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Repaint() not being called if i use ImageIO.read()

When i try to set value to BufferedImage called dinoImage in Dino.java in a constructor i just get a blank screen every time (second picture) because repaint() is not being called, but if i set it to null it is working just fine but without this image (first picture).
No exceptions, everything seems fine in this code, this problem appears when i try to set value to this field using static method getImage of Resource.java which uses this line of code ImageIO.read(new File(path)) and it causes that repaint() is not being called, i guess this line causes such weird behavior but i dont know how to solve it.
Main.java
public class Main {
public static void main(String[] args) {
GameWindow gameWindow = new GameWindow();
gameWindow.startGame();
}
}
GameWindow.java
public class GameWindow extends JFrame {
private GameScreen gameScreen;
public GameWindow() {
super("Runner");
setSize(1000, 500);
setVisible(true);
setResizable(false);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
gameScreen = new GameScreen();
add(gameScreen);
}
public void startGame() {
gameScreen.startThread();
}
}
GameScreen.java
public class GameScreen extends JPanel implements Runnable, KeyListener {
private Thread thread;
public static final double GRAVITY = 0.1;
public static final int GROUND_Y = 300;
private Dino dino;
public GameScreen() {
thread = new Thread(this);
dino = new Dino();
}
public void startThread() {
thread.start();
}
#Override
public void run() {
while(true) {
try {
Thread.sleep(20);
dino.updatePosition();
repaint();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
// g.clearRect(0, 0, getWidth(), getHeight());
g.setColor(Color.RED);
g.drawLine(0, GROUND_Y, getWidth(), GROUND_Y);
dino.draw(g);
}
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e) {
System.out.println("Key Pressed");
dino.jump();
}
#Override
public void keyReleased(KeyEvent e) {
System.out.println("Key Released");
}
}
Dino.java
public class Dino {
private double x = 100;
private double y = 100;
private double speedY = 0;
private BufferedImage dinoImage;
public Dino() {
dinoImage = getImage("data/dino.png");
}
public void updatePosition() {
if(y + speedY >= GROUND_Y - 100) {
speedY = 0;
y = GROUND_Y - 100;
} else {
speedY += GRAVITY;
y += speedY;
}
}
public void jump() {
if(y == GROUND_Y - 100) {
speedY = -5;
y += speedY;
}
}
public void draw(Graphics g) {
g.setColor(Color.BLACK);
g.drawRect((int)x, (int)y, 100, 100);
g.drawImage(dinoImage, (int)x, (int)y, null);
}
}
Resource.java
public class Resource {
public static BufferedImage getImage(String path) {
BufferedImage image = null;
try {
image = ImageIO.read(new File(path));
} catch (IOException e) {
e.printStackTrace();
}
return image;
}
}

setSize(1000, 500);
setVisible(true);
setResizable(false);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
gameScreen = new GameScreen();
add(gameScreen);
Swing components need to be added to the frame BEFORE the frame is made visible. Otherwise the panel has a size of (0, 0) and there is nothing to paint.
The code should be something like:
gameScreen = new GameScreen();
add(gameScreen);
setSize(1000, 500);
setVisible(true);

Java-Image not drawing to screen

I am trying to draw an image to the screen using Java. The problem is that it does not appear and no errors occur.
import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
public class GameClass extends JPanel implements ActionListener, KeyListener{
private BufferedImage image;
public GameClass(){
Timer time = new Timer(15, this);
time.start();
this.addKeyListener(this);
this.setFocusable(true);
}
public void openImage(){
try {
image = ImageIO.read(this.getClass().getResource("spaceship.png"));
} catch (IOException e) {
System.out.println("An error occurred!");
}
}
public void paintComponent(Graphics g){
g.setColor(Color.BLACK);
g.fillRect(0, 0, Main.WW, Main.WH);
g.drawImage(image,Main.WW/2,Main.WH/2,null);
}
public void actionPerformed(ActionEvent e){
repaint();
}
public void keyPressed(KeyEvent e){
}
public void keyReleased(KeyEvent e){
}
public void keyTyped(KeyEvent e){
}
}

You need to call you openImage() method in your constructor.
I renamed this to loadImages() so that this method can handle loading multiple images. I also created a static image loading function.
Note: If you have not already, create a resources/ folder in your projects' src/ folder. This folder will contain your application's assets i.e. text, image, and other data files.
import java.awt.*;
import java.awt.event.*;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*
public class GameClass extends JPanel
implements ActionListener, KeyListener {
private static final long serialVersionUID = -2508183917768834794L;
private Image image;
// Added this, because you did not include it.
private class Main {
static final int WW = 256;
static final int WH = 256;
}
public GameClass() {
Timer time = new Timer(15, this);
time.start();
this.addKeyListener(this);
this.setFocusable(true);
this.loadImages();
}
// Load all required images into instance variables.
public void loadImages() {
image = loadImage("spaceship.png");
}
// Draw the image to the panel.
public void paintComponent(Graphics g) {
g.setColor(Color.BLACK);
g.fillRect(0, 0, Main.WW, Main.WH);
// Dimensions of spaceship
int imgW = image.getWidth(null);
int imgH = image.getHeight(null);
// Dimensions of panel
int pnlW = this.getWidth();
int pnlH = this.getHeight();
// Draw the spaceship in the center of the window.
g.drawImage(image, pnlW/2 - imgW/2, pnlH/2 - imgH/2, null);
}
public void actionPerformed(ActionEvent e) {
repaint();
}
public void keyPressed(KeyEvent e) { }
public void keyReleased(KeyEvent e) { }
public void keyTyped(KeyEvent e) { }
// Static image loader method which utilizes the `ClassLoader`.
public static Image loadImage(String filename) {
try {
return ImageIO.read(GameClass.class.getClassLoader().getResource("resources/" + filename));
} catch (IOException e) {
System.out.println("Error loading image: " + filename);
}
return null;
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
Container panel = new GameClass();
frame.setSize(Main.WW, Main.WH);
frame.setTitle("Spaceship Game");
frame.setContentPane(panel);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
});
}
}

JButton hover effect animation. Changing opacity by Mouse Listener

I'd like to do JButton with nice transition effect. I write a class which extend by JButton and add to it custom MouseAdapter. It almost works, but if opacity should have 0 my one BufferedImage don't vanish.
Here my all source code:
public class ImageHoverButton extends JButton {
public class MouseListener extends MouseAdapter
{
public void mouseExited(MouseEvent me)
{
new Thread(new Runnable()
{
public void run()
{
for (float i = 1f; i >= 0f; i -= .03f)
{
setOpacity(i);
try
{
Thread.sleep(10);
}
catch (Exception e)
{
}
}
}
}).start();
}
public void mouseEntered(MouseEvent me)
{
new Thread(new Runnable()
{
public void run()
{
for (float i = 0f; i <= 1f; i += .03f)
{
setOpacity(i);
try
{
Thread.sleep(10);
}
catch (Exception e)
{
}
}
}
}).start();
}
public void mousePressed(MouseEvent me)
{
new Thread(new Runnable()
{
public void run()
{
for (float i = 1f; i >= 0.6f; i -= .1f)
{
setOpacity(i);
try
{
Thread.sleep(1);
}
catch (Exception e)
{
}
}
}
}).start();
}
}
private static final long serialVersionUID = 1L;
private BufferedImage imgBottom;
private BufferedImage imgHover;
private BufferedImage imgHoverRGB;
// filter to imgInActive
float[] scales = { 1f, 1f, 1f, 0f};
float[] offsets = new float[4];
RescaleOp rop = new RescaleOp(scales, offsets, null);
/**
* Constructor for image path
* #param img
* #param x
* #param y
*/
public ImageHoverButton(String imgBottomPath, String imgHoverPath, int x, int y) {
try {
this.imgBottom = ImageIO.read(new File(imgBottomPath));
this.imgHover = ImageIO.read(new File(imgHoverPath));
imgHoverRGB = new BufferedImage(imgHover.getWidth(null),
imgHover.getHeight(null),
BufferedImage.TYPE_INT_ARGB);
Graphics g = imgHoverRGB.getGraphics();
g.drawImage(imgHover, 0, 0, null);
} catch (IOException e) {
}
this.setBounds(x, y, imgBottom.getWidth() + 40 , imgBottom.getHeight() + 50);
addMouseListener(new MouseListener());
setOpacity(0f);
setOpaque(false);
setBorderPainted(false);
setRolloverEnabled(false);
setCursor(new Cursor(Cursor.HAND_CURSOR));
setLayout(null);
}
public void setOpacity(float opacity) {
scales[3] = opacity;
rop = new RescaleOp(scales, offsets, null);
repaint();
}
public void paint(Graphics g) {
Graphics2D g2d = (Graphics2D)g;
g2d.drawImage(imgBottom, 50, 50, null);
g2d.drawImage(imgHoverRGB, rop, 0, 0);
}
}
Have any idea how to improve this?

I'm not so familiar with RescaleOp, and can't remember having used this before. But it seems like the results of applying it in this case are somewhat unexpected.
As an alternative, you might consider an AlphaComposite. The minimum modification that is necessary to achieve the desired effect would then be to change the line
g2d.drawImage(imgHoverRGB, rop, 0, 0);
to
g2d.setComposite(AlphaComposite.getInstance(
AlphaComposite.SRC_OVER, scales[3]));
g2d.drawImage(imgHoverRGB, 0, 0, null);
However, there are several other issues with the code:
don't override paint. Instead, override paintComponent
don't call setBounds on a component (particlularly not in a constructor). The placement should be done by a layout manager
don't swallow Exceptions silently
don't load the images in the constructor of the button
implement getPreferredSize properly
don't spawn hundreds of threads due to mouse movement. (When you quickly move the mouse in and out, you'll have several threads running - some of them increasing the opacity, and some of them decreasing the opacity)
I created an example showing one possible approach: It contains an OpacityAnimator that allows a transition between two opacities, with a predefined delay in milliseconds. This animator is used to increase the opacity of the foreground image when the button is hovered with the mouse, and to decrease it when the mouse leaves the button.
(Note that this could be generalized further, and there are many possible "configuration settings" (like the transition delay) that could be exposed, but this is just intended as an example)
import java.awt.AlphaComposite;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class HoverButtonTest
{
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
#Override
public void run()
{
try
{
createAndShowGUI();
}
catch (IOException e)
{
e.printStackTrace();
}
}
});
}
private static void createAndShowGUI() throws IOException
{
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
BufferedImage backgroundImage = loadImage("background.png");
BufferedImage foregroundImage = loadImage("foreground.png");
f.getContentPane().setLayout(new FlowLayout());
f.getContentPane().add(
new ImageHoverButton(backgroundImage, foregroundImage));
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
private static BufferedImage loadImage(String path) throws IOException
{
return convertToARGB(ImageIO.read(new File(path)));
}
public static BufferedImage convertToARGB(BufferedImage image)
{
BufferedImage newImage = new BufferedImage(image.getWidth(),
image.getHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D g = newImage.createGraphics();
g.drawImage(image, 0, 0, null);
g.dispose();
return newImage;
}
}
class ImageHoverButton extends JButton
{
private class MouseHoverListener extends MouseAdapter
{
#Override
public void mouseExited(MouseEvent me)
{
opacityAnimator.changeOpacity(0.0f, 250);
}
#Override
public void mouseEntered(MouseEvent me)
{
opacityAnimator.changeOpacity(1.0f, 1000);
}
#Override
public void mousePressed(MouseEvent me)
{
opacityAnimator.changeOpacity(0.5f, 50);
}
}
private class OpacityAnimator
{
private final int DELAY_MS = 10;
private final Timer timer;
private float targetOpacity;
private float currentOpacity;
private float opacityStep;
OpacityAnimator()
{
timer = new Timer(DELAY_MS, new ActionListener()
{
#Override
public void actionPerformed(ActionEvent e)
{
if (currentOpacity > targetOpacity)
{
currentOpacity += opacityStep;
currentOpacity = Math.max(
currentOpacity, targetOpacity);
}
else if (currentOpacity < targetOpacity)
{
currentOpacity += opacityStep;
currentOpacity = Math.min(
currentOpacity, targetOpacity);
}
if (currentOpacity == targetOpacity)
{
timer.stop();
}
setOpacity(currentOpacity);
}
});
}
void changeOpacity(float targetOpacity, int durationMs)
{
timer.stop();
this.targetOpacity = targetOpacity;
float delta = targetOpacity - currentOpacity;
if (durationMs > 0)
{
opacityStep = (delta / durationMs) * DELAY_MS;
}
else
{
opacityStep = delta;
}
timer.start();
}
}
private final OpacityAnimator opacityAnimator;
private final BufferedImage backgroundImage;
private final BufferedImage foregroundImage;
private float opacity = 0.0f;
public ImageHoverButton(BufferedImage backgroundImage,
BufferedImage foregroundImage)
{
this.backgroundImage = backgroundImage;
this.foregroundImage = foregroundImage;
this.opacityAnimator = new OpacityAnimator();
addMouseListener(new MouseHoverListener());
setOpaque(false);
setBorderPainted(false);
setRolloverEnabled(false);
setCursor(new Cursor(Cursor.HAND_CURSOR));
}
#Override
public Dimension getPreferredSize()
{
if (super.isPreferredSizeSet())
{
return super.getPreferredSize();
}
int w = Math
.max(backgroundImage.getWidth(), foregroundImage.getWidth());
int h = Math.max(backgroundImage.getHeight(),
foregroundImage.getHeight());
return new Dimension(w, h);
}
public void setOpacity(float opacity)
{
this.opacity = opacity;
repaint();
}
#Override
protected void paintComponent(Graphics gr)
{
super.paintComponent(gr);
Graphics2D g = (Graphics2D) gr;
g.drawImage(backgroundImage, 0, 0, null);
g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,
opacity));
g.drawImage(foregroundImage, 0, 0, null);
}
}

Don't access Swing components from other threads. Use a swing Timer instead.
See How to use swing timers

How to load two extended JPanel class to one JFrame?

I'm going to make a game with Java, my game will have a menu. the menu is having a background, and 2 JLabel objects. I've make them on separate class, which is passed to one JFrame. And my problem is, I've load 2 of them on a single frame, but one of them always hidden by another.
this is the code:
JFrame class
#SuppressWarnings("serial")
public class Sistem extends JFrame{
private final int lebar=954;
private final int tinggi=540;
private Image bg;
File gbr=new File("res/a.jpg");
public Sistem(){
this.setTitle("Unknown man Unkown power");
this.setSize(new Dimension(lebar,tinggi));
this.setFocusable(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setResizable(false);
this.setContentPane(new Ngrep());
//this.setContentPane(new Menu());
this.setVisible(true);
//loadfont();
//loadbg();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
new Sistem();
}
});
}
}
background class
#SuppressWarnings("serial")
public class Ngrep extends JPanel{
private int l=954;
private int t=540;
private BufferedImage bg;
File gbr=new File("res/a.jpg");
public Ngrep(){
loadbg();
}
private void loadbg() {
// TODO Auto-generated method stub
try {
bg=ImageIO.read(gbr);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
#Override
public void paint(Graphics g) {
// TODO Auto-generated method stub
super.paint(g);
g.drawImage(bg, 0, 0, l, t, null);
}
}
menu class
#SuppressWarnings("serial")
public class Menu extends JPanel implements Runnable,KeyListener{
private int l=954;
private int t=540;
JLabel menu1=new JLabel("MULAI BARU");
JLabel menu2=new JLabel("KELUARRR");
private File fo=new File("res/Mawns.ttf");
JLayeredPane p=new JLayeredPane();
public Menu(){
loadfont();
this.add(menu1);
this.add(menu2);
}
public void loadfont(){
try {
FileInputStream fi=new FileInputStream(fo);
Font f=Font.createFont(Font.TRUETYPE_FONT, fi).deriveFont(Font.TRUETYPE_FONT, 30);
GraphicsEnvironment ge=GraphicsEnvironment.getLocalGraphicsEnvironment();
ge.registerFont(f);
menu1.setFont(f);
menu2.setFont(f);
} catch (Exception ex) {
// TODO Auto-generated catch block
ex.printStackTrace();
}
p.setLayout(new GridLayout(2, 3));
menu1.setBounds(0, 0, getWidth(), getHeight());
menu2.setBounds(0, 0+menu1.getHeight(), getWidth(), getHeight());
p.add(menu1, 2);
p.add(menu2, 2);
}
}
What I want is the menu is in front of background but background still can be seen. and how to arrange the JLabel that I've created to center down of the screen.
How can I achieve the required layout?

public class Ngrep extends JPanel{
Note that since Ngrep is a JPanel you can add components directly to it, making the Menu class redundant.
Something like seen in this SSCCE.
Note that I ended up making so many changes so fast I could not be bothered explicitly documenting most of them. Look over the code carefully, check it against your original code, check the Java Docs, and if there is any change you do not understand, ask me.
import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
import javax.swing.*;
import java.net.URL;
import javax.imageio.ImageIO;
#SuppressWarnings("serial")
public class Sistem extends JFrame {
public Sistem() {
this.setTitle("Unknown man Unkown power");
this.setFocusable(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setContentPane(new Ngrep());
this.setResizable(false);
this.pack();
this.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Sistem();
}
});
}
}
#SuppressWarnings("serial")
class Ngrep extends JPanel {
private int l = 375;
private int t = 150;
private BufferedImage bg;
JLabel menu1 = new JLabel("MULAI BARU");
JLabel menu2 = new JLabel("KELUARRR");
public Ngrep() {
this.add(menu1);
this.add(menu2);
try {
Font f = new Font(Font.MONOSPACED, Font.ITALIC, 30);
menu1.setFont(f);
menu1.setForeground(Color.RED);
menu2.setFont(f);
menu2.setForeground(Color.RED);
URL url = new URL("http://i.stack.imgur.com/OVOg3.jpg");
bg = ImageIO.read(url);
} catch (Exception ex) {
ex.printStackTrace();
}
setLayout(new GridLayout(2, 3));
add(menu1);
add(menu2);
}
public Dimension getPreferredSize() {
return new Dimension(l, t);
}
/*
* For a JComponent, override paintComponent rather than paint
*/
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
// a JPanel IS AN ImageObserver
g.drawImage(bg, 0, 0, getWidth(), getHeight(), this);
}
}

Start by using JFrame#add instead of JFrame#setContentPane, unless you intend to add more components to that (content) pane.
By default JFrame uses a BorderLayout for its LayoutManager. You will need to either change it to something you prefer to use OR add each component to an appropriate position within the BorderLayout
See Laying Out Components Within a Container for more details

solved, because I've found that i use paint() instead of paintComponent().
like this:
#Override
public void paint(Graphics g) {
// TODO Auto-generated method stub
super.paint(g);
g.drawImage(bg, 0, 0, l, t, this);
}
to this :
#Override
public void paintComponent(Graphics g) {
// TODO Auto-generated method stub
super.paintComponents(g);
g.drawImage(bg, 0, 0, l, t, this);
}

How to draw thin line with no gap while dragging the cursor?

I have this following class, which refresh a jpeg file in layer 0 and layer 1 is used to draw/paint/sketch up anything related to smash things. But in my drawing when I want to do a thin line, it breaks. Because the mouse cursor movement needs to be slower.
How to resolve on fast mouse move, that the line remains joined?
Annotation.java
package test;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Annotation {
// Image
private static Image backgroundImage;
private static BufferedImage _bufImage = null;
// Enum
public static enum Shape { RECTANGLE, OVAL, LINE }
private static enum State { IDLE, DRAGGING }
private static final Shape INIIIAL_SHAPE = Shape.RECTANGLE;
private static final Color INITIAL_COLOR = Color.RED;
private static Shape _shape = INIIIAL_SHAPE;
private static Color _color = INITIAL_COLOR;
private static State _state = State.IDLE;
private static Point _start = null;
private static Point _end = null;
// JPanel
private static JPanel p;
private static JPanel mp;
/* Run: */
public static void main(String args[]) {
c();
}
/* GUI */
public static void c() {
try {
backgroundImage = ImageIO.read(new File("/var/tmp/test.jpeg"));
} catch (IOException e) {
e.printStackTrace();
}
myTimer();
loadAnnotation();
loadBackground();
JFrame f;
f = new JFrame();
f.setLayout(new BorderLayout());
f.add(mp);
f.pack();
f.setVisible(true);
}
/* 5 seconds to load picture */
public static void myTimer() {
javax.swing.Timer t = new javax.swing.Timer(5000, new ActionListener() {
public void actionPerformed(ActionEvent ae) {
try {
backgroundImage = ImageIO.read(new File("/var/tmp/test.jpeg"));
mp.repaint();
} catch (IOException e) {
e.printStackTrace();
}
}
});
t.start();
}
/* Layer 0:
* Load background picture */
public static void loadBackground() {
mp = new JPanel() {
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(backgroundImage, 0, 0, 1024, 600, null);
}
public Dimension getPreferredSize() {
return new Dimension(1024, 600);
}
};
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) {
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) {
g2.drawLine(_start.x, _start.y, _end.x , _end.y);
}
}
public Dimension getPreferredSize() {
return new Dimension(1024, 600);
}
};
p.setLayout(new FlowLayout());
p.addMouseListener(new MouseListener() {
#Override
public void mouseClicked(MouseEvent me) {
}
#Override
public void mousePressed(MouseEvent me) {
}
#Override
public void mouseReleased(MouseEvent me) {
//_state = State.IDLE;
_state = State.IDLE;
}
#Override
public void mouseEntered(MouseEvent me) {
}
#Override
public void mouseExited(MouseEvent me) {
}
});
p.addMouseMotionListener(new MouseMotionListener() {
#Override
public void mouseDragged(MouseEvent me) {
System.out.println("drag");
_state = State.DRAGGING;
_start = me.getPoint();
_end = _start;
if (_state == State.DRAGGING) {
Graphics2D g2 = _bufImage.createGraphics();
g2.setColor(Color.red);
g2.setStroke(new BasicStroke(90));
g2.fillOval(_start.x, _start.y, 10, 10);
p.repaint();
}
}
#Override
public void mouseMoved(MouseEvent me) {
System.out.println("move");
}
});
JButton pm = new JButton("+");
pm.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
}
});
p.add(pm);
p.setOpaque(true);
}
}

import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Annotation {
// Image
private static Image backgroundImage;
private static BufferedImage _bufImage = null;
// Enum
public static enum Shape { RECTANGLE, OVAL, LINE }
private static enum State { IDLE, DRAGGING }
private static final Shape INIIIAL_SHAPE = Shape.RECTANGLE;
private static final Color INITIAL_COLOR = Color.RED;
private static Shape _shape = INIIIAL_SHAPE;
private static Color _color = INITIAL_COLOR;
private static State _state = State.IDLE;
private static Point _start = null;
private static Point _end = null;
// JPanel
private static JPanel p;
private static JPanel mp;
/* Run: */
public static void main(String args[]) {
c();
}
/* GUI */
public static void c() {
try {
URL url = new URL("http://pscode.org/media/stromlo2.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() {
mp = new JPanel() {
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(backgroundImage, 0, 0, getWidth(), getHeight(), null);
}
public Dimension getPreferredSize() {
return new Dimension(backgroundImage.getWidth(this), backgroundImage.getHeight(this));
}
};
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) {
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) {
g2.drawLine(_start.x, _start.y, _end.x , _end.y);
}
}
public Dimension getPreferredSize() {
return new Dimension(1024, 600);
}
};
p.setLayout(new FlowLayout());
p.addMouseListener(new MouseListener() {
#Override
public void mouseClicked(MouseEvent me) {
}
#Override
public void mousePressed(MouseEvent me) {
}
#Override
public void mouseReleased(MouseEvent me) {
//_state = State.IDLE;
_state = State.IDLE;
}
#Override
public void mouseEntered(MouseEvent me) {
}
#Override
public void mouseExited(MouseEvent me) {
}
});
p.addMouseMotionListener(new MouseMotionListener() {
#Override
public void mouseDragged(MouseEvent me) {
_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;
}
#Override
public void mouseMoved(MouseEvent me) {
//System.out.println("move");
_start = me.getPoint();
}
});
JButton pm = new JButton("+");
pm.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
}
});
p.add(pm);
p.setOpaque(true);
}
}

I solved this problem by drawing rectangles between points, using the Stroke size (Basic Stroke) for height. It sounds like an icky solution but it does pretty well in reality