SpringUtilities


1   package com.nightlabs.util;
2   
3   import javax.swing.*;
4   import javax.swing.SpringLayout  ;
5   import java.awt.*;
6   
7   /**
8    * A 1.4 file that provides utility methods for
9    * creating form- or grid-style layouts with SpringLayout.
10   * These utilities are used by several programs, such as
11   * SpringBox and SpringCompactGrid.
12   */
13  public class SpringUtilities {
14      /**
15       * A debugging utility that prints to stdout the component's
16       * minimum, preferred, and maximum sizes.
17       */
18      public static void printSizes(Component c) {
19          System.out.println("minimumSize = " + c.getMinimumSize());
20          System.out.println("preferredSize = " + c.getPreferredSize());
21          System.out.println("maximumSize = " + c.getMaximumSize());
22      }
23  
24      /**
25       * Aligns the first <code>rows</code> * <code>cols</code>
26       * components of <code>parent</code> in
27       * a grid. Each component is as big as the maximum
28       * preferred width and height of the components.
29       * The parent is made just big enough to fit them all.
30       *
31       * @param rows number of rows
32       * @param cols number of columns
33       * @param initialX x location to start the grid at
34       * @param initialY y location to start the grid at
35       * @param xPad x padding between cells
36       * @param yPad y padding between cells
37       */
38      public static void makeGrid(Container parent,
39                                  int rows, int cols,
40                                  int initialX, int initialY,
41                                  int xPad, int yPad) {
42          SpringLayout   layout;
43          try {
44              layout = (SpringLayout  )parent.getLayout();
45          } catch (ClassCastException   exc) {
46              System.err.println("The first argument to makeGrid must use SpringLayout.");
47              return;
48          }
49  
50          Spring xPadSpring = Spring.constant(xPad);
51          Spring yPadSpring = Spring.constant(yPad);
52          Spring initialXSpring = Spring.constant(initialX);
53          Spring initialYSpring = Spring.constant(initialY);
54          int max = rows * cols;
55  
56          //Calculate Springs that are the max of the width/height so that all
57          //cells have the same size.
58          Spring maxWidthSpring = layout.getConstraints(parent.getComponent(0)).
59                                      getWidth();
60          Spring maxHeightSpring = layout.getConstraints(parent.getComponent(0)).
61                                      getWidth();
62          for (int i = 1; i < max; i++) {
63              SpringLayout.Constraints   cons = layout.getConstraints(
64                                              parent.getComponent(i));
65  
66              maxWidthSpring = Spring.max(maxWidthSpring, cons.getWidth());
67              maxHeightSpring = Spring.max(maxHeightSpring, cons.getHeight());
68          }
69  
70          //Apply the new width/height Spring. This forces all the
71          //components to have the same size.
72          for (int i = 0; i < max; i++) {
73              SpringLayout.Constraints   cons = layout.getConstraints(
74                                              parent.getComponent(i));
75  
76              cons.setWidth(maxWidthSpring);
77              cons.setHeight(maxHeightSpring);
78          }
79  
80          //Then adjust the x/y constraints of all the cells so that they
81          //are aligned in a grid.
82          SpringLayout.Constraints   lastCons = null;
83          SpringLayout.Constraints   lastRowCons = null;
84          for (int i = 0; i < max; i++) {
85              SpringLayout.Constraints   cons = layout.getConstraints(
86                                                   parent.getComponent(i));
87              if (i % cols == 0) { //start of new row
88                  lastRowCons = lastCons;
89                  cons.setX(initialXSpring);
90              } else { //x position depends on previous component
91                  cons.setX(Spring.sum(lastCons.getConstraint(SpringLayout.EAST),
92                                       xPadSpring));
93              }
94  
95              if (i / cols == 0) { //first row
96                  cons.setY(initialYSpring);
97              } else { //y position depends on previous row
98                  cons.setY(Spring.sum(lastRowCons.getConstraint(SpringLayout.SOUTH),
99                                       yPadSpring));
100             }
101             lastCons = cons;
102         }
103 
104         //Set the parent's size.
105         SpringLayout.Constraints   pCons = layout.getConstraints(parent);
106         pCons.setConstraint(SpringLayout.SOUTH,
107                             Spring.sum(
108                                 Spring.constant(yPad),
109                                 lastCons.getConstraint(SpringLayout.SOUTH)));
110         pCons.setConstraint(SpringLayout.EAST,
111                             Spring.sum(
112                                 Spring.constant(xPad),
113                                 lastCons.getConstraint(SpringLayout.EAST)));
114     }
115 
116     /* Used by makeCompactGrid. */
117     private static SpringLayout.Constraints   getConstraintsForCell(
118                                                 int row, int col,
119                                                 Container parent,
120                                                 int cols) {
121         SpringLayout   layout = (SpringLayout  ) parent.getLayout();
122         Component c = parent.getComponent(row * cols + col);
123         return layout.getConstraints(c);
124     }
125 
126     /**
127      * Aligns the first <code>rows</code> * <code>cols</code>
128      * components of <code>parent</code> in
129      * a grid. Each component in a column is as wide as the maximum
130      * preferred width of the components in that column;
131      * height is similarly determined for each row.
132      * The parent is made just big enough to fit them all.
133      *
134      * @param rows number of rows
135      * @param cols number of columns
136      * @param initialX x location to start the grid at
137      * @param initialY y location to start the grid at
138      * @param xPad x padding between cells
139      * @param yPad y padding between cells
140      */
141     public static void makeCompactGrid(Container parent,
142                                        int rows, int cols,
143                                        int initialX, int initialY,
144                                        int xPad, int yPad) {
145         SpringLayout   layout;
146         try {
147             layout = (SpringLayout  )parent.getLayout();
148         } catch (ClassCastException   exc) {
149             System.err.println("The first argument to makeCompactGrid must use SpringLayout.");
150             return;
151         }
152 
153         //Align all cells in each column and make them the same width.
154         Spring x = Spring.constant(initialX);
155         for (int c = 0; c < cols; c++) {
156             Spring width = Spring.constant(0);
157             for (int r = 0; r < rows; r++) {
158                 width = Spring.max(width,
159                                    getConstraintsForCell(r, c, parent, cols).
160                                        getWidth());
161             }
162             for (int r = 0; r < rows; r++) {
163                 SpringLayout.Constraints   constraints =
164                         getConstraintsForCell(r, c, parent, cols);
165                 constraints.setX(x);
166                 constraints.setWidth(width);
167             }
168             x = Spring.sum(x, Spring.sum(width, Spring.constant(xPad)));
169         }
170 
171         //Align all cells in each row and make them the same height.
172         Spring y = Spring.constant(initialY);
173         for (int r = 0; r < rows; r++) {
174             Spring height = Spring.constant(0);
175             for (int c = 0; c < cols; c++) {
176                 height = Spring.max(height,
177                                     getConstraintsForCell(r, c, parent, cols).
178                                         getHeight());
179             }
180             for (int c = 0; c < cols; c++) {
181                 SpringLayout.Constraints   constraints =
182                         getConstraintsForCell(r, c, parent, cols);
183                 constraints.setY(y);
184                 constraints.setHeight(height);
185             }
186             y = Spring.sum(y, Spring.sum(height, Spring.constant(yPad)));
187         }
188 
189         //Set the parent's size.
190         SpringLayout.Constraints   pCons = layout.getConstraints(parent);
191         pCons.setConstraint(SpringLayout.SOUTH, y);
192         pCons.setConstraint(SpringLayout.EAST, x);
193     }
194 }
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