How to know coordinates of java frame?

问题

I am trying to develop a very basic game and it involves mouse. So what i am trying to do is getting coordinates of mouse to write a integer. I searched internet and find this.

mouse_x=MouseInfo.getPointerInfo().getLocation().getX();
mouse_y=MouseInfo.getPointerInfo().getLocation().getY();

It partially worked and gave me coordinates of mouse on desktop. But what i need is coordinates of mouse on frame. So if only i knew the coordinates of frame's starting (0,0) point (not the window's. the white area without toolbars.) I could calculate mouse's coordinates.
Thanks in advance.
Or if thats not possible i could use how to develop it in fullscreen.
And i need to know location of mouse always. It should refresh position when i run it in a never ending while loop.

回答1:

I just use e.getPoint() which returns the point of the mouse clicked. You could either have your Frame implement MouseListener of you can register a MouseListener to the frame if it is not the main GUI component.

public class MyFrame extends JFrame implements MouseListener {

    @Override
    public void mouseClicked(MouseEvent e) {
        Point p = e.getPoint();
        int x = (int) p.getX();
        int y = (int) p.getY();

        // do something withe the x and y points
    }
}

If you do the above, you also need to override the other MouseListener methods. Though you don't need to implement any action for them

@Override
public void mouseExited(MouseEvent e) {
}

@Override
public void mouseEntered(MouseEvent e) {
}

@Override
public void mousePressed(MouseEvent e) {
}

@Override
public void mouseReleased(MouseEvent e) {
}

If your GUI class didn't extend JFrame, then you can just register the listener to the Frame, in which case you only need to use the MouseAdapter, which allows you to just implement 0 or more action method (i.e. just mouseClicked)

frame.addMouseListener(new MouseAdapter() {
    void mouseClicked(MouseEvent e) {
       Point p = e.getPoint();
       int x = (int) p.getX();
       int y = (int) p.getY();

       // do somthing withe the x and y points
   }
});

Edit for MouseMotionListener

"I want to know location of mouse always not just when clicked."

If you wan't to know the location of the mouse at any given time, you should implement MouseMotionListener and override the mouseDragged and mouseMoved

public class MyFrame extends JFrame implements MouseMotionListener {

    ....

    public void mouseMoved(MouseEvent e){
        Point p = e.getPoint();
        int x = (int) p.getX();
        int y = (int) p.getY();

        // do something withe the x and y points
    }

    public void mouseDragged(MouseEvent e){

    }
}

The mouseMoved will fire an event every time the mouse is moved, and the mouseDragged will fire an event whenever the mouse is dragged

回答2:

You need to add a MouseListener to your JFrame and then you can just get the relative coordinates with MouseEvent.getPoint

frame.addMouseListener(new MouseAdapter() {
    void mouseClicked(MouseEvent e) {
        System.out.println(e.getPoint());
    }
});

回答3:

If you, for some obscure reason, need the coordinates in a situation when mouse events are not available (in which case, take a look at the other answers), you can use SwingUtilities.convertPointFromScreen() to convert the coordinates from MouseInfo to the coordinate system of a Component.

来源：https://stackoverflow.com/questions/20813518/how-to-know-coordinates-of-java-frame

标签

java

swing

jframe

mouseevent

point