Develop Reference

How to clip a BufferedImage with a shape created with Graphics2D?(Java)

Currently, I'm working on my first Java application with which a user can look through photos, cut them and rotate. I have an issue with clipping an image. What I want to achieve is the following:
User clicks on the "Cut" option
Rectangle shape called by repaint method appears on the image
By stretching the rectangle user chooses the area for cutting
When the user releases the mouse(which stops stretching the rectangle) the area that is surrounded with the rectangle is left and all the rest of the image is cut.
As of for now I have several issues:
My image is centralized on JLabel which in its turn is added to JPanel and the last is added to JFrame, so now, when I want to add a rectangle above JLable (so it is to be located on the picture) it's invisible and is added only on JPanel directly.
I drew an image with paintComponent but can't figure out how to move and stretch it and repaint the rectangle again.
Below is the part of my code which (I hope) will describe my problems more precisely:
public class GraphicalUserInterface {
static JPanel background;
static JLabel labelIcon;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new GraphicalUserInterface().go();
}
});
}
public void go() {
buildGui();
}
public void buildGui() {
frame = new JFrame("PicMove");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
BorderLayout layout = new BorderLayout();
background = new JPanel(layout);
/**To center picture on the background**/
labelIcon = new JLabel();
labelIcon.setHorizontalAlignment(JLabel.CENTER);
labelIcon.setVerticalAlignment(JLabel.CENTER);
background.add(BorderLayout.SOUTH, bottom);
background.add(BorderLayout.PAGE_START, bar);
background.add(BorderLayout.CENTER, labelIcon);
background.add(BorderLayout.EAST, chatPanel);
frame.getContentPane().add(BorderLayout.CENTER, background);
frame.setJMenuBar(menuBar);
frame.setVisible(true);
frame.setSize(1300, 1200);}
static class CutImage extends JPanel implements Runnable {
boolean clip;
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
if (clip) {
BasicStroke bs = new BasicStroke(50, BasicStroke.CAP_BUTT, BasicStroke.JOIN_MITER,
10, null, 0);
g2d.setStroke(bs);
QuadCurve2D.Float qc = new QuadCurve2D.Float(20, 50, 100, 140, 460, 170);
g2d.setClip(qc);
}
BasicStroke bs = new BasicStroke(5, BasicStroke.CAP_BUTT, BasicStroke.JOIN_MITER,
10, new float[]{10}, 0);
g2d.setStroke(bs);
g2d.drawRect(260, 50, 80, 120);
}
#Override
public void run() {
CutImage cutPanel = new CutImage();
GraphicalUserInterface.background.add(cutPanel).repaint();
}
}
public class PicChanges implements Runnable{
static BufferedImage newImage;
static File [] selectedFile;
static int currentImage;
FileNameExtensionFilter filter;
JFileChooser fileChooser;
public void openPic() {
currentImage = 0;
try {
fileChooser = new JFileChooser();
fileChooser.setCurrentDirectory(new java.io.File((System.getProperty("user.home"))));
filter = new FileNameExtensionFilter("*.images", "jpg", "gif", "png");
fileChooser.addChoosableFileFilter(filter);
fileChooser.setMultiSelectionEnabled(true);
int result = fileChooser.showOpenDialog(null);
if (result == JFileChooser.OPEN_DIALOG) {
selectedFile = fileChooser.getSelectedFiles();
for (File image : selectedFile) {
if ((image.isFile()) && (selectedFile.length > 0)){
newImage = ImageIO.read(selectedFile[0]);
GraphicalUserInterface.labelIcon.setIcon(new ImageIcon(
new ImageIcon(newImage).getImage().getScaledInstance(
450, 620, Image.SCALE_DEFAULT)));
} else if (result == JFileChooser.CANCEL_OPTION) {
System.out.println("No Pics Selected");
}
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
#Override
public void run() {
Thread.currentThread().interrupt();
openPic();
}
public static void nextPic() {
currentImage++;
try {
newImage = ImageIO.read(selectedFile[currentImage]);
} catch (IOException e) {
e.printStackTrace();
System.out.println("No pictures left");
System.out.println("next"+currentImage);
}
GraphicalUserInterface.labelIcon.setIcon(new ImageIcon(
new ImageIcon(newImage).getImage().getScaledInstance(
450, 620, Image.SCALE_DEFAULT)));
}
static class NextPicture implements Runnable{
#Override
public void run() {
Thread.currentThread().interrupt();
nextPic();
}
}
public static void previousPic () {
currentImage--;
try {
newImage = ImageIO.read(selectedFile[currentImage]);
} catch (IOException e) {
e.printStackTrace();
System.out.println("previous "+currentImage);
}
GraphicalUserInterface.labelIcon.setIcon(new ImageIcon(
new ImageIcon(newImage).getImage().getScaledInstance(
450, 620, Image.SCALE_DEFAULT)));
}
static class PreviousPic implements Runnable{
#Override
public void run() {
Thread.currentThread().interrupt();
previousPic();
}
}
}
My idea was to add MouseListeners but can I add it to the shape created with Graphics2D?
I would be greatful for the help :)
Thank you

Being in search of finding a solution to this question I've asked two more questions(maybe it will be helpful for someone) :
1) Why BufferedImage is not cut according to the drawn in paintComponent method rectangle(its height is calculated wrong)?
2) Repaint() method doesn't invoke paint() & paintComponent() methods one by one, only paintComponent () method is working
that further helped me to find out the way.
My solution is to create a separate frame for displaying copied BufferedImage in it and on this frame to draw a rectangle with the help of MouseListeners. This is the piece of code:
public class ImageScreenShot extends JFrame implements MouseListener, MouseMotionListener {
#Override
public Dimension getPreferredSize() {
return super.getPreferredSize();
}
private static Thread screenShotThread;
public static Thread getScreenShotThread() {
return screenShotThread;
}
public static void setScreenShotThread(Thread screenShot) {
ImageScreenShot.screenShotThread = screenShot;
}
private int drag_status = 0, c1, c2, c3, c4;
public int getC1() {
return c1;
}
public int getC2() {
return c2;
}
public int getC3() {
return c3;
}
public int getC4() {
return c4;
}
class AdditionalPanel extends JLabel {
private BufferedImage img;
public BufferedImage getImg() {
return img;
}
public AdditionalPanel(BufferedImage img) {
this.img = img;
setPreferredSize(new Dimension(2560, 1600));
getPreferredSize();
setLayout(null);
}
#Override
public Dimension getPreferredSize() {
return super.getPreferredSize();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(img, 0, 0, null);
System.out.println("Additional panel class paint method was invoked");
}
}
public void cut() {
AdditionalPanel apanel = new AdditionalPanel(PicChanges.getNewImage());
JScrollPane scrollPane = new JScrollPane(apanel);
scrollPane.addMouseMotionListener(this);
scrollPane.addMouseListener(this);
getContentPane().add(scrollPane, BorderLayout.CENTER);
setPreferredSize(new Dimension(2560, 1600));
getPreferredSize();
pack();
setVisible(true);
}
private void draggedScreen() throws Exception {
int w = c1 - c3;
int h = c2 - c4;
w = w * -1;
h = h * -1;
Robot robot = new Robot();
BufferedImage img = robot.createScreenCapture(new Rectangle(c1, c2, w, h));
File save_path = new File("screen1.jpg");
ImageIO.write(img, "JPG", save_path);
GraphicalUserInterface.getLabelIcon().setIcon(new ImageIcon(new ImageIcon(img).getImage().getScaledInstance(img.getWidth(), img.getHeight(), Image.SCALE_SMOOTH)));
JOptionPane.showConfirmDialog(this, "Would you like to save your cropped Pic?");
System.out.println("Cropped image saved successfully.");
}
#Override
public void mouseClicked(MouseEvent arg0) {
}
#Override
public void mouseEntered(MouseEvent arg0) {
}
#Override
public void mouseExited(MouseEvent arg0) {
}
#Override
public void mousePressed(MouseEvent arg0) {
repaint();
c1 = arg0.getXOnScreen();
c2 = arg0.getYOnScreen();
System.out.println("pressed");
}
#Override
public void mouseReleased(MouseEvent arg0) {
repaint();
if (drag_status == 1) {
c3 = arg0.getXOnScreen();
c4 = arg0.getYOnScreen();
try {
repaint();
draggedScreen();
} catch (Exception e) {
e.printStackTrace();
}
}
}
#Override
public void mouseDragged(MouseEvent arg0) {
repaint();
drag_status = 1;
c3 = arg0.getXOnScreen();
c4 = arg0.getYOnScreen();
}
#Override
public void mouseMoved(MouseEvent arg0) {
}
#Override
public void paint(Graphics g) {
super.paint(g);
int w = c1 - c3;
int h = c2 - c4;
w = w * -1;
h = h * -1;
if (w < 0)
w = w * -1;
g.setColor(Color.RED);
g.drawRect(c1, c2, w, h);
System.out.println("Paint component was invoked in imagescreenshot class");
}
P.S. I know that adding JFrame is not the best solution but I'm still in search for the best way to implement it so do not hesitate to comment on my code and tell what is wrong or what is good)

Why is the this JMenu being displayed on this JPanel?

This illustrates my problem
Im trying to copy a paint like program but whenever I click on the screen the menu bar is displayed in the panel area. It doesn't do it unless I click on the screen (to draw). The menu bar is added before the panel, any help would be much appreciated.
public class Main {
public static Frame frame;
public static Panel panel;
public static MenuBar menubar;
public static void main(String[] args) {
frame = new Frame();
panel = new Panel();
menubar = new MenuBar();
frame.setJMenuBar(menubar);
frame.addMouseMotionListener(panel);
frame.add(panel);
frame.setVisible(true);
}
}
public class Frame extends JFrame {
public Frame() {
setTitle("Paint");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setExtendedState(JFrame.MAXIMIZED_BOTH);
}
}
public class Panel extends JPanel implements MouseMotionListener {
public boolean isMouseDown = false;
public int x1,y1, x2, y2;
public Color colour = Color.BLACK;
public int size = 3;
public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setColor(colour);
g2.setStroke(new BasicStroke(size));
g2.drawLine(x1 - 10, y1 - 80, x2 - 10, y2 - 80);
}
public void mouseDragged(MouseEvent arg0) {
x1 = x2;
y1 = y2;
x2 = arg0.getX();
y2 = arg0.getY();
repaint();
}
public void mouseMoved(MouseEvent arg0) {
x1 = x2;
y1 = y2;
x2 = arg0.getX();
y2 = arg0.getY();
}
public void mouseClicked(MouseEvent arg0) {}
public void mouseEntered(MouseEvent arg0) {}
public void mouseExited(MouseEvent arg0) {}
}
public class MenuBar extends JMenuBar {
JMenu file = new JMenu("File");
JMenu brush = new JMenu("Pen");
JMenu colour = new JMenu("Colour");
Font font = new Font("Times New Romans", Font.PLAIN, 18);
public MenuBar() {
//JMenuBar Code here, left black as very long
}
}

One problems: You need to call super.paintComponent(g); within your paintComponent method. Else the JPanel cannot do its house-keeping painting of its own self.
If you want the drawings to persist, then either create an ArrayList of lines that are then drawn within paintComponent in a for loop, or better, paint onto a BufferedImage which is then displayed within the paintComponent method.
e.g.,
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Stroke;
import java.awt.event.ActionEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import javax.swing.*;
public class MyMain {
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
private static void createAndShowGui() {
MyPainting mainPanel = new MyPainting();
MenuCreator menuCreator = new MenuCreator(mainPanel);
JFrame frame = new JFrame("MyPainting");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.add(mainPanel);
frame.setJMenuBar(menuCreator.getMenubar());
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
}
#SuppressWarnings("serial")
class MyPainting extends JPanel {
private static final int IMG_W = 600;
private static final int IMG_H = 450;
private static final int STROKE_W = 3;
private static final Stroke STROKE = new BasicStroke(STROKE_W);
private BufferedImage img = new BufferedImage(IMG_W, IMG_H, BufferedImage.TYPE_INT_ARGB);
private Color drawColor = Color.BLACK;
public MyPainting() {
setPreferredSize(new Dimension(IMG_W, IMG_H));
MyMouse myMouse = new MyMouse();
addMouseListener(myMouse);
addMouseMotionListener(myMouse);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (img != null) {
g.drawImage(img, 0, 0, this);
}
}
private class MyMouse extends MouseAdapter {
private Graphics2D g2 = null;
private Point p0;
#Override
public void mousePressed(MouseEvent e) {
if (img == null) {
return;
}
g2 = img.createGraphics();
g2.setStroke(STROKE);
g2.setColor(drawColor);
p0 = e.getPoint();
}
#Override
public void mouseDragged(MouseEvent e) {
if (p0 == null) {
return;
}
drawLine(e);
}
#Override
public void mouseReleased(MouseEvent e) {
if (p0 == null) {
return;
}
drawLine(e);
g2.dispose();
p0 = null;
}
private void drawLine(MouseEvent e) {
Point p1 = e.getPoint();
g2.drawLine(p0.x, p0.y, p1.x, p1.y);
repaint();
p0 = p1;
}
}
public void setDrawColor(Color drawColor) {
this.drawColor = drawColor;
}
public void clear() {
img = new BufferedImage(IMG_W, IMG_H, BufferedImage.TYPE_INT_ARGB);
repaint();
}
}
class MenuCreator {
private JMenuBar menubar = new JMenuBar();
private MyPainting myPainting;
public MenuCreator(MyPainting myPainting) {
JMenuItem clearDrawing = new JMenuItem(new AbstractAction("Clear Drawing") {
#Override
public void actionPerformed(ActionEvent arg0) {
if (myPainting != null) {
myPainting.clear();
}
}
});
JMenu fileMenu = new JMenu("File");
fileMenu.add(clearDrawing);
JMenu colourMenu = new JMenu("Colour");
for (MyColor myColor : MyColor.values()) {
colourMenu.add(new JMenuItem(new ColorAction(myColor)));
}
menubar.add(fileMenu);
menubar.add(new JMenu("Pen"));
menubar.add(colourMenu);
this.myPainting = myPainting;
}
public JMenuBar getMenubar() {
return menubar;
}
private class ColorAction extends AbstractAction {
private MyColor myColor;
public ColorAction(MyColor myColor) {
super(myColor.getText());
this.myColor = myColor;
}
#Override
public void actionPerformed(ActionEvent e) {
if (myPainting != null) {
myPainting.setDrawColor(myColor.getColor());
}
}
}
}
enum MyColor {
BLACK("Black", Color.BLACK), RED("Red", Color.RED), ORANGE("Orange", Color.ORANGE), BLUE("Blue", Color.BLUE);
private String text;
private Color color;
private MyColor(String text, Color color) {
this.text = text;
this.color = color;
}
public String getText() {
return text;
}
public Color getColor() {
return color;
}
}

You failed to honour the requirements of the paint chain...
public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setColor(colour);
g2.setStroke(new BasicStroke(size));
g2.drawLine(x1 - 10, y1 - 80, x2 - 10, y2 - 80);
}
Apart from not needing to be public, one of the jobs of paintComponent is to prepare the Graphics context for painting. So, one of the first things you should do is call super.paintComponent before you do any custom painting.
protected void paintComponent(Graphics g) {
super. paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setColor(colour);
g2.setStroke(new BasicStroke(size));
g2.drawLine(x1 - 10, y1 - 80, x2 - 10, y2 - 80);
}
Graphics is a shared context, it is shared amongst the other components which need to be painted, so it is very important that you ensure that it's properly prepared before you paint to it.
It's also important that any significant modifications you make to the context (like transformations or rendering hints) are reversed before the method exists
I would recommend taking a look at Performing Custom Painting and Painting in Swing to gain a better understanding into how the painting system actually works

Drawing shapes in JPanel over an image

I need to draw shapes (circle or free line) over an image that is shown in a JLabel of a JPanel.
I based my code on the questions How to draw thin line with no gap while dragging the cursor? and Draw a circle using 2 mouse clicks.
The code is bellow. The problem is that when I start drawing the image disappears and only reappears after I stop.
If I comment the line super.paintComponent(g); that doesnt happen but when I draw the circle it maintains a path of the previous positions.
public static void main(String args[]) {
try {
URL url = new URL("http://www.senhoritatours.com/wp-content/uploads/2014/05/Porto-.jpg");
backgroundImage = ImageIO.read(url);
} catch (Exception e) {
e.printStackTrace();
}
loadAnnotation();
loadBackground();
JFrame f;
f = new JFrame();
f.setLayout(new BorderLayout());
f.add(mp);
f.pack();
f.setVisible(true);
}
/* Layer 0:
* Load background picture */
public static void loadBackground() {
JLabel lbImg = new JLabel();
lbImg.setBounds(0, 0, new ImageIcon(backgroundImage).getIconWidth(), new ImageIcon(backgroundImage).getIconHeight());
lbImg.setIcon(new ImageIcon(backgroundImage));
mp = new JPanel(new BorderLayout());
btnCircle.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
if(btnCircle.isEnabled())
{
btnCircle.setEnabled(false);
btnLine.setEnabled(true);
}
}
});
btnLine.setEnabled(true);
btnCircle.setEnabled(false);
btnLine.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
if(btnLine.isEnabled())
{
btnLine.setEnabled(false);
btnCircle.setEnabled(true);
}
}
});
mp.add(btnCircle);
mp.add(btnLine);
mp.add(lbImg);
mp.add(p);
}
/* Layer 1:
* Annotation: Draw on top of background picture anything! */
public static void loadAnnotation() {
p = new JPanel() {
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setColor(Color.RED);
if (_bufImage == null) {
int w = this.getWidth();
int h = this.getHeight();
_bufImage = new BufferedImage(1024,600, BufferedImage.TRANSLUCENT);
Graphics2D gc = _bufImage.createGraphics();
}
g2.drawImage(_bufImage, null, 0, 0);
if (_state == State.DRAGGING) {
if (!btnLine.isEnabled())
{
g.drawLine(_start.x, _start.y, _end.x , _end.y);
}
}
if (!btnCircle.isEnabled())
{
g.drawOval(x, y, width, height);
}
}
public Dimension getPreferredSize() {
return new Dimension(1024, 600);
}
};
p.setLayout(new OverlayLayout(p));
p.addMouseListener(new MouseListener() {
#Override
public void mouseClicked(MouseEvent me) {
}
#Override
public void mousePressed(MouseEvent me) {
last = me.getPoint();
dragging = isInsideEllipse(last);
if (!dragging) {
x = last.x;
y = last.y;
width = 0;
height = 0;
}
p.repaint();
}
#Override
public void mouseReleased(MouseEvent me) {
//_state = State.IDLE;
last = null;
dragging = false;
_state = State.IDLE;
p.repaint();
}
#Override
public void mouseEntered(MouseEvent me) {
}
#Override
public void mouseExited(MouseEvent me) {
}
});
p.addMouseMotionListener(new MouseMotionListener() {
#Override
public void mouseDragged(MouseEvent me) {
if(!btnLine.isEnabled())
{
_state = State.DRAGGING;
_end = me.getPoint();
if (_state == State.DRAGGING) {
Graphics2D g2 = _bufImage.createGraphics();
g2.setColor(Color.red);
g2.setStroke(new BasicStroke(2));
g2.drawLine(_start.x, _start.y, _end.x, _end.y);
p.repaint();
//
}
_start = _end;
}
else
{
int dx = me.getX() - last.x;
int dy = me.getY() - last.y;
if (dragging) {
x += dx;
y += dy;
} else {
width += dx;
height += dy;
}
last = me.getPoint();
p.repaint();
}
}
#Override
public void mouseMoved(MouseEvent me) {
//System.out.println("move");
_start = me.getPoint();
}
});
}

Either
Display the image in the same paintComponent method that you're doing your drawing in, via Graphics#drawImage(...). You would call this immediately after the super.paintComponent(g) call.
Or do your drawing in the paintComponent(...) method of your JLabel, the one displaying the image.
For example:
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.*;
#SuppressWarnings("serial")
public class DrawingPanel extends JPanel {
private final static String PATH = "https://upload.wikimedia.org/wikipedia/commons/"
+ "thumb/7/7c/Thomas_Hicks_-_Leopold_Grozelier_-_Presidential_Candidate_"
+ "Abraham_Lincoln_1860_-_cropped_to_lithographic_plate.jpg/"
+ "463px-Thomas_Hicks_-_Leopold_Grozelier_-_Presidential_Candidate_"
+ "Abraham_Lincoln_1860_-_cropped_to_lithographic_plate.jpg";
private static final Color DRAWING_COLOR = new Color(255, 100, 200);
private static final Color FINAL_DRAWING_COLOR = Color.red;
private BufferedImage backgroundImg;
private Point startPt = null;
private Point endPt = null;
private Point currentPt = null;
private int prefW;
private int prefH;
public DrawingPanel() throws IOException {
URL imgUrl = new URL(PATH);
BufferedImage bImg = ImageIO.read(imgUrl);
prefW = bImg.getWidth();
prefH = bImg.getHeight();
backgroundImg = new BufferedImage(prefW, prefH,
BufferedImage.TYPE_INT_ARGB);
Graphics g = backgroundImg.getGraphics();
g.drawImage(bImg, 0, 0, this);
g.dispose();
MyMouseAdapter myMouseAdapter = new MyMouseAdapter();
addMouseMotionListener(myMouseAdapter);
addMouseListener(myMouseAdapter);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (backgroundImg != null) {
g.drawImage(backgroundImg, 0, 0, this);
}
if (startPt != null && currentPt != null) {
g.setColor(DRAWING_COLOR);
int x = Math.min(startPt.x, currentPt.x);
int y = Math.min(startPt.y, currentPt.y);
int width = Math.abs(startPt.x - currentPt.x);
int height = Math.abs(startPt.y - currentPt.y);
g.drawRect(x, y, width, height);
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(prefW, prefH);
}
public void drawToBackground() {
Graphics g = backgroundImg.getGraphics();
g.setColor(FINAL_DRAWING_COLOR);
int x = Math.min(startPt.x, endPt.x);
int y = Math.min(startPt.y, endPt.y);
int width = Math.abs(startPt.x - endPt.x);
int height = Math.abs(startPt.y - endPt.y);
g.drawRect(x, y, width, height);
g.dispose();
startPt = null;
repaint();
}
private class MyMouseAdapter extends MouseAdapter {
#Override
public void mouseDragged(MouseEvent mEvt) {
currentPt = mEvt.getPoint();
DrawingPanel.this.repaint();
}
#Override
public void mouseReleased(MouseEvent mEvt) {
endPt = mEvt.getPoint();
currentPt = null;
drawToBackground();
}
#Override
public void mousePressed(MouseEvent mEvt) {
startPt = mEvt.getPoint();
}
}
private static void createAndShowGui() {
DrawingPanel mainPanel = null;
try {
mainPanel = new DrawingPanel();
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
JFrame frame = new JFrame("Drawing Panel");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}

Adding multiple MouseListeners dynamically JPanel

I am trying to add shapes onto a window using JPanel and then be able to click and drag them around the window. This works if I only have one shape; but when I add more shapes, the click and drag is very funky. It does drag but not with the mouse, it isn't proportional and doesn't drag with the mouse.
Any help is appreciated. Thanks!
public class SimpleDraw {
public static void main(String[] args) {
JFrame frame = new UMLWindow();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setBounds(30, 30, 1000, 700);
frame.getContentPane().setBackground(Color.white);
frame.setVisible(true);
frame.setLocationRelativeTo(null);
// Display the window.
frame.setVisible(true);
}
}
class UMLWindow extends JFrame {
Squares squares = new Squares();
private static final long serialVersionUID = 1L;
public UMLWindow() {
addMenus();
}
public void addMenus() {
getContentPane().add(squares);
JMenuBar menubar = new JMenuBar();
JMenu shapes = new JMenu("Shapes");
JMenuItem rectangleMenuItem = new JMenuItem("New Rectangle");
rectangleMenuItem.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent event) {
squares.addSquare(10, 10, 100, 100);
}
});
shapes.add(rectangleMenuItem);
menubar.add(shapes);
setJMenuBar(menubar);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
}
class Squares extends JPanel {
private static final long serialVersionUID = 1L;
private List<Path2D> squares = new ArrayList<Path2D>();
// private Path2D rect = new Path2D.Double();
int currentIndex;
public void addSquare(int x, int y, int width, int height) {
Path2D rect2 = new Path2D.Double();
rect2.append(new Rectangle(getWidth() / 2 - width / 2, getHeight() / 2
- height / 2, width, height), true);
squares.add(rect2);
// rect = rect2;
MyMouseAdapter myMouseAdapter = new MyMouseAdapter();
addMouseListener(myMouseAdapter);
addMouseMotionListener(myMouseAdapter);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
this.setOpaque(true);
this.setBackground(Color.WHITE);
Graphics2D g2 = (Graphics2D) g;
for (Path2D rect : squares) {
g2.draw(rect);
}
repaint();
}
class MyMouseAdapter extends MouseAdapter {
private boolean pressed = false;
private Point point;
#Override
public void mousePressed(MouseEvent e) {
if (e.getButton() != MouseEvent.BUTTON1) {
return;
}
for (int i = 0; i < squares.size(); i++) {
if (squares.get(i) != null
&& squares.get(i).contains(e.getPoint())) {
currentIndex = i;
pressed = true;
this.point = e.getPoint();
}
}
}
#Override
public void mouseDragged(MouseEvent e) {
if (pressed) {
int deltaX = e.getX() - point.x;
int deltaY = e.getY() - point.y;
squares.get(currentIndex).transform(
AffineTransform.getTranslateInstance(deltaX, deltaY));
point = e.getPoint();
repaint();
}
}
#Override
public void mouseReleased(MouseEvent e) {
pressed = false;
}
}
}

Lot of problems...
Most important, no you don't want to add a bunch of MouseListeners/MouseMotionListeners to your JPanel. You only want to add one, and have it control any and all squares that the JPanel holds.
Don't put a repaint() in your paintComponent method as that's a poor way to try to create an animation loop, a loop that you have absolutely no control over. Plus there's no need. The MouseAdapter should drive all the animation by itself.
class Squares extends JPanel {
private static final long serialVersionUID = 1L;
public Squares() {
MyMouseAdapter myMouseAdapter = new MyMouseAdapter();
addMouseListener(myMouseAdapter);
addMouseMotionListener(myMouseAdapter);
}
private List<Path2D> squares = new ArrayList<Path2D>();
// private Path2D rect = new Path2D.Double();
int currentIndex;
public void addSquare(int x, int y, int width, int height) {
Path2D rect2 = new Path2D.Double();
rect2.append(new Rectangle(getWidth() / 2 - width / 2, getHeight() / 2
- height / 2, width, height), true);
squares.add(rect2);
repaint(); // !!
// rect = rect2;
// !! MyMouseAdapter myMouseAdapter = new MyMouseAdapter();
// addMouseListener(myMouseAdapter);
// addMouseMotionListener(myMouseAdapter);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
this.setOpaque(true);
this.setBackground(Color.WHITE);
Graphics2D g2 = (Graphics2D) g;
for (Path2D rect : squares) {
g2.draw(rect);
}
// !! repaint();
}

Problem with my whiteboard application

I have to develop a whiteboard application in which both the local user and the remote user should be able to draw simultaneously, is this possible? If possible then any logic?
I have already developed a code but in which i am not able to do this, when the remote user starts drawing the shape which i am drawing is being replaced by his shape and co-ordinates.
This problem is only when both draw simultaneously.
any idea guys?
Here is my code
class Paper extends JPanel implements MouseListener,MouseMotionListener,ActionListener
{
static BufferedImage image;
int bpressed;
Color color;
Point start;
Point end;
Point mp;
Button elipse=new Button("elipse");
Button rectangle=new Button("rect");
Button line=new Button("line");
Button empty=new Button("");
JButton save=new JButton("Save");
JButton erase=new JButton("Erase");
String selected;
int ex,ey;//eraser
DatagramSocket dataSocket;
JButton button = new JButton("test");
Client client;
Point p=new Point();
int w,h;
public Paper(DatagramSocket dataSocket)
{
this.dataSocket=dataSocket;
client=new Client(dataSocket);
System.out.println("paper");
setBackground(Color.white);
addMouseListener(this);
addMouseMotionListener(this);
color = Color.black;
setBorder(BorderFactory.createLineBorder(Color.black));
//save.setPreferredSize(new Dimension(100,20));
save.setMaximumSize(new Dimension(75,27));
erase.setMaximumSize(new Dimension(75,27));
}
public void paintComponent(Graphics g)
{
try
{
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));
else if(selected==("rect"))
g2.drawRect(start.x, start.y, (end.x-start.x),(end.y-start.y));
else if(selected==("line"))
g2.drawLine(start.x,start.y,end.x,end.y);
}
catch(Exception e)
{}
}
//Function to draw the shape on image
public void draw()
{
Graphics2D g2 = image.createGraphics();
g2.setPaint(color);
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));
if(selected=="rect")
g2.drawRect(start.x, start.y, (end.x-start.x),(end.y-start.y));
repaint();
g2.dispose();
start=null;
}
//To add the point to the board which is broadcasted by the server
public synchronized void addPoint(Point ps,String varname,String shape,String event)
{
try
{
if(end==null)
end = new Point();
if(start==null)
start = new Point();
if(shape.equals("elipse"))
selected="elipse";
else if(shape.equals("line"))
selected="line";
else if(shape.equals("rect"))
selected="rect";
else if(shape.equals("erase"))
{
selected="erase";
erase();
}
if(end!=null && start!=null)
{
if(varname.equals("end"))
end=ps;
if(varname.equals("mp"))
mp=ps;
if(varname.equals("start"))
start=ps;
if(event.equals("drag"))
repaint();
else if(event.equals("release"))
draw();
}
}
catch(Exception e)
{
e.printStackTrace();
}
}
//To set the size of the image
public void setWidth(int x,int y)
{
System.out.println("("+x+","+y+")");
w=x;
h=y;
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();
}
//Function which provides the erase functionality
public void erase()
{
Graphics2D pic=(Graphics2D) image.getGraphics();
pic.setPaint(Color.white);
pic.fillRect(start.x, start.y, 10, 10);
}
//Function to add buttons into the panel, calling this function returns a panel
public JPanel addButtons()
{
JPanel buttonpanel=new JPanel();
JPanel row1=new JPanel();
JPanel row2=new JPanel();
JPanel row3=new JPanel();
JPanel row4=new JPanel();
buttonpanel.setPreferredSize(new Dimension(80,80));
//buttonpanel.setMinimumSize(new Dimension(150,150));
row1.setLayout(new BoxLayout(row1,BoxLayout.X_AXIS));
row1.setPreferredSize(new Dimension(150,150));
row2.setLayout(new BoxLayout(row2,BoxLayout.X_AXIS));
row3.setLayout(new BoxLayout(row3,BoxLayout.X_AXIS));
row4.setLayout(new BoxLayout(row4,BoxLayout.X_AXIS));
buttonpanel.setLayout(new BoxLayout(buttonpanel,BoxLayout.Y_AXIS));
elipse.addActionListener(this);
rectangle.addActionListener(this);
line.addActionListener( this);
save.addActionListener( this);
erase.addActionListener( this);
buttonpanel.add(Box.createRigidArea(new Dimension(10,10)));
row1.add(elipse);
row1.add(Box.createRigidArea(new Dimension(5,0)));
row1.add(rectangle);
buttonpanel.add(row1);
buttonpanel.add(Box.createRigidArea(new Dimension(10,10)));
row2.add(line);
row2.add(Box.createRigidArea(new Dimension(5,0)));
row2.add(empty);
buttonpanel.add(row2);
buttonpanel.add(Box.createRigidArea(new Dimension(10,10)));
row3.add(save);
buttonpanel.add(row3);
buttonpanel.add(Box.createRigidArea(new Dimension(10,10)));
row4.add(erase);
buttonpanel.add(row4);
return buttonpanel;
}
//To save the image drawn
public void save()
{
try
{
ByteArrayOutputStream bos = new ByteArrayOutputStream();
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(bos);
JFileChooser fc = new JFileChooser();
fc.showSaveDialog(this);
encoder.encode(image);
byte[] jpgData = bos.toByteArray();
FileOutputStream fos = new FileOutputStream(fc.getSelectedFile()+".jpeg");
fos.write(jpgData);
fos.close();
//add replce confirmation here
}
catch (IOException e)
{
System.out.println(e);
}
}
public void mouseClicked(MouseEvent arg0) {
// TODO Auto-generated method stub
}
#Override
public void mouseEntered(MouseEvent arg0) {
}
public void mouseExited(MouseEvent arg0) {
// TODO Auto-generated method stub
}
public void mousePressed(MouseEvent e)
{
if(selected=="line"||selected=="erase")
{
start=e.getPoint();
client.broadcast(start,"start", selected,"press");
}
else if(selected=="elipse"||selected=="rect")
{
mp = e.getPoint();
client.broadcast(mp,"mp", selected,"press");
}
}
public void mouseReleased(MouseEvent e)
{
if(start!=null)
{
if(selected=="line")
{
end=e.getPoint();
client.broadcast(end,"end", selected,"release");
}
else if(selected=="elipse"||selected=="rect")
{
end.x = Math.max(mp.x,e.getX());
end.y = Math.max(mp.y,e.getY());
client.broadcast(end,"end", selected,"release");
}
draw();
}
//start=null;
}
public void mouseDragged(MouseEvent e)
{
if(end==null)
end = new Point();
if(start==null)
start = new Point();
if(selected=="line")
{
end=e.getPoint();
client.broadcast(end,"end", selected,"drag");
}
else if(selected=="erase")
{
start=e.getPoint();
erase();
client.broadcast(start,"start", selected,"drag");
}
else if(selected=="elipse"||selected=="rect")
{
start.x = Math.min(mp.x,e.getX());
start.y = Math.min(mp.y,e.getY());
end.x = Math.max(mp.x,e.getX());
end.y = Math.max(mp.y,e.getY());
client.broadcast(start,"start", selected,"drag");
client.broadcast(end,"end", selected,"drag");
}
repaint();
}
#Override
public void mouseMoved(MouseEvent arg0) {
// TODO Auto-generated method stub
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==elipse)
selected="elipse";
if(e.getSource()==line)
selected="line";
if(e.getSource()==rectangle)
selected="rect";
if(e.getSource()==save)
save();
if(e.getSource()==erase)
{
selected="erase";
erase();
}
}
}
class Button extends JButton
{
String name;
public Button(String name)
{
this.name=name;
Dimension buttonSize = new Dimension(35,35);
setMaximumSize(buttonSize);
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
//g2.setStroke(new BasicStroke(1.2f));
if (name == "line") g.drawLine(5,5,30,30);
if (name == "elipse") g.drawOval(5,7,25,20);
if (name== "rect") g.drawRect(5,5,25,23);
}
}

Try maintaining a panel for each user, and layer them on top of each other. As long as the backgrounds are transparent, you should see them all fine.
Edit: To achieve the layers, you could try JLayeredPane.

I don't see any code there that handles requests arriving from the client. Assuming that is happening on a background thread, make sure you use SwingUtilities.invokeLater to make the changes on the EDT. Updating UI components from anywhere but the EDT will cause unpredictable behavior. See also Concurrency in Swing
Also, this sort of thing isn't going to work:
if (name == "line") g.drawLine(5,5,30,30);
In Java, the == operator performs an identity comparison. It evaluates true if name and "line" are the same object. It will evaluate false if they reference different objects, even if they both have the same value. To compare equality, you need to use the .equals() method.