using SpringLayout to create a forms-type layout : SpringLayout « Swing « Java Tutorial






using SpringLayout to create a forms-type layout
/*
 *
 * Copyright (c) 1998 Sun Microsystems, Inc. All Rights Reserved.
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 * provided that i) this copyright notice and license appear on all copies of
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 * which is disparaging to Sun.
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 */


/*
 * A 1.4 application that uses SpringLayout to create a forms-type layout.
 * Other files required: SpringUtilities.java.
 */

import javax.swing.*;
import java.awt.*;

public class SpringForm {
    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        String[] labels = {"Name: ", "Fax: ", "Email: ", "Address: "};
        int numPairs = labels.length;

        //Create and populate the panel.
        JPanel p = new JPanel(new SpringLayout());
        for (int i = 0; i < numPairs; i++) {
            JLabel l = new JLabel(labels[i], JLabel.TRAILING);
            p.add(l);
            JTextField textField = new JTextField(10);
            l.setLabelFor(textField);
            p.add(textField);
        }

        //Lay out the panel.
        SpringUtilities.makeCompactGrid(p,
                                        numPairs, 2, //rows, cols
                                        6, 6,        //initX, initY
                                        6, 6);       //xPad, yPad

        //Create and set up the window.
        JFrame frame = new JFrame("SpringForm");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Set up the content pane.
        p.setOpaque(true);  //content panes must be opaque
        frame.setContentPane(p);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}


class SpringUtilities {
  /**
   * A debugging utility that prints to stdout the component's minimum,
   * preferred, and maximum sizes.
   */
  public static void printSizes(Component c) {
    System.out.println("minimumSize = " + c.getMinimumSize());
    System.out.println("preferredSize = " + c.getPreferredSize());
    System.out.println("maximumSize = " + c.getMaximumSize());
  }

  /**
   * Aligns the first <code>rows</code> * <code>cols</code> components of
   * <code>parent</code> in a grid. Each component is as big as the maximum
   * preferred width and height of the components. The parent is made just big
   * enough to fit them all.
   * 
   * @param rows
   *          number of rows
   * @param cols
   *          number of columns
   * @param initialX
   *          x location to start the grid at
   * @param initialY
   *          y location to start the grid at
   * @param xPad
   *          x padding between cells
   * @param yPad
   *          y padding between cells
   */
  public static void makeGrid(Container parent, int rows, int cols, int initialX, int initialY,
      int xPad, int yPad) {
    SpringLayout layout;
    try {
      layout = (SpringLayout) parent.getLayout();
    } catch (ClassCastException exc) {
      System.err.println("The first argument to makeGrid must use SpringLayout.");
      return;
    }

    Spring xPadSpring = Spring.constant(xPad);
    Spring yPadSpring = Spring.constant(yPad);
    Spring initialXSpring = Spring.constant(initialX);
    Spring initialYSpring = Spring.constant(initialY);
    int max = rows * cols;

    // Calculate Springs that are the max of the width/height so that all
    // cells have the same size.
    Spring maxWidthSpring = layout.getConstraints(parent.getComponent(0)).getWidth();
    Spring maxHeightSpring = layout.getConstraints(parent.getComponent(0)).getWidth();
    for (int i = 1; i < max; i++) {
      SpringLayout.Constraints cons = layout.getConstraints(parent.getComponent(i));

      maxWidthSpring = Spring.max(maxWidthSpring, cons.getWidth());
      maxHeightSpring = Spring.max(maxHeightSpring, cons.getHeight());
    }

    // Apply the new width/height Spring. This forces all the
    // components to have the same size.
    for (int i = 0; i < max; i++) {
      SpringLayout.Constraints cons = layout.getConstraints(parent.getComponent(i));

      cons.setWidth(maxWidthSpring);
      cons.setHeight(maxHeightSpring);
    }

    // Then adjust the x/y constraints of all the cells so that they
    // are aligned in a grid.
    SpringLayout.Constraints lastCons = null;
    SpringLayout.Constraints lastRowCons = null;
    for (int i = 0; i < max; i++) {
      SpringLayout.Constraints cons = layout.getConstraints(parent.getComponent(i));
      if (i % cols == 0) { // start of new row
        lastRowCons = lastCons;
        cons.setX(initialXSpring);
      } else { // x position depends on previous component
        cons.setX(Spring.sum(lastCons.getConstraint(SpringLayout.EAST), xPadSpring));
      }

      if (i / cols == 0) { // first row
        cons.setY(initialYSpring);
      } else { // y position depends on previous row
        cons.setY(Spring.sum(lastRowCons.getConstraint(SpringLayout.SOUTH), yPadSpring));
      }
      lastCons = cons;
    }

    // Set the parent's size.
    SpringLayout.Constraints pCons = layout.getConstraints(parent);
    pCons.setConstraint(SpringLayout.SOUTH, Spring.sum(Spring.constant(yPad), lastCons
        .getConstraint(SpringLayout.SOUTH)));
    pCons.setConstraint(SpringLayout.EAST, Spring.sum(Spring.constant(xPad), lastCons
        .getConstraint(SpringLayout.EAST)));
  }

  /* Used by makeCompactGrid. */
  private static SpringLayout.Constraints getConstraintsForCell(int row, int col, Container parent,
      int cols) {
    SpringLayout layout = (SpringLayout) parent.getLayout();
    Component c = parent.getComponent(row * cols + col);
    return layout.getConstraints(c);
  }

  /**
   * Aligns the first <code>rows</code> * <code>cols</code> components of
   * <code>parent</code> in a grid. Each component in a column is as wide as
   * the maximum preferred width of the components in that column; height is
   * similarly determined for each row. The parent is made just big enough to
   * fit them all.
   * 
   * @param rows
   *          number of rows
   * @param cols
   *          number of columns
   * @param initialX
   *          x location to start the grid at
   * @param initialY
   *          y location to start the grid at
   * @param xPad
   *          x padding between cells
   * @param yPad
   *          y padding between cells
   */
  public static void makeCompactGrid(Container parent, int rows, int cols, int initialX,
      int initialY, int xPad, int yPad) {
    SpringLayout layout;
    try {
      layout = (SpringLayout) parent.getLayout();
    } catch (ClassCastException exc) {
      System.err.println("The first argument to makeCompactGrid must use SpringLayout.");
      return;
    }

    // Align all cells in each column and make them the same width.
    Spring x = Spring.constant(initialX);
    for (int c = 0; c < cols; c++) {
      Spring width = Spring.constant(0);
      for (int r = 0; r < rows; r++) {
        width = Spring.max(width, getConstraintsForCell(r, c, parent, cols).getWidth());
      }
      for (int r = 0; r < rows; r++) {
        SpringLayout.Constraints constraints = getConstraintsForCell(r, c, parent, cols);
        constraints.setX(x);
        constraints.setWidth(width);
      }
      x = Spring.sum(x, Spring.sum(width, Spring.constant(xPad)));
    }

    // Align all cells in each row and make them the same height.
    Spring y = Spring.constant(initialY);
    for (int r = 0; r < rows; r++) {
      Spring height = Spring.constant(0);
      for (int c = 0; c < cols; c++) {
        height = Spring.max(height, getConstraintsForCell(r, c, parent, cols).getHeight());
      }
      for (int c = 0; c < cols; c++) {
        SpringLayout.Constraints constraints = getConstraintsForCell(r, c, parent, cols);
        constraints.setY(y);
        constraints.setHeight(height);
      }
      y = Spring.sum(y, Spring.sum(height, Spring.constant(yPad)));
    }

    // Set the parent's size.
    SpringLayout.Constraints pCons = layout.getConstraints(parent);
    pCons.setConstraint(SpringLayout.SOUTH, y);
    pCons.setConstraint(SpringLayout.EAST, x);
  }
}








14.92.SpringLayout
14.92.1.SpringLayoutSpringLayout
14.92.2.How to Use SpringLayoutHow to Use SpringLayout
14.92.3.Specifying locations for each componentSpecifying locations for each component
14.92.4.Define the right (east) and bottom (south) edges of the containerDefine the right (east) and bottom (south) edges of the container
14.92.5.Using SpringLayout to lay out a gridUsing SpringLayout to lay out a grid
14.92.6.Using SpringLayout to create a compact gridUsing SpringLayout to create a compact grid
14.92.7.using SpringLayout to create a forms-type layoutusing SpringLayout to create a forms-type layout
14.92.8.Using SpringLayout to create a single rowUsing SpringLayout to create a single row
14.92.9.Using a SpringLayout ManagerUsing a SpringLayout Manager
14.92.10.Springs and Component SizeSprings and Component Size
14.92.11.SpringLayout Utilities