SpringLayoutUtils.java

/*
 * Created on Aug 25, 2004
 */
package edu.stanford.hci.r3.util.layout;

import java.awt.Component;
import java.awt.Container;

import javax.swing.Spring;
import javax.swing.SpringLayout;

public class SpringLayoutUtils {
        /* 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);
        }

        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 each column
                for (int c = 0; c < cols; c++) {
                        Spring width = Spring.constant(0);

                        // find the widest cell (go down the rows) and create a spring out of it
                        for (int r = 0; r < rows; r++) {

                                // get the larger of the two widths
                                width = Spring.max(width, getConstraintsForCell(r, c, parent, cols).getWidth());
                        }

                        // apply the spring to each cell
                        for (int r = 0; r < rows; r++) {
                                final 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++) {
                                final 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);
        }

        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)));
        }

        public static void printSizes(Component c) {
                System.out.println("minimumSize = " + c.getMinimumSize());
                System.out.println("preferredSize = " + c.getPreferredSize());
                System.out.println("maximumSize = " + c.getMaximumSize());
        }
}

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