We Keep Coding

Clearing the screen for new graphics in Java (awt)

I have this code which is basically a home menu with two clickable rectangles.
Start Game
Info
Start Game works fine.
Info is what is not really working. When pressed, the info screen will appear, but the home menu buttons will still be there though not visible (can be clicked).. it seems that when the info menu is appearing, the home menu buttons are not getting cleared.
Also, any point on the info menu is clickable and will show the home menu again. (not what intended, only the back buttons should do that).
How can I fix those problems ?
package test;
import javax.swing.*;
import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.font.FontRenderContext;
import java.awt.font.TextLayout;
import java.awt.geom.Rectangle2D;
import java.awt.image.ImageObserver;
import java.awt.image.ImageProducer;
public class HomeMenu extends JComponent implements MouseListener, MouseMotionListener {
private static final String GAME_TITLE = "BRICK DESTROY";
private static final String START_TEXT = "START";
private static final String INFO_TEXT = "INFO";
private static final String howtoPlay = """
1- Click Start\n
2- Choose the mode\n
3- Each mode has 3 levels\n
4- To play/pause press space, use 'A' and 'D' to move\n
5- To open pause menu press 'ESC'\n
6- To open DebugPanel press 'ALT-SHIFT-F1'""";
private static final String backText = "BACK";
private static final Color BORDER_COLOR = new Color(200,8,21); //Venetian Red
private static final Color DASH_BORDER_COLOR = new Color(255, 216, 0);//school bus yellow
private static final Color TEXT_COLOR = new Color(255, 255, 255);//white
private static final Color CLICKED_BUTTON_COLOR = Color.ORANGE.darker();;
private static final Color CLICKED_TEXT = Color.ORANGE.darker();
private static final int BORDER_SIZE = 5;
private static final float[] DASHES = {12,6};
private Rectangle menuFace;
private Rectangle infoFace;
private Rectangle startButton;
private Rectangle infoButton;
private Rectangle backButton;
private BasicStroke borderStoke;
private BasicStroke borderStoke_noDashes;
private Image img = Toolkit.getDefaultToolkit().createImage("1.jpeg");
private Font gameTitleFont;
private Font infoFont;
private Font buttonFont;
private Font howtoPlayFont;
private GameFrame owner;
private boolean startClicked;
private boolean infoClicked = false;
private boolean backClicked = false;
public HomeMenu(GameFrame owner,Dimension area){
this.setFocusable(true);
this.requestFocusInWindow();
this.addMouseListener(this);
this.addMouseMotionListener(this);
this.owner = owner;
menuFace = new Rectangle(new Point(0,0),area);
infoFace = new Rectangle(new Point(0,0),area);
this.setPreferredSize(area);
Dimension btnDim = new Dimension(area.width / 3, area.height / 12);
startButton = new Rectangle(btnDim);
infoButton = new Rectangle(btnDim);
backButton = new Rectangle(btnDim);
borderStoke = new BasicStroke(BORDER_SIZE,BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND,0,DASHES,0);
borderStoke_noDashes = new BasicStroke(BORDER_SIZE,BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND);
gameTitleFont = new Font("Calibri",Font.BOLD,28);
infoFont = new Font("Calibri",Font.BOLD,24);
buttonFont = new Font("Calibri",Font.BOLD,startButton.height-2);
howtoPlayFont = new Font("Calibri",Font.PLAIN,14);
}
public void paint(Graphics g){
drawMenu((Graphics2D)g);
}
public void drawMenu(Graphics2D g2d){
if(infoClicked) {
drawInfoMenu(g2d);
return;
}else{
drawContainer(g2d);
Color prevColor = g2d.getColor();
Font prevFont = g2d.getFont();
double x = menuFace.getX();
double y = menuFace.getY();
g2d.translate(x,y);
//methods calls
drawText(g2d);
drawButton(g2d);
//end of methods calls
g2d.translate(-x,-y);
g2d.setFont(prevFont);
g2d.setColor(prevColor);
}
Toolkit.getDefaultToolkit().sync();
}
private void drawContainer(Graphics2D g2d){
Color prev = g2d.getColor();
//g2d.setColor(BG_COLOR);
g2d.drawImage(img,0,0,menuFace.width,menuFace.height,this);
//g2d.fill(menuFace);
Stroke tmp = g2d.getStroke();
g2d.setStroke(borderStoke_noDashes);
g2d.setColor(DASH_BORDER_COLOR);
g2d.draw(menuFace);
g2d.setStroke(borderStoke);
g2d.setColor(BORDER_COLOR);
g2d.draw(menuFace);
g2d.setStroke(tmp);
g2d.setColor(prev);
}
private void drawText(Graphics2D g2d){
g2d.setColor(TEXT_COLOR);
FontRenderContext frc = g2d.getFontRenderContext();
Rectangle2D gameTitleRect = gameTitleFont.getStringBounds(GAME_TITLE,frc);
int sX,sY;
sY = (int)(menuFace.getHeight() / 4);
sX = (int)(menuFace.getWidth() - gameTitleRect.getWidth()) / 2;
sY += (int) gameTitleRect.getHeight() * 1.1;//add 10% of String height between the two strings
g2d.setFont(gameTitleFont);
g2d.drawString(GAME_TITLE,sX,sY);
}
private void drawButton(Graphics2D g2d){
FontRenderContext frc = g2d.getFontRenderContext();
Rectangle2D txtRect = buttonFont.getStringBounds(START_TEXT,frc);
Rectangle2D mTxtRect = buttonFont.getStringBounds(INFO_TEXT,frc);
g2d.setFont(buttonFont);
int x = (menuFace.width - startButton.width) / 2;
int y =(int) ((menuFace.height - startButton.height) * 0.5);
startButton.setLocation(x,y);
x = (int)(startButton.getWidth() - txtRect.getWidth()) / 2;
y = (int)(startButton.getHeight() - txtRect.getHeight()) / 2;
x += startButton.x;
y += startButton.y + (startButton.height * 0.9);
if(startClicked){
Color tmp = g2d.getColor();
g2d.setColor(CLICKED_BUTTON_COLOR);
g2d.draw(startButton);
g2d.setColor(CLICKED_TEXT);
g2d.drawString(START_TEXT,x,y);
g2d.setColor(tmp);
}
else{
g2d.draw(startButton);
g2d.drawString(START_TEXT,x,y);
}
x = startButton.x;
y = startButton.y;
y *= 1.3;
infoButton.setLocation(x,y);
x = (int)(infoButton.getWidth() - mTxtRect.getWidth()) / 2;
y = (int)(infoButton.getHeight() - mTxtRect.getHeight()) / 2;
x += infoButton.getX();
y += infoButton.getY() + (startButton.height * 0.9);
if(infoClicked){
Color tmp = g2d.getColor();
g2d.setColor(CLICKED_BUTTON_COLOR);
g2d.draw(infoButton);
g2d.setColor(CLICKED_TEXT);
g2d.drawString(INFO_TEXT,x,y);
g2d.setColor(tmp);
}
else{
g2d.draw(infoButton);
g2d.drawString(INFO_TEXT,x,y);
}
}
private void drawInfoMenu(Graphics2D g2d){
FontRenderContext frc = g2d.getFontRenderContext();
Rectangle2D infoRec = infoFont.getStringBounds(INFO_TEXT,frc);
Color prev = g2d.getColor();
Stroke tmp = g2d.getStroke();
g2d.setStroke(borderStoke_noDashes);
g2d.setColor(DASH_BORDER_COLOR);
g2d.draw(infoFace);
g2d.setStroke(borderStoke);
g2d.setColor(BORDER_COLOR);
g2d.draw(infoFace);
g2d.fillRect(0,0,infoFace.width,infoFace.height);
g2d.setStroke(tmp);
g2d.setColor(prev);
g2d.setColor(TEXT_COLOR);
int sX,sY;
sY = (int)(infoFace.getHeight() / 15);
sX = (int)(infoFace.getWidth() - infoRec.getWidth()) / 2;
sY += (int) infoRec.getHeight() * 1.1;//add 10% of String height between the two strings
g2d.setFont(infoFont);
g2d.drawString(INFO_TEXT,sX,sY);
TextLayout layout = new TextLayout(howtoPlay, howtoPlayFont, frc);
String[] outputs = howtoPlay.split("\n");
for(int i=0; i<outputs.length; i++) {
g2d.setFont(howtoPlayFont);
g2d.drawString(outputs[i], 40, (int) (80 + i * layout.getBounds().getHeight() + 0.5));
}
backButton.setLocation(getWidth()/3,getHeight()-50);
int x = (int)(backButton.getWidth() - infoRec.getWidth()) / 2;
int y = (int)(backButton.getHeight() - infoRec.getHeight()) / 2;
x += backButton.x+11;
y += backButton.y + (layout.getBounds().getHeight() * 1.35);
backButton.setLocation(getWidth()/3,getHeight()-50);
if(backClicked){
Color tmp1 = g2d.getColor();
g2d.setColor(CLICKED_BUTTON_COLOR);
g2d.draw(backButton);
g2d.setColor(CLICKED_TEXT);
g2d.drawString(backText,x,y);
g2d.setColor(tmp1);
infoClicked = false;
repaint();
}
else{
g2d.draw(backButton);
g2d.drawString(backText,x,y);
}
}
#Override
public void mouseClicked(MouseEvent mouseEvent) {
Point p = mouseEvent.getPoint();
if(startButton.contains(p)){
owner.enableGameBoard();
}
else if(infoButton.contains(p)){
infoClicked = true;
}
else if(backButton.contains(p)){
infoClicked = false;
}
repaint();
}
#Override
public void mousePressed(MouseEvent mouseEvent) {
Point p = mouseEvent.getPoint();
if(startButton.contains(p)){
startClicked = true;
repaint(startButton.x,startButton.y,startButton.width+1,startButton.height+1);
}
else if(infoButton.contains(p)){
infoClicked = true;
}
else if(backButton.contains(p)){
infoClicked = false;
}
repaint();
}
#Override
public void mouseReleased(MouseEvent mouseEvent) {
if(startClicked){
startClicked = false;
repaint(startButton.x,startButton.y,startButton.width+1,startButton.height+1);
}
else if(infoClicked){
infoClicked = false;
}
else if(backClicked){
infoClicked = true;
}
repaint();
}
#Override
public void mouseEntered(MouseEvent mouseEvent) {
}
#Override
public void mouseExited(MouseEvent mouseEvent) {
}
#Override
public void mouseDragged(MouseEvent mouseEvent) {
}
#Override
public void mouseMoved(MouseEvent mouseEvent) {
Point p = mouseEvent.getPoint();
if(startButton.contains(p) || infoButton.contains(p) || backButton.contains(p)) {
this.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
}
else {
this.setCursor(Cursor.getDefaultCursor());
}
}
}
Here are the images of both windows
main menu
info menu, pressing anywhere = back to home menu, pressing roughly in the middle = start game or back to main menu too

First read, Performing Custom Painting and Painting in AWT and Swing to get a better understanding how painting in Swing works and how you're suppose to work with it.
But I already have ...
public void paint(Graphics g){
drawMenu((Graphics2D)g);
}
would suggest otherwise. Seriously, go read those links so you understand all the issues that the above decision is going to create for you.
You're operating in a OO language, you need to take advantage of that and decouple your code and focus on the "single responsibility" principle.
I'm kind of tired of talking about it, so you can do some reading:
https://softwareengineering.stackexchange.com/questions/244476/what-is-decoupling-and-what-development-areas-can-it-apply-to
Cohesion and Decoupling, what do they represent?
Single Responsibility Principle
Single Responsibility Principle in Java with Examples
SOLID Design Principles Explained: The Single Responsibility Principle
These are basic concepts you really need to understand as they will make your live SOOO much easier and can be applied to just about any language.
As an example, from your code...
public HomeMenu(GameFrame owner,Dimension area){
//...
this.setPreferredSize(area);
There is no good reason (other than laziness (IMHO)) that any caller should be telling a component what size it should be, that's not their responsibility. It's the responsibility of the component to tell the parent container how big it would like to be and for the parent component to figure out how it's going to achieve that (or ignore it as the case may be).
The "basic" problem you're having is a simple one. Your "God" class is simply trying to do too much (ie it's taken on too much responsibility). Now we "could" add a dozen or more flags into the code to compensate for this, which is just going to increase the coupling and complexity, making it harder to understand and maintain, or we can take a step back, break it down into individual areas of responsibility and build the solution around those, for example...
import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Stroke;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.font.FontRenderContext;
import java.awt.font.TextLayout;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.add(new HomePane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class HomePane extends JPanel {
public HomePane() {
setLayout(new BorderLayout());
navigateToMenu();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
protected void navigateToMenu() {
removeAll();
HomeMenuPane pane = new HomeMenuPane(new HomeMenuPane.NavigationListener() {
#Override
public void navigateToInfo(HomeMenuPane source) {
HomePane.this.navigateToInfo();
}
#Override
public void navigateToStartGame(HomeMenuPane source) {
startGame();
}
});
add(pane);
revalidate();
repaint();
}
protected void navigateToInfo() {
removeAll();
HowToPlayPane pane = new HowToPlayPane(new HowToPlayPane.NavigationListener() {
#Override
public void navigateBack(HowToPlayPane source) {
navigateToMenu();
}
});
add(pane);
revalidate();
repaint();
}
protected void startGame() {
removeAll();
add(new JLabel("This is pretty awesome, isn't it!", JLabel.CENTER));
revalidate();
repaint();
}
}
public abstract class AbstractBaseMenuPane extends JPanel {
protected static final Color BORDER_COLOR = new Color(200, 8, 21); //Venetian Red
protected static final Color DASH_BORDER_COLOR = new Color(255, 216, 0);//school bus yellow
protected static final Color TEXT_COLOR = new Color(255, 255, 255);//white
protected static final Color CLICKED_BUTTON_COLOR = Color.ORANGE.darker();
protected static final Color CLICKED_TEXT = Color.ORANGE.darker();
protected static final int BORDER_SIZE = 5;
protected static final float[] DASHES = {12, 6};
private Rectangle border;
private BasicStroke borderStoke;
private BasicStroke borderStoke_noDashes;
private BufferedImage backgroundImage;
public AbstractBaseMenuPane() {
borderStoke = new BasicStroke(BORDER_SIZE, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND, 0, DASHES, 0);
borderStoke_noDashes = new BasicStroke(BORDER_SIZE, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND);
border = new Rectangle(new Point(0, 0), getPreferredSize());
// You are now responsible for filling the background
setOpaque(false);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
BufferedImage backgroundImage = getBackgroundImage();
if (backgroundImage != null) {
g2d.drawImage(backgroundImage, 0, 0, getWidth(), getHeight(), this);
}
Color prev = g2d.getColor();
Stroke tmp = g2d.getStroke();
g2d.setStroke(borderStoke_noDashes);
g2d.setColor(DASH_BORDER_COLOR);
g2d.draw(border);
g2d.setStroke(borderStoke);
g2d.setColor(BORDER_COLOR);
g2d.draw(border);
g2d.dispose();
}
public void setBackgroundImage(BufferedImage backgroundImage) {
this.backgroundImage = backgroundImage;
repaint();
}
public BufferedImage getBackgroundImage() {
return backgroundImage;
}
}
public class HomeMenuPane extends AbstractBaseMenuPane {
public static interface NavigationListener {
public void navigateToInfo(HomeMenuPane source);
public void navigateToStartGame(HomeMenuPane source);
}
private static final String GAME_TITLE = "BRICK DESTROY";
private static final String START_TEXT = "START";
private static final String INFO_TEXT = "INFO";
private Rectangle startButton;
private Rectangle infoButton;
private Font gameTitleFont;
private Font buttonFont;
// Don't do this, this just sucks (for so many reasons)
// Use ImageIO.read instead and save yourself a load of frustration
//private Image img = Toolkit.getDefaultToolkit().createImage("1.jpeg");
private Point lastClickPoint;
private NavigationListener navigationListener;
public HomeMenuPane(NavigationListener navigationListener) {
this.navigationListener = navigationListener;
try {
setBackgroundImage(ImageIO.read(getClass().getResource("/images/BrickWall.jpg")));
} catch (IOException ex) {
Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
}
this.addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent mouseEvent) {
Point p = mouseEvent.getPoint();
lastClickPoint = p;
if (startButton.contains(p)) {
peformStartGameAction();
} else if (infoButton.contains(p)) {
performInfoAction();
}
repaint();
}
#Override
public void mouseReleased(MouseEvent mouseEvent) {
lastClickPoint = null;
repaint();
}
});
this.addMouseMotionListener(new MouseAdapter() {
#Override
public void mouseMoved(MouseEvent mouseEvent) {
Point p = mouseEvent.getPoint();
if (startButton.contains(p) || infoButton.contains(p)) {
setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
} else {
setCursor(Cursor.getDefaultCursor());
}
}
});
Dimension area = getPreferredSize();
Dimension btnDim = new Dimension(area.width / 3, area.height / 12);
startButton = new Rectangle(btnDim);
infoButton = new Rectangle(btnDim);
gameTitleFont = new Font("Calibri", Font.BOLD, 28);
buttonFont = new Font("Calibri", Font.BOLD, startButton.height - 2);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
Color prevColor = g2d.getColor();
Font prevFont = g2d.getFont();
//methods calls
drawText(g2d);
drawButton(g2d);
//end of methods calls
g2d.setFont(prevFont);
g2d.setColor(prevColor);
g2d.dispose();
}
private void drawText(Graphics2D g2d) {
g2d.setColor(TEXT_COLOR);
FontRenderContext frc = g2d.getFontRenderContext();
Rectangle2D gameTitleRect = gameTitleFont.getStringBounds(GAME_TITLE, frc);
int sX, sY;
sY = (int) (getHeight() / 4);
sX = (int) (getWidth() - gameTitleRect.getWidth()) / 2;
sY += (int) gameTitleRect.getHeight() * 1.1;//add 10% of String height between the two strings
g2d.setFont(gameTitleFont);
g2d.drawString(GAME_TITLE, sX, sY);
}
private void drawButton(Graphics2D g2d) {
FontRenderContext frc = g2d.getFontRenderContext();
Rectangle2D txtRect = buttonFont.getStringBounds(START_TEXT, frc);
Rectangle2D mTxtRect = buttonFont.getStringBounds(INFO_TEXT, frc);
g2d.setFont(buttonFont);
int x = (getWidth() - startButton.width) / 2;
int y = (int) ((getHeight() - startButton.height) * 0.5);
startButton.setLocation(x, y);
x = (int) (startButton.getWidth() - txtRect.getWidth()) / 2;
y = (int) (startButton.getHeight() - txtRect.getHeight()) / 2;
x += startButton.x;
y += startButton.y + (startButton.height * 0.9);
if (lastClickPoint != null && startButton.contains(lastClickPoint)) {
Color tmp = g2d.getColor();
g2d.setColor(CLICKED_BUTTON_COLOR);
g2d.draw(startButton);
g2d.setColor(CLICKED_TEXT);
g2d.drawString(START_TEXT, x, y);
g2d.setColor(tmp);
} else {
g2d.draw(startButton);
g2d.drawString(START_TEXT, x, y);
}
x = startButton.x;
y = startButton.y;
y *= 1.3;
infoButton.setLocation(x, y);
x = (int) (infoButton.getWidth() - mTxtRect.getWidth()) / 2;
y = (int) (infoButton.getHeight() - mTxtRect.getHeight()) / 2;
x += infoButton.getX();
y += infoButton.getY() + (startButton.height * 0.9);
if (lastClickPoint != null && infoButton.contains(lastClickPoint)) {
Color tmp = g2d.getColor();
g2d.setColor(CLICKED_BUTTON_COLOR);
g2d.draw(infoButton);
g2d.setColor(CLICKED_TEXT);
g2d.drawString(INFO_TEXT, x, y);
g2d.setColor(tmp);
} else {
g2d.draw(infoButton);
g2d.drawString(INFO_TEXT, x, y);
}
}
protected void peformStartGameAction() {
navigationListener.navigateToStartGame(this);
}
protected void performInfoAction() {
navigationListener.navigateToInfo(this);
}
}
public class HowToPlayPane extends AbstractBaseMenuPane {
public static interface NavigationListener {
public void navigateBack(HowToPlayPane source);
}
private static final String HOW_TO_PLAY_TEXT = """
1- Click Start\n
2- Choose the mode\n
3- Each mode has 3 levels\n
4- To play/pause press space, use 'A' and 'D' to move\n
5- To open pause menu press 'ESC'\n
6- To open DebugPanel press 'ALT-SHIFT-F1'""";
private static final String BACK_TEXT = "BACK";
private static final String INFO_TEXT = "INFO";
private Rectangle backButton;
private boolean backClicked = false;
private Font infoFont;
private Font howtoPlayFont;
private NavigationListener navigationListener;
public HowToPlayPane(NavigationListener navigationListener) {
this.navigationListener = navigationListener;
this.addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent mouseEvent) {
Point p = mouseEvent.getPoint();
if (backButton.contains(p)) {
backClicked = true;
repaint();
performBackAction();
}
}
#Override
public void mouseReleased(MouseEvent e) {
backClicked = false;
}
});
this.addMouseMotionListener(new MouseAdapter() {
#Override
public void mouseMoved(MouseEvent mouseEvent) {
Point p = mouseEvent.getPoint();
if (backButton.contains(p)) {
setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
} else {
setCursor(Cursor.getDefaultCursor());
}
}
});
Dimension btnDim = new Dimension(getPreferredSize().width / 3, getPreferredSize().height / 12);
backButton = new Rectangle(btnDim);
infoFont = new Font("Calibri", Font.BOLD, 24);
howtoPlayFont = new Font("Calibri", Font.PLAIN, 14);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(BORDER_COLOR);
g2d.fillRect(0, 0, getWidth(), getHeight());
FontRenderContext frc = g2d.getFontRenderContext();
Rectangle2D infoRec = infoFont.getStringBounds(INFO_TEXT, frc);
//
// Color prev = g2d.getColor();
//
// Stroke tmp = g2d.getStroke();
//
// g2d.setStroke(borderStoke_noDashes);
// g2d.setColor(DASH_BORDER_COLOR);
// g2d.draw(infoFace);
//
// g2d.setStroke(borderStoke);
// g2d.setColor(BORDER_COLOR);
// g2d.draw(infoFace);
//
// g2d.fillRect(0, 0, infoFace.width, infoFace.height);
//
// g2d.setStroke(tmp);
//
// g2d.setColor(prev);
//
g2d.setColor(TEXT_COLOR);
int sX, sY;
sY = (int) (getHeight() / 15);
sX = (int) (getWidth() - infoRec.getWidth()) / 2;
sY += (int) infoRec.getHeight() * 1.1;//add 10% of String height between the two strings
g2d.setFont(infoFont);
g2d.drawString(INFO_TEXT, sX, sY);
TextLayout layout = new TextLayout(HOW_TO_PLAY_TEXT, howtoPlayFont, frc);
String[] outputs = HOW_TO_PLAY_TEXT.split("\n");
for (int i = 0; i < outputs.length; i++) {
g2d.setFont(howtoPlayFont);
g2d.drawString(outputs[i], 40, (int) (80 + i * layout.getBounds().getHeight() + 0.5));
}
backButton.setLocation(getWidth() / 3, getHeight() - 50);
int x = (int) (backButton.getWidth() - infoRec.getWidth()) / 2;
int y = (int) (backButton.getHeight() - infoRec.getHeight()) / 2;
x += backButton.x + 11;
y += backButton.y + (layout.getBounds().getHeight() * 1.35);
backButton.setLocation(getWidth() / 3, getHeight() - 50);
if (backClicked) {
Color tmp1 = g2d.getColor();
g2d.setColor(CLICKED_BUTTON_COLOR);
g2d.draw(backButton);
g2d.setColor(CLICKED_TEXT);
g2d.drawString(BACK_TEXT, x, y);
g2d.setColor(tmp1);
repaint();
} else {
g2d.draw(backButton);
g2d.drawString(BACK_TEXT, x, y);
}
g2d.dispose();
}
protected void performBackAction() {
navigationListener.navigateBack(this);
}
}
}
Now, this example makes use of components to present different views (it even has a nice abstract implementation to allow for code re-use 😱), but it occurs to me, that, if you "really" wanted to, you could have a series of "painter" classes, which could be used to delegate the painting of the current state to, and mouse clicks/movements could be delegated to, meaning you could have a single component, which would simple delegate the painting (via the paintComponent method) to which ever painter is active.
And, wouldn't you know it, they have a design principle for that to, the Delegation Pattern
The above example also makes use of the observer pattern, so you might want to have a look into that as well

Java - How to center a Render after a Scale Operation with the good mouse Position

In the code below, when I move the wheel of the mouse, the square is zooming in or out and I always detect the square position everywhere in the screen if my mouse go inside it, even if the map is scrolling.
That's really great :)
If I change the boolean "centerScreen" to true, I can zoom and the square is always in the center of the screen.
It is really very great ...
... but the mouse detection is not good :(
How can I modify my code to zoom in or out with the Render still in center of screen but with a perfect mouse detection with the square ?
Thanks for your help !
Here is my full "clean code" -- work with copy paste (in 3 class) --
Main Class
package main;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class ZoomDemo extends JPanel
{
private static final long serialVersionUID = 1L;
private Rectangle2D square;
private Mouse mouse;
private ScrollMap scrollMap;
private static int screenWidth;
private static int screenHeight;
private static int centerScreenWidth;
private static int centerScreenHeight;
private static boolean centerScreen;
private List<Point> listStar = new ArrayList<Point>();
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(800, 800);
frame.setLocationRelativeTo(null);
screenWidth = frame.getWidth();
screenHeight = frame.getHeight();
centerScreenWidth = screenWidth / 2;
centerScreenHeight = screenHeight / 2;
centerScreen = false;
ZoomDemo zoomDemo = new ZoomDemo();
frame.add(zoomDemo);
frame.setVisible(true);
}
public ZoomDemo()
{
mouse = new Mouse();
addMouseListener(mouse);
addMouseMotionListener(mouse);
addMouseWheelListener(mouse);
scrollMap = new ScrollMap(mouse, screenWidth, screenHeight);
int centerX = (int) getCenter(0, screenWidth, 50, true);
int centerY = (int) getCenter(0, screenHeight, 50, true);
square = new Rectangle2D.Double(centerX, centerY, 50, 50);
Random rand = new Random();
for (int i = 0; i < 50; i++)
{
int x = rand.nextInt(screenWidth);
int y = rand.nextInt(screenHeight);
listStar.add(new Point(x, y));
}
}
#Override
public void paint(Graphics g)
{
Graphics2D g2d = (Graphics2D) g.create();
/* Optimization */
g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_SPEED);
g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_SPEED);
g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_OFF);
g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_DISABLE);
/* Background */
g2d.setColor(Color.GRAY);
g2d.fillRect(0, 0, this.getWidth(), this.getHeight());
/* Translatation center -- it is working, but mouse detection is not good */
if (centerScreen)
g2d.translate(centerScreenWidth, centerScreenHeight);
/* Listener Wheel Mouse for zooming and translation */
mouse.zoom(g2d);
/* Restore Translatation center */
if (centerScreen)
g2d.translate(-centerScreenWidth, -centerScreenHeight);
render(g2d);
g2d.dispose();
//#formatter:off
try { Thread.sleep(10); } catch (InterruptedException e) { e.printStackTrace(); }
//#formatter:on
repaint();
}
public void render(Graphics2D g2d)
{
/* Ask for scroll */
isScrolling(g2d);
/* Mouse Detection */
int xMouse = (int) (mouse.pMousePosition.x - scrollMap.getMapX());
int yMouse = (int) (mouse.pMousePosition.y - scrollMap.getMapY());
boolean detection = square.contains(xMouse, yMouse);
/* Graphic render */
g2d.setColor(Color.WHITE);
for (int i = 0; i < listStar.size(); i++)
g2d.fillRect(listStar.get(i).x, listStar.get(i).y, 4, 4);
g2d.setColor(detection ? Color.red : Color.black);
g2d.fill(square);
/* End of Scroll */
endScrolling(g2d);
}
private void isScrolling(Graphics2D g2d)
{
/* If Mouse on edge, so change value for scrolling */
scrollMap.scrolling();
/* Translation scrolling */
g2d.translate(scrollMap.getMapX(), scrollMap.getMapY());
}
private void endScrolling(Graphics2D g2d)
{
g2d.translate(-scrollMap.getMapX(), -scrollMap.getMapY());
}
public float getCenter(float startXZone, float longueurZone, float longueurElem, boolean round)
{
float s = startXZone + (longueurZone - longueurElem) / 2f;
return (round) ? Math.round(s) : s;
}
}
Mouse Class
package main;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import java.awt.geom.AffineTransform;
import java.awt.geom.NoninvertibleTransformException;
public class Mouse implements MouseMotionListener, MouseWheelListener, MouseListener
{
public Point pMousePosition = new Point();
public double scaleCoef;
public double inverseScaleCoef;
public boolean clic;
private AffineTransform affineScale;
private AffineTransform inverseScale;
public Mouse()
{
scaleCoef = 1;
inverseScaleCoef = 1;
transform();
}
private void transform()
{
affineScale = AffineTransform.getScaleInstance(scaleCoef, scaleCoef);
//#formatter:off
try { inverseScale = affineScale.createInverse(); } catch (NoninvertibleTransformException e) { }
//#formatter:on
}
public void zoom(Graphics2D g2)
{
transform();
g2.transform(affineScale);
}
#Override
public void mouseWheelMoved(MouseWheelEvent e)
{
if (e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL)
{
scaleCoef -= (0.1 * e.getWheelRotation());
scaleCoef = Math.max(0.1, scaleCoef);
inverseScaleCoef = 1d / scaleCoef;
}
}
#Override
public void mouseMoved(MouseEvent e)
{
pMousePosition = e.getPoint();
inverseScale.transform(pMousePosition, pMousePosition);
}
#Override
public void mousePressed(MouseEvent e)
{
clic = true;
}
#Override
public void mouseReleased(MouseEvent e)
{
clic = false;
}
#Override
public void mouseClicked(MouseEvent e)
{
}
#Override
public void mouseEntered(MouseEvent e)
{
}
#Override
public void mouseExited(MouseEvent e)
{
}
#Override
public void mouseDragged(MouseEvent e)
{
}
}
(Optional)
Scroll class
package main;
public class ScrollMap
{
private float mapX = 0;
private float mapY = 0;
private int speedScroll = 1;
private int edgeDetection = 70;
private int screenWidth;
private int screenHeight;
private Mouse mouse;
public ScrollMap(Mouse mouse, int screenWidth, int screenHeight)
{
this.mouse = mouse;
this.screenWidth = screenWidth;
this.screenHeight = screenHeight;
}
/**
* Scrolling ecran
*/
public void scrolling()
{
double scale = mouse.inverseScaleCoef;
/* Mouse to Right */
if ((mouse.pMousePosition.x > screenWidth * scale - edgeDetection))
{
for (int k = 0; k < speedScroll; k++)
moveMapToRight();
}
/* Mouse to Left */
else if ((mouse.pMousePosition.x < edgeDetection * scale))
{
for (int k = 0; k < speedScroll; k++)
moveMapToLeft();
}
/* Mouse to Down */
if ((mouse.pMousePosition.y < edgeDetection * scale))
{
for (int k = 0; k < speedScroll; k++)
moveMaptoDown();
}
/* Mouse to Up */
else if ((mouse.pMousePosition.y > screenHeight * scale - edgeDetection))
{
for (int k = 0; k < speedScroll; k++)
moveMapToUp();
}
}
public float moveMapToRight()
{
return mapX--;
}
public float moveMapToLeft()
{
return mapX++;
}
public float moveMapToUp()
{
return mapY--;
}
public float moveMaptoDown()
{
return mapY++;
}
public float getMapY()
{
return mapY;
}
public float getMapX()
{
return mapX;
}
}

Java 3D Engine Pixel Drawing Problems

my 3 programs seem to work alone but when I try to run them together It seems to give me an out of bounds error but I cant tell where exactly if anyone can tell me where exactly it is and how to fix the error that would be great, I wanted to use a debugger but im having some problems getting it to work.
Here is my Code for the 3 Classes :
Render.java
package com.mime.Game.graphics;
public class Render {
public final int width;
public final int height;
public final int[] pixels;
public Render(int width, int height) {
this.width = width;
this.height = height;
pixels = new int[width * height];
}
public void draw(Render render, int xOffset, int yOffset) {
for(int x = 0; x < this.height; x++) {
int yPix = x + yOffset;
for(int y = 0; y < this.width; y++) {
int xPix = y + xOffset;
pixels[xPix + yPix * width] = render.pixels[x + y *
render.width];
}
}
}
}
Display.java
package com.mime.Game;
import java.awt.Canvas;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
import com.mime.Game.graphics.Render;
import com.mime.Game.graphics.Screen;
import java.awt.image.DataBufferInt;
public class Display extends Canvas implements Runnable{
public static final long serialVersionUID = 1L;
public static final int WIDTH = 800;
public static final int HEIGHT = 600;
private Thread thread;
private Screen screen;
private BufferedImage img;
private boolean running = false;
private Render render;
private int[] pixels;
public Display() {
screen = new Screen(WIDTH, HEIGHT);
img = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
pixels = ((DataBufferInt)img.getRaster().getDataBuffer()).getData();
}
private void start() {
if(running)
return;
running = true;
thread = new Thread(this);
thread.start();
System.out.println("Working");
}
public void stop() {
if(!running)
return;
running = false;
try{
thread.join();
}catch(Exception e) {
e.printStackTrace();
System.exit(0);
}
}
public void run() {
while(running) {
tick();
render();
}
}
private void tick() {
}
private void render() {
BufferStrategy bs = this.getBufferStrategy();
if(bs == null) {
createBufferStrategy(3);
return;
}
screen.render();
for(int i = 0; i < WIDTH * HEIGHT; i++) {
pixels[i] = screen.pixels[i];
}
Graphics g = bs.getDrawGraphics();
g.drawImage(img, 0, 0, WIDTH, HEIGHT, null);
g.dispose();
bs.show();
}
public static void main(String[] args) {
Display game = new Display();
JFrame frame = new JFrame();
frame.setResizable(false);
frame.setSize(WIDTH, HEIGHT);
frame.add(game);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("Chronicles of Walshy Alpha 0.01");
game.start();
}
}
screen.java :
package com.mime.Game.graphics;
import java.util.Random;
public class Screen extends Render{
private Render test;
public Screen(int width, int height) {
super(width, height);
Random random = new Random();
test = new Render(256, 256);
for(int i = 0; i < 256*256; i++) {
test.pixels[i] = random.nextInt();
}
}
public void render() {
draw(test, 0, 0);
}
}

In your Render.draw method you copy pixels from another Render object and you use this.width and this.height to access those pixels. This will fail when the other Render object's pixel size is smaller, which is the case in your code. You get an ArrayOutOfBoundsException when reading from render.pixels[x + y * render.width] because you're trying to read pixels from a 256*256 array as if it was a 800*600 array.
Additionally if you ever call draw with offset values, you will get another ArrayOutOfBoundsException, because you're simply adding the offsets to your x and y values without checking if the resulting index is too big when writing to pixels[xPix + yPix * width].
To fix this, you have to skip any value that goes beyond the width or height of either pixels array:
if (xPix > this.width || yPix > this.height || x > render.width || y > render.height)
{
continue;
}

dynamically update JPanel background does't work

After reading image from JFilechooser, I am trying to read pixel of an image one by one and display it to JPanel after some delay in sequential manner. can't update the background of JPanel.
public class ImageMain extends JFrame implements ActionListener {
/**
*
*/
private static final long serialVersionUID = 2916361361443483318L;
private JFileChooser fc = null;
private JMenuItem item1, item2;
private BufferedImage image = null;
private JPanel panel = null;
private int width = 0;
private int height = 0;
private BorderLayout card;
private Container contentPane;
//private int loopcount = 0;
//private int counter = 0;
public ImageMain() {
JFrame frame = new JFrame("Image Extraction Tool");
frame.setExtendedState(Frame.MAXIMIZED_BOTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
contentPane = frame.getContentPane();
panel = new JPanel();
card = new BorderLayout();
panel.setLayout(card);
panel.setBackground(Color.white);
JMenuBar menuBar = new JMenuBar();
JMenu menu = new JMenu("Menu");
menuBar.add(menu);
item1 = new JMenuItem("Browse an image");
item2 = new JMenuItem("Exit");
item1.addActionListener(this);
item2.addActionListener(this);
menu.add(item1);
menu.add(item2);
frame.setJMenuBar(menuBar);
contentPane.add(panel);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
try {
SwingUtilities.invokeAndWait(new Runnable() {
#Override
public void run() {
ImageMain img = new ImageMain();
}
});
} catch (InvocationTargetException | InterruptedException e) {
e.printStackTrace();
}
}
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == item1) {
if (fc == null)
fc = new JFileChooser();
int retVal = fc.showOpenDialog(null);
if (retVal == JFileChooser.APPROVE_OPTION) {
File file = fc.getSelectedFile();
try {
image = ImageIO.read(file);
height = image.getHeight();
width = image.getWidth();
// final int[][] pixelData = new int[height * width][3];
// int[] rgb;
for (int i = 0; i < height; i++) {
for (int j = 0; j < width; j++) {
System.out.println(i + " " + j);
Color c = new Color(image.getRGB(j, i));
panel.setBackground(c);
panel.invalidate();
panel.validate();
panel.repaint();
}
}
} catch (IOException e1) {
System.out.println("IO::" + e1.getMessage());
} catch (Exception e1) {
System.out.println("Exception::" + e1.getMessage());
}
}
}
if (e.getSource() == item2) {
System.exit(0);
}
}}
Inside ActionPerformed, I got Color object by reading RGB values and then I am stuck at displaying them to JApplet. Suggestion are welcome if there is a better way to achieve this.
Thanks in advance.

The main problem is your performing a long running task within the context of the Event Dispatching Thread, which is responsible for, amongst other things, processing repaint requests.
#Override
public void actionPerformed(ActionEvent e) {
//...
// Nothing will be updated until after the
// actionPerformed method exists
for (int i = 0; i < height; i++) {
for (int j = 0; j < width; j++) {
System.out.println(i + " " + j);
Color c = new Color(image.getRGB(j, i));
panel.setBackground(c);
panel.invalidate();
panel.validate();
panel.repaint();
}
}
The other problem you have is that you are required to only modify the state of the UI from within the context of the EDT
Depending on your exact needs, you could use a SwingWorker, which would allow you to process the pixels in the background while updating the UI from within the context of the EDT, however, because SwingWorker consolidates it's updates, you could miss color changes.
A better solution might be to use a java.swing.Timer which would allow you to trigger updates at a specified period, which are triggered within the context of the EDT.
See Concurrency in Swing for more details...
Updated with example
In order to draw pixels, you need something to draw them on. Now, you could simply add each pixel you want to paint to an array and loop that array each time you need to repaint the component, but that's kind of expensive...
Instead, it would be simpler to have a backing buffer of some kind, onto which you paint the pixels and then paint that buffer to the component, which should be faster.
Basically, the allows you to supply the height and width of the expected image and then supply each pixel as you need..
public class ImagePane extends JPanel {
private BufferedImage img;
public ImagePane() {
}
public void reset(int width, int height) {
img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
revalidate();
}
public void reset() {
img = null;
revalidate();
}
public void setPixelAt(int x, int y, int pixel) {
img.setRGB(x, y, pixel);
}
#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();
if (img != null) {
int x = (getWidth() - img.getWidth()) / 2;
int y = (getHeight() - img.getHeight()) / 2;
g2d.drawImage(img, x, y, this);
}
g2d.dispose();
}
}
Take a look at Performing Custom Painting for more details...
Then you need some way to process the original image and update the image panel...Now, based on the updated requirements, I would use a SwingWorker, the reason for this, is that the SwingWorker can cache what is passed back to the EDT, this allows the background thread to continue processing and caching the output until the EDT (and system) is ready to process it...
public class PixelExposerWorker extends SwingWorker<Void, Pixel> {
private final BufferedImage img;
private final ImagePane imagePane;
private final List<Point> points;
public PixelExposerWorker(BufferedImage img, ImagePane imagePane) {
this.img = img;
this.imagePane = imagePane;
points = new ArrayList<>(img.getWidth() * img.getHeight());
for (int x = 0; x < img.getWidth(); x++) {
for (int y = 0; y < img.getHeight(); y++) {
points.add(new Point(x, y));
}
}
}
#Override
protected void process(List<Pixel> chunks) {
System.out.println("Publish " + chunks.size());
for (Pixel pixel : chunks) {
imagePane.setPixelAt(pixel.getX(), pixel.getY(), pixel.getColor());
}
imagePane.repaint();
}
#Override
protected Void doInBackground() throws Exception {
int pixelCount = (int) (points.size() * 0.005);
while (!points.isEmpty()) {
for (int count = 0; count < pixelCount && !points.isEmpty(); count++) {
int index = (int) (Math.random() * (points.size() - 1));
Point p = points.remove(index);
Pixel pixel = new Pixel(p.x, p.y, img.getRGB(p.x, p.y));
publish(pixel);
}
Thread.yield();
}
return null;
}
}
Basically, this SwingWorker builds a List of "pixel points", it uses the list to randomly remove points from the list, generate a virtual Pixel and publish back to the EDT for processing. The worker will process around 0.5% of the pixels at a time, meaning that the work is always trying to send a "bunch" of pixels back to the EDT, rather the one at a time.
Finally, it will yield to allow other threads to run (and the hopefully for the EDT to update it self)
An image of 650x975 takes roughly 1m and 10s to fully renderer
And the full code...
import core.util.StopWatch;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
import javax.swing.Timer;
public class PixelShower implements ActionListener {
private static final long serialVersionUID = 2916361361443483318L;
private JFileChooser fc = null;
private JMenuItem item1, item2;
private BufferedImage image = null;
private ImagePane panel = null;
private int width = 0;
private int height = 0;
private BorderLayout card;
private Container contentPane;
public PixelShower() {
JFrame frame = new JFrame("Image Extraction Tool");
frame.setExtendedState(Frame.MAXIMIZED_BOTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
contentPane = frame.getContentPane();
panel = new ImagePane();
card = new BorderLayout();
panel.setLayout(card);
panel.setBackground(Color.white);
JMenuBar menuBar = new JMenuBar();
JMenu menu = new JMenu("Menu");
menuBar.add(menu);
item1 = new JMenuItem("Browse an image");
item2 = new JMenuItem("Exit");
item1.addActionListener(this);
item2.addActionListener(this);
menu.add(item1);
menu.add(item2);
frame.setJMenuBar(menuBar);
contentPane.add(panel);
frame.setVisible(true);
}
public static void main(String[] args) {
try {
SwingUtilities.invokeAndWait(new Runnable() {
#Override
public void run() {
PixelShower img = new PixelShower();
}
});
} catch (InvocationTargetException | InterruptedException e) {
e.printStackTrace();
}
}
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == item1) {
if (fc == null) {
fc = new JFileChooser();
}
int retVal = fc.showOpenDialog(null);
if (retVal == JFileChooser.APPROVE_OPTION) {
File file = fc.getSelectedFile();
try {
image = ImageIO.read(file);
panel.reset(image.getWidth(), image.getHeight());
PixelExposerWorker worker = new PixelExposerWorker(image, panel);
worker.execute();
} catch (IOException e1) {
e1.printStackTrace();
} catch (Exception e1) {
e1.printStackTrace();
}
}
}
if (e.getSource() == item2) {
System.exit(0);
}
}
public class ImagePane extends JPanel {
private BufferedImage img;
public ImagePane() {
}
public void reset(int width, int height) {
img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
revalidate();
}
public void reset() {
img = null;
revalidate();
}
public void setPixelAt(int x, int y, int pixel) {
img.setRGB(x, y, pixel);
}
#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();
if (img != null) {
int x = (getWidth() - img.getWidth()) / 2;
int y = (getHeight() - img.getHeight()) / 2;
g2d.drawImage(img, x, y, this);
}
g2d.dispose();
}
}
public class Pixel {
private int x;
private int y;
private int color;
public Pixel(int x, int y, int color) {
this.x = x;
this.y = y;
this.color = color;
}
public int getColor() {
return color;
}
public int getX() {
return x;
}
public int getY() {
return y;
}
}
public class PixelExposerWorker extends SwingWorker<Void, Pixel> {
private final BufferedImage img;
private final ImagePane imagePane;
private final List<Point> points;
public PixelExposerWorker(BufferedImage img, ImagePane imagePane) {
this.img = img;
this.imagePane = imagePane;
points = new ArrayList<>(img.getWidth() * img.getHeight());
for (int x = 0; x < img.getWidth(); x++) {
for (int y = 0; y < img.getHeight(); y++) {
points.add(new Point(x, y));
}
}
}
#Override
protected void process(List<Pixel> chunks) {
System.out.println("Publish " + chunks.size());
for (Pixel pixel : chunks) {
imagePane.setPixelAt(pixel.getX(), pixel.getY(), pixel.getColor());
}
imagePane.repaint();
}
#Override
protected Void doInBackground() throws Exception {
StopWatch sw = StopWatch.newInstance().start();
int pixelCount = (int) (points.size() * 0.005);
System.out.println("pixelCount = " + pixelCount + "; " + points.size());
while (!points.isEmpty()) {
StopWatch sw1 = StopWatch.newInstance().start();
for (int count = 0; count < pixelCount && !points.isEmpty(); count++) {
int index = (int) (Math.random() * (points.size() - 1));
Point p = points.remove(index);
Pixel pixel = new Pixel(p.x, p.y, img.getRGB(p.x, p.y));
publish(pixel);
}
Thread.yield();
}
System.out.println("Took " + sw.stop());
return null;
}
}
}

NullPointerException in my game, can't be fixed

I'm making an rpg with a custom pixel engine, and when I try to run it I just get a NullPointerException and I know why, but when I try to initialize that variable I get another one in a different location and I fix that and now it won't run at all and I still get a NullPointerException. This is the class that gets an error, and the console tells me that the error is on the line that says screen.render();
import java.awt.Canvas;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;
import java.awt.image.BufferedImage;
import java.awt.image.DataBufferInt;
import java.io.IOException;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import sprites.SpriteSheetLoader;
public class Game extends Canvas implements Runnable{
private static final long serialVersionUID = 1L;
public static final int HEIGHT = 120;
public static final int WIDTH = 120;
public static final int SCALE = 3;
public static final String NAME = "TypicalRPG";
public SpriteSheetLoader loader;
private BufferedImage img = new BufferedImage(WIDTH * SCALE, HEIGHT * SCALE, BufferedImage.TYPE_INT_RGB);
private int[] pixels = ((DataBufferInt) img.getRaster().getDataBuffer()).getData();
private boolean running = false;
private Screen screen = new Screen(WIDTH, HEIGHT, loader);
Random random = new Random();
public void start(){
running = true;
new Thread(this).start();
}
public static void main(String args[]){
Game game = new Game();
game.setPreferredSize(new Dimension(WIDTH * SCALE, HEIGHT * SCALE));
game.setMaximumSize(new Dimension(WIDTH * SCALE, HEIGHT * SCALE));
game.setMinimumSize(new Dimension(WIDTH * SCALE, HEIGHT * SCALE));
JFrame jf = new JFrame(NAME);
jf.add(game);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf.pack();
jf.setVisible(true);
jf.setResizable(true);
game.start();
}
public void run(){
while(running){
tick();
render();
try{
Thread.sleep(5);
}
catch(InterruptedException e){ e.printStackTrace(); }
}
}
public void stop(){ running = false; }
public void tick(){
screen.render(0, 0, 0, 16, 16);
}
public void render(){
BufferStrategy bs = getBufferStrategy();
if(bs == null){
createBufferStrategy(3);
requestFocus();
return;
}
for(int i = 0; i < screen.pixels.length; i++){
pixels[i] = screen.pixels[i];
}
Graphics g = bs.getDrawGraphics();
g.drawImage(img, 0, 0, getWidth(), getHeight(), null);
g.dispose();
bs.show();
}
public void init(){
BufferedImage sheet = null;
try {
sheet = ImageIO.read(Game.class.getResourceAsStream("res/tiles.png"));
}
catch (IOException e) {
e.printStackTrace();
}
loader = new SpriteSheetLoader(sheet);
screen = new Screen(WIDTH, HEIGHT, loader);
}
}
and this is the class that has render():
import sprites.SpriteSheetLoader;
public class Screen{
public int[] pixels;
private SpriteSheetLoader loader;
private int w, h;
int xoff = 0, yoff = 0;
public Screen(int w, int h, SpriteSheetLoader loader){
this.loader = loader;
this.w = w;
this.h = h;
pixels = new int[w * h];
}
public void render(int xpos, int ypos, int tile, int width, int height){
loader.grabTile(tile, width, height);
xpos -= xoff;
ypos -= yoff;
for(int y = 0; y < height; y++){
if(ypos + y < 0 || ypos + y >= h) continue;
for(int x = 0; x < width; x++){
if(xpos + x < 0 || xpos + x >= w) continue;
int col = loader.pixels[x + (y * height)];
if(col != -65281) pixels[(x + xpos) + (y + ypos)] = col;
}
}
}
}

Seems like you never initiate the loader in your first class.
You define your variables like this:
public SpriteSheetLoader loader;
private Screen screen = new Screen(WIDTH, HEIGHT, loader);
Hence, you pass a null-object to your Screen. And from there you try to call a method on that null-object:
loader.grabTile(tile, width, height);

You have only declared loader, but never initiated it.
public SpriteSheetLoader loader;