CODEWITHSUNDEEP
javamouseeventmouseover
ack
ack

Reputation: 1251

How can I highlight JPanels on mouse hover?

I have 16 Jpanels that I want to be highlighted when I hover my mouse over them. I created the JPanels anonymously and then added them to a parent, and added a MouseListener to each of them. I then added a MouseListener to the parent. The thing is, now it just highlights the parent. How can I fix this?

NOTE: Sometimes the JFrame doesn't show anything - you just have to keep running it until it does (usually takes 2-3 tries). Comment if it still isn't working after >5 tries.

HighlightJPanels (creates the JFrame, the container, and the children, and adds the MouseListeners)

public class HighlightJPanels extends JFrame{
    private static final long serialVersionUID = 7163215339973706671L;
    private static final Dimension containerSize = new Dimension(640, 477);
    private JLayeredPane layeredPane;
    static JPanel container;

    public HighlightJPanels() {
        super("Highlight Test");
        setSize(640, 477);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setResizable(false);
        setVisible(true);

        layeredPane = new JLayeredPane();
        layeredPane.setPreferredSize(containerSize);
        getContentPane().add(layeredPane);

        createContainer();

        layeredPane.add(container, JLayeredPane.DEFAULT_LAYER);

        createChildren(4, 4);

        container.addMouseMotionListener(new HighlightJPanelsContainerMouseListener());
    }

    private void createChildren(int columns, int rows){
        for (int i = 0; i < columns; i++){
            for (int j = 0; j < rows; j++){
                JPanel child = new JPanel(new BorderLayout());
                child.setBackground(Color.LIGHT_GRAY);
                child.addMouseListener(new HighlightJPanelsMouseListeners());
                container.add(child);
            }
        }
    }

    private JPanel createContainer(){
        container = new JPanel();
        container.setLayout(createLayout(4, 4, 1, 1));
        container.setPreferredSize(containerSize);
        container.setBounds(0, 0, containerSize.width, containerSize.height);
        return container;
    }

    private GridLayout createLayout(int rows, int columns, int hGap, int vGap){
        GridLayout layout = new GridLayout(rows, columns);
        layout.setHgap(hGap);
        layout.setVgap(vGap);
        return layout;
    }

    public static void main(String[] args) {
        new HighlightJPanels();
    }
}

HighlightJPanelsChildMouseListeners (creates the MouseListeners that will be added to the children)

public class HighlightJPanelsChildMouseListeners implements MouseListener{
    private Border grayBorder = BorderFactory.createLineBorder(Color.DARK_GRAY);

    public HighlightJPanelsChildMouseListeners() {
    }

    public void mouseEntered(MouseEvent e) {
        Component comp = HighlightJPanels.container.findComponentAt(HighlightJPanelsContainerMouseListener.eX, HighlightJPanelsContainerMouseListener.eY);
        JPanel parent = (JPanel) comp;
        parent.setBorder(grayBorder);
        parent.revalidate();
    }

    public void mouseExited(MouseEvent e) {
        Component comp = HighlightJPanels.container.findComponentAt(HighlightJPanelsContainerMouseListener.eX, HighlightJPanelsContainerMouseListener.eY);
        JPanel parent = (JPanel) comp;
        parent.setBorder(null);
        parent.revalidate();
    }

    public void mousePressed(MouseEvent e){}
    public void mouseReleased(MouseEvent e){}
    public void mouseClicked(MouseEvent e) {}
}

HighlightJPanelsContainerMouseListener (creates the MouseListener that will be added to the container)

public class HighlightJPanelsContainerMouseListener implements MouseMotionListener{
    static int eX;
    static int eY;

    public void mouseDragged(MouseEvent e) {}

    public void mouseMoved(MouseEvent e) {
        eX = e.getX();
        eY = e.getY();
    }
}

Upvotes: 0

Views: 4145

Answers (1)

resueman
resueman

Reputation: 10613

The problem is being caused by how you find the JPanel to highlight, on this line:

Component comp = HighlightJPanels.container.findComponentAt(HighlightJPanelsContainerMouseListener.eX, HighlightJPanelsContainerMouseListener.eY);

Fortunately, there's already a function that will do what you want. You can just use getSource() on the event, and it will tell you which panel to highlight. So change your function to this:

public void mouseEntered(MouseEvent e) {
    JPanel parent = (JPanel)e.getSource();
    parent.setBorder(grayBorder);
    parent.revalidate();
}

and do the same thing with mouseExited, and you'll see it highlight the correct panel. And this will remove the need for HighlightJPanelsContainerMouseListener.

Upvotes: 5

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