Swing GridBagLayout锚点位于窗口外部

Question

I'm playing around with GridBagLayout in Swing and I noticed the anchor point on the left is correct, but the one at the top is at -60 pixels. I know the exact size of the window, 960x640. I'm making two columns: one with two panels on the left (grid heights are 2 for both) and another with three panels on the right (grid heights are 1, 2 and 1). This is the code:

    gameFrame.setLayout(new GridBagLayout());

    GridBagConstraints constraints = new GridBagConstraints();
    constraints.anchor = GridBagConstraints.NORTHWEST;

    InfoPanel infoPanel = new InfoPanel();
    infoPanel.setPreferredSize(new Dimension(320, 320));
    infoPanel.setMinimumSize(new Dimension(320, 320));
    infoPanel.setMaximumSize(new Dimension(320, 320));
    infoPanel.setBackground(Color.BLUE);
    constraints.gridx = 0;
    constraints.gridy = 0;
    //constraints.gridwidth = 1;
    constraints.gridheight = 2;

    gameFrame.add(infoPanel, constraints);


    InfoPanel infoPanel2 = new InfoPanel();
    infoPanel2.setPreferredSize(new Dimension(320, 320));
    infoPanel2.setMinimumSize(new Dimension(320, 320));
    infoPanel2.setMaximumSize(new Dimension(320, 320));
    infoPanel2.setBackground(Color.RED);
    constraints.gridx = 0;
    constraints.gridy = 2;
    //constraints.gridwidth = 1;
    constraints.gridheight = 2;

    gameFrame.add(infoPanel2, constraints);


    InfoPanel infoPanel3 = new InfoPanel();
    infoPanel3.setPreferredSize(new Dimension(640, 200));
    infoPanel3.setMinimumSize(new Dimension(640, 200));
    infoPanel3.setMaximumSize(new Dimension(640, 200));
    infoPanel3.setBackground(Color.GREEN);
    constraints.gridx = 1;
    constraints.gridy = 0;
    //constraints.gridwidth = 1;
    constraints.gridheight = 1;

    gameFrame.add(infoPanel3, constraints);


    InfoPanel infoPanel4 = new InfoPanel();
    infoPanel4.setPreferredSize(new Dimension(640, 240));
    infoPanel4.setMinimumSize(new Dimension(640, 240));
    infoPanel4.setMaximumSize(new Dimension(640, 240));
    infoPanel4.setBackground(Color.YELLOW);
    constraints.gridx = 1;
    constraints.gridy = 1;
    //constraints.gridwidth = 1;
    constraints.gridheight = 2;

    gameFrame.add(infoPanel4, constraints);


    InfoPanel infoPanel5 = new InfoPanel();
    infoPanel5.setPreferredSize(new Dimension(640, 200));
    infoPanel5.setMinimumSize(new Dimension(640, 200));
    infoPanel5.setMaximumSize(new Dimension(640, 200));
    infoPanel5.setBackground(Color.PINK);
    constraints.gridx = 1;
    constraints.gridy = 3;
    //constraints.gridwidth = 1;
    //constraints.gridheight = 1;

    gameFrame.add(infoPanel5, constraints);

    gameFrame.pack();
    gameFrame.setLocationRelativeTo(null);

I appreciate that the code isn't clean, it's not what it will look like, I just wanted to make sure I can get the layout I need working first.

Here is the result:

Because the layout starts placing objects at -60 pixels off the top, there's a 60 pixel gap at the bottom.

Has anyone come across something like this? It baffles me.

Answer 1

I think this is one of those moments that that layout manager has thrown it's arms up in the air and said, "Well, that's the best I can do with what you've given me" .

If you change constraints.gridheight = 2; to constraints.gridheight = 3; for infoPanel2 it'll work.

I "think" it has a combination of things to do with the total height of the second column when compared to the first (without consideration to the row spanning). Allowing the second row to expand beyond the the two rows seems to allow it to collapse the extra space.

For what it's worth. I would have probably put the two columns into individual panels and laid out those two panels instead, but that's just me...