it flops, show us your code, and we'll likely be able to help you.
EDIT 2
The BufferedImage constructor will need the image width, height and an image type -- something I'm not 100% familiar with. I usually use BufferedImage.TYPE_INT_RGB for general purpose drawing, and BufferedImage.TYPE_INT_ARGB for general purpose that needs an alpha too. Then you'll extract a Graphics object out of the BufferedImage, say getGraphics() if all you need is a Graphics object and not a Graphics2D object. Then when you initialize the BufferedImage in your constructor, fill it with a Color.white, just as you for your JPanel. Then dispose the Graphics object. Then each time you want to draw, you getGraphics, draw with it, just like you do in the paintComponent method, dispose of the Graphics when done, and finally draw the BufferedImage in the paintComponent via the drawImage method.
EDIT 3
Example program that doesn't do quite what you are trying to do but does illustrate use of a BufferedImage with drawing. This program changes the color each time a new path or curve is drawn.
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.util.ArrayList;
import javax.swing.*;
public class STTestSimple {
private static void createAndShowUI() {
STDrawPanel drawPanel = new STDrawPanel();
STMouseAdapter mAdapter = new STMouseAdapter(drawPanel);
drawPanel.addMouseListener(mAdapter);
drawPanel.addMouseMotionListener(mAdapter);
JFrame frame = new JFrame("Drawing");
frame.getContentPane().add(drawPanel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(false);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
createAndShowUI();
}
});
}
}
#SuppressWarnings("serial")
class STDrawPanel extends JPanel {
private static final int ST_WIDTH = 700;
private static final int ST_HEIGHT = 500;
private static final Color BACKGROUND_COLOR = Color.white;
private static final float STROKE_WIDTH = 6f;
private static final Stroke STROKE = new BasicStroke(STROKE_WIDTH,
BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND);
private static final Color[] colors = {Color.black, Color.blue, Color.red,
Color.green, Color.orange, Color.MAGENTA};
private BufferedImage bImage = new BufferedImage(ST_WIDTH, ST_HEIGHT,
BufferedImage.TYPE_INT_RGB);
private Color color = Color.black;
private ArrayList<Point> points = new ArrayList<Point>();
private int colorIndex = 0;
public STDrawPanel() {
Graphics g = bImage.getGraphics();
g.setColor(BACKGROUND_COLOR);
g.fillRect(0, 0, ST_WIDTH, ST_HEIGHT);
g.dispose();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(bImage, 0, 0, null);
Graphics2D g2 = (Graphics2D) g;
drawCurve(g2);
}
private void addCurveToBufferedImage() {
Graphics2D g2 = bImage.createGraphics();
drawCurve(g2);
g2.dispose();
}
private void drawCurve(Graphics2D g2) {
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.setStroke(STROKE);
g2.setColor(color);
if (points != null && points.size() > 1) {
for (int i = 0; i < points.size() - 1; i++) {
int x1 = points.get(i).x;
int y1 = points.get(i).y;
int x2 = points.get(i + 1).x;
int y2 = points.get(i + 1).y;
g2.drawLine(x1, y1, x2, y2);
}
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(ST_WIDTH, ST_HEIGHT);
}
public void curveStart(Point point) {
points.clear();
points.add(point);
}
public void curveEnd(Point point) {
points.add(point);
addCurveToBufferedImage();
points.clear();
repaint();
colorIndex++;
colorIndex %= colors.length;
setColor(colors[colorIndex]);
}
public void curveAdd(Point point) {
points.add(point);
repaint();
}
public void setColor(Color color) {
this.color = color;
}
}
class STMouseAdapter extends MouseAdapter {
private STDrawPanel drawPanel;
public STMouseAdapter(STDrawPanel drawPanel) {
this.drawPanel = drawPanel;
}
#Override
public void mousePressed(MouseEvent e) {
drawPanel.curveStart(e.getPoint());
}
#Override
public void mouseReleased(MouseEvent e) {
drawPanel.curveEnd(e.getPoint());
}
#Override
public void mouseDragged(MouseEvent e) {
drawPanel.curveAdd(e.getPoint());
}
}

Custom Painting Approaches gives two ideas on how you might do this.

Thanks hovercraft, i've done it looking at your code and fiddling around lol.
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.util.ArrayList;
import javax.swing.BorderFactory;
import javax.swing.JPanel;
public class STDrawingArea extends JPanel {
/**
*
*/
private static final int DA_WIDTH = 700;
private static final int DA_HEIGHT = 500;
private static final Color DA_BGCOLOR = Color.WHITE;
private static final long serialVersionUID = 1L;
ArrayList<Point> points = new ArrayList<Point>();
private Color currentColor;
BufferedImage bImage = new BufferedImage(DA_WIDTH, DA_HEIGHT, BufferedImage.TYPE_INT_RGB);
public STDrawingArea()
{
setBorder(BorderFactory.createLineBorder(Color.black));
//Basic Settings for bImage
Graphics g2d = bImage.getGraphics();
g2d.setColor(DA_BGCOLOR);
g2d.fillRect(0, 0, DA_WIDTH, DA_HEIGHT);
g2d.dispose();
addMouseListener(new MouseAdapter(){
public void mousePressed(MouseEvent e)
{
points.clear();
points.add(e.getPoint());
}
});
addMouseMotionListener(new MouseAdapter() {
public void mouseDragged(MouseEvent e)
{
points.add(e.getPoint());
repaint();
}
});
addMouseListener(new MouseAdapter(){
public void mouseReleased(MouseEvent e)
{
points.add(e.getPoint());
points.clear();
System.out.println("mouseReleased X: "+e.getX()+"mouseReleased Y: "+e.getY());
repaint();
}
});
}
#Override
public Dimension getPreferredSize() {
return new Dimension(DA_WIDTH,DA_HEIGHT);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
drawIntoBufferedImage();
g.drawImage(bImage,0,0,null);
freehandLines(g);
}
public void drawIntoBufferedImage()
{
Graphics g = bImage.getGraphics();
freehandLines(g);
g.dispose();
}
public void freehandLines(Graphics g)
{
if(points != null && points.size() > 1)
{
g.setColor(getCurrentColor());
for(int i = 0; i < points.size()-1;i++)
{
int x1 = points.get(i).x;
int y1 = points.get(i).y;
int x2 = points.get(i+1).x;
int y2 = points.get(i+1).y;
g.drawLine(x1, y1, x2, y2);
}
}
}
//clear drawings method
public void clearDrawings()
{
if(points!=null)
{
points.clear();
Graphics g = bImage.getGraphics();
g.setColor(DA_BGCOLOR);
g.fillRect(0, 0, DA_WIDTH, DA_WIDTH);
g.dispose();
repaint();
}
}
public void setCurrentColor(Color currentColor) {
if(currentColor == null)
{
currentColor = Color.BLACK;
}else{
this.currentColor = currentColor;
}
}
public Color getCurrentColor() {
if (currentColor == null)
return Color.BLACK;
else
return currentColor;
}
}
main class
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class STTestMain extends JFrame {
STDrawingArea drawingArea = new STDrawingArea();
public STTestMain()
{
//JFrame settings
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Spelling Trainer");
setResizable(false);
setVisible(true);
//Panel of buttons
JPanel buttonContainer = new JPanel();
JButton btnRedPen = new JButton("Red Pen");
JButton btnGreenPen = new JButton("Green Pen");
JButton btnClear = new JButton("Clear");
buttonContainer.add(btnRedPen);
buttonContainer.add(btnGreenPen);
buttonContainer.add(btnClear);
//Drawing Area instantiation
//Adding things to JFrame
getContentPane().add(drawingArea);
getContentPane().add(buttonContainer,BorderLayout.PAGE_END);
pack();
//button listener
btnRedPen.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
drawingArea.setCurrentColor(Color.RED);
}
});
btnGreenPen.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
drawingArea.setCurrentColor(Color.GREEN);
}
});
btnClear.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
drawingArea.clearDrawings();
}
});
}
public static void main(String args[])
{
STTestMain test = new STTestMain();
}
}

problem displaying mouse coordinates on the screen in java

I'm trying to display mouse coordinates (math coordinates) in my JPanel , but i get each coordinates on top of the other ,can' figure out why .
here's my code :
import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.geom.Line2D;
import java.awt.geom.Point2D;
import java.applet.*;
import javax.swing.JPanel;
import javax.swing.event.MouseInputAdapter;
public class drawarea extends JPanel {
int n;
private Point mouseCoords = null;
int UNIT = 20;
drawarea() {
super();
setBackground(Color.white);
addMouseMotionListener(new MouseInputAdapter() {
public void mouseMoved(MouseEvent e) {
super.mouseMoved(e);
mouseCoords = new Point(e.getX(), e.getY());
repaint();
}
/**
* #see java.awt.event.MouseListener#mouseExited(MouseEvent)
*/
public void mouseExited(MouseEvent e) {
super.mouseExited(e);
mouseCoords = null;
repaint();
}
});
setCursor(new Cursor(Cursor.CROSSHAIR_CURSOR));
}
public void paint(Graphics g) {
//draw axis x and y
g.setColor(Color.red);
g.drawLine(0, r.height / 2, r.width, r.height / 2);
g.drawLine(r.width / 2, 0, r.width / 2, r.height);
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
dessinBoule(g2);
}
private void dessinBoule(Graphics2D g) {
// if mouse isnt inside the ara where
// i want the coordinates to bes displayed
if (mouseCoords == null) {
return;
}
g.setColor(Color.BLACK);
int decPolice = 15;
g.drawString("x = " + getFormatedString("" + mouseCoords.x)
+ " , y = " + getFormatedString("" + mouseCoords.y), 2, 15);
}
private String getFormatedString(String s) {
if (s.length() > 4) {
return s.substring(0, 3);
}
return s;
}
}
thanks.

You're drawing on your graphics area, so g.drawString(...) draws a string on top of what is already there. You must either erase what is there first, by drawing a rectangle in the background colour, or use a separate component that you can manage with a separate paint(...) method.

An example of #richj's suggestion is shown below. Note that in Swing you should override paintComponent(). Also, the implementation of MouseInputAdapter is empty, so you don't need to invoke super().
import java.awt.*;
import java.awt.event.MouseEvent;
import javax.swing.*;
import javax.swing.event.MouseInputAdapter;
public class DrawArea extends JPanel {
private Point mouseCoords = new Point();
DrawArea() {
super();
this.setPreferredSize(new Dimension(320, 240));
setBackground(Color.white);
addMouseMotionListener(new MouseInputAdapter() {
#Override
public void mouseMoved(MouseEvent e) {
mouseCoords = e.getPoint();
repaint();
}
#Override
public void mouseExited(MouseEvent e) {
mouseCoords = null;
repaint();
}
});
setCursor(new Cursor(Cursor.CROSSHAIR_CURSOR));
}
#Override
public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.clearRect(0, 0, getWidth(), getHeight());
g2.setColor(Color.red);
if (!(mouseCoords == null)) {
g2.drawString(mouseCoords.toString(), 10, getHeight() - 10);
}
}
private static void create() {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new DrawArea());
f.pack();
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
create();
}
});
}
}

Why can't I draw an ellipse with this code?

package test;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.Ellipse2D;
import java.awt.image.BufferedImage;
import javax.swing.*;
public class test_bmp extends JPanel implements MouseListener,MouseMotionListener,ActionListener
{
static BufferedImage image;
Color color;
Point start=new Point();
Point end =new Point();
JButton elipse=new JButton("Elipse");
JButton rectangle=new JButton("Rectangle");
JButton line=new JButton("Line");
String selected;
public test_bmp()
{
color = Color.black;
setBorder(BorderFactory.createLineBorder(Color.black));
addMouseListener(this);
addMouseMotionListener(this);
}
public void paintComponent(Graphics g)
{
//super.paintComponent(g);
g.drawImage(image, 0, 0, this);
Graphics2D g2 = (Graphics2D)g;
g2.setPaint(Color.black);
if(selected=="elipse")
{
g2.drawOval(start.x, start.y, (end.x-start.x),(end.y-start.y));
System.out.println("Start : "+start.x+","+start.y);
System.out.println("End : "+end.x+","+end.y);
}
if(selected=="line")
g2.drawLine(start.x,start.y,end.x,end.y);
}
//Draw on Buffered image
public void draw()
{
Graphics2D g2 = image.createGraphics();
g2.setPaint(color);
System.out.println("draw");
if(selected=="line")
g2.drawLine(start.x, start.y, end.x, end.y);
if(selected=="elipse")
{
g2.drawOval(start.x, start.y, (end.x-start.x),(end.y-start.y));
System.out.println("Start : "+start.x+","+start.y);
System.out.println("End : "+end.x+","+end.y);
}
repaint();
g2.dispose();
}
public JPanel addButtons()
{
JPanel buttonpanel=new JPanel();
buttonpanel.setBackground(color.lightGray);
buttonpanel.setLayout(new BoxLayout(buttonpanel,BoxLayout.Y_AXIS));
elipse.addActionListener(this);
rectangle.addActionListener(this);
line.addActionListener(this);
buttonpanel.add(elipse);
buttonpanel.add(Box.createRigidArea(new Dimension(15,15)));
buttonpanel.add(rectangle);
buttonpanel.add(Box.createRigidArea(new Dimension(15,15)));
buttonpanel.add(line);
return buttonpanel;
}
public static void main(String args[])
{
test_bmp application=new test_bmp();
//Main window
JFrame frame=new JFrame("Whiteboard");
frame.setLayout(new BorderLayout());
frame.add(application.addButtons(),BorderLayout.WEST);
frame.add(application);
//size of the window
frame.setSize(600,400);
frame.setLocation(0,0);
frame.setVisible(true);
int w = frame.getWidth();
int h = frame.getHeight();
image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = image.createGraphics();
g2.setPaint(Color.white);
g2.fillRect(0,0,w,h);
g2.dispose();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
#Override
public void mouseClicked(MouseEvent arg0) {
// TODO Auto-generated method stub
}
#Override
public void mouseEntered(MouseEvent arg0) {
// TODO Auto-generated method stub
}
#Override
public void mouseExited(MouseEvent arg0) {
// TODO Auto-generated method stub
}
#Override
public void mousePressed(MouseEvent event)
{
start = event.getPoint();
}
#Override
public void mouseReleased(MouseEvent event)
{
end = event.getPoint();
draw();
}
#Override
public void mouseDragged(MouseEvent e)
{
end=e.getPoint();
repaint();
}
#Override
public void mouseMoved(MouseEvent arg0) {
// TODO Auto-generated method stub
}
#Override
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==elipse)
selected="elipse";
if(e.getSource()==line)
selected="line";
draw();
}
}
I need to create a paint application. When I draw ellipse by dragging mouse from left to right it displays nothing. Why? Should I use any other function here?

Your program does draw an ellipse when you drag the mouse down and to the right. It's dragging up and/or left that does not work, because Graphics.drawOval does not work with a negative width or height.
Try adding a method like this:
private Shape createEllipse() {
Ellipse2D e = new Ellipse2D.Double();
e.setFrameFromDiagonal(start, end);
return e;
}
Then call it from draw and paintComponent like this:
if(selected=="elipse") {
g2.draw(createEllipse());
}
Also you probably do not need the call to draw() at the end of actionPerformed. If you switch between line and ellipse mode it will draw an ellipse with the same coordinates as the most recent line or vice-versa.
And one coding style issue: Using string literals for selected is confusing (although it does work.) I would define an enum instead.