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Draw Line between 2 buttons in java gui swift , it worked but its not accurate

I have this simple code:
class Success extends JFrame {
public JButton button1;
public JButton button2;
public Success() {
JPanel panel = new JPanel();
getContentPane().add(panel);
setSize(600, 800);
button1 = new JButton("press");
button2 = new JButton("this");
button1.setBounds(100, 200, 100, 100);
button2.setBounds(400, 500, 100, 100);
panel.add(button1);
panel.add(button2);
panel.setLayout(null);
}
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2 = (Graphics2D) g;
g2.drawLine(button1.getX(), button1.getY(), button2.getX(), button2.getY());
}
public static void main(String []args) {
Success s = new Success();
s.setVisible(true);
}
}
it works but checkout this image:
I want the accurate position of buttons.
I tried getLocationOnScreen() and getLocation() but they had the same problem.

First of all, you should never override the paint method of a JFrame, but rather the paintComponent method of your content panel.
That being said, SwingUtilities has methods to find the coordinates, given the source (the button in your case) and the destination (the frame in your case) Component objects :
public void paint(final Graphics g) {
super.paint(g);
Graphics2D g2 = (Graphics2D) g;
Point p1 = SwingUtilities.convertPoint(button1, 0, 0, this);
Point p2 = SwingUtilities.convertPoint(button2, 0, 0, this);
g2.drawLine(p1.x, p1.y, p2.x, p2.y);
}
Note that you probably encountered the problem of the frame's title bar/border not being taken into account, hence the vertical shift .

Jbutton issues within my code

i have been working on a flashing beacon on java using Jpanel, paint component and timers, however i am having trouble trying to get the buttons within the code to function. when the code is run, the flash button is supposed to prompt the beacon to start blinking/flashing whereas the steady button keeps it on the same colour. the alternating colours for the beacon are orange and grey.As well as this i cant seem to get rid of a button that keeps appearing in the top left of the window when the code is run. so far, this is what i have
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
/**
* Created by Enoch on 26/03/2015.
*/
class BelishaBeacon extends JPanel {
Color startLight, stopLight, color;
public void paintComponent(Graphics g) {
super.paintComponents(g);
Graphics2D g2 = (Graphics2D) g;
g2.setColor(color);
Ellipse2D firstOval = new Ellipse2D.Double(130, 70, 50, 50);
g2.draw(firstOval);
g2.fill(firstOval);
g2.setColor(Color.BLACK);
Rectangle rect1 = new Rectangle(150, 119, 10, 35);
g2.draw(rect1);
g2.fill(rect1);
g2.setColor(Color.WHITE);
Rectangle rect2 = new Rectangle(150, 150, 10, 35);
g2.draw(rect2);
g2.fill(rect2);
g2.setColor(Color.BLACK);
Rectangle rect3 = new Rectangle(150, 180, 10, 35);
g2.draw(rect3);
g2.fill(rect3);
g2.setColor(Color.WHITE);
Rectangle rect4 = new Rectangle(150, 210, 10, 35);
g2.draw(rect4);
g2.fill(rect4);
g2.setColor(Color.BLACK);
Rectangle rect5 = new Rectangle(150, 240, 10, 35);
g2.draw(rect5);
g2.fill(rect5);
g2.setColor(Color.WHITE);
Rectangle rect6 = new Rectangle(150, 270, 10, 35);
g2.draw(rect6);
g2.fill(rect6);
g2.setColor(Color.BLACK);
Rectangle rect7 = new Rectangle(150, 300, 10, 35);
g2.draw(rect7);
g2.fill(rect7);
g2.setColor(Color.WHITE);
Rectangle rect8 = new Rectangle(150, 330, 10, 35);
g2.draw(rect8);
g2.fill(rect8);
g2.setColor(Color.BLACK);
Rectangle rect9 = new Rectangle(150, 360, 10, 35);
g2.draw(rect9);
g2.fill(rect9);
g2.setColor(Color.WHITE);
Rectangle rect10 = new Rectangle(150, 390, 10, 35);
g2.draw(rect10);
g2.fill(rect10);
}
public BelishaBeacon() {
startLight = Color.ORANGE;
stopLight = Color.LIGHT_GRAY;
color = startLight;
new Blinker(this);
setBackground(Color.white);
}
public void blink()
{
color = (color == startLight ? stopLight : startLight);
repaint();
}
}
//
class Blinker
{
BelishaBeacon blinkPanel;
public Blinker(BelishaBeacon bp)
{
blinkPanel = bp;
new Timer(500, new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
blinkPanel.blink();
}
}).start();
}
}
//
class BelishaBeaconViewer extends JFrame {
JButton jbtFlash = new JButton("Flash");
JButton jbtSteady = new JButton("Steady");
JPanel bPanel = new JPanel();
BelishaBeacon bBPanel = new BelishaBeacon();
public BelishaBeaconViewer() {
bPanel.add(jbtFlash);
this.add(bPanel, BorderLayout.SOUTH);
bPanel.add(jbtSteady);
this.add(bBPanel, BorderLayout.CENTER);
jbtFlash.addActionListener(new FlashListener());
jbtSteady.addActionListener(new SteadyListener());
}
class FlashListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
repaint();
}
}
class SteadyListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
repaint();
}
}
public static void main(String[] args) {
JFrame bBFrame = new BelishaBeaconViewer();
bBFrame.setTitle("Belisha Beacon");
bBFrame.setSize(300, 300);
bBFrame.setDefaultCloseOperation((JFrame.EXIT_ON_CLOSE));
bBFrame.setVisible(true);
}
}

i cant seem to get rid of a button that keeps appearing in the top left of the window
//super.paintComponents(g); // typo
super.paintComponent(g); // should be
Don't start the Timer automatically.
The FlashListener should start the Timer, no need for the repaint
The SteadyListner should stop the Timer, no need for the repaint.

How to disable java.awt.Graphics.fillRect(int x, int y, int width, int height)'s effect?

It's the original image:
I use java.awt.Graphics.fillRect(int x, int y, int width, int height) to add a coloured rectangle on the image.
Graphics imageGraphics = image.createGraphics();
Color color = new Color(0,0,0,100);
imageGraphics.setColor(color);
imageGraphics.fillRect(0, 0, 800, 600);
So the image has been inverted and looks like this:
After that,I want to clear the black transparent rectangle partly and show the original image.
imageGraphics.clearRect(100,100,100,100);
But the effect is like this:
What my requirement is:
I want to know why it doesn't work and is there any other way to realize it?

Remember, painting is destructive. It might be possible to use AlphaComposite to achieve this result, but a simpler solution might be to simple constructive a compound shape and paint that instead.
The following example creates two Rectangles, one been the area we want to fill and one been the area we want to show, the second is then subtracted from the first (to create the window) and then the result is painted on top of the image
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.geom.Area;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class ShowArea {
public static void main(String[] args) {
new ShowArea();
}
public ShowArea() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private BufferedImage img;
public TestPane() {
try {
img = ImageIO.read(new File("sample.png"));
Rectangle bounds = new Rectangle(0, 0, img.getWidth(), img.getHeight());
Rectangle clip = new Rectangle(150, 10, 100, 100);
Area area = new Area(bounds);
area.subtract(new Area(clip));
Graphics2D g2d = img.createGraphics();
g2d.setColor(Color.BLACK);
g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f));
g2d.fill(area);
g2d.dispose();
} catch (IOException ex) {
ex.printStackTrace();
}
}
#Override
public Dimension getPreferredSize() {
return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
int x = (getWidth() - img.getWidth()) / 2;
int y = (getHeight() - img.getHeight()) / 2;
g2d.drawImage(img, x, y, this);
g2d.dispose();
}
}
}
If I were doing some kind of paint program, I would do this all within the paintComponent method or in some way that it didn't effect the original image, otherwise you've basic destroyed the image until you re-load it
Another solution might be to take a copy of the original area you want to keep and repaint it back on top after, for example...
img = ImageIO.read(new File("sample.png"));
// This is the portion of the image we want to save...
BufferedImage cutout = img.getSubimage(150, 10, 100, 100);
// This is the area we want to paint over...
Rectangle bounds = new Rectangle(0, 0, img.getWidth(), img.getHeight());
Graphics2D g2d = img.createGraphics();
g2d.setColor(Color.BLACK);
// Save the current Composite so we can reset it...
Composite comp = g2d.getComposite();
// Apply the composite and fill the area...
g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f));
g2d.fill(area);
// Reset the composite
g2d.setComposite(comp);
// Draw the part of the image we saved previously...
g2d.drawImage(cutout, 150, 10, this);
g2d.dispose();

You cant do that the way you're trying to.
It can be done by creating a BufferedImage filled with Color(0,0,0,200), then in that image draw rectangle with color Color(0,0,0,200) and then apply it on image.
Remember, that drawing filledRectange is not a "undo operation"- it is written on pixels and it can't be undone.
EDIT
Icon imageIcon = new javax.swing.ImageIcon("image.jpg");
BufferedImage mask = new BufferedImage(imageIcon.getIconWidth(), imageIcon.getIconHeight(), BufferedImage.TYPE_4BYTE_ABGR);
BufferedImage image = new BufferedImage(imageIcon.getIconWidth(), imageIcon.getIconHeight(), BufferedImage.TYPE_4BYTE_ABGR);
imageIcon.paintIcon(null, image.getGraphics(), 0, 0);
Graphics maskGraphics = mask.getGraphics();
//drawing grey background
maskGraphics.setColor(new Color(0, 0, 0, 120));
maskGraphics.fillRect(0, 0, mask.getWidth(), mask.getHeight());
//drawing black frame
maskGraphics.setColor(new Color(0, 0, 0, 255));
maskGraphics.drawRect(99, 99, 301, 301);
//drawing original image window
maskGraphics.drawImage(image, 100, 100, 400, 400, 100, 100, 400, 400, null);
//apply mask on image
new ImageIcon(mask).paintIcon(null, image.getGraphics(), 0, 0);
//result presentation
label.setIcon(new ImageIcon(image));

Yes this is easily doable. The problem is that any draw operation is destructive, what you see is what you get, the information that was painted upon is lost.
Something like this where you store a subimage, do your paint operation then draw the subimage back on top.
public class Q23709070 {
public static void main(String[] args) {
JFrame frame = new JFrame();
Panel p = new Panel();
frame.getContentPane().add(p);
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
static class Panel extends JPanel {
int w = 400;
int h = 400;
int x = 100;
int y = 100;
BufferedImage img;
BufferedImage subImg;
BufferedImage save;
public Panel() {
try {
img = ImageIO.read(getClass().getResourceAsStream("0qzCf.jpg"));
} catch (IOException e) {
}
subImg = img.getSubimage(x, y, w, h);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
Color g2dColor = g2d.getColor();
Color fillColor = new Color(0, 0, 0, 100);
g2d.drawImage(img, 0, 0, null);
g2d.setColor(fillColor);
g2d.fillRect(0, 0, img.getWidth(), img.getHeight());
g2d.drawImage(subImg, x, y, null);
g2d.setColor(g2dColor);
if (save == null) {
save = new BufferedImage(img.getWidth(), img.getHeight(),
img.getType());
this.paint(save.getGraphics());
try {
ImageIO.write(save, "jpg", new File("save.jpg"));
} catch (IOException e) {
}
}
}
#Override
#Transient
public Dimension getPreferredSize() {
return new Dimension(img.getWidth(), img.getHeight());
}
}
}
Rendering

JPanel gradient background

I googled but could find no correct answer. I have a JPanel and I want it to have a gradient that comes from top to bottom. I'm just going to use two colors. How can I achieve this?

Here you go:
import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class TestPanel extends JPanel {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
int w = getWidth(), h = getHeight();
Color color1 = Color.RED;
Color color2 = Color.GREEN;
GradientPaint gp = new GradientPaint(0, 0, color1, w, h, color2);
g2d.setPaint(gp);
g2d.fillRect(0, 0, w, h);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
TestPanel panel = new TestPanel();
frame.add(panel);
frame.setSize(200, 200);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
});
}
}

You can use this :
JPanel contentPane = new JPanel() {
#Override
protected void paintComponent(Graphics grphcs) {
super.paintComponent(grphcs);
Graphics2D g2d = (Graphics2D) grphcs;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
GradientPaint gp = new GradientPaint(0, 0,
getBackground().brighter().brighter(), 0, getHeight(),
getBackground().darker().darker());
g2d.setPaint(gp);
g2d.fillRect(0, 0, getWidth(), getHeight());
}
};
hope that help;
you can also back to this artical for more help:
Gradient background to any jcomponent

What is the simplest way to draw in Java?

What is the simplest way to draw in Java?
import java.awt.*;
import javax.swing.*;
public class Canvas
{
private JFrame frame;
private Graphics2D graphic;
private JPanel canvas;
public Canvas()
{
frame = new JFrame("A title");
canvas = new JPanel();
frame.setContentPane(canvas);
frame.pack();
frame.setVisible(true);
}
public void paint(Graphics g){
BufferedImage offImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Grapics2D g2 = offImg.createGraphics();
g2.setColor(new Color(255,0,0));
g2.fillRect(10,10,200,50);
}
}
This doesn't work and I have no idea how to get anything to appear.

Easiest way:
public class Canvas extends JPanel {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
// painting code goes here.
}
}
You simply need to extend JPanel and override the paintComponent method of the panel.
I'd like to reiterate that you should not be overriding the paint method.
Here is a very minimalistic example that works.
public static void main(String[] args) {
JFrame f = new JFrame();
JPanel p = new JPanel() {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawLine(0, 0, 100, 100);
}
};
f.add(p);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}

// No. 1
// Create a graphics context on the buffered image
Graphics2D g2d = bimage.createGraphics();
// Draw on the buffered image
g2d.setColor(Color.red);
g2d.fill(new Ellipse2D.Float(0, 0, 200, 100));
g2d.dispose();
// No.2
// In case the buffered image supports transparency
g2d = bimage.createGraphics();
// Transparency is created on all the filled pixels
Color transparent = new Color(0, 0, 0, 0);
g2d.setColor(transparent);
g2d.setComposite(AlphaComposite.Src);
g2d.fill(new Rectangle2D.Float(20, 20, 100, 20));
g2d.dispose();

To make something appear in paint(Graphics g) you need to call the drawing methods (like fillRect) on that Graphics. You are creating a bitmap and then drawing to the bitmap, not the screen.
public void paint(Graphics g){
g.setColor(new Color(255,0,0));
g.fillRect(10,10,200,50);
}

jjnguy already wrote how to do it right ... but here why it does not work in your example:
import java.awt.*;
import javax.swing.*;
public class Canvas
Here you have a class which does not relate in any way to Swing or AWT.
(By the way, you may want to select another name to avoid confusion with java.awt.Canvas.)
{
private JFrame frame;
private Graphics2D graphic;
private JPanel canvas;
public Canvas()
{
frame = new JFrame("A title");
canvas = new JPanel();
frame.setContentPane(canvas);
Here you are creating a new JPanel (for confusion also named canvas), and add it to the frame.
Is is this panel's paint and paintComponent methods which are called when the system shows your frame.
frame.pack();
frame.setVisible(true);
}
public void paint(Graphics g){
BufferedImage offImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Grapics2D g2 = offImg.createGraphics();
g2.setColor(new Color(255,0,0));
g2.fillRect(10,10,200,50);
}
This paint method is never used at all (since it is not part of a component), and if it would be called, then you are only painting to some BufferedImage, not to the screen.
}