overlapping JPanels in the GUI

问题

I am using BorderLayout in my application. I have a main panel to which I add two JPanels at the center. I want one of them to be transparent. My code is :

 mainPanel = new JPanel();
 mainPanel.setLayout(new BorderLayout());
 mainPanel.add(getGraphPaneScrollPane(), BorderLayout.CENTER);
 mainPanel.add(getSituationPanel(), BorderLayout.CENTER);

Code for these two functions is :

public JScrollPane getGraphPaneScrollPane() {
    if (graphPaneScrollPane == null) {
        graphPaneScrollPane = new JScrollPane();
        graphPaneScrollPane.setViewportView(getGraphEditorPane());
    }
    return graphPaneScrollPane;
}
private JScrollPane getSituationPanel(){
    if(situationPanel == null){
        logs.debug("Initializing Situation Panel");

        situationPanel = new JScrollPane();

        situationLabel = new JLabel("");
        situationLabel.setVerticalTextPosition(JLabel.BOTTOM);
        situationLabel.setHorizontalTextPosition(JLabel.CENTER);
        situationLabel.setVerticalAlignment(JLabel.TOP);
        situationLabel.setHorizontalAlignment(JLabel.CENTER);
        situationLabel.setBorder(BorderFactory.createTitledBorder(""));
        situationLabel.setBackground(Color.WHITE);
        situationLabel.setOpaque(true);
        situationLabel.setVerticalAlignment(SwingConstants.TOP);

        situationPanel.setViewportView(situationLabel); 

    } 

    return situationPanel;
}

Now I want situationPanel to be transparent and getGraphPaneScrollPane to be above that in the GUI, because getGraphPaneScrollPane is the canvas, which I use to draw nodes.

回答1:

I want situationPanel to be transparent and getGraphPaneScrollPane to be above that in the GUI,

The panel that is on top is the panel that needs to be transparent. If the panel on top is opaque then you will never see the panel under the top panel.

So making changes to the layout is the last thing I want.

Well that is what you are going to need to do. You can't just add two panels to one panel and expect it to work the way you want it to. Most Swing layout managers are designed to lay out components in two dimensions, not on top of one another.

Your current code is:

mainPanel.setLayout(new BorderLayout());
mainPanel.add(getGraphPaneScrollPane(), BorderLayout.CENTER);
mainPanel.add(getSituationPanel(), BorderLayout.CENTER);

You could try using the OverlayLayout, it is designed to lay out panels on top of on another. The code should be something like:

JPanel overlay = new JPanel();
overlay.setLayout( new OverlayLayout(overlay) );
overlay.add(getSituationPanel(), BorderLayout.CENTER); // add transparent panel first
overlay.add(getGraphPaneScrollPane(), BorderLayout.CENTER);
mainPanel.setLayout(new BorderLayout()); 
mainPanel.add(overlay);

来源：https://stackoverflow.com/questions/16555080/overlapping-jpanels-in-the-gui

标签

java

swing

user-interface

netbeans

jpanel