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How to get rid of circle inside rectangle when switching between objects [closed]

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I have a combobox in which I can choose to draw either a rectangle, a circle or by freehand.
If I choose to draw a circle it draws it perfectly. If I then switch to draw a rectangle it draws a circle inside the rectangle. The same happens if I first choose to draw a rectangle and then a circle. (See Picture below)
My questions are:
How can I switch between drawing a circle and a rectangle without the circle appearing inside the rectangle?
How can I get the rectangle/circle to show while I'm dragging the mouse. What I mean is how can the lines show until I release the mouse click?
Why doesn't it work drawing by free hand?
This is my testclass:
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
public class Lab6 extends JFrame implements ActionListener {
int startX, startY, endX, endY, w, h;
ArrayList<Shape> shapeList = new ArrayList<Shape>();
Container cp = getContentPane();
private JPanel topPanel;
private JComboBox comboBox;
private final String[] boxOptions = new String[] {"Rektangel", "Cirkel", "Frihand"};
public Lab6(String title) {
super(title);
this.setLayout(new BorderLayout());
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.setLocationRelativeTo(null);
this.setSize(840, 500);
this.initComponents();
this.setVisible(true);
}
private void initComponents() {
topPanel = new JPanel(new GridLayout(1,2));
topPanel.setPreferredSize(new Dimension(0,40));
comboBox = new JComboBox(boxOptions);
comboBox.setSelectedIndex(0);
comboBox.addActionListener(this);
topPanel.add(comboBox);
this.add(topPanel, BorderLayout.PAGE_START);
}
#Override
public void paint(Graphics g) {
for (Shape s : shapeList) {
s.draw(g);
}
}
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource().equals(comboBox)) {
JComboBox cb = (JComboBox)e.getSource();
if (cb.getSelectedItem().equals("Rektangel")) {
cp.addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent e) {
startX = e.getX();
startY = e.getY();
}
#Override
public void mouseReleased(MouseEvent e) {
endX = e.getX();
endY = e.getY();
int width = startX - endX;
int height = startY - endY;
w = Math.abs(width);
h = Math.abs(height);
Rectangle r = new Rectangle(startX, startY, w, h);
shapeList.add(r);
repaint();
}
});
}
else if (cb.getSelectedItem().equals("Cirkel")) {
cp.addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent e) {
startX = e.getX();
startY = e.getY();
}
#Override
public void mouseReleased(MouseEvent e) {
endX = e.getX();
endY = e.getY();
int width = startX - endX;
int height = startY - endY;
w = Math.abs(width);
h = Math.abs(height);
Circle c = new Circle(startX, startY, w, h);
shapeList.add(c);
repaint();
}
});
}
else if (cb.getSelectedItem().equals("Frihand")) { //I need help with this part
cp.addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent e) {
startX = e.getX();
startY = e.getY();
}
#Override
public void mouseDragged(MouseEvent e) {
FreeHand fh = new FreeHand(startX, startY, e.getX(), e.getY());
shapeList.add(fh);
repaint();
}
});
}
}
}
public static void main(String args[]) {
new Lab6("Drawing Program");
}
}
In class Rectangle (class Circle looks the same):
import java.awt.*;
public class Rectangle extends Shape {
public Rectangle(int x, int y, int width, int height) {
super(x, y, width, height);
}
public Rectangle() {
super();
}
#Override
public void draw(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setColor(Color.RED);
g2.setStroke(new BasicStroke(4));
g.drawRect(getX(), getY(), getWidth(), getHeight());
}
}
In class FreeHand (I need help with this part):
import java.awt.*;
public class FreeHand extends Shape {
public FreeHand(int x, int y, int width, int height) {
super(x, y, width, height);
}
public FreeHand() {
super();
}
#Override
public void draw(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setColor(Color.BLUE);
g2.setStroke(new BasicStroke(4));
g2.drawLine(getX(), getY(), getWidth(), getHeight());
}
}
In class shape:
import java.awt.Graphics;
import javax.swing.JPanel;
public abstract class Shape extends JPanel {
private int startX, startY, width, height;
public Shape() {
this(0, 0, 1, 1);
}
public Shape(int startX, int startY, int width, int height) {
this.startX = startX;
this.startY = startY;
this.width = width;
this.height = height;
}
public abstract void draw(Graphics g);
#Override
public int getX() {
return startX;
}
#Override
public int getY() {
return startY;
}
#Override
public int getWidth() {
return width;
}
#Override
public int getHeight() {
return height;
}
}

There are a multitude of things going on...
Overriding paint of JFrame
Not calling super.paint before performing custom painting.
Adding a new MosueListener EVERY time you change the shape
Instead, create a custom component, extending from something like JPanel and override it's paintComponent method. Use this component has your basic drawing surface (your controls should contained in another component).
Make sure you call super.paintComponent before performing any custom painting so you don't break the paint chain
See Performing Custom Painting and Painting in AWT and Swing for more details
Create a SINGLE MouseListener and register it to the panel. When the use selects a different shape, change a state variable within the panel (via a setter) which tells the MouseListener what it should do when the user starts drawing.
Updated...
Create a custom class that extends from JPanel...
public static class ShapePane extends JPanel {
}
Override the classes paintComponent method...
public static class ShapePane extends JPanel {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// Custom Painting here...
}
}
Provide some sizing hints for the layout manager...
public static class ShapePane extends JPanel {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// Custom Painting here...
}
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
Provide a means by which the type of shape can be changed...so you know what to paint...
public static class ShapePane extends JPanel {
public enum ShapeType {
CIRCLE,
RECTANGLE
}
private ShapeType currentShapeType;
public void setCurrentShapeType(ShapeType currentShapeType) {
this.currentShapeType = currentShapeType;
}
public ShapeType getCurrentShapeType() {
return currentShapeType;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// Custom Painting here...
}
}
Add a SINGLE MouseListener to the custom class to create the required type of shapes...
public static class ShapePane extends JPanel {
public enum ShapeType {
CIRCLE,
RECTANGLE
}
private ShapeType currentShapeType;
public ShapePane() {
addMouseListener(new MouseAdapter() {
private Point clickPoint;
#Override
public void mousePressed(MouseEvent e) {
clickPoint = e.getPoint();
}
#Override
public void mouseReleased(MouseEvent e) {
Point releasePoint = e.getPoint();
int x = Math.min(releasePoint.x, clickPoint.x);
int y = Math.min(releasePoint.y, clickPoint.y);
int width = Math.abs(clickPoint.x - releasePoint.x);
int height = Math.abs(clickPoint.y - releasePoint.y);
switch (getCurrentShapeType()) {
case CIRCLE:
// Make a circle
break;
case RECTANGLE:
// Make a rectangle...
break;
}
repaint();
}
});
}
public void setCurrentShapeType(ShapeType currentShapeType) {
this.currentShapeType = currentShapeType;
}
public ShapeType getCurrentShapeType() {
return currentShapeType;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// Custom Painting here...
}
}
Fill in the blanks...
Create another JPanel (you can simply create an instance this time), add your controls to it
Create an instance of a JFrame, add the custom class to it and the controls panel (make sure they are laid out correctly so they don't override each other - see Laying Out Components Within a Container for more details)
Use appropriate listeners to the controls to determine the type of shape the user wants to draw and set the currentShapeType property accordingly...

How can I get this Paintcomponent to act as I intended?

I was given the assignment to make a simple paint program in java that utilizes a GUI and has basic I/O capabilities. That was all I was told to do by my professor. However, I've only made one GUI program before, so jumping straight into this paint program has been a headache. Now I'm nearly done, but the program isn't really behaving as I expected. When new objects are drawn on the Panel, they draw invisible white rectangles on the objects underneath them that erases those objects. I think this is the result of the repaint(xMin, yMin, xMax - xMin + 1, yMax - yMin + 1); method in DrawShapes, but can't think of a way to fix it.
On the other hand, the objects are also not saving properly. I can get it to export a jpg as I intended, however, it will only export the last image drawn and not everything on the paintComponent canvas.
Lastly, the clear method in DrawShapes is working in a very similar way. When the clear method is activated, it will clear everything but the last image drawn.
Is there anyone more familiar than me with these tools that can see a way to fix these? This is only the first program I've utilized draw on, and I/O.
Here is the class for the panel that the shapes are supposed to drawn on:
/**
* #author me
*/
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.event.*;
public class DrawShapes extends JPanel{
Point startPoint = null;
Point endPoint = null;
public int drawType = 1;
BufferedImage image;
Graphics2D g2d;
public DrawShapes(){
setBackground(Color.WHITE);
MyMouseListener m1 = new MyMouseListener();
addMouseListener(m1);
addMouseMotionListener(m1);
}//end constructor
//sets draw type, which is the decider of what is being drawn.
public void setType(int type){
if(type == 1)
{
drawType = 1;
}
else if(type == 2)
{
drawType = 2;
}
else if(type == 3)
{
drawType = 3;
}
}//end setType
public void paintComponent(Graphics g)
{
super.paintComponent(g);
if (image == null)
{
createEmptyImage();
}
g.drawImage(image, 0, 0, null);
if (startPoint != null && endPoint != null)
{
int x = Math.min(startPoint.x, endPoint.x);
int y = Math.min(startPoint.y, endPoint.y);
int width = Math.abs(startPoint.x - endPoint.x);
int height = Math.abs(startPoint.y - endPoint.y);
switch (drawType)
{
case 1:
g.drawRect(x, y, width, height);
break;
case 2:
g.drawOval(x, y, width, height);
break;
case 3:
g.drawLine(startPoint.x, startPoint.y, endPoint.x, endPoint.y);
break;
}
}
}//end paintComponent
public void save()
{
BufferedImage bi = new BufferedImage(this.getSize().width, this.getSize().height, BufferedImage.TYPE_INT_RGB);
Graphics g = bi.createGraphics();
this.paint(g);
g.dispose();
try{ImageIO.write(bi, "png",new File("test.png"));
}catch (Exception e){}
}
private void createEmptyImage()
{
image = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_ARGB);
g2d = (Graphics2D)image.getGraphics();
g2d.setColor(Color.BLACK);
g2d.drawString("Add a shape by clicking and dragging.", 40, 15);
}
public void addRect(int x, int y, int width, int height, Color color)
{
g2d.setColor( color );
g2d.drawRect(x, y, width, height);
repaint();
}
public void addOval(int x, int y, int width, int height, Color color)
{
g2d.setColor( color );
g2d.drawOval(x, y, width, height);
repaint();
}
public void addLine(int x1, int y1, int x2, int y2, Color color)
{
g2d.setColor(color);
g2d.drawLine(x1, y1, x2, y2);
repaint();
}
public void clear()
{
createEmptyImage();
repaint();
}
class MyMouseListener extends MouseInputAdapter
{
private int xMin;
private int xMax;
private int yMin;
private int yMax;
public void mousePressed(MouseEvent e)
{
startPoint = e.getPoint();
endPoint = startPoint;
xMin = startPoint.x;
xMax = startPoint.x;
yMin = startPoint.y;
yMax = startPoint.y;
}
public void mouseDragged(MouseEvent e)
{
//This is code I found that should make it so the only area affected by the dragging is repainted.
endPoint = e.getPoint();
xMin = Math.min(xMin, endPoint.x);
xMax = Math.max(xMax, endPoint.x);
yMin = Math.min(yMin, endPoint.y);
yMax = Math.max(yMax, endPoint.y);
repaint(xMin, yMin, xMax - xMin + 1, yMax - yMin + 1);
}
public void mouseRelease(MouseEvent e)
{
//This code paints the shapes on the Buffered Image created as a canvas
int x = Math.min(startPoint.x, endPoint.x);
int y = Math.min(startPoint.y, endPoint.y);
int width = Math.abs(startPoint.x - endPoint.x);
int height = Math.abs(startPoint.y - endPoint.y);
if (width != 0 || height != 0)
{
g2d.setColor( e.getComponent().getForeground() );
// g2d.drawRect(x, y, width, height);
switch (drawType)
{
case 1:
addRect(x, y, width, height, e.getComponent().getForeground());
break;
case 2:
addOval(x, y, width, height, e.getComponent().getForeground());
break;
case 3:
addLine(startPoint.x, startPoint.y, endPoint.x, endPoint.y, e.getComponent().getForeground());
break;
}//end switch statement.
}
startPoint = null;
// repaint();
}
}
}//end class
And here is the code for the UI:
/*#author Me*/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class MyDrawUI extends JFrame
{
private DrawShapes draw = new DrawShapes();
private JPanel ButtonPanel = new JPanel();
private JFrame window = new JFrame("Draw!");
//constructor
MyDrawUI(){
buildUI();
}
void buildUI()
{
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setLayout(new GridLayout(2,2));
window.add(draw);
window.add(ButtonPanel, BorderLayout.SOUTH);
ButtonPanel.setBackground(Color.LIGHT_GRAY);
draw.setBackground(Color.WHITE);
//define buttons
JButton rectangle = new JButton("Rectangle");
JButton oval = new JButton("Oval");
JButton line = new JButton("Line");
JButton exit = new JButton("Exit");
JButton save = new JButton("Save");
JButton clear = new JButton("Clear");
//add buttons
ButtonPanel.add(rectangle, BorderLayout.SOUTH);
ButtonPanel.add(oval, BorderLayout.SOUTH);
ButtonPanel.add(line, BorderLayout.SOUTH);
ButtonPanel.add(clear, BorderLayout.SOUTH);
ButtonPanel.add(save, BorderLayout.SOUTH);
ButtonPanel.add(exit, BorderLayout.SOUTH);
ButtonPanel.setSize(100, 100);
save.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
draw.save();
}
});
clear.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
draw.clear();
}
});
rectangle.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
draw.setType(1);
}
});
oval.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
draw.setType(2);
}
});
line.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
draw.setType(3);
}
});
exit.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
{
System.exit(0);
}
});
window.setVisible(true);
window.setSize(1024, 800);
}
}

There are a few issues I can see, the main one is the fact that you "think" you've overridden a method in the MouseAdaptor class, but haven't
mouseRelease is not method that will cause any events to trigger it. The method you're after is mouseReleased.
When overriding methods, make use the #Override annotation, it will cause a compiler error if the method you "think" you're overriding doesn't exist in any of the parent classes.
#Override
public void mouseReleased(MouseEvent e) {
Several other things pop out.
You're MyDrawUI classes extends from JFrame, but you create a instance of another JFrame called window, onto which you create your UI. In this case, drop the extends JFrame from the MyDrawUI class, as it just adds confusion...
Maintaining a reference to a Graphics context, even one you created, is ill advised in this context. On some systems, until you call dispose it's possible that nothing will be committed to the underlying implementation. Instead, simply use image.getGraphics when you need it and call g2d.dispose when you're done with it.

Scaling image through thread - JAVA

Let say I have an image. I put the image in a JPanel and add the JPanel inside a JFrame. The image moves from the bottom part of the frame to top of the frame while its size is also decreased using AffineTransform. The variable changes using thread.
So here's the following code:
public class SplashScreen extends JFrame{
Image img1;
int w=1,h=1;
int x=0,y=0;
Thread th = new Thread(new Runnable() {
#Override
public void run() {
while(true){
w-=0.05;
h-=0.05;
y-=2;
x+=1;
if(y==-100){
new MainMenu_BlueJay().setVisible(true);
dispose();
}
repaint();
try {
Thread.sleep(10);
} catch (InterruptedException ex) {
Logger.getLogger(SplashScreen.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
});
JPanel p = new JPanel();
public SplashScreen(){
setLayout(new BorderLayout());
p.setPreferredSize(new Dimension(900,600));
p.setBackground(Color.black);
p.setLayout(new GridLayout());
add(p);
setTitle("BlueJay");
setSize(900,600);
getContentPane().setBackground(Color.black);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setVisible(true);
th.start();
requestFocus();
setFocusable(true);
}
#Override
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2d = (Graphics2D) g;
img1 = new ImageIcon("images/Intro/BJ Production 2013.png").getImage();
AffineTransform at = new AffineTransform();
at.scale(w,h);
g2d.setTransform(at);
g2d.drawImage(img1, x, y, p);
}
public static void main(String[] args) {
new SplashScreen();
}
However what I get from code above is only black screen. What's the matter? Anyway, If I don't use the AffineTransform function (just move it from bottom to top), the image is shown and moves BUT the frame is flickered (blinking) rapidly.
Any idea to solve this problem so I could move the image while decrease its size and also solve the flickered/rapid blinking frame?

You should not override the paint method of the JFrame. If you want to paint anything, you should paint this in a class that extends JPanel, where you override the paintComponent method.
You should NOT load the image in the painting method. This is horribly inefficient. You should load the image only ONCE, probably in a constructor.
You should not call Graphics2D#setTransform(). Have a look at the JavaDoc at http://docs.oracle.com/javase/7/docs/api/java/awt/Graphics2D.html#setTransform%28java.awt.geom.AffineTransform%29 , which explicitly states
WARNING: This method should never be used to apply a new coordinate transform on top of an existing transform
You should think about your w and h values. Should they be the size of the image that is painted, or used as scaling factors for the image? Setting them as the scaling factors of an AffineTransform will NOT have the effect of scaling an image to the desired size. At the moment, they are declared as int values, so something like w-=0.05 does not really make sense anyhow.
You should have a clear idea of how you are going to describe the animation that the image should perform.
One could possibly summarize this:
You should not write code and assume it is "correct" only because there are no compilation errors ;-)
However, the following snippet may be a first step towards your goal:
package stackoverflow;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class SplashScreen extends JFrame
{
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
#Override
public void run()
{
new SplashScreen();
}
});
}
private PaintPanel paintPanel;
public SplashScreen()
{
setTitle("BlueJay");
setDefaultCloseOperation(EXIT_ON_CLOSE);
getContentPane().setBackground(Color.BLACK);
getContentPane().setLayout(new BorderLayout());
paintPanel = new PaintPanel();
getContentPane().add(paintPanel, BorderLayout.CENTER);
setSize(900,600);
setLocationRelativeTo(null);
setFocusable(true);
requestFocus();
setVisible(true);
startAnimation();
}
void startAnimation()
{
Thread thread = new Thread(new Runnable()
{
int x = 100;
int y = 100;
int w = 0;
int h = 0;
#Override
public void run()
{
try
{
Thread.sleep(500);
}
catch (InterruptedException ex)
{
Thread.currentThread().interrupt();
return;
}
while (true)
{
if (y == 200)
{
// new MainMenu_BlueJay().setVisible(true);
dispose();
}
x += 2;
y += 1;
w += 1;
h += 1;
paintPanel.setImageCoordinates(x, y, w, h);
repaint();
try
{
Thread.sleep(10);
}
catch (InterruptedException ex)
{
Thread.currentThread().interrupt();
return;
}
}
}
});
thread.start();
}
}
class PaintPanel extends JPanel
{
private final Image image;
private int imageX, imageY;
private int imageW, imageH;
PaintPanel()
{
image = new ImageIcon("Clipboard02.jpg").getImage();
imageX = 0;
imageY = 0;
imageW = 0;
imageH = 0;
}
void setImageCoordinates(int imageX, int imageY, int imageW, int imageH)
{
this.imageX = imageX;
this.imageY = imageY;
this.imageW = imageW;
this.imageH = imageH;
repaint();
}
#Override
protected void paintComponent(Graphics gr)
{
super.paintComponent(gr);
Graphics2D g = (Graphics2D) gr;
float scalingX = (float) imageW / image.getWidth(null);
float scalingY = (float) imageH / image.getHeight(null);
g.scale(scalingX, scalingY);
int ix = (int)(imageX / scalingX);
int iy = (int)(imageY / scalingY);
g.drawImage(image, ix, iy, null);
}
}

Don't paint on top-level containers like JFrame. Instead use a JPanel and override its paintComponent method and call super.paintComponent
No need to call Thread.sleep(). Instead Use a javax.swing.Timer.
Run your program from the EDT
Don't create a new ImageIcon in the paint method. It will create new ImageIcon object every time repaint() is called. Instead, instantiate it in the constructor.
Here's a refactor of the code.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class SplashScreen extends JFrame {
Image img1;
int w = 900, h = 600;
int x = 0, y = 0;
public SplashScreen() {
setLayout(new BorderLayout());
add(new MyPanel());
setTitle("BlueJay");
setSize(900, 600);
getContentPane().setBackground(Color.black);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setVisible(true);
requestFocus();
setFocusable(true);
}
private class MyPanel extends JPanel {
public MyPanel() {
img1 = new ImageIcon(SplashScreen.class.getResource("/resources/stackoverflow5.png")).getImage();
setBackground(Color.black);
setLayout(new GridLayout());
Timer timer = new Timer(20, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
w -= 5;
h -= 5;
y -= 2;
x += 1;
if (y == -250) {
new MainMenu_BlueJay().setVisible(true);
dispose();
}
repaint();
}
});
timer.start();
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
//AffineTransform at = new AffineTransform();
// at.scale(w, h);
// g2d.setTransform(at);
g2d.drawImage(img1, x, y, w, h, this);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(900, 600);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new SplashScreen();
}
});
}
}
I'm not too familiar with Graphics2D so I commented out the AffirmTransformation stuff, but fixed your other problems.

Java JPanel getGraphics()

Since Java only supports single inheritance, I desire to paint directly on an instance of a JPanel that is a member of the class Panel. I grab an instance of Graphics from the member and then paint whatever I desire onto it.
How can I not inherit from JComponent or JPanel and still utilize getGraphics() for painting on this without overriding public void paintComponent(Graphics g)?
private class Panel {
private JPanel panel;
private Graphics g;
public Panel() {
panel = new JPanel();
}
public void draw() {
g = panel.getGraphics();
g.setColor(Color.CYAN);
g.draw(Some Component);
panel.repaint();
}
}
The panel is added to a JFrame that is made visible prior to calling panel.draw(). This approach is not working for me and, although I already know how to paint custom components by inheriting from JPanel and overriding public void paintComponent(Graphics g), I did not want to inherit from JPanel.

Here are some very simple examples which show how to paint outside paintComponent.
The drawing actually happens on a java.awt.image.BufferedImage, and we can do that anywhere, as long as we're on the Event Dispatch Thread. (For discussion of multithreading with Swing, see here and here.)
Then, I'm overriding paintComponent, but only to paint the image on to the panel. (I also paint a little swatch in the corner.)
This way the drawing is actually permanent, and Swing is able to repaint the panel if it needs to without causing a problem for us. We could also do something like save the image to a file easily, if we wanted to.
import javax.swing.*;
import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
/**
* Holding left-click draws, and
* right-clicking cycles the color.
*/
class PaintAnyTime {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new PaintAnyTime();
}
});
}
Color[] colors = {Color.red, Color.blue, Color.black};
int currentColor = 0;
BufferedImage img = new BufferedImage(256, 256, BufferedImage.TYPE_INT_ARGB);
Graphics2D imgG2 = img.createGraphics();
JFrame frame = new JFrame("Paint Any Time");
JPanel panel = new JPanel() {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// Creating a copy of the Graphics
// so any reconfiguration we do on
// it doesn't interfere with what
// Swing is doing.
Graphics2D g2 = (Graphics2D) g.create();
// Drawing the image.
int w = img.getWidth();
int h = img.getHeight();
g2.drawImage(img, 0, 0, w, h, null);
// Drawing a swatch.
Color color = colors[currentColor];
g2.setColor(color);
g2.fillRect(0, 0, 16, 16);
g2.setColor(Color.black);
g2.drawRect(-1, -1, 17, 17);
// At the end, we dispose the
// Graphics copy we've created
g2.dispose();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(img.getWidth(), img.getHeight());
}
};
MouseAdapter drawer = new MouseAdapter() {
boolean rButtonDown;
Point prev;
#Override
public void mousePressed(MouseEvent e) {
if (SwingUtilities.isLeftMouseButton(e)) {
prev = e.getPoint();
}
if (SwingUtilities.isRightMouseButton(e) && !rButtonDown) {
// (This just behaves a little better
// than using the mouseClicked event.)
rButtonDown = true;
currentColor = (currentColor + 1) % colors.length;
panel.repaint();
}
}
#Override
public void mouseDragged(MouseEvent e) {
if (prev != null) {
Point next = e.getPoint();
Color color = colors[currentColor];
// We can safely paint to the
// image any time we want to.
imgG2.setColor(color);
imgG2.drawLine(prev.x, prev.y, next.x, next.y);
// We just need to repaint the
// panel to make sure the
// changes are visible
// immediately.
panel.repaint();
prev = next;
}
}
#Override
public void mouseReleased(MouseEvent e) {
if (SwingUtilities.isLeftMouseButton(e)) {
prev = null;
}
if (SwingUtilities.isRightMouseButton(e)) {
rButtonDown = false;
}
}
};
PaintAnyTime() {
// RenderingHints let you specify
// options such as antialiasing.
imgG2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
imgG2.setStroke(new BasicStroke(3));
//
panel.setBackground(Color.white);
panel.addMouseListener(drawer);
panel.addMouseMotionListener(drawer);
Cursor cursor =
Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR);
panel.setCursor(cursor);
frame.setContentPane(panel);
frame.pack();
frame.setResizable(false);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
It's also possible to set up a JLabel with an ImageIcon, although personally I don't like this method. I don't think JLabel and ImageIcon are required by their specifications to see changes we make to the image after we've passed it to the constructors.
This way also doesn't let us do stuff like painting the swatch. (For a slightly more complicated paint program, on the level of e.g. MSPaint, we'd want to have a way to select an area and draw a bounding box around it. That's another place we'd want to be able to paint directly on the panel, in addition to drawing to the image.)
import javax.swing.*;
import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
/**
* Holding left-click draws, and
* right-clicking cycles the color.
*/
class PaintAnyTime {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new PaintAnyTime();
}
});
}
Color[] colors = {Color.red, Color.blue, Color.black};
int currentColor = 0;
BufferedImage img = new BufferedImage(256, 256, BufferedImage.TYPE_INT_ARGB);
Graphics2D imgG2 = img.createGraphics();
JFrame frame = new JFrame("Paint Any Time");
JLabel label = new JLabel(new ImageIcon(img));
MouseAdapter drawer = new MouseAdapter() {
boolean rButtonDown;
Point prev;
#Override
public void mousePressed(MouseEvent e) {
if (SwingUtilities.isLeftMouseButton(e)) {
prev = e.getPoint();
}
if (SwingUtilities.isRightMouseButton(e) && !rButtonDown) {
// (This just behaves a little better
// than using the mouseClicked event.)
rButtonDown = true;
currentColor = (currentColor + 1) % colors.length;
label.repaint();
}
}
#Override
public void mouseDragged(MouseEvent e) {
if (prev != null) {
Point next = e.getPoint();
Color color = colors[currentColor];
// We can safely paint to the
// image any time we want to.
imgG2.setColor(color);
imgG2.drawLine(prev.x, prev.y, next.x, next.y);
// We just need to repaint the
// label to make sure the
// changes are visible
// immediately.
label.repaint();
prev = next;
}
}
#Override
public void mouseReleased(MouseEvent e) {
if (SwingUtilities.isLeftMouseButton(e)) {
prev = null;
}
if (SwingUtilities.isRightMouseButton(e)) {
rButtonDown = false;
}
}
};
PaintAnyTime() {
// RenderingHints let you specify
// options such as antialiasing.
imgG2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
imgG2.setStroke(new BasicStroke(3));
//
label.setPreferredSize(new Dimension(img.getWidth(), img.getHeight()));
label.setBackground(Color.white);
label.setOpaque(true);
label.addMouseListener(drawer);
label.addMouseMotionListener(drawer);
Cursor cursor =
Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR);
label.setCursor(cursor);
frame.add(label, BorderLayout.CENTER);
frame.pack();
frame.setResizable(false);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}

class SomeComponent extends JComponent {
private Graphics2D g2d;
public void paintComponent(Graphics g) {
g2d = (Graphics2D) g.create();
g2d.setColor(Color.BLACK);
g2d.scale(scale, scale);
g2d.drawOval(0, 0, importance, importance);
}
public Graphics2D getG2d() {
return g2d;
}
public void setG2d(Graphics2D g2d) {
this.g2d = g2d;
}
}
then you can do the following
get the SomeComponent instance in the panel and modify it
Graphics2D x= v.getPanel().get(i).getG2d;
x.setColor(Color.BLUE);
v.getPanel().get(i).setG2d(x);
v.getPanel().repaint();
v.getPanel().revalidate();
V is a class that extends JFrame and contains the panel in it AND
i is instance of SomeComponent

.drawLine() issues and buffered image

I have a paint programme and i have all the buttons and sliders done however i am having a problem with the actual painting itself. When I drag the cursor across the screen instead of an unbroken line I am getting almost a dotted line which i dont want. Here's the code for the MouseListener in the JPanel and BufferedImage:
public void mouseDragged(MouseEvent e) {
Graphics g=buffered.getGraphics();
g.setColor(mycol);
Graphics2D graph=(Graphics2D)g;
BasicStroke stroke=new BasicStroke(30);
graph.setStroke(stroke);
// g.fillRect(xcor, ycor, 20, 20);
/ /varx=e.getX();
ycor=e.getY();
xcor=e.getX();
int bad=xcor;
int good=ycor;
graph.drawLine(xcor, ycor, bad, good);
// buffered.setRGB(xcor, ycor, mycol.getRGB());
repaint();
// g.drawLine(xcor, ycor, x, x)
repaint();
}

Just to justify my comment, I am adding this answer, though a slight
change from the comment is here, which being the use of
mousePressed(...) instead of mouseClicked(...).
One more addition being, since you wanted the Graphics2D object of
the BufferedImage so instead of using getGraphics() always use
createGraphics() which returns the Graphics2D object, hence you
don't really have to worry about the Cast thingy in this.
Please do have a look at the example below :
======================
import java.awt.*;
import java.awt.image.BufferedImage;
import java.awt.event.*;
import java.net.URL;
import javax.swing.*;
import javax.imageio.ImageIO;
public class PaintingExample {
private BufferedImage bImage;
private ImageIcon image;
private JLabel imageLabel;
private int xClicked = 0;
private int yClicked = 0;
private int xDragged = 0;
private int yDragged = 0;
private MouseAdapter mouseListener = new MouseAdapter() {
#Override
public void mousePressed(MouseEvent me) {
xClicked = me.getX();
yClicked = me.getY();
}
#Override
public void mouseDragged(MouseEvent me) {
xDragged = me.getX();
yDragged = me.getY();
Graphics2D g2 = bImage.createGraphics();
g2.setColor(Color.WHITE);
BasicStroke stroke=new BasicStroke(30);
g2.setStroke(stroke);
g2.drawLine(xClicked, yClicked, xDragged, yDragged);
g2.dispose();
imageLabel.setIcon(new ImageIcon(bImage));
}
};
public PaintingExample() {
try {
bImage = ImageIO.read(new URL(
"http://i.imgur.com/fHiBMwI.jpg"));
image = new ImageIcon(bImage);
} catch(Exception e) {
e.printStackTrace();
}
}
private void displayGUI() {
JFrame frame = new JFrame("Painting on Image");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel contentPane = new JPanel();
imageLabel = new JLabel(image);
imageLabel.addMouseListener(mouseListener);
imageLabel.addMouseMotionListener(mouseListener);
contentPane.add(imageLabel);
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String... args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new PaintingExample().displayGUI();
}
});
}
}

If I'm understanding your problem correctly, the major issue you are going to have is the number of updates you will receive when the mouse is dragged.
Even if you drag slowly, you will not always be notified of EVERY pixel movement, instead the system waits for a "idle" state (or threshold) to notify you so it "appears" to be a smooth movement.
I was able to put this together by modifying your code slightly
private MouseAdapter mouseListener =
new MouseAdapter() {
private boolean paint = false;
#Override
public void mousePressed(MouseEvent me) {
xClicked = me.getX();
yClicked = me.getY();
xDragged = xClicked;
yDragged = yClicked;
paint = true;
}
#Override
public void mouseReleased(MouseEvent e) {
xClicked = -1;
xClicked = -1;
xDragged = -1;
yDragged = -1;
paint = false;
}
#Override
public void mouseMoved(MouseEvent me) {
}
#Override
public void mouseDragged(MouseEvent me) {
if (paint) {
xClicked = xDragged;
yClicked = yDragged;
xDragged = me.getX();
yDragged = me.getY();
xDragged = me.getX();
yDragged = me.getY();
Graphics2D g2 = bImage.createGraphics();
g2.setColor(Color.WHITE);
g2.drawLine(xClicked, yClicked, xDragged, yDragged);
g2.dispose();
imageLabel.setIcon(new ImageIcon(bImage));
me.getComponent().invalidate();
me.getComponent().repaint();
}
}
};
Basically, the idea is to draw a line from the last "known location" to the current location.
Hope this is in the ball park

Thirty pixels is a very wide line, and I can imagine that when drawn without antialiasing, it's going to look very jagged; that's probably what you're seeing. You might want to try something like
graph.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
On the other hand, maybe you're already getting antialiasing, and you want to turn it off; then
graph.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_OFF);
One of these is guaranteed to change the appearance of your image; hopefully it will be more to your liking.