We Keep Coding

Printing a timer that updates every second into a simple game

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.ArrayList;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.Timer;
public class FinalFlappy implements ActionListener, MouseListener,
KeyListener
{
public static FinalFlappy finalFlappy;
public final int WIDTH = 800, HEIGHT = 800;
public FinalFlappyRend renderer;
public Rectangle bee;
public ArrayList<Rectangle> rect_column;
public int push, yMotion, score;
public boolean gameOver, started;
public Random rand;
public FinalFlappy()
{
JFrame jframe = new JFrame();
Timer timer = new Timer(16, this);
renderer = new FinalFlappyRend();
rand = new Random();
jframe.add(renderer);
jframe.setTitle("Flappy Bee");
jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jframe.setSize(WIDTH, HEIGHT);
jframe.addMouseListener(this);
jframe.addKeyListener(this);
jframe.setResizable(false);
jframe.setVisible(true);
bee = new Rectangle(WIDTH / 2 - 10, HEIGHT / 2 - 10, 40, 40);
rect_column = new ArrayList<Rectangle>();
addColumn(true);
addColumn(true);
addColumn(true);
addColumn(true);
timer.start();
}
public void addColumn(boolean start)
{
int space = 300;
int width = 60;
int height = 50 + rand.nextInt(300);
if (start)
{
rect_column.add(new Rectangle(WIDTH + width + rect_column.size() * 300, HEIGHT - height - 120, width, height));
rect_column.add(new Rectangle(WIDTH + width + (rect_column.size() - 1) * 300, 0, width, HEIGHT - height - space));
}
else
{
rect_column.add(new Rectangle(rect_column.get(rect_column.size() - 1).x + 600, HEIGHT - height - 120, width, height));
rect_column.add(new Rectangle(rect_column.get(rect_column.size() - 1).x, 0, width, HEIGHT - height - space));
}
}
public void jump()
{
if (gameOver)
{
bee = new Rectangle(WIDTH / 2 - 10, HEIGHT / 2 - 10, 40, 40);
rect_column.clear();
yMotion = 0;
score = 0;
addColumn(true);
addColumn(true);
addColumn(true);
addColumn(true);
gameOver = false;
}
if (!started)
{
started = true;
}
else if (!gameOver)
{
if (yMotion > 0)
{
yMotion = 0;
}
yMotion -= 10;
}
}
#Override
public void actionPerformed(ActionEvent e)
{
int speed = 10;
push++;
if (started)
{
for (int i = 0; i < rect_column.size(); i++)
{
Rectangle column = rect_column.get(i);
column.x -= speed;
}
if (push % 2 == 0 && yMotion < 15)
{
yMotion += 2;
}
for (int i = 0; i < rect_column.size(); i++)
{
Rectangle column = rect_column.get(i);
if (column.x + column.width < 0)
{
rect_column.remove(column);
if (column.y == 0)
{
addColumn(false);
}
}
}
bee.y += yMotion;
for (Rectangle column : rect_column)
{
if (column.y == 0 && bee.x + bee.width / 2 > column.x + column.width / 2 - 10 && bee.x + bee.width / 2 < column.x + column.width / 2 + 10)
{
score++;
}
if (column.intersects(bee))
{
gameOver = true;
if (bee.x <= column.x)
{
bee.x = column.x - bee.width;
}
else
{
if (column.y != 0)
{
bee.y = column.y - bee.height;
}
else if (bee.y < column.height)
{
bee.y = column.height;
}
}
}
}
if (bee.y > HEIGHT - 120 || bee.y < 0)
{
gameOver = true;
}
if (bee.y + yMotion >= HEIGHT - 120)
{
bee.y = HEIGHT - 120 - bee.height;
gameOver = true;
}
}
renderer.repaint();
}
public void paintColumn(Graphics g, Rectangle column)
{
g.setColor(Color.green.darker());
g.fillRect(column.x, column.y, column.width, column.height);
g.fillRect(column.x-20, column.y+column.height-10, column.width+40, 10);
g.fillRect(column.x-20, column.y-10, column.width+40, 10);
}
public void repaint(Graphics g)
{
g.setColor(new Color(153,204,255));
g.fillRect(0, 0, WIDTH, HEIGHT);
g.setColor(new Color(255,255,255));
g.fillOval(50, 50, 100, 100);
g.setColor(Color.YELLOW);
g.fillOval(600, 50, 100, 100);
g.setColor(new Color(156,93,82));
g.fillRect(0, HEIGHT - 120, WIDTH, 120);
g.setColor(new Color(128,255,0));
g.fillRect(0, HEIGHT - 120, WIDTH, 20);
g.setColor(Color.YELLOW);
g.fillRect(bee.x, bee.y, bee.width, bee.height);
for (Rectangle column : rect_column)
{
paintColumn(g, column);
}
g.setColor(Color.white);
g.setFont(new Font("Times New Roman", 1, 100));
if (!started)
{
g.drawString("Push A to start", 100, HEIGHT / 2 - 50);
}
if (gameOver)
{
g.drawString("Game Over", 100, HEIGHT / 2 - 50);
g.drawString("A to replay", 100, HEIGHT / 2 + 90);
}
}
public static void main(String[] args)
{
finalFlappy = new FinalFlappy();
}
#Override
public void mouseClicked(MouseEvent e)
{
jump();
}
#Override
public void keyReleased(KeyEvent e)
{
if (e.getKeyCode() == KeyEvent.VK_A)
{
jump();
}
}
#Override
public void mousePressed(MouseEvent e)
{
}
#Override
public void mouseReleased(MouseEvent e)
{
}
#Override
public void mouseEntered(MouseEvent e)
{
}
#Override
public void mouseExited(MouseEvent e)
{
}
#Override
public void keyTyped(KeyEvent e)
{
}
#Override
public void keyPressed(KeyEvent e)
{
}
}
import java.awt.Graphics;
import javax.swing.JPanel;
public class FinalFlappyRend extends JPanel
{
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
FinalFlappy.finalFlappy.repaint(g);
}
}
I am working on making a Flappy bird game and I am stuck on how to make and display a timer that updates every second onto the screen
How do I make it start as the game starts and end as the game over pops up?

There are a few ways you might achieve what you're asking. The important thing to remember is, any solution is going to have a degree of drift, meaning that it's unlikely to absolutely accurate, the degree of drift will depend on a lot of factors, so just beware.
You could use a Swing Timer
It's among the safest means for updating the UI on a regular basis, it's also useful if your main loop is already based on a Swing Timer
See How to Use Swing Timers for more details
You could...
Maintain some kind of counter within in your main loop. This assumes that you're using a separate thread (although you can do the same thing with a Swing Timer) and are simply looping at some consistent rate
long tick = System.nanoTime();
long lastUpdate = -1;
while (true) {
long diff = System.nanoTime() - tick;
long seconds = TimeUnit.SECONDS.convert(diff, TimeUnit.NANOSECONDS);
if (seconds != lastUpdate) {
lastUpdate = seconds;
updateTimerLabel(seconds);
}
Thread.sleep(100);
}
This basically runs a while-loop, which calculates the difference between a given point in time (tick) and now, if it's a "second" difference, it then updates the UI (rather than constantly updating the UI with the same value)
The updateTimerLabel method basically updates the label with the specified time, but does so in a manner which is thread safe
protected void updateTimerLabel(long seconds) {
if (EventQueue.isDispatchThread()) {
timerLabel.setText(Long.toString(seconds));
} else {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
updateTimerLabel(seconds);
}
});
}
}

To make and display a timer that updates every second, Put this code in your main class:
private Timer timer = new Timer();
private JLabel timeLabel = new JLabel(" ", JLabel.CENTER);
timer.schedule(new UpdateUITask(), 0, 1000);
private class UpdateUITask extends TimerTask {
int nSeconds = 0;
#Override
public void run() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
timeLabel.setText(String.valueOf(nSeconds++));
}
});
}
}

How do I paint multiple objetcs that move at different speeds in Java?

I am working on homework for class, and its late because I can't seem to understand the material despite all the research that I am doing. I am a beginner and do not know much in the way of java. Also, this is my first post so please be forgiving when you are reading this.
I am building on source code from my textbook, which I updated recently for past homework, but now I am trying to generate a class that draws multiple squares and moves those objects independently and at different speeds. They will all need to rebound off the walls as well. I followed the instructions and created two arrays that will hold the random x and y values between 1 and 10. However, I struggle with arrays and I am sure that I am not doing it correctly. So, I would love some feedback to see if I have it set up correctly.
I have a the jpanel pulling up and drawing, and as long as there is 1 square it is working fine bouncing off the walls, but things change when I draw more than one. The do not move independently and they also share the same speed. Some even disappear from time to time. This has really thrown me off. I appreciate any help!
In short, I am trying to paint new squares that all travel in different directions and at different speeds. Per the instructions we are suppose create and use a two arrays that handle the x and y values.
Here is what I have so far:
public class DotsPanel extends JPanel
{
private int delay = 15;
private final int SIZE = 7, IMAGE_SIZE = 3; // radius of each dot
private Timer timer;
private int x, y, i;
private ArrayList<Point> pointList;
static int [] xarray = new int [1000];
static int [] yarray = new int [1000];
Random rand = new Random();
//-----------------------------------------------------------------
// Constructor: Sets up this panel to listen for mouse events.
//-----------------------------------------------------------------
public DotsPanel()
{
pointList = new ArrayList<Point>();
int [] xarray = new int [1000];
int [] yarray = new int [1000];
timer = new Timer(delay, new ReboundListener());
addMouseListener (new DotsListener());
addMouseMotionListener (new DotsListener());
setBackground(Color.gray);
setPreferredSize(new Dimension(700, 500));
for(int i = 0; i < xarray.length; i++)
{
xarray[i] = rand.nextInt(7);
yarray[i] = rand.nextInt(7);
}
timer.start();
}
//-----------------------------------------------------------------
// Draws all of the dots stored in the list.
//-----------------------------------------------------------------
public void paintComponent(Graphics page)
{
super.paintComponent(page);
page.setColor(Color.BLUE);
for (Point spot : pointList)
{
page.fillRect(spot.x-SIZE, spot.y-SIZE, 25, 25);
page.drawString("Count: " + pointList.size(), 5, 15);
}
}
//*****************************************************************
// Represents the listener for mouse events.
//*****************************************************************
private class DotsListener implements MouseListener, MouseMotionListener
{
//--------------------------------------------------------------
// Adds the current point to the list of points and redraws
// the panel whenever the mouse button is pressed.
//--------------------------------------------------------------
public void mousePressed(MouseEvent event)
{
pointList.add(event.getPoint());
repaint();
}
public void mouseDragged(MouseEvent event)
{
// initially I had two xarray and yarray in here just like in
// mouseClicked
// but it did not change anything when removed
}
//--------------------------------------------------------------
// Provide empty definitions for unused event methods.
//--------------------------------------------------------------
public void mouseClicked(MouseEvent event)
{
xarray[i] = rand.nextInt(7);
yarray[i] = rand.nextInt(7);
}
public void mouseReleased(MouseEvent event) {}
public void mouseEntered(MouseEvent event) {}
public void mouseExited(MouseEvent event) {}
public void mouseMoved(MouseEvent e) {}
}
private class ReboundListener implements ActionListener
{
//--------------------------------------------------------------
// Updates the position of the image and possibly the direction
// of movement whenever the timer fires an action event.
//--------------------------------------------------------------
public void actionPerformed(ActionEvent event)
{
for (Point spot : pointList)
{
spot.x += xarray[i];
spot.y += yarray[i];
if (spot.x <= 0 || spot.x >= 700)
xarray[i] = xarray[i] * -1;
if (spot.y <= 0 || spot.y >= 500)
yarray[i] = yarray[i] * -1;
repaint();
}
}
}
}

However, I struggle with arrays and I am sure that I am not doing it correctly.
I wouldn't use Arrays.
Instead, have a Ball object manage its own state. Then you can have different color, speed, size etc for each Ball. Then when the Timer fires you just calculate the new position and repaint the Ball.
Here is an example to get you started:
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.util.*;
import javax.swing.*;
import javax.swing.Timer;
public class BallAnimation4
{
private static void createAndShowUI()
{
BallPanel panel = new BallPanel();
JFrame frame = new JFrame("BallAnimation4");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add( panel );
frame.setSize(800, 600);
frame.setLocationRelativeTo( null );
//frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.setVisible( true );
panel.addBalls(5);
panel.startAnimation();
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowUI();
}
});
}
}
class BallPanel extends JPanel implements ActionListener
{
private ArrayList<Ball> balls = new ArrayList<Ball>();
public BallPanel()
{
setLayout( null );
setBackground( Color.BLACK );
}
public void addBalls(int ballCount)
{
Random random = new Random();
for (int i = 0; i < ballCount; i++)
{
Ball ball = new Ball();
ball.setRandomColor(true);
ball.setLocation(random.nextInt(getWidth()), random.nextInt(getHeight()));
ball.setMoveRate(32, 32, 1, 1, true);
// ball.setMoveRate(16, 16, 1, 1, true);
ball.setSize(32, 32);
balls.add( ball );
}
}
#Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
for (Ball ball: balls)
{
ball.draw(g);
}
}
public void startAnimation()
{
Timer timer = new Timer(75, this);
timer.start();
}
public void actionPerformed(ActionEvent e)
{
move();
repaint();
}
private void move()
{
for (Ball ball : balls)
{
ball.move(this);
}
}
class Ball
{
public Color color = Color.BLACK;
public int x = 0;
public int y = 0;
public int width = 1;
public int height = 1;
private int moveX = 1;
private int moveY = 1;
private int directionX = 1;
private int directionY = 1;
private int xScale = moveX;
private int yScale = moveY;
private boolean randomMove = false;
private boolean randomColor = false;
private Random myRand = null;
public Ball()
{
myRand = new Random();
setRandomColor(randomColor);
}
public void move(JPanel parent)
{
int iRight = parent.getSize().width;
int iBottom = parent.getSize().height;
x += 5 + (xScale * directionX);
y += 5 + (yScale * directionY);
if (x <= 0)
{
x = 0;
directionX *= (-1);
xScale = randomMove ? myRand.nextInt(moveX) : moveX;
if (randomColor) setRandomColor(randomColor);
}
if (x >= iRight - width)
{
x = iRight - width;
directionX *= (-1);
xScale = randomMove ? myRand.nextInt(moveX) : moveX;
if (randomColor) setRandomColor(randomColor);
}
if (y <= 0)
{
y = 0;
directionY *= (-1);
yScale = randomMove ? myRand.nextInt(moveY) : moveY;
if (randomColor) setRandomColor(randomColor);
}
if (y >= iBottom - height)
{
y = iBottom - height;
directionY *= (-1);
yScale = randomMove ? myRand.nextInt(moveY) : moveY;
if (randomColor) setRandomColor(randomColor);
}
}
public void draw(Graphics g)
{
g.setColor(color);
g.fillOval(x, y, width, height);
}
public void setColor(Color c)
{
color = c;
}
public void setLocation(int x, int y)
{
this.x = x;
this.y = y;
}
public void setMoveRate(int xMove, int yMove, int xDir, int yDir, boolean randMove)
{
this.moveX = xMove;
this.moveY = yMove;
directionX = xDir;
directionY = yDir;
randomMove = randMove;
}
public void setRandomColor(boolean randomColor)
{
this.randomColor = randomColor;
switch (myRand.nextInt(3))
{
case 0: color = Color.BLUE;
break;
case 1: color = Color.GREEN;
break;
case 2: color = Color.RED;
break;
default: color = Color.BLACK;
break;
}
}
public void setSize(int width, int height)
{
this.width = width;
this.height = height;
}
}
}
Since your Arrays only contain the Point you want to paint you don't have any information about the speed each point should be moved at. The best you could do is create a random amount each point should be moved each time its location is changed. This would give erratic movement as each time you move a point the distance would be random.
If you want more constant speed then you would need to create a second Array to contain the distance each point should move every time.
This starts to get messy creating a new Array every time you want a new property to be unique for the object you want to paint. That is why the approach to create a custom Object with multiple properties is easier to manage.

Java: I need help to moove JLabel with keyboards [duplicate]

I'm new to Java graphics and threads, and I'm trying to make a game (specifically, Pong). The idea is that two people can play on the same keyboard (i.e. there are two paddles that are controlled through different keys). Currently, both players can't move their paddle at the same time.
Is there a solution to this? Are separate threads the answer?
If possible, I'd like the paddles to be able to move (at least seemingly) at the same time.
Update: It seems like using a Set<Integer> to store pressed keys is the best option. I've done that (and it works), but I'm wondering if any of this code is not on the Event Dispatching Thread (EDT) and if I need to use SwingUtilities.invokeLater();. Here's the necessary code:
private Set<Integer> keysDown = Collections.synchronizedSet(new HashSet<Integer>());
public void keyPressed(KeyEvent e)
{
keysDown.add(e.getKeyCode());
}
public void keyReleased(KeyEvent e)
{
keysDown.remove(e.getKeyCode());
}
public void updatePaddlePositions()
{
if (keysDown.contains(KeyEvent.VK_W))
paddleOne.move(-PADDLE_MOVE_INCREMENT);
if (keysDown.contains(KeyEvent.VK_S))
paddleOne.move(PADDLE_MOVE_INCREMENT);
if (keysDown.contains(KeyEvent.VK_UP))
paddleTwo.move(-PADDLE_MOVE_INCREMENT);
if (keysDown.contains(KeyEvent.VK_DOWN))
paddleTwo.move(PADDLE_MOVE_INCREMENT);
try {
Thread.sleep(DELAY);
} catch (InterruptedException e) {
System.out.println("You Interrupted the game!");
}
canvas.repaint();
}
Here's the paintComponent method of the canvas object:
public void paintComponent(Graphics g)
{
super.paintComponent(g);
paddleOne.paint(g);
paddleTwo.paint(g);
updatePaddlePositions(); // Does this need to be SwingUtilities.invokeLater(this)?
// And should updatePaddlePositions() be run() as a result?
}
And here's the paint method of the paddleOne and paddleTwo objects:
public void paint(Graphics g)
{
g.setColor(Color.BLACK);
g.fillRect(x, y, PADDLE_WIDTH, PADDLE_HEIGHT);
}
Feel free to comment on my design if anything pops out as "bad" to you. Lastly, what does Collections.synchronizedSet(new HashSet<Integer>()) mean/do?
Update #2: It seems like key bindings are the way to go (even though they take more code, in this case). What make key bindings better? Is it that they work separately from everything else (and don't need window focus like key listeners)?
Also, I understand that HashSet<Integer> is just a subclass of Set<Integer>, but what is the purpose of Collections.synchronizedSet(...)? I'm assuming it has to do with threads, but I don't know why it's needed in this program (if it is at all).

First off, use Swing KeyBindings Also I see no real need for multi-threadung unless you want your game multi-threaded.
To clarify the problem is you need to be able for 2 players to press different keys?
If so:
Solution:
Simply use booleans to flag whether or not a key is pressed down, you would than of course have to reset the flag when the key is released.
In your game logic you would check the states if the booleans and act appropriately.
See my below example (both paddles can move independently using W and S and UP and DOWN keys):
public class GameLogic {
public GameLogic() {
initComponents();
}
private void initComponents() {
JFrame frame = new JFrame("Game Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//create the gamepanel
final GamePanel gp = new GamePanel(600, 500);
//create panel to hold buttons to start pause and stop the game
JPanel buttonPanel = new JPanel();
buttonPanel.setOpaque(false);
final JButton startButton = new JButton("Start");
final JButton pauseButton = new JButton("Pause");
final JButton stopButton = new JButton("Stop");
pauseButton.setEnabled(false);
stopButton.setEnabled(false);
//add listeners to buttons (most of the actions - excuse the pun - takes palce here :)
startButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
//clear enitites currently in array
gp.clearEntities();
ArrayList<BufferedImage> ballEntityImages = new ArrayList<>();
ArrayList<Long> ballEntityTimings = new ArrayList<>();
ballEntityImages.add(createColouredImage("white", 50, 50, true));
ballEntityTimings.add(500l);
Entity ballEntity = new Entity(gp.getWidth() / 2, gp.getHeight() / 2, ballEntityImages, ballEntityTimings);
ballEntity.RIGHT = true;
//create images for entities
ArrayList<BufferedImage> advEntityImages = new ArrayList<>();
ArrayList<Long> advEntityTimings = new ArrayList<>();
advEntityImages.add(createColouredImage("orange", 10, 100, false));
advEntityTimings.add(500l);
advEntityImages.add(createColouredImage("blue", 10, 100, false));
advEntityTimings.add(500l);
//create entities
AdvancedSpritesEntity player1Entity = new AdvancedSpritesEntity(0, 100, advEntityImages, advEntityTimings);
ArrayList<BufferedImage> entityImages = new ArrayList<>();
ArrayList<Long> entityTimings = new ArrayList<>();
entityImages.add(createColouredImage("red", 10, 100, false));
entityTimings.add(500l);//as its the only image it doesnt really matter what time we put we could use 0l
//entityImages.add(createColouredImage("magenta", 100, 100));
//entityTimings.add(500l);
Entity player2Entity = new Entity(gp.getWidth() - 10, 200, entityImages, entityTimings);
gp.addEntity(player1Entity);
gp.addEntity(player2Entity);//just a standing still Entity for testing
gp.addEntity(ballEntity);//just a standing still Entity for testing
//create Keybingings for gamepanel
GameKeyBindings gameKeyBindings = new GameKeyBindings(gp, player1Entity, player2Entity);
GamePanel.running.set(true);
//start the game loop which will repaint the screen
runGameLoop(gp);
startButton.setEnabled(false);
pauseButton.setEnabled(true);
stopButton.setEnabled(true);
}
});
pauseButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
boolean b = GamePanel.paused.get();
GamePanel.paused.set(!b);//set it to the opposite of what it was i.e paused to unpaused and vice versa
if (pauseButton.getText().equals("Pause")) {
pauseButton.setText("Un-pause");
} else {
pauseButton.setText("Pause");
}
}
});
stopButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
GamePanel.running.set(false);
GamePanel.paused.set(false);
/* if we want enitites to be cleared and a blank panel shown
gp.clearEntities();
gp.repaint();
*/
if (!pauseButton.getText().equals("Pause")) {
pauseButton.setText("Pause");
}
startButton.setEnabled(true);
pauseButton.setEnabled(false);
stopButton.setEnabled(false);
}
});
//add buttons to panel
buttonPanel.add(startButton);
buttonPanel.add(pauseButton);
buttonPanel.add(stopButton);
//add gamepanel to jframe and button panel
frame.add(gp);
frame.add(buttonPanel, BorderLayout.SOUTH);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
//Simply used for testing (to simulate sprites) can create different colored images
public static BufferedImage createColouredImage(String color, int w, int h, boolean circular) {
BufferedImage img = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = img.createGraphics();
switch (color.toLowerCase()) {
case "green":
g2.setColor(Color.GREEN);
break;
case "magenta":
g2.setColor(Color.MAGENTA);
break;
case "red":
g2.setColor(Color.RED);
break;
case "yellow":
g2.setColor(Color.YELLOW);
break;
case "blue":
g2.setColor(Color.BLUE);
break;
case "orange":
g2.setColor(Color.ORANGE);
break;
case "cyan":
g2.setColor(Color.CYAN);
break;
case "gray":
g2.setColor(Color.GRAY);
break;
default:
g2.setColor(Color.WHITE);
break;
}
if (!circular) {
g2.fillRect(0, 0, img.getWidth(), img.getHeight());
} else {
g2.fillOval(0, 0, img.getWidth(), img.getHeight());
}
g2.dispose();
return img;
}
//Starts a new thread and runs the game loop in it.
private void runGameLoop(final GamePanel gp) {
Thread loop = new Thread(new Runnable() {
#Override
public void run() {
gp.gameLoop();
}
});
loop.start();
}
//Code starts here
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
try {//attempt to set look and feel to nimbus Java 7 and up
for (UIManager.LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
GameLogic gameLogic = new GameLogic();
}
});
}
}
class GameKeyBindings {
public GameKeyBindings(JComponent gp, final Entity entity, final Entity entity2) {
gp.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_W, 0, false), "W pressed");
gp.getActionMap().put("W pressed", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent ae) {
entity.UP = true;
}
});
gp.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_W, 0, true), "W released");
gp.getActionMap().put("W released", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent ae) {
entity.UP = false;
}
});
gp.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_S, 0, false), "S pressed");
gp.getActionMap().put("S pressed", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent ae) {
entity.DOWN = true;
}
});
gp.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_S, 0, true), "S released");
gp.getActionMap().put("S released", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent ae) {
entity.DOWN = false;
}
});
gp.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0, false), "down pressed");
gp.getActionMap().put("down pressed", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent ae) {
entity2.DOWN = true;
}
});
gp.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0, true), "down released");
gp.getActionMap().put("down released", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent ae) {
entity2.DOWN = false;
}
});
gp.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0, false), "up pressed");
gp.getActionMap().put("up pressed", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent ae) {
entity2.UP = true;
}
});
gp.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0, true), "up released");
gp.getActionMap().put("up released", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent ae) {
entity2.UP = false;
}
});
}
}
class AdvancedSpritesEntity extends Entity {
public AdvancedSpritesEntity(int x, int y, ArrayList<BufferedImage> images, ArrayList<Long> timings) {
super(x, y, images, timings);
}
void setAnimation(ArrayList<BufferedImage> images, ArrayList<Long> timings) {
reset();//reset variables of animator class
setFrames(images, timings);//set new frames for animation
}
}
class Entity extends Animator {
private int speed = 5;
public boolean UP = false, DOWN = false, LEFT = false, RIGHT = false, visible;
private Rectangle2D.Double rect;
public Entity(int x, int y, ArrayList<BufferedImage> images, ArrayList<Long> timings) {
super(images, timings);
UP = false;
DOWN = false;
LEFT = false;
RIGHT = false;
visible = true;
rect = new Rectangle2D.Double(x, y, getCurrentImage().getWidth(), getCurrentImage().getHeight());
}
public void setSpeed(int speed) {
this.speed = speed;
}
public int getSpeed() {
return speed;
}
public boolean isVisible() {
return visible;
}
public void setVisible(boolean visible) {
this.visible = visible;
}
public HashSet<String> getMask(Entity e) {
HashSet<String> mask = new HashSet<>();
int pixel, a;
BufferedImage bi = e.getCurrentImage();//gets the current image being shown
for (int i = 0; i < bi.getWidth(); i++) { // for every (x,y) component in the given box,
for (int j = 0; j < bi.getHeight(); j++) {
pixel = bi.getRGB(i, j); // get the RGB value of the pixel
a = (pixel >> 24) & 0xff;
if (a != 0) { // if the alpha is not 0, it must be something other than transparent
mask.add((e.getX() + i) + "," + (e.getY() - j)); // add the absolute x and absolute y coordinates to our set
}
}
}
return mask; //return our set
}
// Returns true if there is a collision between object a and object b
public boolean checkPerPixelCollision(Entity b) {
// This method detects to see if the images overlap at all. If they do, collision is possible
int ax1 = (int) getX();
int ay1 = (int) getY();
int ax2 = ax1 + (int) getWidth();
int ay2 = ay1 + (int) getHeight();
int bx1 = (int) b.getX();
int by1 = (int) b.getY();
int bx2 = bx1 + (int) b.getWidth();
int by2 = by1 + (int) b.getHeight();
if (by2 < ay1 || ay2 < by1 || bx2 < ax1 || ax2 < bx1) {
return false; // Collision is impossible.
} else { // Collision is possible.
// get the masks for both images
HashSet<String> maskPlayer1 = getMask(this);
HashSet<String> maskPlayer2 = getMask(b);
maskPlayer1.retainAll(maskPlayer2); // Check to see if any pixels in maskPlayer2 are the same as those in maskPlayer1
if (maskPlayer1.size() > 0) { // if so, than there exists at least one pixel that is the same in both images, thus
return true;
}
}
return false;
}
public void move() {
if (UP) {
rect.y -= speed;
}
if (DOWN) {
rect.y += speed;
}
if (LEFT) {
rect.x -= speed;
}
if (RIGHT) {
rect.x += speed;
}
}
#Override
public void update(long elapsedTime) {
super.update(elapsedTime);
getWidth();//set the rectangles height accordingly after image update
getHeight();//set rectangles height accordingle after update
}
public boolean intersects(Entity e) {
return rect.intersects(e.rect);
}
public double getX() {
return rect.x;
}
public double getY() {
return rect.y;
}
public double getWidth() {
if (getCurrentImage() == null) {//there might be no image (which is unwanted ofcourse but we must not get NPE so we check for null and return 0
return rect.width = 0;
}
return rect.width = getCurrentImage().getWidth();
}
public double getHeight() {
if (getCurrentImage() == null) {
return rect.height = 0;
}
return rect.height = getCurrentImage().getHeight();
}
}
class Animator {
private ArrayList<BufferedImage> frames;
private ArrayList<Long> timings;
private int currIndex;
private long animationTime;
private long totalAnimationDuration;
private AtomicBoolean done;//used to keep track if a single set of frames/ an animtion has finished its loop
public Animator(ArrayList<BufferedImage> frames, ArrayList< Long> timings) {
currIndex = 0;
animationTime = 0;
totalAnimationDuration = 0;
done = new AtomicBoolean(false);
this.frames = new ArrayList<>();
this.timings = new ArrayList<>();
setFrames(frames, timings);
}
public boolean isDone() {
return done.get();
}
public void reset() {
totalAnimationDuration = 0;
done.getAndSet(false);
}
public void update(long elapsedTime) {
if (frames.size() > 1) {
animationTime += elapsedTime;
if (animationTime >= totalAnimationDuration) {
animationTime = animationTime % totalAnimationDuration;
currIndex = 0;
done.getAndSet(true);
}
while (animationTime > timings.get(currIndex)) {
currIndex++;
}
}
}
public BufferedImage getCurrentImage() {
if (frames.isEmpty()) {
return null;
} else {
try {
return frames.get(currIndex);
} catch (Exception ex) {//images might have been altered so we reset the index and return first image of the new frames/animation
currIndex = 0;
return frames.get(currIndex);
}
}
}
public void setFrames(ArrayList<BufferedImage> frames, ArrayList< Long> timings) {
if (frames == null || timings == null) {//so that constructor super(null,null) cause this to throw NullPointerException
return;
}
this.frames = frames;
this.timings.clear();
for (long animTime : timings) {
totalAnimationDuration += animTime;
this.timings.add(totalAnimationDuration);
}
}
}
class GamePanel extends JPanel {
private final static RenderingHints textRenderHints = new RenderingHints(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
private final static RenderingHints imageRenderHints = new RenderingHints(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
private final static RenderingHints colorRenderHints = new RenderingHints(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
private final static RenderingHints interpolationRenderHints = new RenderingHints(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);
private final static RenderingHints renderHints = new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
public static AtomicBoolean running = new AtomicBoolean(false), paused = new AtomicBoolean(false);
private int width, height, frameCount = 0, fps = 0;
private ArrayList<Entity> entities = new ArrayList<>();
private final Random random = new Random();
public GamePanel(int w, int h) {
super(true);//make sure double buffering is enabled
setIgnoreRepaint(true);//mustnt repaint itself the gameloop will do that
width = w;
height = h;
}
#Override
public Dimension getPreferredSize() {
return new Dimension(width, height);
}
public void addEntity(Entity e) {
entities.add(e);
}
void clearEntities() {
entities.clear();
}
//Only run this in another Thread!
public void gameLoop() {
//This value would probably be stored elsewhere.
final double GAME_HERTZ = 30.0;
//Calculate how many ns each frame should take for our target game hertz.
final double TIME_BETWEEN_UPDATES = 1000000000 / GAME_HERTZ;
//At the very most we will update the game this many times before a new render.
//If you're worried about visual hitches more than perfect timing, set this to 1.
final int MAX_UPDATES_BEFORE_RENDER = 5;
//We will need the last update time.
double lastUpdateTime = System.nanoTime();
//Store the last time we rendered.
double lastRenderTime = System.nanoTime();
//If we are able to get as high as this FPS, don't render again.
final double TARGET_FPS = 60;
final double TARGET_TIME_BETWEEN_RENDERS = 1000000000 / TARGET_FPS;
//Simple way of finding FPS.
int lastSecondTime = (int) (lastUpdateTime / 1000000000);
//store the time we started this will be used for updating map and charcter animations
long currTime = System.currentTimeMillis();
while (running.get()) {
if (!paused.get()) {
double now = System.nanoTime();
long elapsedTime = System.currentTimeMillis() - currTime;
currTime += elapsedTime;
int updateCount = 0;
//Do as many game updates as we need to, potentially playing catchup.
while (now - lastUpdateTime > TIME_BETWEEN_UPDATES && updateCount < MAX_UPDATES_BEFORE_RENDER) {
updateGame(elapsedTime);//Update the entity movements and collision checks etc (all has to do with updating the games status i.e call move() on Enitites)
lastUpdateTime += TIME_BETWEEN_UPDATES;
updateCount++;
}
//If for some reason an update takes forever, we don't want to do an insane number of catchups.
//If you were doing some sort of game that needed to keep EXACT time, you would get rid of this.
if (now - lastUpdateTime > TIME_BETWEEN_UPDATES) {
lastUpdateTime = now - TIME_BETWEEN_UPDATES;
}
drawGame();//draw the game by invokeing repaint (which will call paintComponent) on this JPanel
lastRenderTime = now;
//Update the frames we got.
int thisSecond = (int) (lastUpdateTime / 1000000000);
if (thisSecond > lastSecondTime) {
//System.out.println("NEW SECOND " + thisSecond + " " + frameCount);
fps = frameCount;
frameCount = 0;
lastSecondTime = thisSecond;
}
//Yield until it has been at least the target time between renders. This saves the CPU from hogging.
while (now - lastRenderTime < TARGET_TIME_BETWEEN_RENDERS && now - lastUpdateTime < TIME_BETWEEN_UPDATES) {
//allow the threading system to play threads that are waiting to run.
Thread.yield();
//This stops the app from consuming all your CPU. It makes this slightly less accurate, but is worth it.
//You can remove this line and it will still work (better), your CPU just climbs on certain OSes.
//FYI on some OS's this can cause pretty bad stuttering. Scroll down and have a look at different peoples' solutions to this.
//On my OS(Windows 7 x64 intel i3) it does not allow for time to make enityt etc move thus all stands still
try {
Thread.sleep(1);
} catch (Exception e) {
}
now = System.nanoTime();
}
}
}
fps = 0;//no more running set fps to 0
}
private void drawGame() {
//Both revalidate and repaint are thread-safe — you need not invoke them from the event-dispatching thread. http://docs.oracle.com/javase/tutorial/uiswing/layout/howLayoutWorks.html
repaint();
}
private void updateGame(long elapsedTime) {
updateEntityMovements(elapsedTime);
checkForCollisions();
}
private void checkForCollisions() {
if (entities.get(0).intersects(entities.get(2)) || entities.get(1).intersects(entities.get(2))) {
if (entities.get(2).LEFT) {
entities.get(2).RIGHT = true;
entities.get(2).LEFT = false;
} else {
entities.get(2).LEFT = true;
entities.get(2).RIGHT = false;
}
System.out.println("Intersecting");
} /*
//This is best used when images have transparent and non-transparent pixels (only detects pixel collisions of non-transparent pixels)
if (entities.get(0).checkPerPixelCollision(entities.get(2)) | entities.get(1).checkPerPixelCollision(entities.get(2))) {
if (entities.get(2).LEFT) {
entities.get(2).RIGHT = true;
entities.get(2).LEFT = false;
} else {
entities.get(2).LEFT = true;
entities.get(2).RIGHT = false;
}
System.out.println("Intersecting");
}
*/
}
private void updateEntityMovements(long elapsedTime) {
for (Entity e : entities) {
e.update(elapsedTime);
e.move();
}
}
#Override
protected void paintComponent(Graphics grphcs) {
super.paintComponent(grphcs);
Graphics2D g2d = (Graphics2D) grphcs;
applyRenderHints(g2d);
drawBackground(g2d);
drawEntitiesToScreen(g2d);
drawFpsCounter(g2d);
frameCount++;
}
public static void applyRenderHints(Graphics2D g2d) {
g2d.setRenderingHints(textRenderHints);
g2d.setRenderingHints(imageRenderHints);
g2d.setRenderingHints(colorRenderHints);
g2d.setRenderingHints(interpolationRenderHints);
g2d.setRenderingHints(renderHints);
}
private void drawEntitiesToScreen(Graphics2D g2d) {
for (Entity e : entities) {
if (e.isVisible()) {
g2d.drawImage(e.getCurrentImage(), (int) e.getX(), (int) e.getY(), null);
}
}
}
private void drawFpsCounter(Graphics2D g2d) {
g2d.setColor(Color.WHITE);
g2d.drawString("FPS: " + fps, 5, 10);
}
private void drawBackground(Graphics2D g2d) {
g2d.setColor(Color.BLACK);
g2d.fillRect(0, 0, getWidth(), getHeight());
//thanks to trashgod for lovely testing background :) http://stackoverflow.com/questions/3256269/jtextfields-on-top-of-active-drawing-on-jpanel-threading-problems/3256941#3256941
g2d.setColor(Color.BLACK);
for (int i = 0; i < 128; i++) {
g2d.setColor(new Color(random.nextInt(256), random.nextInt(256), random.nextInt(256)));//random color
g2d.drawLine(getWidth() / 2, getHeight() / 2, random.nextInt(getWidth()), random.nextInt(getHeight()));
}
}
}

This may be a legitimate use case for the low-level access afforded to a KeyListener. See How to Write a Key Listener and KeyEventDemo; don't forget to requestFocusInWindow(). Also consider offering keyboard control for one player and mouse control for the other.
Addendum: #David Kroukamp has adduced an appealing counter-example using key bindings. For reference, the example cited here illustrates one approach to managing key preferences.

Java continue movement right away after key pressed?

Well when I am pressing any of the key arrows, the red box moves, yes it moves 10px and then stops for 1 second & continues moving, instead of move right away without stopping.
example of the occurring issue:
(source: gyazo.com)
Can you see how it stopped for 1 or 0.5 secs and continued?
How can I fix it?
I am using KeyEventDispatcher
My key detecting:
Whole src:
public class Game extends Frame {
private class Keyboard implements KeyEventDispatcher {
private Game game;
public Keyboard(Game game) {
this.game = game;
}
#Override
public boolean dispatchKeyEvent(KeyEvent e) {
if (e.getID() == KeyEvent.KEY_PRESSED) {
this.movement(e);
} else if (e.getID() == KeyEvent.KEY_RELEASED) {
} else if (e.getID() == KeyEvent.KEY_TYPED) {
}
return false;
}
public void movement(KeyEvent e) {
int keyCode = e.getKeyCode();
switch( keyCode ) {
case KeyEvent.VK_UP:
game.movePlayer(0, -10);
break;
case KeyEvent.VK_DOWN:
game.movePlayer(0, 10);
break;
case KeyEvent.VK_LEFT:
game.movePlayer(-10, 0);
break;
case KeyEvent.VK_RIGHT :
game.movePlayer(10, 0);
break;
}
}
}
private static final long serialVersionUID = 1L;
private int coordinateX = 1;
private int coordinateY = 1;
public int width = 300;
public int height = width / 16 * 9;
public int scale = 3;
public int mouseY = MouseInfo.getPointerInfo().getLocation().y;
public int mouseX = MouseInfo.getPointerInfo().getLocation().x;
private Player player = new Player(0, 0);
public Game() {
Dimension size = new Dimension(width * scale, height * scale);
setPreferredSize(size);
frame.setSize(width, height);
frame.setResizable(false);
frame.setTitle("First game");
JPanel j = new JPanel();
j.setVisible(true);
JLabel text = new JLabel("coords");
j.add(text);
frame.add(this);
frame.pack();
frame.add(j);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
KeyboardFocusManager manager = KeyboardFocusManager.getCurrentKeyboardFocusManager();
manager.addKeyEventDispatcher(new Keyboard(this));
}
private void movePlayer(int x, int y) {
/**
* Main region area
*/
int pX = 0, pY = 0;
if (y == 0) { // x
if (player.getX() + x + 100 > frame.getContentPane().getWidth() || player.getX() + x < 0) {
if (player.getX() + x < 0) {
player.setX(0);
return;
}
if (player.getX() + x > 0) {
player.setX(frame.getContentPane().getWidth() - 100);
return;
}
return;
}
pX = x;
}
else if (x == 0) { // y
if (player.getY() + y + 100 > frame.getContentPane().getHeight() || player.getY() + y < 0) {
if (player.getY() + y < 0) {
player.setY(0);
return;
}
if (player.getY() + y > 0) {
player.setY(frame.getContentPane().getHeight() - 100);
return;
}
return;
}
pY = y;
}
player.updatePosition(pX, pY);
}
public void update() {
}
public void render() {
bs = getBufferStrategy();
if (bs == null) {
createBufferStrategy(3);
return;
}
g = bs.getDrawGraphics();
g.setColor(Color.BLACK);
g.fillRect(0, 0, getWidth(), getHeight());
g.setColor(Color.RED);
g.fillRect(player.getX(), player.getY(), 100, 100);
g.dispose();
bs.show();
}
}
Frame.java:
public class Frame extends Canvas {
public static final long serialVersionUID = 8L;
public static JFrame frame = new JFrame();
public static Threads thread;
public static Game game;
public Graphics g;
public BufferStrategy bs;
/**
* #param args
*/
public static void main(String[] args) {
thread = new Threads(new Game());
thread.start();
}
}

The problem is the repeat rate for KeyStrokes. This is controlled by the OS.
The solution is to use a Swing Timer to schedule the animation as soon as the key is pressed.
See Motion Using the Keyboard for more information and a complete working example.
Also, you should NOT be using a KeyListener but intead should be using KeyBindings.

Custom ScrollPane using just a Panel or any other Container

I'm trying to mimic a ScrollPane by simply inheriting from a Panel which itself moves its child around.
Should be a simple task but the child doesn't get clipped properly, meaning if I scroll around using setScrollPosition(Point) the content is visible although its outside the parent Panel.
public class ScrollFrame
extends Container
{
public ScrollFrame() {
setLayout(null);
}
public void paint(Graphics g) {
g.drawRect(0, 0, getWidth() - 1, getHeight() - 1);
super.paint(g);
}
public void setScrollPosition(Point p) {
setScrollPosition(p.x, p.y);
}
public void setScrollPosition(int x, int y) {
synchronized (getTreeLock()) {
Component component = getComponent(0);
int viewPortWidth = getWidth(),
viewPortHeight = getHeight(),
componentWidth = component.getWidth(),
componentHeight = component.getHeight(),
componentX = component.getX(),
componentY = component.getY();
if (x < 0) {
x = 0;
} else if (x > 0 && x + viewPortWidth > componentWidth) {
x = componentWidth - viewPortWidth;
if (x < 0)
x = 0;
}
if (y < 0) {
y = 0;
} else if (y > 0 && y + viewPortHeight > componentHeight) {
y = componentHeight - viewPortHeight;
if (y < 0)
y = 0;
}
component.setLocation(x * -1, y * -1);
validate();
}
}
public Point getScrollPosition() {
synchronized (getTreeLock()) {
Point p = getComponent(0).getLocation();
p.x *= -1;
p.y *= -1;
return p;
}
}
}
Problem: The child component added to the ScrollFrame is visible outside the boundaries of the ScrollFrame.
And finally a SSCCE for some C&P testing, just click into the red area and move the mouse up and down:
import java.awt.*;
import java.awt.event.*;
public class TestScrollPane extends Frame implements MouseListener,
MouseMotionListener
{
/* starting point */
public static void main(String[] args)
{
TestScrollPane window = new TestScrollPane();
window.setSize(800, 480);
window.setVisible(true);
}
/*
* a translucent element to be placed above all other components to receive
* the MouseEvents
*/
public class GlassPane extends Component
{
public void paint(Graphics g)
{
g.setColor(Color.RED);
g.fillRect(0, 0, getWidth(), getHeight());
super.paint(g);
}
}
public class ScrollContainer extends Container
{
public ScrollContainer()
{
setLayout(null);
}
public void paint(Graphics g)
{
g.drawRect(0, 0, getWidth() - 1, getHeight() - 1);
super.paint(g);
}
public void printComponents(Graphics g)
{
Component c = getComponent(0);
Point p = c.getLocation();
Graphics cg = g.create();
try {
cg.clipRect(0, 0, getWidth(), getHeight());
cg.translate(p.x * -1, p.y * -1);
c.paintAll(cg);
} finally {
cg.dispose();
}
}
public void setScrollPosition(Point p)
{
setScrollPosition(p.x, p.y);
}
public void setScrollPosition(int x, int y)
{
synchronized (getTreeLock()) {
Component component = getComponent(0);
int viewPortWidth = getWidth(), viewPortHeight = getHeight(), componentWidth = component
.getWidth(), componentHeight = component.getHeight(), componentX = component
.getX(), componentY = component.getY();
if (x < 0) {
x = 0;
} else if (x > 0 && x + viewPortWidth > componentWidth) {
x = componentWidth - viewPortWidth;
if (x < 0)
x = 0;
}
if (y < 0) {
y = 0;
} else if (y > 0 && y + viewPortHeight > componentHeight) {
y = componentHeight - viewPortHeight;
if (y < 0)
y = 0;
}
component.setLocation(x * -1, y * -1);
}
}
public Point getScrollPosition()
{
synchronized (getTreeLock()) {
Point p = getComponent(0).getLocation();
p.x *= -1;
p.y *= -1;
return p;
}
}
}
private ScrollContainer scrollPane;
private Panel scrollPaneContainer;
private GlassPane glassPane;
private boolean scrolling = false;
private Point scrollingStartMouse;
private Point scrollingStartPane;
public TestScrollPane()
{
/* simple test window */
super("TestScrollPane");
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e)
{
e.getWindow().dispose();
System.exit(0);
}
});
setLayout(null);
/*
* the ScrollPane provides the ability to show only a limited of a much
* larger child element. Note that the ScrollPane is a container for
* only ONE element, but the child element may act as a container, e.g.
* a Panel
*/
scrollPane = new ScrollContainer();
scrollPane.addMouseListener(this);
scrollPane.setBounds(30, 50, 300, 300);
/*
* the element we place in the scrollpane, a panel with null layout to
* place the children
*/
scrollPaneContainer = new Panel();
scrollPaneContainer.setLayout(null);
/* add some random buttons for testing purposes */
for (int i = 0; i < 30; ++i) {
Button button = new Button("Click Me " + i);
button.addMouseListener(this);
button.setBounds(0, 40 * i, 100, 30);
scrollPaneContainer.add(button);
}
/*
* a translucent component on top of all elements placed inside the
* scrollPaneContainer to receive the MouseEvent's and properly scroll
* the ScrollPane or propagate the event
*/
glassPane = new GlassPane();
glassPane.setBounds(0, 0, 1, 1);
glassPane.addMouseListener(this);
glassPane.addMouseMotionListener(this);
/*
* we do need to add the GlassPane first to place it above all other
* elements
*/
// scrollPaneContainer.add(glassPane);
/*
* the GlassPane and the scrollPaneContainer need to have the same size.
* you have to set a size on the scrollPaneContainer else there won't be
* any scrolling ;)
*/
scrollPaneContainer.setSize(100, 1190);
scrollPaneContainer.setPreferredSize(new Dimension(100, 1190));
/* place the scrollPaneContainer (Panel) inside the ScrollPane */
scrollPane.add(scrollPaneContainer);
scrollPane.setBounds(30, 30, 150, 300);
glassPane.setBounds(30, 30, 30, 300);
Panel all = new Panel();
all.setLayout(null);
all.setBounds(30, 30, 400, 400);
all.add(glassPane);
all.add(scrollPane);
add(all);
}
/* MouseListener implementation */
public void mouseClicked(MouseEvent e)
{
}
public void mouseEntered(MouseEvent e)
{
}
public void mouseExited(MouseEvent e)
{
}
public void mouseReleased(MouseEvent e)
{
if (e.getSource().equals(glassPane)) {
scrolling = false;
}
}
public void mousePressed(MouseEvent e)
{
if (e.getSource().equals(glassPane)) {
scrolling = true;
scrollingStartMouse = e.getPoint();
scrollingStartPane = scrollPane.getScrollPosition();
}
}
/* MouseMotionListener implementation */
public void mouseDragged(MouseEvent e)
{
if (scrolling) {
Point currentPos = e.getPoint();
int mouseDeltaX = currentPos.x - scrollingStartMouse.x;
int mouseDeltaY = currentPos.y - scrollingStartMouse.y;
scrollPane.setScrollPosition(scrollingStartPane.x - mouseDeltaX,
scrollingStartPane.y - mouseDeltaY);
}
}
public void mouseMoved(MouseEvent e)
{
}
void log(String message)
{
System.out.println(message);
}
void log(String message, MouseEvent e)
{
log(e.getComponent().getClass().getName() + ": " + message);
}
}