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How to delete shapes drawn on an Image

I am developing a small Paint tool. And I am able to load and draw Lines or Circles and other shapes on an image. Also I have an eraser tool to erase the shapes that I have drawn.
This is code for that:
g.setColor(getColor().WHITE);
g.fillRect(getXAxis() - getThickness(), getYAxis() - getThickness(), getThickness() * 2, getThickness() * 2);
My problem is that, If I have loaded an image and drawn some shapes on it. Then when I tried to erase the shapes, the image is also gets replaced with white color.
Is there any way to set the image as the background while using fillRect() to erase the shape, so that my image will be untouched.

Here is the example. To test it you need to replace my image with your background image.
import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.WindowConstants;
/**
* <code>PaintTryout</code>.
*
* #author smedvynskyy
*/
public class PaintPanel extends JPanel {
private Image backgroundImage;
private BufferedImage paintImage;
public PaintPanel() {
try {
// replace this image with your image
backgroundImage = ImageIO.read(new File("E:\\icons\\blackboard.png"));
paintImage = new BufferedImage(backgroundImage.getWidth(this),
backgroundImage.getHeight(this), BufferedImage.TYPE_INT_ARGB);
} catch (final Exception e) {
e.printStackTrace();
}
}
public void fillRect() {
final Graphics g = paintImage.createGraphics();
g.setColor(Color.RED);
g.fillRect(0, 0, 50, 50);
g.dispose();
repaint();
}
public void clearRect() {
final Graphics2D g = paintImage.createGraphics();
g.setColor(new Color(0, 0, 0, 0));
g.setComposite(AlphaComposite.Clear); // overpaint
g.fillRect(0, 0, 50, 50);
g.dispose();
repaint();
}
/**
* {#inheritDoc}
*/
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(backgroundImage, 0, 0, this);
g.drawImage(paintImage, 0, 0, this);
}
/**
* {#inheritDoc}
*/
#Override
public Dimension getPreferredSize() {
return new Dimension(backgroundImage.getWidth(this),
backgroundImage.getHeight(this));
}
public static void main(String[] args) {
final JFrame frm = new JFrame("Tesp paint");
final PaintPanel p = new PaintPanel();
frm.add(p);
final JPanel buttons = new JPanel();
final JButton fill = new JButton("Fill Rect");
fill.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
p.fillRect();
}
});
final JButton clear = new JButton("Clear Rect");
clear.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
p.clearRect();
}
});
buttons.add(fill);
buttons.add(clear);
frm.add(buttons, BorderLayout.SOUTH);
frm.pack();
frm.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frm.setLocationRelativeTo(null);
frm.setVisible(true);
}
}

The easy way to do this is to draw the lines in XOR mode. Then, to erase them, you just draw them again.

Transparent JFrame doesn't clear on repaint

When I try to repaint a transparent window, and draw a rectangle on it, the previous rectangle will stay. The goal is to select an area on your screen by clicking and moving your mouse. It'll look like this if you move your mouse for a while
By removing the transparency it works just fine.
I tried everything I could find on Stack Overflow about this topic, But I wasn't able to get it working on both Windows and Linux.
Main class
import javax.swing.*;
import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
public class Main {
private JFrame frame;
private boolean pressing = false;
private boolean selected = false;
private ScreenSelectPanel p;
public Main() {
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
frame = new JFrame("ScreenSelection");
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setSize(dim);
frame.setUndecorated(true);
frame.setContentPane(p = new ScreenSelectPanel());
registerListeners();
frame.getContentPane().setBackground(new Color(255, 255, 255, 0));
frame.setBackground(new Color(255, 255, 255, 0));
frame.setLayout(new BorderLayout());
frame.setAlwaysOnTop(true);
frame.setVisible(true);
}
private void registerListeners() {
p.setFocusable(true);
p.requestFocusInWindow();
p.addMouseMotionListener(new MouseMotionAdapter() {
#Override
public void mouseDragged(MouseEvent e) {
if (selected)
return;
setLoc(e);
p.repaint();
}
#Override
public void mouseMoved(MouseEvent e) {
if (selected)
return;
setLoc(e);
if (!pressing)
setStartLoc(e);
p.repaint();
}
});
p.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
setLoc(e);
setStartLoc(e);
p.repaint();
}
#Override
public void mouseEntered(MouseEvent e) {
setLoc(e);
setStartLoc(e);
p.repaint();
}
});
}
public void setStartLoc(MouseEvent e) {
p.mouseStartX = e.getX();
p.mouseStartY = e.getY();
}
public void setLoc(MouseEvent e) {
p.mouseX = e.getX();
p.mouseY = e.getY();
}
public static void main(String[] args) {
new Main();
}
}
ScreenSelectPanel class
import javax.swing.*;
import java.awt.*;
import java.awt.geom.Point2D;
import java.awt.image.BufferedImage;
public class ScreenSelectPanel extends JPanel {
public int mouseX = 0;
public int mouseY = 0;
public int mouseStartX = 0;
public int mouseStartY = 0;
private Color borderColor;
public ScreenSelectPanel() {
setOpaque(false);
borderColor = Color.BLACK;
}
public void setBorderColor(Color c) {
this.borderColor = c;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(borderColor);
Rectangle rect = new Rectangle();
rect.setFrameFromDiagonal(new Point2D.Float(mouseStartX, mouseStartY), new Point2D.Float(mouseX, mouseY));
Stroke dashed = new BasicStroke(3, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL, 0, new float[]{9}, 0);
g2d.setStroke(dashed);
g2d.drawRect(rect.x, rect.y, rect.width, rect.height);
g2d.dispose();
}
}
Thanks :)

You can't use transparency with Swing components. A transparent background causes these types of painting problems. A Swing component is either opaque or non-opaque.
Check out Backgrounds With Transparency for more information on this problem. However in this cause it is not the problem because you are trying to use full transparency on the Swing panel.
When I try to repaint a transparent window, and draw a rectangle on it, the previous rectangle will stay.
The code you posted does anything (at least on Windows). When you set a frame to be completely transparent then the MouseEvents are no longer handled by Swing and instead are handled by the application below the frame.
I made the following changes to your code and it seems to work for me:
//frame.getContentPane().setBackground(new Color(255, 255, 255, 0));
//frame.setBackground(new Color(255, 255, 255, 0));
frame.setBackground(new Color(255, 255, 255, 10));

custom JPanel not updating

the code:
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class PaintWindow {
private JFrame frame;
private aJPanel panel;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
PaintWindow window = new PaintWindow();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public PaintWindow() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
panel = new aJPanel();
frame.getContentPane().add(panel, BorderLayout.CENTER);
JButton btnNewButton = new JButton("New button");
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
panel.stam();
}
});
frame.getContentPane().add(btnNewButton, BorderLayout.NORTH);
frame.setBounds(100, 100, 450, 300);
frame.setVisible(true);
}
public class aJPanel extends JPanel {
private static final long serialVersionUID = 8874943072526915834L;
private Graphics g;
public aJPanel() {
super();
System.out.println("Constructor");
}
public void paint(Graphics g) {
super.paint(g);
System.out.println("paint");
g.fillRect(10, 10, 10, 10);
this.g = g;
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
System.out.println("paintComponent");
g.fillRect(20, 20, 20, 20);
this.g = g;
}
public void stam() {
System.out.println("stam");
this.g.fillRect(40, 40, 40, 40);
this.repaint();
}
}
}
what I want to do is paint custom shapes (lines, rectangles etc) after the user clicks a button or triggers a mouse event. but calling aJPanel.stam() does not show the rectangle its supposed to. I am fairly new to JPanel. any suggestions?

First of all:
class names should start with a capital letter
class names should be descriptive.
"aJPanel" does not follow either of the above.
but calling aJPanel.stam() does not show the rectangle its supposed to
See Custom Painting Apporoaches for the two common ways to do dynamic painting:
Add objects to a List and iterate the List to paint all the objects
Paint directly to a BufferedImage and then paint the BufferedImage
The examples add the Rectangle by dragging the mouse, but you can easily add Rectangles by just invoking the addRectangle(...) method when you click a button.

How to 'undraw' an Image?

I am trying to make a simple game in Java, All i need to do is draw an im onto the screen and then wait for 5 seconds then 'undraw it'.
Code (this class draws the image on the screen):
package com.mainwindow.draw;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.Timer;
import javax.swing.ImageIcon;
import javax.swing.JPanel;
#SuppressWarnings("serial")
public class MainWindow extends JPanel{
Image Menu;
String LogoSource = "Logo.png";
public MainWindow() {
ImageIcon ii = new ImageIcon(this.getClass().getResource(LogoSource));
Menu = ii.getImage();
Timer timer = new Timer(5, new ActionListener() {
public void actionPerformed(ActionEvent e) {
repaint();
}
});
timer.start();
}
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2 = (Graphics2D) g;
g2.drawImage(Menu, 0, 0, getWidth(), getHeight(), null);
}
}
Code #2 (this creates the JFrame)
package com.mainwindow.draw;
import javax.swing.JFrame;
#SuppressWarnings("serial")
public class Frame extends JFrame {
public Frame() {
add(new MainWindow());
setTitle("Game Inviroment Graphics Test");
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(640, 480);
setLocationRelativeTo(null);
setVisible(true);
setResizable(false);
}
public static void main(String[] args) {
new Frame();
}
}

Use some kind of flag to determine if the image should be drawn or not and simply change it's state as needed...
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
if (draw) {
g2.drawImage(Menu, 0, 0, getWidth(), getHeight(), null);
}
}
Then change the state of the flag when you need to...
Timer timer = new Timer(5, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
draw = false;
repaint();
}
});
Note: It's not recommended to to override paint, paint is at the top of the paint change and can easily break how the paint process works, causing no end of issues. Instead, it's normally recommended to use paintComponent instead. See Performing Custom Painting for more details
Also note: javax.swing.Timer expects the delay in milliseconds...5 is kind of fast...

java statusbar resize corner (handle)

I try to make a window with a resize handle at the bottom right.
So far I managed to detect the mouse hover and dragging.
The mouse cursor is changing to resize cursor successfully.
But the actually resize operation I'm unsure how to solve.
The Idea I testet at first place is to just setsize on parent when dragging on resize handle.
It works, but then the window get's resize immediately, that's not how the standard resize looks.
The standard resize is a transparent window with white border (may be different on different systems and look and feel).
Is it possible to trigger/use the built in resize mechanism?
Below you have a sample code.
Thanks!
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Polygon;
import java.awt.RenderingHints;
import java.awt.event.InputEvent;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
public class main extends JFrame {
private JPanel contentPane;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
main frame = new main();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public class StatusBar extends JPanel implements MouseListener, MouseMotionListener {
private Polygon resizeCorner = new Polygon();
private int offsetX;
private int offsetY;
private Dimension offsetSize;
private Cursor resizeCursor = new Cursor(Cursor.SE_RESIZE_CURSOR);
private Cursor defaultCursor = new Cursor(Cursor.DEFAULT_CURSOR);
public StatusBar() {
super();
setPreferredSize(new Dimension(200,40));
this.addMouseListener(this);
this.addMouseMotionListener(this);
}
private void createResizeHandle() {
resizeCorner.reset();
resizeCorner.addPoint(getWidth()-2, getHeight()-2);
resizeCorner.addPoint(getWidth()-40, getHeight()-2);
resizeCorner.addPoint(getWidth()-2, getHeight()-40);
}
#Override
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2;
g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.setRenderingHint(RenderingHints.KEY_RENDERING,
RenderingHints.VALUE_RENDER_QUALITY);
g2.setColor(Color.red);
createResizeHandle();
g2.drawPolygon(resizeCorner);
}
#Override
public void mouseDragged(MouseEvent e) {
if ((e.getModifiers() & InputEvent.BUTTON1_MASK) != 0) {
int width = (int) (this.offsetSize.getWidth() - this.offsetX + e.getXOnScreen());
int height = (int) (this.offsetSize.getHeight() - this.offsetY + e.getYOnScreen());
this.getRootPane().getParent().setSize(width, height);
createResizeHandle();
}
}
#Override
public void mouseMoved(MouseEvent e) {
if (resizeCorner.contains(e.getX(), e.getY())) {
setCursor(resizeCursor);
} else {
setCursor(defaultCursor);
}
}
#Override
public void mouseClicked(MouseEvent arg0) {
}
#Override
public void mouseEntered(MouseEvent arg0) {
}
#Override
public void mouseExited(MouseEvent arg0) {
}
#Override
public void mousePressed(MouseEvent e) {
if (resizeCorner.contains(e.getX(), e.getY())) {
this.offsetX = e.getXOnScreen();
this.offsetY = e.getYOnScreen();
this.offsetSize = this.getRootPane().getParent().getSize();
}
}
#Override
public void mouseReleased(MouseEvent arg0) {
}
}
public main() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 300);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
contentPane.setLayout(new BorderLayout(0, 0));
setContentPane(contentPane);
JLabel lblNewLabel = new JLabel("New label");
StatusBar bar = new StatusBar();
contentPane.add(lblNewLabel, BorderLayout.NORTH);
contentPane.add(bar, BorderLayout.SOUTH);
}
}

lots of small mistakes, starts with correct naming for ClassName ... end with usage java reserved words for class/void/method's name(s)
minor changes (now it works for me), with one my mistake against Swing rules, I set there setPreferredSize(new Dimension(400, 300));, lets childrens returns PreferredSize for Container
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
public class MyToolBar extends JFrame {
private static final long serialVersionUID = 1L;
private JPanel contentPane;
public class StatusBarX extends JPanel implements MouseListener, MouseMotionListener {
private static final long serialVersionUID = 1L;
private Polygon resizeCorner = new Polygon();
private int offsetX;
private int offsetY;
private Dimension offsetSize;
private Cursor resizeCursor = new Cursor(Cursor.SE_RESIZE_CURSOR);
private Cursor defaultCursor = new Cursor(Cursor.DEFAULT_CURSOR);
public StatusBarX() {
super();
setPreferredSize(new Dimension(200, 40));
this.addMouseListener(this);
this.addMouseMotionListener(this);
}
private void createResizeHandle() {
resizeCorner.reset();
resizeCorner.addPoint(getWidth() - 2, getHeight() - 2);
resizeCorner.addPoint(getWidth() - 40, getHeight() - 2);
resizeCorner.addPoint(getWidth() - 2, getHeight() - 40);
}
#Override
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2;
g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
g2.setColor(Color.red);
createResizeHandle();
g2.drawPolygon(resizeCorner);
}
#Override
public void mouseDragged(MouseEvent e) {
if ((e.getModifiers() & InputEvent.BUTTON1_MASK) != 0) {
int width = (int) (this.offsetSize.getWidth() - this.offsetX + e.getXOnScreen());
int height = (int) (this.offsetSize.getHeight() - this.offsetY + e.getYOnScreen());
this.getRootPane().getParent().setSize(width, height);
createResizeHandle();
}
}
#Override
public void mouseMoved(MouseEvent e) {
if (resizeCorner.contains(e.getX(), e.getY())) {
setCursor(resizeCursor);
} else {
setCursor(defaultCursor);
}
}
#Override
public void mouseClicked(MouseEvent arg0) {
}
#Override
public void mouseEntered(MouseEvent arg0) {
}
#Override
public void mouseExited(MouseEvent arg0) {
}
#Override
public void mousePressed(MouseEvent e) {
if (resizeCorner.contains(e.getX(), e.getY())) {
this.offsetX = e.getXOnScreen();
this.offsetY = e.getYOnScreen();
this.offsetSize = this.getRootPane().getParent().getSize();
}
}
#Override
public void mouseReleased(MouseEvent arg0) {
}
}
public MyToolBar() {
JLabel lblNewLabel = new JLabel("New label");
StatusBarX bar = new StatusBarX();
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
contentPane.setLayout(new BorderLayout(0, 0));
contentPane.add(lblNewLabel, BorderLayout.NORTH);
contentPane.add(bar, BorderLayout.SOUTH);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocation(100, 100);
setPreferredSize(new Dimension(400, 300));
add(contentPane);
pack();
setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
MyToolBar frame = new MyToolBar();
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
}

The standard resize is a transparent window with white border (may be different on different systems and look and feel).
When using Windows XP the standard is to resize top level components (frame, dialog etc) immediately. It doesn't matter what the LAF is.
In general other components don't have resizing functionality built in. The only exception to this that I can think of is JInternalFrame. In this case is does support the "outline" resizing of a component.
So if you want to add this type of functionality to your component then you would need to look at the internal frame UI to find the resizing code.
I would guess that the code would display a Glass Pane when dragging starts and then do the outline custom painting on the Glass Plane. Then on mouseReleased the frame size would be changed.
In case you are interested, Component Resizing shows how I do resizing for any component. It does immediate resizing, not outline resizing.