libs/WrapLayout.java

   1 package be.nikiroo.utils;
   2
   3 import java.awt.Component;
   4 import java.awt.Container;
   5 import java.awt.Dimension;
   6 import java.awt.FlowLayout;
   7 import java.awt.Insets;
   8
   9 import javax.swing.JScrollPane;
  10 import javax.swing.SwingUtilities;
  11
  12 /**
  13  * FlowLayout subclass that fully supports wrapping of components.
  14  *
  15  * @author https://tips4java.wordpress.com/2008/11/06/wrap-layout/
  16  */
  17 public class WrapLayout extends FlowLayout {
  18         private static final long serialVersionUID = 1L;
  19
  20         /**
  21          * Constructs a new <code>WrapLayout</code> with a left alignment and a
  22          * default 5-unit horizontal and vertical gap.
  23          */
  24         public WrapLayout() {
  25                 super();
  26         }
  27
  28         /**
  29          * Constructs a new <code>FlowLayout</code> with the specified alignment and
  30          * a default 5-unit horizontal and vertical gap. The value of the alignment
  31          * argument must be one of <code>WrapLayout</code>, <code>WrapLayout</code>,
  32          * or <code>WrapLayout</code>.
  33          *
  34          * @param align
  35          *            the alignment value
  36          */
  37         public WrapLayout(int align) {
  38                 super(align);
  39         }
  40
  41         /**
  42          * Creates a new flow layout manager with the indicated alignment and the
  43          * indicated horizontal and vertical gaps.
  44          * <p>
  45          * The value of the alignment argument must be one of
  46          * <code>WrapLayout</code>, <code>WrapLayout</code>, or
  47          * <code>WrapLayout</code>.
  48          *
  49          * @param align
  50          *            the alignment value
  51          * @param hgap
  52          *            the horizontal gap between components
  53          * @param vgap
  54          *            the vertical gap between components
  55          */
  56         public WrapLayout(int align, int hgap, int vgap) {
  57                 super(align, hgap, vgap);
  58         }
  59
  60         /**
  61          * Returns the preferred dimensions for this layout given the <i>visible</i>
  62          * components in the specified target container.
  63          *
  64          * @param target
  65          *            the component which needs to be laid out
  66          * @return the preferred dimensions to lay out the subcomponents of the
  67          *         specified container
  68          */
  69         @Override
  70         public Dimension preferredLayoutSize(Container target) {
  71                 return layoutSize(target, true);
  72         }
  73
  74         /**
  75          * Returns the minimum dimensions needed to layout the <i>visible</i>
  76          * components contained in the specified target container.
  77          *
  78          * @param target
  79          *            the component which needs to be laid out
  80          * @return the minimum dimensions to lay out the subcomponents of the
  81          *         specified container
  82          */
  83         @Override
  84         public Dimension minimumLayoutSize(Container target) {
  85                 Dimension minimum = layoutSize(target, false);
  86                 minimum.width -= (getHgap() + 1);
  87                 return minimum;
  88         }
  89
  90         /**
  91          * Returns the minimum or preferred dimension needed to layout the target
  92          * container.
  93          *
  94          * @param target
  95          *            target to get layout size for
  96          * @param preferred
  97          *            should preferred size be calculated
  98          * @return the dimension to layout the target container
  99          */
 100         private Dimension layoutSize(Container target, boolean preferred) {
 101                 synchronized (target.getTreeLock()) {
 102                         // Each row must fit with the width allocated to the containter.
 103                         // When the container width = 0, the preferred width of the
 104                         // container
 105                         // has not yet been calculated so lets ask for the maximum.
 106
 107                         int targetWidth = target.getSize().width;
 108                         Container container = target;
 109
 110                         while (container.getSize().width == 0
 111                                         && container.getParent() != null) {
 112                                 container = container.getParent();
 113                         }
 114
 115                         targetWidth = container.getSize().width;
 116
 117                         if (targetWidth == 0)
 118                                 targetWidth = Integer.MAX_VALUE;
 119
 120                         int hgap = getHgap();
 121                         int vgap = getVgap();
 122                         Insets insets = target.getInsets();
 123                         int horizontalInsetsAndGap = insets.left + insets.right
 124                                         + (hgap * 2);
 125                         int maxWidth = targetWidth - horizontalInsetsAndGap;
 126
 127                         // Fit components into the allowed width
 128
 129                         Dimension dim = new Dimension(0, 0);
 130                         int rowWidth = 0;
 131                         int rowHeight = 0;
 132
 133                         int nmembers = target.getComponentCount();
 134
 135                         for (int i = 0; i < nmembers; i++) {
 136                                 Component m = target.getComponent(i);
 137
 138                                 if (m.isVisible()) {
 139                                         Dimension d = preferred ? m.getPreferredSize() : m
 140                                                         .getMinimumSize();
 141
 142                                         // Can't add the component to current row. Start a new
 143                                         // row.
 144
 145                                         if (rowWidth + d.width > maxWidth) {
 146                                                 addRow(dim, rowWidth, rowHeight);
 147                                                 rowWidth = 0;
 148                                                 rowHeight = 0;
 149                                         }
 150
 151                                         // Add a horizontal gap for all components after the
 152                                         // first
 153
 154                                         if (rowWidth != 0) {
 155                                                 rowWidth += hgap;
 156                                         }
 157
 158                                         rowWidth += d.width;
 159                                         rowHeight = Math.max(rowHeight, d.height);
 160                                 }
 161                         }
 162
 163                         addRow(dim, rowWidth, rowHeight);
 164
 165                         dim.width += horizontalInsetsAndGap;
 166                         dim.height += insets.top + insets.bottom + vgap * 2;
 167
 168                         // When using a scroll pane or the DecoratedLookAndFeel we need
 169                         // to
 170                         // make sure the preferred size is less than the size of the
 171                         // target containter so shrinking the container size works
 172                         // correctly. Removing the horizontal gap is an easy way to do
 173                         // this.
 174
 175                         Container scrollPane = SwingUtilities.getAncestorOfClass(
 176                                         JScrollPane.class, target);
 177
 178                         if (scrollPane != null && target.isValid()) {
 179                                 dim.width -= (hgap + 1);
 180                         }
 181
 182                         return dim;
 183                 }
 184         }
 185
 186         /*
 187          * A new row has been completed. Use the dimensions of this row to update
 188          * the preferred size for the container.
 189          *
 190          * @param dim update the width and height when appropriate
 191          *
 192          * @param rowWidth the width of the row to add
 193          *
 194          * @param rowHeight the height of the row to add
 195          */
 196         private void addRow(Dimension dim, int rowWidth, int rowHeight) {
 197                 dim.width = Math.max(dim.width, rowWidth);
 198
 199                 if (dim.height > 0) {
 200                         dim.height += getVgap();
 201                 }
 202
 203                 dim.height += rowHeight;
 204         }
 205 }