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Is there a way in Java to be able to click through a JFrame?

I'm trying to make an overlay for a HTML-based game running in a browser window and created an JFrame which is opaque. I'd like to be able to still play the game whilst having the overlay above the window. I tried some solutions that I've found but those didn't work for me.
I've thought of catching the click-event on my JFrame and "simulating" the click on the game window. But sadly I don't have an idea how thats possible.
My current code is using the JNA libarys to access the position and scale of the window (in my test code Task-Manager).
I'm fine with using another libary or something like that, if it's even possible.
Thats my code so far:
import com.sun.jna.platform.DesktopWindow;
import com.sun.jna.platform.WindowUtils;
import javax.swing.*;
import java.awt.*;
public class Test {
public static void main(String[] args) throws InterruptedException {
JFrame frame = new JFrame("title");
frame.setUndecorated(true);
frame.setBackground(new Color(255, 69, 0, 100));
frame.setAlwaysOnTop(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Rectangle rect = null;
while (true) {
for (DesktopWindow desktopWindow : WindowUtils.getAllWindows(true)) {
if (desktopWindow.getTitle().contains("Task-Manager")) {
rect = desktopWindow.getLocAndSize();
frame.setSize(rect.width - 16, rect.height - 8);
frame.setLocation(rect.x + 8, rect.y);
frame.setVisible(true);
Thread.sleep(10);
}
}
}
}
}

A JFrame is a heavyweight component. There is a window in the host OS GUI system to go with it. The host OS GUI directs mouse events to the window. Perhaps using a lightweight component for your overlay and then disabling mouse events on it would be a better solution.
Your idea of catching the click event and "simulating it" on you game window should be fairly easy. If your JFrame event processing code has a reference to your game engine, it can determine the relative position of the windows and tell your game engine the corresponding point at which it should act as if it received a click. I.e. just call the same method of your game engine for click events that it received normally and also for the simulated ones.
An ugly hack (there is noticeable flicker) would be to hide the window and send the click through with the Robot class... like this:
import java.awt.AWTException;
import java.awt.Color;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.Robot;
import java.awt.event.InputEvent;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.SwingUtilities;
public class ClickThrough extends Frame implements MouseListener, MouseMotionListener {
private final Robot robot;
private Color bgColor = new Color(0x80808080, true);
private Point dragPoint;
public ClickThrough() throws AWTException {
setAlwaysOnTop(true);
robot = new Robot();
}
public static void main(String[] args) throws AWTException {
ClickThrough w = new ClickThrough();
w.setUndecorated(true);
w.setSize(200, 100);
w.setOpacity(0.7f);
w.addMouseListener(w);
w.addMouseMotionListener(w);
w.setVisible(true);
}
#Override
public void paint(Graphics g) {
int w = getWidth();
int h = getHeight();
g.setColor(Color.GRAY);
g.fillRect(0, 0, w, 16);
g.setColor(bgColor);
g.fillRect(0, 16, w, h-16);
g.setColor(Color.BLACK);
g.drawString("Go ahead, click on me...", 20, 50);
}
private void makeHole(MouseEvent e) {
// Tried making a shape with a hole where the mouse was clicked,... didn't work (macOS).
//setShape(windowWithHoleShape);
setVisible(false);
}
private void repairHole(MouseEvent e) {
//setShape(windowShape);
setVisible(true);
}
#Override
public void mousePressed(MouseEvent e) {
Point p = e.getPoint();
// give it a draggable area at the top
if (p.y < 16) {
dragPoint = p;
return;
}
dragPoint = null;
SwingUtilities.convertPointToScreen(p,this);
makeHole(e);
robot.mouseMove(p.x, p.y);
robot.mousePress(InputEvent.getMaskForButton(e.getButton()));
repairHole(e);
}
#Override public void mouseReleased(MouseEvent e) { }
#Override public void mouseClicked(MouseEvent e) { }
#Override public void mouseEntered(MouseEvent e) { }
#Override public void mouseExited(MouseEvent e) { }
#Override
public void mouseDragged(MouseEvent e) {
if (dragPoint != null) {
Point p = e.getPoint();
SwingUtilities.convertPointToScreen(p, this);
p.translate(-dragPoint.x, -dragPoint.y);
setLocation(p);
}
}
#Override
public void mouseMoved(MouseEvent e) { }
}
I tried to see if I could cut a hole in the window by setting the window Shape, but at least on macOS the hole does not allow the mouse events through.
I should also point out that if you switch your GUI framework to JAvaFX, then you have the option of running your HTML-based game UI in a JavaFX WebView, so you can integrate your game and overlay into a single coherent application. You could specifically make your overlay "mouse transparent". IMO that would be a much better approach than hacking around with the mouse events.

I am not sure what is incorrect

I am creating a small Java Jpanel game in which I am supposed to have a rocket that moves up and down via arrows and fires via space.
The firing method should work like this: Space bar pressed, thing fires and moves across screen , and then when it hits a certain x, it disappears. Also, you can only fire once until the other bullet disappears.
I do not know what I am doing wrong. For one, as soon as my code starts you can see a bullet flying across the screen.
2nd, the bullet is not disappearing.
3rd, even though the other bullet is still visible, it allows me to fire again.
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.io.File;
import java.io.IOException;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.swing.*;
#SuppressWarnings("serial")
public class SpaceGame extends JPanel implements ActionListener{
Timer t = new Timer(2, this);
private ImageIcon rocket,asteroid,bullet;
private JLabel rocketlabel,ast1,ast2,ast3,bulletLabel;
public static int y=90,dy=0,bulletX=110,bulletY,i=0,canFire;
//public sound sound;
static boolean bulletFired=false;;
static JFrame f = new JFrame();
SpaceGame(){
this.setBackground(Color.black);
rocket = new ImageIcon(getClass().getResource("rocketFinal.png"));
rocketlabel= new JLabel(rocket);
this.add(rocketlabel);
asteroid = new ImageIcon(getClass().getResource("asteroid.png"));
ast1=new JLabel(asteroid);
ast2=new JLabel(asteroid);
ast3=new JLabel(asteroid);
bullet = new ImageIcon(getClass().getResource("bulletReal.png"));
bulletLabel = new JLabel(bullet);
canFire=1;
bulletLabel.setVisible(false);
this.add(ast1);this.add(ast2);this.add(ast3);this.add(bulletLabel);
f.addKeyListener(new controller());
this.setLayout(null);
this.setVisible(true);
}
public class controller implements KeyListener{
#Override
public void keyPressed(KeyEvent e) {
int keyCode = e.getKeyCode();
if(keyCode== KeyEvent.VK_UP) {
dy=-1;
}
if(keyCode== KeyEvent.VK_DOWN) {
dy=1;
}
if(keyCode== KeyEvent.VK_SPACE) {
if(canFire==0) {
System.out.println(String.valueOf(canFire));
bulletFired = true;
bulletY = y;
bulletX=110;
}canFire=1;
}
}
#Override
public void keyReleased(KeyEvent e) {
int key = e.getKeyCode();
switch(key) {
case KeyEvent.VK_UP: dy=0; break;
case KeyEvent.VK_DOWN: dy=0; break;
}
}
#Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
rocketlabel.setBounds(45,y,rocket.getIconWidth(),80);
fireBullet();
paintStars(g);
t.start();
}
public void paintStars(Graphics g) {
g.setColor(Color.yellow);
for(int i=0; i<5;i++) {
Random rand = new Random();
int o = rand.nextInt(500);
int p = rand.nextInt(300);
g.fillOval(o, p, 3, 3);
}
}
public void actionPerformed(ActionEvent e) {
if(y==-20) y=249;
if(y==250)y=-20;
y+=dy;
if(bulletFired=true) {
bulletX++;
if(bulletX==455)bulletFired=false;bulletLabel.setVisible(false);System.out.println(String.valueOf(bulletX)); canFire=0;
}
repaint();
}
public void fireBullet(){
if(bulletFired=true) {
bulletLabel.setVisible(true);
bulletLabel.setBounds(bulletX,bulletY+25,bullet.getIconHeight(),bullet.getIconWidth());
}
}
public static void main(String[] args) {
String filepath = "SpaceGameMusic.wav";
musicStuff musicPlayer = new musicStuff();
musicPlayer.playMusic(filepath);
SpaceGame t = new SpaceGame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.getContentPane().add(t);
f.setSize(500,335);
f.setVisible(true);
f.setResizable(false);
}
}

For one, as soon as my code starts you can see a bullet flying across the screen.
The paintComponent() method is for painting only. You can't control when Swing will determine a component needs to be repainted.
So, for example:
t.start();
should NOT be in the painting method. As soon as the frame is made visible the panel will be painted and the Timer will be started.
You application code should control when the Timer is started.
Other issues:
you should not be using static variables. The variable should simply be instances of your class.
the paintStars() method should not generate random locations. Again. a painting method should only paint the current state of the class. So if you want to change the location of the stars you should have a method like randomizeStars(). In this method you would update an ArrayList of Point objects. Each Point instance would represent the location of a star. Then the paintStars() method would simply iterate through the ArrayList and paint each star.
you should not be using a KeyListener. A KeyListener only works if a component has focus. You can't guarantee that your component will lose focus. Instead you should be using Key Bindings. Key bindings allow you to handle a KeyEvent even if the component doesn't have focus. See Motion Using the Keyboard for more information and a working example.
you can only fire once until the other bullet disappears
Your canFire variable should be a boolean variable so it only has true/false values. Again you have a method that sets the state. Your game logic will then check the state before firing the bullet again.
if(y==-20) y=249;
if(y==250)y=-20;
Don't hardcode values. The number should be based on the size of your panel. So you use methods like getWidth() and getHeight() to determine the current size of the panel.

The problem was quite simply that I had forgotten to use == in my if(boolean) statements.

Draw Line While Dragging The Mouse

What I'm trying to do is to draw circles and lines.
When the mouse is first pressed, I draw a small circle. Then, I need
to draw a line connecting the original point to the current
position of the mouse. When the mouse is released, the line
remains, but when I click again, everything disappears and I draw a
circle and a line all over again.
This is the code I have so far:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Canvas4 extends JComponent implements MouseListener, MouseMotionListener {
//constructor
public Canvas4() {
super();
addMouseListener(this);
addMouseMotionListener(this);
}
//some variables I may or may not use
int pressedX;
int pressedY;
int currentX;
int currentY;
int startDragX;
int startDragY;
int endDragX;
int endDragY;
int mouseReleasedX;
int mouseReleasedY;
//mouse events
public void mouseClicked(MouseEvent event) { }
public void mouseEntered(MouseEvent event) { }
public void mouseExited(MouseEvent event) { }
public void mousePressed(MouseEvent event) {
pressedX = event.getX();
pressedY = event.getY();
drawCircle();
startDragX = pressedX;
startDragY = pressedY;
}
public void mouseReleased(MouseEvent event) {
mouseReleasedX = event.getX();
mouseReleasedY = event.getY();
//repaint() here maybe???
}
//mouse motion events
public void mouseDragged(MouseEvent event) {
System.out.println("You dragged the mouse.");
endDragX = event.getX();
endDragY = event.getY();
drawLine();
}
public void mouseMoved(MouseEvent event) { }
//draw circle when mouse pressed
//this method works fine
public void drawCircle() {
Graphics g1 = this.getGraphics();
g1.setColor(Color.CYAN);
g1.fillOval(pressedX, pressedY, 10, 10);
}
//draw line when mouse dragged
//this is where I need help
public void drawLine() {
Graphics g2 = this.getGraphics();
g2.setColor(Color.RED);
g2.drawLine(pressedX, pressedY, mouseReleasedX, mouseReleasedY);
}
}
Then of course, there's a main method that creates the class object and adds it to a frame and whatnot.
My two specific questions are:
how do I draw a line as it's dragged? The code I have currently only draws a line to the last point of mouse release.
When do I repaint? If I repaint in the drawCircle() method, the circle blinks in and out instead of disappearing on the next click.

If you want to draw circles and lines then you need to keep an ArrayList of Shapes to draw. You would add an Ellipse2D.Double for the circle and a Line2D.Double for the line.
In the mousePressed event you add the Ellipse2D.Double object to the ArrayList, then you set up a temporary Line2D.Double object to contain your line information.
In the mouseDragged event you update Line2D.Double object with the new end point and then invoke repaint().
In the mouseReleased event you add the Line2D.Double object to the ArrayList and clear the variable referencing the Line2D.Double object.
Then in the paintComponent() method you add logic to:
iterate through the ArrayList to paint each Shape.
draw the Line2D.Double object when not null
Check out the Draw On Component example found in Custom Painting Approaches. This will show you the basic concept of this approach.
In the example the ArrayList only contains information on Rectangles so you will need to make it more generic to hold a Shape object. Both Ellispse2D.Double and Line2D.Double implement the Shape interface.

For drawing lines i have this.When you click mouse left you retain a point next click will retain another point making a line between them , and with mouse right you make the line between first point and last point (you can delete this "if (isClosed)" if you dont want)
Another thing : it's not a good precision because pointlocation return a double and drawline need an integer and the cast loses precision.
public class PolygonOnClick extends JPanel implements MouseListener, MouseMotionListener {
ArrayList<Point> points = new ArrayList<>();
static boolean isClosed = false;
PolygonOnClick() {
JFrame frame = new JFrame("Polygon ON CLICK");
frame.addMouseListener(this);
frame.setLocation(80, 50);
frame.setSize(1000, 700);
frame.add(this);
frame.setResizable(false);
frame.setVisible(true);
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
}
public void paintComponent(Graphics graphics) {
super.paintComponent(graphics);
graphics.drawString("Click stanga pentru a incepe a desena , click dreapta pentru a inchide poligonul ", 15, 15);
for (int i = 1; i < points.size(); i++) {
graphics.drawLine((int) points.get(i - 1).getX(), (int) points.get(i - 1).getY(), (int) points.get(i).getX(), (int) points.get(i).getY());
}
if (isClosed) {
graphics.drawLine((int) points.get(points.size() - 1).getX(), (int) points.get(points.size() - 1).getY(), (int) points.get(0).getX(), (int) points.get(0).getY());
}
}
#Override
public void mousePressed(MouseEvent e) {
if (!isClosed) {
if (e.getButton() == MouseEvent.BUTTON1) {
points.add(e.getPoint().getLocation());
}
}
if (e.getButton() == MouseEvent.BUTTON3) {
isClosed = true;
}
repaint();
}

How to find and write the final coordinates(x,y) of the all the components created in to a text file by clicking a write button

This program is about creating components and moving them randomly in JApplet and removing the components if required. Every mouse click creates a new component. After creating component we can click on it and drag it where ever we want. Double clicking on the component removes it. I was successful in creating, moving and removing components.
For example i created three components on the JApplet by clicking three times randomly at different places on the JApplet.Please click here to view created components I moved them randomly around the screen. Please click here to view JApplet after randomly moving them around screen My goal is to write the final coordinates(x,y) of their position on the screen for all components created in to a text file by clicking a write button. I have no idea about mouseReleased method. Please help me with this. Thank you. Your help is very much appreciated.
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import java.awt.geom.*;
import javax.swing.*;
This is my main class
public class MouseTest extends JApplet
{
public void init()
{
EventQueue.invokeLater(new Runnable() {
public void run()
{
MousePanel panel = new MousePanel();
add(panel);
}
});
}
public static void main(String[] args)
{
EventQueue.invokeLater(new mainThread());
}
}
class mainThread implements Runnable
{
public void run()
{
JPanel panel = new MousePanel();
JFrame frame = new JFrame("MouseTest");
frame.add(panel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(300,200);
frame.setVisible(true);
}
}
class MousePanel extends JPanel
{
public MousePanel()
{
squares = new ArrayList<Rectangle2D>();
current = null;
addMouseListener(new MouseHandler());
addMouseMotionListener(new MouseMotionHandler());
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
// draw all squares
for (Rectangle2D r : squares)
g2.draw(r);
}
/**
* Finds the first square containing a point.
* #param p a point
* #return the first square that contains p
*/
public Rectangle2D find(Point2D p)
{
for (Rectangle2D r : squares)
{
if (r.contains(p)) return r;
}
return null;
}
/**
* Adds a square to the collection.
* #param p the center of the square
*/
public void add(Point2D p)
{
double x = p.getX();
double y = p.getY();
current = new Rectangle2D.Double(x - SIDELENGTH / 2, y - SIDELENGTH / 2, SIDELENGTH,
SIDELENGTH);
squares.add(current);
repaint();
}
/**
* Removes a square from the collection.
* #param s the square to remove
*/
public void remove(Rectangle2D s)
{
if (s == null) return;
if (s == current) current = null;
squares.remove(s);
repaint();
}
private static final int SIDELENGTH = 10;
private ArrayList<Rectangle2D> squares;
private Rectangle2D current;
// the square containing the mouse cursor
these are methods for defining and dragging and removing the object
private class MouseHandler extends MouseAdapter
{
public void mousePressed(MouseEvent event)
{
// add a new square if the cursor isn't inside a square
current = find(event.getPoint());
if (current == null) add(event.getPoint());
}
public void mouseClicked(MouseEvent event)
{
// remove the current square if double clicked
current = find(event.getPoint());
if (current != null && event.getClickCount() >= 2) remove(current);
}
}
private class MouseMotionHandler implements MouseMotionListener
{
public void mouseMoved(MouseEvent event)
{
// set the mouse cursor to cross hairs if it is inside
// a rectangle
if (find(event.getPoint()) == null) setCursor(Cursor.getDefaultCursor());
else setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
}
public void mouseDragged(MouseEvent event)
{
if (current != null)
{
int x = event.getX();
int y = event.getY();
// drag the current rectangle to center it at (x, y)
current.setFrame(x - SIDELENGTH / 2, y - SIDELENGTH / 2, SIDELENGTH, SIDELENGTH);
repaint();
}
}
}
}

Why do you keep changing the requirement???? See original question: How to find final coordinates(x & y) of the objects position in JApplet and write them to a text file
First you wanted to write out the location of the moved component after the drag was finished.
Then you wanted to write out the location of "all" components after the drag was finished.
Now you want to write out the location of all the components after a "button" is clicked.
I have no idea about mouseReleased method.
What does this have to do with anything? That was the suggestion for your requirement in your last question. Since your requirement has changed it is no longer needed.
My goal is to write the final coordinates(x,y) of their position on the screen for all components created in to a text file by clicking a write button.
Then you need to add an ActionListener to the button. You have already been given a link to the Swing tutorial on How to Write an ActionListener so I guess the question is what code should be included in the ActionListener?
In you last question you stated:
I know how to get the location of a component
I know how to write data to a file
So the only remaining problem is how to get all the components on the panel? To do this you can use the Container.getComponents() method on your panel containing all the dragged components. The basic code for your ActionListener would be something like:
for (Component component: panel.getComponents())
{
Point location = component.getLocation();
// write the location to the file
}
I'll let you add the code for opening/closing the file.

Trouble using mouse to click on JComponent

Hey Everyone I am trying to create a somewhat dynamic program in which you can add shapes or images to a JPanel and then select and move the shapes after you have added them. The problem is that when I click on the specific JComponent nothing happens. In fact clicking on any of the components I have created to test the project returns false for all JComponents. However it seems that if I click inside the bounds of my JComponent in the top left corner I will get returned true for all JComponents, ie click in the area bounded by (0,0,50,68).
The idea is that if I click one of the JComponents it will set that specific JComponent to be movable however I cannot get past the part of actually selecting a specific JComponent.
Here is a basic SSCE that I built to recreate the problem:
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
public class SSCE1 extends JPanel {
private ArrayList<Shape> shapeList = new ArrayList<Shape>();
SSCE1() {
setLayout(null);
/* Debug Stuff */
System.out.println("Debug:");
/* Add The First Shape To The List */
shapeList.add(0, new Shape(100, 100));
add(shapeList.get(0));
shapeList.add(1, new Shape(610, 0));
add(shapeList.get(1));
shapeList.add(2, new Shape(500, 900));
add(shapeList.get(2));
addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
for (Shape shape : shapeList) {
if (shape.contains(e.getPoint())) {
System.out.println("Hello");
} else {
System.out.println("Goodbye");
}
}
}
});
}
}
class Shape extends JComponent {
int xLocation, yLocation, xBounds1, yBounds1;
Shape(int xLocation, int yLocation) {
this.xLocation = xLocation;
this.yLocation = yLocation;
this.xBounds1 = 50;
this.yBounds1 = 68;
setBounds(xLocation, yLocation, xBounds1, yBounds1);
setLocation(xLocation, yLocation);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.blue);
g.fillRect(0, 0, 100, 100);
}
}
class Run {
public static void main(String[] args) {
JFrame main = new JFrame();
SSCE1 p1 = new SSCE1();
main.setSize(new Dimension(1000, 1000));
main.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
main.setLocation(new Point(0, 0));
main.setVisible(true);
main.add(p1);
}
}

Basically, the problem is, Shape is expecting any mouse coordinates you pass it to be defined within the context of the Shape. That is, the top, left corner of Shape is always 0x0
The mouse point you are processing is within the context of the parent container, therefore, unless Shape is positioned at 0x0 within the parent container, Shape will never contain the mouse point.
You need to translate the mouse point to the context of the Shape before checking it
For example...
addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
for (Shape shape : shapeList) {
Point shapePoint = SwingUtilities.convertPoint(e.getComponent(), e.getPoint(), shape);
if (shape.contains(shapePoint) {
System.out.println("Hello");
} else {
System.out.println("Goodbye");
}
}
}
});

Use next mouseListener it works:
addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
for (Shape shape : shapeList) {
Point convertPoint = SwingUtilities.convertPoint(SSCE1.this, e.getPoint(), shape);
if (shape.contains(convertPoint)) {
System.out.println("Hello");
} else {
System.out.println("Goodbye");
}
}
}
});
The reason is next according docs in contains method the point's x and y coordinates are defined to be relative to the coordinate system of this component. because of that works for (0,0,50,68). All what you need convert point from JPanel to Shape with help of SwingUtilities.convertPoint(...)