http://www.cnblogs.com/TLightSky/p/3482454.html
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原来的WrapLayout有点小bug，会引起抖动，稍微改了一下，现在比较好用了
package com.miui.theme.tool.gui; import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Insets; import javax.swing.JScrollPane;
import javax.swing.SwingUtilities; /**
* FlowLayout subclass that fully supports wrapping of components.
*/
public class WrapLayout extends FlowLayout {
private Dimension preferredLayoutSize; /**
* Constructs a new <code>WrapLayout</code> with a left alignment and a
* default 5-unit horizontal and vertical gap.
*/
public WrapLayout() {
super();
} /**
* Constructs a new <code>FlowLayout</code> with the specified alignment and
* a default 5-unit horizontal and vertical gap. The value of the alignment
* argument must be one of <code>WrapLayout</code>, <code>WrapLayout</code>,
* or <code>WrapLayout</code>.
*
* @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.
* <p>
* The value of the alignment argument must be one of
* <code>WrapLayout</code>, <code>WrapLayout</code>, or
* <code>WrapLayout</code>.
*
* @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 <i>visible</i>
* 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 <i>visible</i>
* 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)
return new Dimension();
// 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;
}
}