WrapLayout with a left
+ * alignment and a default 5-unit horizontal and vertical gap.
+ */
+ public WrapLayout()
+ {
+ super();
+ }
+
+ /**
+ * Constructs a new FlowLayout with the specified
+ * alignment and a default 5-unit horizontal and vertical gap.
+ * The value of the alignment argument must be one of
+ * WrapLayout, WrapLayout,
+ * or WrapLayout.
+ * @param align the alignment value
+ */
+ public WrapLayout(int align)
+ {
+ super(align);
+ }
+
+ /**
+ * Creates a new flow layout manager with the indicated alignment
+ * and the indicated horizontal and vertical gaps.
+ *
+ * The value of the alignment argument must be one of
+ * WrapLayout, WrapLayout,
+ * or WrapLayout.
+ * @param align the alignment value
+ * @param hgap the horizontal gap between components
+ * @param vgap the vertical gap between components
+ */
+ public WrapLayout(int align, int hgap, int vgap)
+ {
+ super(align, hgap, vgap);
+ }
+
+ /**
+ * Returns the preferred dimensions for this layout given the
+ * visible components in the specified target container.
+ * @param target the component which needs to be laid out
+ * @return the preferred dimensions to lay out the
+ * subcomponents of the specified container
+ */
+ @Override
+ public Dimension preferredLayoutSize(Container target)
+ {
+ return layoutSize(target, true);
+ }
+
+ /**
+ * Returns the minimum dimensions needed to layout the visible
+ * components contained in the specified target container.
+ * @param target the component which needs to be laid out
+ * @return the minimum dimensions to lay out the
+ * subcomponents of the specified container
+ */
+ @Override
+ public Dimension minimumLayoutSize(Container target)
+ {
+ Dimension minimum = layoutSize(target, false);
+ minimum.width -= (getHgap() + 1);
+ return minimum;
+ }
+
+ /**
+ * Returns the minimum or preferred dimension needed to layout the target
+ * container.
+ *
+ * @param target target to get layout size for
+ * @param preferred should preferred size be calculated
+ * @return the dimension to layout the target container
+ */
+ private Dimension layoutSize(Container target, boolean preferred)
+ {
+ synchronized (target.getTreeLock())
+ {
+ // Each row must fit with the width allocated to the containter.
+ // When the container width = 0, the preferred width of the container
+ // has not yet been calculated so lets ask for the maximum.
+
+ int targetWidth = target.getSize().width;
+
+ if (targetWidth == 0)
+ targetWidth = Integer.MAX_VALUE;
+
+ int hgap = getHgap();
+ int vgap = getVgap();
+ Insets insets = target.getInsets();
+ int horizontalInsetsAndGap = insets.left + insets.right + (hgap * 2);
+ int maxWidth = targetWidth - horizontalInsetsAndGap;
+
+ // Fit components into the allowed width
+
+ Dimension dim = new Dimension(0, 0);
+ int rowWidth = 0;
+ int rowHeight = 0;
+
+ int nmembers = target.getComponentCount();
+
+ for (int i = 0; i < nmembers; i++)
+ {
+ Component m = target.getComponent(i);
+
+ if (m.isVisible())
+ {
+ Dimension d = preferred ? m.getPreferredSize() : m.getMinimumSize();
+
+ // Can't add the component to current row. Start a new row.
+
+ if (rowWidth + d.width > maxWidth)
+ {
+ addRow(dim, rowWidth, rowHeight);
+ rowWidth = 0;
+ rowHeight = 0;
+ }
+
+ // Add a horizontal gap for all components after the first
+
+ if (rowWidth != 0)
+ {
+ rowWidth += hgap;
+ }
+
+ rowWidth += d.width;
+ rowHeight = Math.max(rowHeight, d.height);
+ }
+ }
+
+ addRow(dim, rowWidth, rowHeight);
+
+ dim.width += horizontalInsetsAndGap;
+ dim.height += insets.top + insets.bottom + vgap * 2;
+
+ // When using a scroll pane or the DecoratedLookAndFeel we need to
+ // make sure the preferred size is less than the size of the
+ // target containter so shrinking the container size works
+ // correctly. Removing the horizontal gap is an easy way to do this.
+
+ Container scrollPane = SwingUtilities.getAncestorOfClass(JScrollPane.class, target);
+
+ if (scrollPane != null && target.isValid())
+ {
+ dim.width -= (hgap + 1);
+ }
+
+ return dim;
+ }
+ }
+
+ /*
+ * A new row has been completed. Use the dimensions of this row
+ * to update the preferred size for the container.
+ *
+ * @param dim update the width and height when appropriate
+ * @param rowWidth the width of the row to add
+ * @param rowHeight the height of the row to add
+ */
+ private void addRow(Dimension dim, int rowWidth, int rowHeight)
+ {
+ dim.width = Math.max(dim.width, rowWidth);
+
+ if (dim.height > 0)
+ {
+ dim.height += getVgap();
+ }
+
+ dim.height += rowHeight;
+ }
+}
+