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Getting graphics object to draw with buffer strategy

I've made a JFrame with a canvas on it and I want to draw on that canvas. At a later date the canvas will be updating many times a second so I am using a buffer strategy for this. Here is the code:
package mainPackage;
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;
import javax.swing.JFrame;
public class TickPainter {
//just some presets for a window.
public static JFrame makeWindow(String title, int width, int height) {
JFrame mainWindow = new JFrame();
mainWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainWindow.setSize(width, height);
mainWindow.setVisible(true);
mainWindow.setLocationRelativeTo(null);
mainWindow.setTitle(title);
return mainWindow;
}
public static void main(String[] args) {
JFrame mainWindow = makeWindow("Practice", 800, 600);
Canvas mainCanvas = new Canvas();
mainWindow.add(mainCanvas);
mainCanvas.setSize(mainWindow.getWidth(), mainWindow.getHeight());
mainCanvas.setBackground(Color.white);
mainCanvas.createBufferStrategy(3);
BufferStrategy bufferStrat = mainCanvas.getBufferStrategy();
Graphics g = bufferStrat.getDrawGraphics();
g.setColor(Color.black);
g.fillRect(250, 250, 250, 250);
g.dispose();
bufferStrat.show();
}
}
The program does not draw the black rectangle as intended, I feel like I've missed something really obvious here and I just can't see it. At the moment the program just makes a blank white canvas. I feel like part of the issue is that the buffer is just passing the frame with the rectangle faster than I can see, but there is no frame to load after that so I don't know why it's doing this.

A BufferStrategy has a number of initial requirements which must be meet before it can be rendered to. Also, because of the nature of how it works, you might need to repeat a paint phases a number of times before it's actually accepted by the hardware layer.
I recommend going through the JavaDocs and tutorial, they provide invaluable examples into how you're suppose to use a BufferStrategy
The following example uses a Canvas as the base component and sets up a rendering loop within a custom Thread. It's very basic, but shows the basic concepts you'd need to implement...
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;
import java.util.concurrent.atomic.AtomicBoolean;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
TestCanvas canvas = new TestCanvas();
JFrame frame = new JFrame();
frame.add(canvas);
frame.setTitle("Test");
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
canvas.start();
}
});
}
public class TestCanvas extends Canvas {
private Thread thread;
private AtomicBoolean keepRendering = new AtomicBoolean(true);
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
public void stop() {
if (thread != null) {
keepRendering.set(false);
try {
thread.join();
} catch (InterruptedException ex) {
ex.printStackTrace();
}
}
}
public void start() {
if (thread != null) {
stop();
}
keepRendering.set(true);
thread = new Thread(new Runnable() {
#Override
public void run() {
createBufferStrategy(3);
do {
BufferStrategy bs = getBufferStrategy();
while (bs == null) {
System.out.println("get buffer");
bs = getBufferStrategy();
}
do {
// The following loop ensures that the contents of the drawing buffer
// are consistent in case the underlying surface was recreated
do {
// Get a new graphics context every time through the loop
// to make sure the strategy is validated
System.out.println("draw");
Graphics graphics = bs.getDrawGraphics();
// Render to graphics
// ...
graphics.setColor(Color.RED);
graphics.fillRect(0, 0, 100, 100);
// Dispose the graphics
graphics.dispose();
// Repeat the rendering if the drawing buffer contents
// were restored
} while (bs.contentsRestored());
System.out.println("show");
// Display the buffer
bs.show();
// Repeat the rendering if the drawing buffer was lost
} while (bs.contentsLost());
System.out.println("done");
try {
Thread.sleep(100);
} catch (InterruptedException ex) {
ex.printStackTrace();
}
} while (keepRendering.get());
}
});
thread.start();
}
}
}
Remember, the point of BufferStrategy is to give you full control over the painting process, so it works outside the normal painting process generally implemented by AWT and Swing
"At a later date the canvas will be updating many times a second so I am using a buffer strategy for this" - Before going down the "direct to hardware" solution, I'd consider using a Swing Timer and the normal painting process to see how well it works

How to overwrite a BufferedImage drawn to JPanel outside PaintComponent() with getGraphics()

I am working on a simple 2D game. Each tick, I want to check an effects queue that will start a thread for a certain effect(fading transitions, audio fade in and out, etc). For example, pressing "Play" on the menu screen will add a "FadeOut" message to this queue, which will be processed and start a thread to draw a black rectangle with an increasing alpha value over my GamePanel.
I'm overriding paintComponent() and sending my Graphics object to my GameStateManager, which passes along the Graphics object to the current states' draw(). I currently don't have an effects state (which maybe I should) to route the paintComponent() graphics object to, but I do pass my gamepanel to my effects thread, where I can use getGraphics() to draw on it. Drawing a rectangle to the GamePanel directly just causes flickering, as the gameloop is still rendering the game.
I found I can draw a black rectangle with increasing alpha to a BufferedImage, set the composite to AlphaComposite.Src (which causes the new draw to replace the old) then draw the BufferedImage over the game panel. The problem is the BufferedImages drawn to the game panel don't get overridden each draw, so the fade out happens really quickly because these black BufferedImages of various alphas just stack on each other.
I wrote this short program to test composite settings and see what is getting overridden. All drawing is done in the draw(), which would be my run() in the effects thread.
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class ScratchPad extends JPanel implements Runnable
{
private JFrame oFrame = null;
private Thread oGameThread = null;
private Graphics2D oPanelGraphics = null;
private Graphics2D oImageGraphics = null;
private BufferedImage oImage = null;
public static void main(String args[]) throws Exception
{
new ScratchPad();
}
public ScratchPad()
{
createFrame();
initPanel();
addAndShowComponents();
oGameThread = new Thread(this, "Game_Loop");
oGameThread.start();
}
private void addAndShowComponents()
{
oFrame.add(this);
oFrame.setVisible(true);
}
private void initPanel()
{
this.setOpaque(true);
this.setBackground(Color.cyan);
}
private void createFrame()
{
oFrame = new JFrame("Fade");
oFrame.setSize(700, 300);
oFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
oFrame.setLocationRelativeTo(null);
}
public void run()
{
oImage = new BufferedImage(200, 200, BufferedImage.TYPE_INT_ARGB);
while(true)
{
try
{
draw();
Thread.sleep(100);
}
catch(InterruptedException e)
{
}
}
}
private void draw()
{
oPanelGraphics = (Graphics2D)this.getGraphics();
oImageGraphics = oImage.createGraphics();
oImageGraphics.setComposite(AlphaComposite.Src);
oImageGraphics.setColor(new Color(0,0,0,90));
oImageGraphics.fillRect(0, 0, oImage.getWidth(), oImage.getHeight());
oPanelGraphics.drawImage(oImage, 10, 10, null);
oImageGraphics.setColor(new Color(0,0,0,60));
oImageGraphics.fillRect(0, 0, oImage.getWidth(), oImage.getHeight());
oPanelGraphics.drawImage(oImage, 220, 10, null);
oImageGraphics.setColor(new Color(0,0,0,30));
oImageGraphics.fillRect(0, 0, oImage.getWidth(), oImage.getHeight());
oPanelGraphics.drawImage(oImage, 430, 10, null);
// Drawing this image over location of first image, should overwrite first
// after setting composite to 'Src'
oPanelGraphics.setComposite(AlphaComposite.Src);
oImageGraphics.setColor(new Color(0,0,0,10));
oImageGraphics.fillRect(0, 0, oImage.getWidth(), oImage.getHeight());
oPanelGraphics.drawImage(oImage, 10, 10, null);
oImageGraphics.dispose();
oPanelGraphics.dispose();
}
} // end class
What's interesting is setting the composite on 'oPanelGraphics' causes any alpha to the BufferedImage to go away, resulting in a fully opaque black image being drawn over the image that was previously there. Even setting the color to something other than black doesn't have an effect.
What's also interesting is setting the composite for the BufferedImage to:
oImageGraphics.setComposite(AlphaComposite.SrcIn);
causes nothing to be shown. The Oracle documentation on compositing graphics in Java2D states this for 'SrcIn':
"If pixels in the source and the destination overlap, only the source pixels in the overlapping area are rendered."
So, I would expect this to have the same behavior I get with AlphaComposite.Src.
Maybe someone out there can shed some light on whats going on with these composites, and how I could achieve my desired effect.

There are a number issues with what you "seem" to be trying to do
Don't call getGraphics on a component. This can return null and only returns a snapshot of what was last painted during a Swing paint cycle. Anything you paint to it will be erased on the next paint cycle
You should also never dispose of Graphics context you did not create, doing so could effect other components that are painted by Swing
Painting is compounding, this means that painting to the same Graphics context (or BufferedImage) over and over again, will continue to apply those changes over the top of what was previously painted
You also don't seem to have a concept of how animation should work. Instead of trying to paint your fade effect in a single pass, where the results can't be applied to the screen, you need to apply a phase on each cycle and allow that to be updated to the screen before the next pass runs.
The following is a really basic example of what I'm talking about. It takes a "base" image (this could be the "base" state of the game, but I've used a static image) and the paints effects over the top.
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private Engine engine;
private Image frame;
public TestPane() {
engine = new Engine();
engine.setEngineListener(new EngineListener() {
#Override
public void updateDidOccur(Image img) {
frame = img;
repaint();
}
});
engine.start();
addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
engine.addEffect(new FadeOutEffect(Color.BLACK));
}
});
}
#Override
public Dimension getPreferredSize() {
return engine.getSize();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (frame != null) {
Graphics2D g2d = (Graphics2D) g.create();
g2d.drawImage(frame, 0, 0, null);
g2d.dispose();
}
}
}
public interface EngineListener {
public void updateDidOccur(Image img);
}
public class Engine {
// This is the "base" image, without effects
private BufferedImage base;
private Timer timer;
private EngineListener listener;
private List<Effect> effects = new ArrayList<Effect>(25);
public Engine() {
try {
base = ImageIO.read(new File("/Volumes/Big Fat Extension/Dropbox/MegaTokyo/megatokyo_omnibus_1_3_cover_by_fredrin-d4oupef 50%.jpg"));
} catch (IOException ex) {
ex.printStackTrace();
}
timer = new Timer(10, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
int width = base.getWidth();
int height = base.getHeight();
BufferedImage frame = new BufferedImage(width, height, base.getType());
Graphics2D g2d = frame.createGraphics();
g2d.drawImage(base, 0, 0, null);
Iterator<Effect> it = effects.iterator();
while (it.hasNext()) {
Effect effect = it.next();
if (!effect.applyEffect(g2d, width, height)) {
it.remove();
}
}
g2d.dispose();
if (listener != null) {
listener.updateDidOccur(frame);
}
}
});
}
public void start() {
timer.start();
}
public void stop() {
timer.stop();
}
public void addEffect(Effect effect) {
effects.add(effect);
}
public void setEngineListener(EngineListener listener) {
this.listener = listener;
}
public Dimension getSize() {
return base == null ? new Dimension(200, 200) : new Dimension(base.getWidth(), base.getHeight());
}
}
public interface Effect {
public boolean applyEffect(Graphics2D context, int width, int height);
}
public class FadeOutEffect implements Effect {
private int tick = 0;
private Color fadeToColor;
public FadeOutEffect(Color fadeToColor) {
this.fadeToColor = fadeToColor;
}
#Override
public boolean applyEffect(Graphics2D context, int width, int height) {
tick++;
float alpha = (float) tick / 100.0f;
if (alpha > 1.0) {
return false;
}
Graphics2D g2d = (Graphics2D) context.create();
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha));
g2d.setColor(fadeToColor);
g2d.fillRect(0, 0, width, height);
g2d.dispose();
return true;
}
}
}
Remember, every effect or change should be applied within the same "main loop", this means you shouldn't have multiple threads, in fact, since Swing is not thread safe, you should avoid having any additional threads if possible. This example make use of a Swing Timer to act as the "main loop" because the ActionListers actionPerformed method is called within the context of the EDT, making it safe to update the UI from. It also provides a simple synchronisation method, as the UI can't be painted while the actionPerformed method is been called

Set JButton to the location of another JButton

I'm trying to move a JButton to the location of another one but the button I want to move moves to a wrong point. My idea is that this happens because I use multiple JPanels. I tried: getLocationOnScreen, getBounds and getLocation, but none of them worked, how to solve it? When an user selects a card on the table or from a player by clicking this card the the target is set, the sender is set by clicking a card from the top panel. playerCardSpotTargetand playerCardSpotSender are both of type Card. When I try to move the for example eight of diamonds this card moves to a point behind the eight and nine of clubs.
Code:
This events belong to the blue cards on the table and the cards for the players(I have to change the name of the event, I know).
private void PlayerOneMouseClicked(java.awt.event.MouseEvent evt){
playerCardSpotTarget=(Card)evt.getSource();
if(playerCardSpotTarget.isBorderPainted()){
playerCardSpotTarget.setBorderPainted(false);
}
else{
playerCardSpotTarget.setBorderPainted(true);
}
}
This event belongs to the cards in the top panel.
private void MouseClicked(java.awt.event.MouseEvent evt) {
playerCardSpotSender=(Card)evt.getSource();
System.out.println(playerCardSpotSender.suit+" "+playerCardSpotSender.kind);
if (playerCardSpotTarget != null && playerCardSpotTarget.isBorderPainted()) {
playerCardSpotSender.setLocation(playerCardSpotTarget.getLocation());
System.out.println(playerCardSpotTarget.getLocationOnScreen());
System.out.println(playerCardSpotSender.getLocationOnScreen());
}
}
Layout for the center panel in the JFrame (BorderLayout.CENTER)
JPanel centerPanelNorth;
JPanel centerPanelCenter;
JPanel centerPanelEast;
JPanel centerPanelSouth;
JPanel centerPanelWest;
JLabel tablePicture;
JPanel centerPanel;
centerPanel=new JPanel(new BorderLayout());
tablePicture = new JLabel(new ImageIcon(this.getClass().getResource(Constants.POKERTABLE_ICON)));
centerPanelNorth=new JPanel();
centerPanelEast=new JPanel();
centerPanelSouth=new JPanel();
centerPanelWest=new JPanel();
centerPanelCenter=new JPanel();
centerPanel.add(centerPanelCenter,BorderLayout.CENTER);
centerPanelCenter.add(tablePicture);
//add
tablePicture.add(boardCard1);
tablePicture.add(boardCard2);
tablePicture.add(boardCard3);
tablePicture.setLayout(new GridBagLayout());
//PLAYER NORTH
centerPanel.add(centerPanelNorth,BorderLayout.NORTH);
centerPanelNorth.add(playerOneCardOne);
centerPanelNorth.add(playerOneCardTwo);
//PLAYER EAST
centerPanel.add(centerPanelEast,BorderLayout.EAST);
centerPanelEast.setLayout(new BoxLayout(centerPanelEast,BoxLayout.X_AXIS));
centerPanelEast.add(playerTwoCardOne);
centerPanelEast.add(playerTwoCardTwo);
//PLAYER SOUTH
centerPanel.add(centerPanelSouth,BorderLayout.SOUTH);
centerPanelSouth.add(playerThreeCardOne);
centerPanelSouth.add(playerThreeCardTwo);
//PLAYER WEST
centerPanel.add(centerPanelWest,BorderLayout.WEST);
centerPanelWest.setLayout(new BoxLayout(centerPanelWest,BoxLayout.X_AXIS));
centerPanelWest.add(playerFourCardOne);
centerPanelWest.add(playerFourCardTwo);
Card.java
public class Card extends JButton{
int suit;
int kind;
boolean known;
String iconPath;
Integer boardPosition;
}

Animating the button movement isn't actually the hardest problem, the hardest problem is trying to move the data about in away in which you can manage it and how to connect the source component with the target...
To start with, you need a means by which you can move a component across container boundaries. While there are probably a few ways to do this, the simplest is to probably use the glass pane of the frame
public class AnimationPane extends JPanel {
public AnimationPane() {
setOpaque(false);
setLayout(null);
}
}
This is nothing special, it's just a JPanel which is transparent and has no layout manager, normally, not recommended, but in the case, we're going to take control..
Now, we need some way to animate the movement...
public enum Animator {
INSTANCE;
private List<IAnimatable> animatables;
private Timer timer;
private Animator() {
animatables = new ArrayList<>(25);
timer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
IAnimatable[] anins = animatables.toArray(new IAnimatable[animatables.size()]);
for (IAnimatable animatable : anins) {
animatable.update();
}
}
});
timer.start();
}
public void addAnimatable(IAnimatable animatable) {
animatables.add(animatable);
}
public void removeAnimatable(IAnimatable animatable) {
animatables.remove(animatable);
}
}
public interface IAnimatable {
public void update();
}
public interface IMoveAnimatable extends IAnimatable{
public JComponent getSourceComponent();
public IImportable getImportable();
}
So the Animator is the core "engine", it's basically a Swing Timer which simply calls update on any IAnimatables it might be managing. The intention with this approach is you can have a number of animations running, but it won't degrade the system (greatly) as you only have a single update/timer point.
Now, normally I'd just use something like the Timing Framework or the Trident Framework or even the Universal Tween Engine
The IAnimatable interfaces just define the basic contracts that provide functionality for the animation.
We need to define some kind of contract the defines objects which can take part in the animation process and receive information, or the "target"
public interface IImportable {
public JComponent getView();
public void importValue(String value);
}
public abstract class AbstractImportable extends JPanel implements IImportable {
#Override
public JComponent getView() {
return this;
}
}
Now it occurs to me that we could tap into the pre-existing Transferable API, which would allow you to also implement drag-n-drop (and even copy/cut and paste), this would be used to define a lookup mechanism where you match a given data type with potential targets based on the DataFlavor ... but I'll leave you to investigate how that might work...
The core mechanism basically removes the source component from it's current container, adds it to the AnimationPane, moves the source component across the AnimationPane and then imports the data into the target...
The problem is, you need to translate the location of component from it's current context to the AnimationPane.
A components location is relative to it's parents context. It's relatively easy to do with SwingUtilities.convertPoint(Component, Point, Component)
We calculate the origin point of the source component and the target point, relative to the AnimationPane. We then, on each call to update, calculate the progress of the animation. Instead of using a "delta" movement, we calculate the different between the time we started and a predefined duration (1 second in this case), this generally produces a more flexible animation
public class DefaultAnimatable implements IMoveAnimatable {
public static final double PLAY_TIME = 1000d;
private Long startTime;
private JComponent sourceComponent;
private IImportable importable;
private JComponent animationSurface;
private Point originPoint, destinationPoint;
private String value;
public DefaultAnimatable(JComponent animationSurface, JComponent sourceComponent, IImportable importable, String value) {
this.sourceComponent = sourceComponent;
this.importable = importable;
this.animationSurface = animationSurface;
this.value = value;
}
public String getValue() {
return value;
}
public JComponent getAnimationSurface() {
return animationSurface;
}
#Override
public JComponent getSourceComponent() {
return sourceComponent;
}
#Override
public IImportable getImportable() {
return importable;
}
#Override
public void update() {
if (startTime == null) {
System.out.println("Start");
IImportable importable = getImportable();
JComponent target = importable.getView();
originPoint = SwingUtilities.convertPoint(getSourceComponent().getParent(), getSourceComponent().getLocation(), getAnimationSurface());
destinationPoint = SwingUtilities.convertPoint(target.getParent(), target.getLocation(), getAnimationSurface());
destinationPoint.x = destinationPoint.x + ((target.getWidth() - getSourceComponent().getWidth()) / 2);
destinationPoint.y = destinationPoint.y + ((target.getHeight() - getSourceComponent().getHeight()) / 2);
Container parent = getSourceComponent().getParent();
getAnimationSurface().add(getSourceComponent());
getSourceComponent().setLocation(originPoint);
parent.invalidate();
parent.validate();
parent.repaint();
startTime = System.currentTimeMillis();
}
long duration = System.currentTimeMillis() - startTime;
double progress = Math.min(duration / PLAY_TIME, 1d);
Point location = new Point();
location.x = progress(originPoint.x, destinationPoint.x, progress);
location.y = progress(originPoint.y, destinationPoint.y, progress);
getSourceComponent().setLocation(location);
getAnimationSurface().repaint();
if (progress == 1d) {
getAnimationSurface().remove(getSourceComponent());
Animator.INSTANCE.removeAnimatable(this);
animationCompleted();
}
}
public int progress(int startValue, int endValue, double fraction) {
int value = 0;
int distance = endValue - startValue;
value = (int) Math.round((double) distance * fraction);
value += startValue;
return value;
}
protected void animationCompleted() {
getImportable().importValue(getValue());
}
}
Okay, now this produces a linear animation, which is pretty boring, now if you have plenty of time, you could create an easement like this or just use one of the animation frameworks...
Now, we need to put it together...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.LineBorder;
public class AnimationTest {
public static void main(String[] args) {
new AnimationTest();
}
public AnimationTest() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
AnimationPane animationPane = new AnimationPane();
LeftPane leftPane = new LeftPane(animationPane);
RightPane rightPane = new RightPane();
leftPane.setImportabale(rightPane);
rightPane.setImportabale(leftPane);
JFrame frame = new JFrame("Testing");
frame.setLayout(new GridLayout(1, 2));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(leftPane, BorderLayout.WEST);
frame.add(rightPane, BorderLayout.WEST);
frame.setGlassPane(animationPane);
animationPane.setVisible(true);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class RightPane extends AbstractImportable {
private IImportable source;
private JButton imported;
private String importedValue;
public RightPane() {
setLayout(new GridBagLayout());
setBorder(new LineBorder(Color.DARK_GRAY));
}
public void setImportabale(IImportable source) {
this.source = source;
}
#Override
public void importValue(String value) {
if (imported != null) {
// May re-animate the movement back...
remove(imported);
}
importedValue = value;
imported = new JButton(">> " + value + "<<");
add(imported);
revalidate();
repaint();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
public class LeftPane extends AbstractImportable {
private IImportable importable;
public LeftPane(AnimationPane animationPane) {
setLayout(new GridBagLayout());
JButton btn = new JButton("Lefty");
btn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
DefaultAnimatable animatable = new DefaultAnimatable(animationPane, btn, importable, "Lefty");
Animator.INSTANCE.addAnimatable(animatable);
}
});
add(btn);
setBorder(new LineBorder(Color.DARK_GRAY));
}
public void setImportabale(IImportable target) {
this.importable = target;
}
#Override
public void importValue(String value) {
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
}

Maybe use mousePressed(),when you move the card,you press it until the target.And in the process, you get the information about JButton.getLocation() by the event,and than you need to solve the collision problem between two cards.So it's good!Of course, this is my advice ,you should have better idea!

Java: Repaint in Swing Not Working

I am learning java swing and am having trouble with the following program. It creates a small frame with a quit button at top. The objective is to display coordinates wherever the mouse is clicked. When I click the mouse 2 unwanted things are happening:
the quit button is overridden by the mouse clicks and it no longer responds (instead of responding to event and quitting, it displays coordinates on top of the quit button).
when I click at a new location, the coordinates from the old location persist.
I used removeAll() and revalidate() before doing repaint() based on this discussion but that has not helped. This code is taken from here and the code to says to research online documentation for why this is happening.
Any pointers?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.Color;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.BorderLayout;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JLabel;
public class QuitCoordinateTest {
public static void main(String[] args){
GUI gui = new GUI();
}
}
class MyFrame extends JFrame implements ActionListener{
int clickX;
int clickY;
public void paint(Graphics g){
g.drawString("" + clickX + ", " + clickY, clickX, clickY);
}
public void actionPerformed(ActionEvent e){
System.exit(0);
}
}
//=======================================================//
class GUI extends MyFrame {
JButton quitButton = new JButton("Quit");
public GUI(){
MyFrame displayWindow = new MyFrame();
displayWindow.setTitle("Title");
/*
JPanel buttonPanel = new JPanel();
buttonPanel.add(quitButton);
displayWindow.getContentPane().add(buttonPanel,BorderLayout.NORTH);
JPanel textPanel = new JPanel();
*/
displayWindow.getContentPane().add(quitButton,BorderLayout.NORTH);
quitButton.addActionListener(displayWindow);
displayWindow.setSize(201,201);
displayWindow.setVisible(true);
// displayWindow.pack();
displayWindow.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
displayWindow.addMouseListener(new MouseProc(displayWindow));
}//end constructor
}//end class GUI definition
//=======================================================//
//This listener class monitors for mouse presses and
// displays the coordinates of the mouse pointer when the
// mouse is pressed on the source object.
class MouseProc extends MouseAdapter{
MyFrame refToWin;
MouseProc(MyFrame inWin){
refToWin = inWin;
}
//Override the mousePressed method to determine and
// display the coordinates when the mouse is pressed.
public void mousePressed(MouseEvent e){
refToWin.removeAll();
refToWin.clickX = e.getX();
refToWin.clickY = e.getY();
//Force the JFrame object to be repainted in order to
// display the coordinate information.
refToWin.removeAll();
refToWin.validate();
refToWin.repaint();
}
}

repaint() is working fine.
Avoid drawing directly on the JFrame.
Instead draw in the protected void paintComponent(Graphics g) method override of a JPanel that is then displayed in your JFrame.
Be sure to call the super's paintComponent(g) method inside of your paintComponent override -- this will erase the old images and is the reason for one of your problems.
Use reasonable comments in your code. Too many comments and too much text distracts and makes understanding your code harder, not easier.
Calling removeAll() on your JFrame will do just that -- remove all components including your button. Why are you calling this? Are you sure that you want to call this method?
A minor nitpick -- you'll want to avoid directly setting the fields of another class, such as your clickX and clickY fields. Instead, make them private, and only allow outside classes to modify them through public methods. While it may not matter much for this small program, it will matter greatly when you start scaling up your programming and create large programs with complex interactions. The key to success here will be to limit and control all communication between classes to avoid hard to detect side effects.
For example, something like...
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
String str = String.format("[%d, %d]", clickX, clickY);
g.drawString(str, clickX, clickY);
}
public int getClickX() {
return clickX;
}
public void setClickX(int clickX) {
this.clickX = clickX;
}
public int getClickY() {
return clickY;
}
public void setClickY(int clickY) {
this.clickY = clickY;
}
For example
import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.*;
#SuppressWarnings("serial")
public class DetectClicks extends JPanel {
private static final int PREF_W = 800;
private static final int PREF_H = 650;
private int clickX;
private int clickY;
public DetectClicks() {
MyMouseListener mouseAdapter = new MyMouseListener(this);
addMouseListener(mouseAdapter);
addMouseMotionListener(mouseAdapter); // to allow dragging!
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
String str = String.format("[%d, %d]", clickX, clickY);
g.drawString(str, clickX, clickY);
}
public int getClickX() {
return clickX;
}
public void setClickX(int clickX) {
this.clickX = clickX;
}
public int getClickY() {
return clickY;
}
public void setClickY(int clickY) {
this.clickY = clickY;
}
private static void createAndShowGui() {
DetectClicks mainPanel = new DetectClicks();
JFrame frame = new JFrame("DetectClicks");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class MyMouseListener extends MouseAdapter {
private DetectClicks detectClicks;
public MyMouseListener(DetectClicks detectClicks) {
this.detectClicks = detectClicks;
}
#Override
public void mousePressed(MouseEvent evt) {
showPoint(evt);
}
#Override
public void mouseDragged(MouseEvent evt) {
showPoint(evt);
}
private void showPoint(MouseEvent evt) {
detectClicks.setClickX(evt.getX());
detectClicks.setClickY(evt.getY());
detectClicks.repaint();
}
}

Your event is getting consumed by the handler that prints the coordinates, you need to redispatch the event so that the button can see it. You can do it like this, inside the coordinate display event handler:
Component c = e.getComponent();
c.getParent().dispatchEvent( e );
Also, I'd be tempted to use the glass pane of the frame, and put a JLabel on it with the co-ordinates rather than messing with the paint method.

you don't have to use any of repaint(),invalidate() etc.
i highly recommend to use
SwingUtilities.invokeLater(new Runnable() {
public void run() {
//TODO udpdate UI compontents, layouts etc.
}
});
this guarantees that UI components update on real time. Because we don't know when the system update UI hierarchy so we can't force it. This allow system to determine by it's self.

Manual Positioning of Image in JFrame

I am trying to create a JFrame that displays an image from a file path onto a particular position on the JFrame. At a later time (when a button is clicked), I want the image to move positions, say, 50 pixles to the left. If a layout manager is necessary, I want to use the null layout, as this is a project for myself and I am not quite ready to learn how to write my own layout manager.
So far, I have managed to display a BufferedImage in a frame, but I do not know how to specify its position.
Is using a BufferedImage even the correct approach? What is the best way to go about doing this?
Update: I tried to follow your suggestion of using mouselistener and it resulted in this:
class ImgComponent extends JComponent implements ChangeListener, MouseListener {
MovableImage mi;
public ImgComponent(MovableImage mi) {
this.mi = mi;
mi.addListener(this);
mi.addListener1(this);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(mi.i, mi.getX(), mi.getY(), null);
}
#Override
public void stateChanged(ChangeEvent e) {
repaint();
}
#Override
public void mouseClicked(MouseEvent e) {
mi.setPos(100, 100);
System.out.println("yay");
}
}
But unfortinely, the mouseClicked event never triggers. I just want that damn image to move, lol.

Here's a complete example that uses the model/view/controller pattern. (Just dump all snippets after each other in a single .java file.)
import java.awt.*;
import java.awt.event.ActionEvent;
import java.util.*;
import java.util.List;
import javax.swing.*;
import javax.swing.event.*;
// A class encapsulating an image and a x-coordinate (a "model")
class MovableImage {
Image i = new ImageIcon("duke.png").getImage();
private int x = 0;
// Observers that are interested in movements.
List<ChangeListener> listeners = new ArrayList<ChangeListener>();
public void addListener(ChangeListener cl) {
listeners.add(cl);
}
public int getX() {
return x;
}
public void incrementX() {
x += 10;
// Notify those interested.
for (ChangeListener cl : listeners)
cl.stateChanged(null);
}
}
// A graphical component displaying the model.
// Object of this class are interested in movement because when the image moves,
// this component needs to be repainted.
class ImgComponent extends JComponent implements ChangeListener {
// The movable image to present.
MovableImage mi;
public ImgComponent(MovableImage mi) {
this.mi = mi;
mi.addListener(this);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(mi.i, mi.getX(), 10, null);
}
// This method is called from MovableImage when the position changes.
#Override
public void stateChanged(ChangeEvent e) {
repaint();
}
}
// Main class.
public class FrameTestBase extends JFrame {
public static void main(String args[]) {
// Create the "model".
final MovableImage mi = new MovableImage();
FrameTestBase t = new FrameTestBase();
t.setLayout(new BorderLayout());
// Add a component presenting the model.
t.add(new ImgComponent(mi), BorderLayout.CENTER);
// Create a button which increments x when clicked on.
t.add(new JButton(new AbstractAction("Move right") {
#Override
public void actionPerformed(ActionEvent e) {
mi.incrementX();
}
}), BorderLayout.SOUTH);
// Show it.
t.setDefaultCloseOperation(EXIT_ON_CLOSE);
t.setSize(400, 400);
t.setVisible(true);
}
}
Regarding your edit:
You need to add the mouse listener as well. In the constructor:
public ImgComponent(MovableImage mi) {
this.mi = mi;
mi.addListener(this);
mi.addListener1(this);
}
add the following line at the bottom:
addMouseListener(this);