/*
* Copyright 2010 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
/*
* Taken from http://tips4java.wordpress.com/2008/11/06/wrap-layout/ and
* originally written by Rob Camick. The About link for the web site at
* http://tips4java.wordpress.com/about/ says this about IP rights:
*
* "You are free to use and/or modify any or all code posted on the Java Tips
* Weblog without restriction. A credit in the code comments would be nice,
* but not in any way mandatory."
*/
package com.google.gwt.dev.shell;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Insets;
/**
* 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);
}
/**
* Layout the components in the Container using the layout logic of the parent
* FlowLayout class.
*
* @param target the Container using this WrapLayout
*/
@Override
public void layoutContainer(Container target) {
Dimension size = preferredLayoutSize(target);
// When a frame is minimized or maximized the preferred size of the
// Container is assumed not to change. Therefore we need to force a
// validate() to make sure that space, if available, is allocated to
// the panel using a WrapLayout.
if (size.equals(preferredLayoutSize)) {
super.layoutContainer(target);
} else {
preferredLayoutSize = size;
Container top = target;
while (top.getParent() != null) {
top = top.getParent();
}
top.validate();
}
}
/**
* 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) {
return layoutSize(target, false);
}
/**
* 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);
}
/*
* 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;
}
/**
* 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();
if (rowWidth + d.width > maxWidth) {
// Can't add the component to current row. Start a new row.
addRow(dim, rowWidth, rowHeight);
rowWidth = 0;
rowHeight = 0;
}
if (rowWidth != 0) {
// Add a horizontal gap for all components after the first
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.
dim.width -= (hgap + 1);
return dim;
}
}
}