Making a JPanel manually resizable

问题

I have a JFrame with BorderLayout as the layout manager.

In the south border, I have a JPanel, I want this JPanel's size to be adjustable by the user, i.e. the user can click on the edge of the border and drag it up to make it larger.

Is there any way you know that I can do this?

回答1:

In order to make panels in a frame individually resizable you need to add them onto a JSplitPane.

Instead of putting it in the South portion of the Frame, put the JSplitPane in the Center. The split pane will make the bottom panel in the split seem like it is in the South, and the top panel in the split will be in the Center of the frame.

Make sure you set the orientation of the two panels with setOrientation(JSplitPane.VERTICAL_SPLIT ).

Then, you can resize the panels that are in the pane.

回答2:

I think you meant to say JPanel. You can add a custom mouseListener and handle mouse clicks, drags and mouse releases and then resize the panel programmaticaly.

This will demonstrate this. Note that the jframe does NOT resize automatically with the JPanel. To make the effect more visible i painted the panel red and added a beveled border :

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;

import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.BevelBorder;

@SuppressWarnings("serial")
public class ResizablePanel extends JPanel {

    private boolean drag = false;
    private Point dragLocation  = new Point();

    public  ResizablePanel() {
        setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED));
        setPreferredSize(new Dimension(500, 500));
        final JFrame f = new JFrame("Test");
        addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent e) {
                drag = true;
                dragLocation = e.getPoint();
            }

            @Override
            public void mouseReleased(MouseEvent e) {
                drag = false;
            }
        });
        addMouseMotionListener(new MouseMotionAdapter() {
            @Override
            public void mouseDragged(MouseEvent e) {
                if (drag) {
                    if (dragLocation.getX()> getWidth()-10 && dragLocation.getY()>getHeight()-10) {
                        System.err.println("in");
                        setSize((int)(getWidth()+(e.getPoint().getX()-dragLocation.getX())),
                                (int)(getHeight()+(e.getPoint().getY()-dragLocation.getY())));
                        dragLocation = e.getPoint();
                    }
                }
            }
        });
        f.getContentPane().setLayout(new BorderLayout());
        f.getContentPane().add(this,BorderLayout.CENTER);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.pack();
        f.setVisible(true);
    }

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

    public void paintComponent(Graphics g) {
        g.setColor(Color.red);
        g.fillRect(0, 0, getWidth(), getHeight());
    }

}

回答3:

I made a class for that if you want to take a look. It isn`t finished yet.

package projetoSplitPainel;

import java.awt.Component;
import java.util.ArrayList;

import javax.swing.JSplitPane;

/**
 * This Components is based on the JSplitPane. JSplitPane is used to divide two
 * (and only two) Components. This class intend to manipulate the JSplitPane in
 * a way that can be placed as many Component as wanted.
 * 
 * @author Bode
 *
 */
public class JSplitPaneMultiTabs extends JSplitPane {
    private ArrayList<JSplitPane> ecanpsulationList = new ArrayList<JSplitPane>();
    private int numberOfComponents = 1;
    private int sizeOfDivision = 6;

    /**
     * Builds the Pane
     */
    public JSplitPaneMultiTabs() {
        super();
        this.setLeftComponent(null);
        this.setBorder(null);
        ecanpsulationList.add(this);
        setAllBorders(sizeOfDivision);
    }

    /**
     * 
     * @param comp - adds a Component to the Pane
     */
    public void addComponent(Component comp) {
        JSplitPane capsule = new JSplitPane();

        capsule.setRightComponent(null);
        capsule.setLeftComponent(comp);
        capsule.setDividerSize(sizeOfDivision);
        capsule.setBorder(null);

        ecanpsulationList.get(numberOfComponents - 1).setRightComponent(capsule);
        ecanpsulationList.add(capsule);
        numberOfComponents++;
        this.fixWeights();
    }

    /**
     * 
     * @param orientation
     *            JSplitPane.HORIZONTAL_SPLIT - sets the orientation of the
     *            Components to horizontal alignment
     * @param orientation
     *            JSplitPane.VERTICAL_SPLIT - sets the orientation of the
     *            Components to vertical alignment
     */
    public void setAlignment(int orientation) {
        for (int i = 0; i < numberOfComponents; i++) {
            ecanpsulationList.get(i).setOrientation(orientation);

        }
    }

    /**
     * 
     * @param newSize - resizes the borders of the all the Components of the Screen
     */
    public void setAllBorders(int newSize) {
        this.setDividerSize(newSize);
        for (int i = 0; i < numberOfComponents; i++) {
            ecanpsulationList.get(i).setDividerSize(newSize);
        }

    }

    /**
     * each Component added needs to be readapteded to the screen
     */
    private void fixWeights() {
        ecanpsulationList.get(0).setResizeWeight(1.0);
        for (int i = 1; i < numberOfComponents; i++) {
            double resize = (double) 1 / (double) (i + 1);
            ecanpsulationList.get(numberOfComponents - i - 1).setResizeWeight(
                    resize);
        }
        ecanpsulationList.get(numberOfComponents - 1).setResizeWeight(0.0);
    }

}