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1 /* |
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2 * Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Sun designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Sun in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
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22 * CA 95054 USA or visit www.sun.com if you need additional information or |
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23 * have any questions. |
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24 */ |
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25 |
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26 |
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27 package javax.swing; |
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28 |
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29 import java.awt.*; |
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30 import java.beans.ConstructorProperties; |
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31 import java.io.Serializable; |
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32 import java.io.PrintStream; |
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33 |
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34 /** |
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35 * A layout manager that allows multiple components to be laid out either |
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36 * vertically or horizontally. The components will not wrap so, for |
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37 * example, a vertical arrangement of components will stay vertically |
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38 * arranged when the frame is resized. |
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39 * <TABLE ALIGN="RIGHT" BORDER="0" SUMMARY="layout"> |
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40 * <TR> |
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41 * <TD ALIGN="CENTER"> |
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42 * <P ALIGN="CENTER"><IMG SRC="doc-files/BoxLayout-1.gif" |
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43 * alt="The following text describes this graphic." |
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44 * WIDTH="191" HEIGHT="201" ALIGN="BOTTOM" BORDER="0"> |
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45 * </TD> |
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46 * </TR> |
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47 * </TABLE> |
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48 * <p> |
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49 * Nesting multiple panels with different combinations of horizontal and |
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50 * vertical gives an effect similar to GridBagLayout, without the |
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51 * complexity. The diagram shows two panels arranged horizontally, each |
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52 * of which contains 3 components arranged vertically. |
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53 * |
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54 * <p> The BoxLayout manager is constructed with an axis parameter that |
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55 * specifies the type of layout that will be done. There are four choices: |
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56 * |
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57 * <blockquote><b><tt>X_AXIS</tt></b> - Components are laid out horizontally |
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58 * from left to right.</blockquote> |
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59 * |
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60 * <blockquote><b><tt>Y_AXIS</tt></b> - Components are laid out vertically |
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61 * from top to bottom.</blockquote> |
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62 * |
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63 * <blockquote><b><tt>LINE_AXIS</tt></b> - Components are laid out the way |
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64 * words are laid out in a line, based on the container's |
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65 * <tt>ComponentOrientation</tt> property. If the container's |
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66 * <tt>ComponentOrientation</tt> is horizontal then components are laid out |
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67 * horizontally, otherwise they are laid out vertically. For horizontal |
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68 * orientations, if the container's <tt>ComponentOrientation</tt> is left to |
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69 * right then components are laid out left to right, otherwise they are laid |
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70 * out right to left. For vertical orientations components are always laid out |
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71 * from top to bottom.</blockquote> |
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72 * |
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73 * <blockquote><b><tt>PAGE_AXIS</tt></b> - Components are laid out the way |
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74 * text lines are laid out on a page, based on the container's |
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75 * <tt>ComponentOrientation</tt> property. If the container's |
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76 * <tt>ComponentOrientation</tt> is horizontal then components are laid out |
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77 * vertically, otherwise they are laid out horizontally. For horizontal |
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78 * orientations, if the container's <tt>ComponentOrientation</tt> is left to |
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79 * right then components are laid out left to right, otherwise they are laid |
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80 * out right to left. For vertical orientations components are always |
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81 * laid out from top to bottom.</blockquote> |
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82 * <p> |
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83 * For all directions, components are arranged in the same order as they were |
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84 * added to the container. |
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85 * <p> |
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86 * BoxLayout attempts to arrange components |
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87 * at their preferred widths (for horizontal layout) |
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88 * or heights (for vertical layout). |
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89 * For a horizontal layout, |
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90 * if not all the components are the same height, |
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91 * BoxLayout attempts to make all the components |
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92 * as high as the highest component. |
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93 * If that's not possible for a particular component, |
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94 * then BoxLayout aligns that component vertically, |
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95 * according to the component's Y alignment. |
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96 * By default, a component has a Y alignment of 0.5, |
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97 * which means that the vertical center of the component |
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98 * should have the same Y coordinate as |
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99 * the vertical centers of other components with 0.5 Y alignment. |
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100 * <p> |
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101 * Similarly, for a vertical layout, |
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102 * BoxLayout attempts to make all components in the column |
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103 * as wide as the widest component. |
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104 * If that fails, it aligns them horizontally |
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105 * according to their X alignments. For <code>PAGE_AXIS</code> layout, |
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106 * horizontal alignment is done based on the leading edge of the component. |
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107 * In other words, an X alignment value of 0.0 means the left edge of a |
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108 * component if the container's <code>ComponentOrientation</code> is left to |
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109 * right and it means the right edge of the component otherwise. |
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110 * <p> |
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111 * Instead of using BoxLayout directly, many programs use the Box class. |
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112 * The Box class is a lightweight container that uses a BoxLayout. |
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113 * It also provides handy methods to help you use BoxLayout well. |
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114 * Adding components to multiple nested boxes is a powerful way to get |
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115 * the arrangement you want. |
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116 * <p> |
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117 * For further information and examples see |
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118 * <a |
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119 href="http://java.sun.com/docs/books/tutorial/uiswing/layout/box.html">How to Use BoxLayout</a>, |
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120 * a section in <em>The Java Tutorial.</em> |
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121 * <p> |
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122 * <strong>Warning:</strong> |
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123 * Serialized objects of this class will not be compatible with |
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124 * future Swing releases. The current serialization support is |
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125 * appropriate for short term storage or RMI between applications running |
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126 * the same version of Swing. As of 1.4, support for long term storage |
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127 * of all JavaBeans<sup><font size="-2">TM</font></sup> |
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128 * has been added to the <code>java.beans</code> package. |
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129 * Please see {@link java.beans.XMLEncoder}. |
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130 * |
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131 * @see Box |
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132 * @see java.awt.ComponentOrientation |
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133 * @see JComponent#getAlignmentX |
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134 * @see JComponent#getAlignmentY |
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135 * |
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136 * @author Timothy Prinzing |
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137 */ |
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138 public class BoxLayout implements LayoutManager2, Serializable { |
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139 |
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140 /** |
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141 * Specifies that components should be laid out left to right. |
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142 */ |
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143 public static final int X_AXIS = 0; |
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144 |
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145 /** |
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146 * Specifies that components should be laid out top to bottom. |
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147 */ |
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148 public static final int Y_AXIS = 1; |
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149 |
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150 /** |
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151 * Specifies that components should be laid out in the direction of |
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152 * a line of text as determined by the target container's |
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153 * <code>ComponentOrientation</code> property. |
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154 */ |
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155 public static final int LINE_AXIS = 2; |
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156 |
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157 /** |
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158 * Specifies that components should be laid out in the direction that |
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159 * lines flow across a page as determined by the target container's |
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160 * <code>ComponentOrientation</code> property. |
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161 */ |
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162 public static final int PAGE_AXIS = 3; |
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163 |
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164 /** |
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165 * Creates a layout manager that will lay out components along the |
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166 * given axis. |
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167 * |
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168 * @param target the container that needs to be laid out |
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169 * @param axis the axis to lay out components along. Can be one of: |
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170 * <code>BoxLayout.X_AXIS</code>, |
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171 * <code>BoxLayout.Y_AXIS</code>, |
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172 * <code>BoxLayout.LINE_AXIS</code> or |
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173 * <code>BoxLayout.PAGE_AXIS</code> |
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174 * |
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175 * @exception AWTError if the value of <code>axis</code> is invalid |
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176 */ |
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177 @ConstructorProperties({"target", "axis"}) |
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178 public BoxLayout(Container target, int axis) { |
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179 if (axis != X_AXIS && axis != Y_AXIS && |
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180 axis != LINE_AXIS && axis != PAGE_AXIS) { |
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181 throw new AWTError("Invalid axis"); |
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182 } |
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183 this.axis = axis; |
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184 this.target = target; |
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185 } |
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186 |
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187 /** |
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188 * Constructs a BoxLayout that |
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189 * produces debugging messages. |
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190 * |
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191 * @param target the container that needs to be laid out |
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192 * @param axis the axis to lay out components along. Can be one of: |
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193 * <code>BoxLayout.X_AXIS</code>, |
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194 * <code>BoxLayout.Y_AXIS</code>, |
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195 * <code>BoxLayout.LINE_AXIS</code> or |
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196 * <code>BoxLayout.PAGE_AXIS</code> |
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197 * |
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198 * @param dbg the stream to which debugging messages should be sent, |
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199 * null if none |
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200 */ |
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201 BoxLayout(Container target, int axis, PrintStream dbg) { |
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202 this(target, axis); |
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203 this.dbg = dbg; |
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204 } |
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205 |
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206 /** |
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207 * Returns the container that uses this layout manager. |
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208 * |
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209 * @return the container that uses this layout manager |
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210 * |
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211 * @since 1.6 |
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212 */ |
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213 public final Container getTarget() { |
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214 return this.target; |
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215 } |
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216 |
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217 /** |
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218 * Returns the axis that was used to lay out components. |
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219 * Returns one of: |
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220 * <code>BoxLayout.X_AXIS</code>, |
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221 * <code>BoxLayout.Y_AXIS</code>, |
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222 * <code>BoxLayout.LINE_AXIS</code> or |
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223 * <code>BoxLayout.PAGE_AXIS</code> |
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224 * |
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225 * @return the axis that was used to lay out components |
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226 * |
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227 * @since 1.6 |
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228 */ |
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229 public final int getAxis() { |
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230 return this.axis; |
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231 } |
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232 |
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233 /** |
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234 * Indicates that a child has changed its layout related information, |
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235 * and thus any cached calculations should be flushed. |
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236 * <p> |
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237 * This method is called by AWT when the invalidate method is called |
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238 * on the Container. Since the invalidate method may be called |
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239 * asynchronously to the event thread, this method may be called |
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240 * asynchronously. |
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241 * |
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242 * @param target the affected container |
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243 * |
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244 * @exception AWTError if the target isn't the container specified to the |
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245 * BoxLayout constructor |
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246 */ |
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247 public synchronized void invalidateLayout(Container target) { |
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248 checkContainer(target); |
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249 xChildren = null; |
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250 yChildren = null; |
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251 xTotal = null; |
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252 yTotal = null; |
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253 } |
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254 |
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255 /** |
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256 * Not used by this class. |
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257 * |
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258 * @param name the name of the component |
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259 * @param comp the component |
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260 */ |
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261 public void addLayoutComponent(String name, Component comp) { |
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262 invalidateLayout(comp.getParent()); |
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263 } |
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264 |
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265 /** |
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266 * Not used by this class. |
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267 * |
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268 * @param comp the component |
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269 */ |
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270 public void removeLayoutComponent(Component comp) { |
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271 invalidateLayout(comp.getParent()); |
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272 } |
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273 |
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274 /** |
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275 * Not used by this class. |
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276 * |
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277 * @param comp the component |
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278 * @param constraints constraints |
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279 */ |
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280 public void addLayoutComponent(Component comp, Object constraints) { |
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281 invalidateLayout(comp.getParent()); |
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282 } |
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283 |
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284 /** |
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285 * Returns the preferred dimensions for this layout, given the components |
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286 * in the specified target container. |
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287 * |
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288 * @param target the container that needs to be laid out |
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289 * @return the dimensions >= 0 && <= Integer.MAX_VALUE |
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290 * @exception AWTError if the target isn't the container specified to the |
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291 * BoxLayout constructor |
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292 * @see Container |
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293 * @see #minimumLayoutSize |
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294 * @see #maximumLayoutSize |
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295 */ |
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296 public Dimension preferredLayoutSize(Container target) { |
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297 Dimension size; |
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298 synchronized(this) { |
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299 checkContainer(target); |
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300 checkRequests(); |
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301 size = new Dimension(xTotal.preferred, yTotal.preferred); |
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302 } |
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303 |
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304 Insets insets = target.getInsets(); |
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305 size.width = (int) Math.min((long) size.width + (long) insets.left + (long) insets.right, Integer.MAX_VALUE); |
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306 size.height = (int) Math.min((long) size.height + (long) insets.top + (long) insets.bottom, Integer.MAX_VALUE); |
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307 return size; |
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308 } |
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309 |
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310 /** |
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311 * Returns the minimum dimensions needed to lay out the components |
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312 * contained in the specified target container. |
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313 * |
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314 * @param target the container that needs to be laid out |
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315 * @return the dimensions >= 0 && <= Integer.MAX_VALUE |
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316 * @exception AWTError if the target isn't the container specified to the |
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317 * BoxLayout constructor |
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318 * @see #preferredLayoutSize |
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319 * @see #maximumLayoutSize |
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320 */ |
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321 public Dimension minimumLayoutSize(Container target) { |
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322 Dimension size; |
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323 synchronized(this) { |
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324 checkContainer(target); |
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325 checkRequests(); |
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326 size = new Dimension(xTotal.minimum, yTotal.minimum); |
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327 } |
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328 |
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329 Insets insets = target.getInsets(); |
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330 size.width = (int) Math.min((long) size.width + (long) insets.left + (long) insets.right, Integer.MAX_VALUE); |
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331 size.height = (int) Math.min((long) size.height + (long) insets.top + (long) insets.bottom, Integer.MAX_VALUE); |
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332 return size; |
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333 } |
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334 |
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335 /** |
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336 * Returns the maximum dimensions the target container can use |
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337 * to lay out the components it contains. |
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338 * |
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339 * @param target the container that needs to be laid out |
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340 * @return the dimenions >= 0 && <= Integer.MAX_VALUE |
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341 * @exception AWTError if the target isn't the container specified to the |
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342 * BoxLayout constructor |
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343 * @see #preferredLayoutSize |
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344 * @see #minimumLayoutSize |
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345 */ |
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346 public Dimension maximumLayoutSize(Container target) { |
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347 Dimension size; |
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348 synchronized(this) { |
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349 checkContainer(target); |
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350 checkRequests(); |
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351 size = new Dimension(xTotal.maximum, yTotal.maximum); |
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352 } |
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353 |
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354 Insets insets = target.getInsets(); |
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355 size.width = (int) Math.min((long) size.width + (long) insets.left + (long) insets.right, Integer.MAX_VALUE); |
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356 size.height = (int) Math.min((long) size.height + (long) insets.top + (long) insets.bottom, Integer.MAX_VALUE); |
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357 return size; |
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358 } |
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359 |
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360 /** |
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361 * Returns the alignment along the X axis for the container. |
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362 * If the box is horizontal, the default |
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363 * alignment will be returned. Otherwise, the alignment needed |
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364 * to place the children along the X axis will be returned. |
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365 * |
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366 * @param target the container |
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367 * @return the alignment >= 0.0f && <= 1.0f |
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368 * @exception AWTError if the target isn't the container specified to the |
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369 * BoxLayout constructor |
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370 */ |
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371 public synchronized float getLayoutAlignmentX(Container target) { |
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372 checkContainer(target); |
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373 checkRequests(); |
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374 return xTotal.alignment; |
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375 } |
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376 |
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377 /** |
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378 * Returns the alignment along the Y axis for the container. |
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379 * If the box is vertical, the default |
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380 * alignment will be returned. Otherwise, the alignment needed |
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381 * to place the children along the Y axis will be returned. |
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382 * |
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383 * @param target the container |
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384 * @return the alignment >= 0.0f && <= 1.0f |
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385 * @exception AWTError if the target isn't the container specified to the |
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386 * BoxLayout constructor |
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387 */ |
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388 public synchronized float getLayoutAlignmentY(Container target) { |
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389 checkContainer(target); |
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390 checkRequests(); |
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391 return yTotal.alignment; |
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392 } |
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393 |
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394 /** |
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395 * Called by the AWT <!-- XXX CHECK! --> when the specified container |
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396 * needs to be laid out. |
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397 * |
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398 * @param target the container to lay out |
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399 * |
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400 * @exception AWTError if the target isn't the container specified to the |
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401 * BoxLayout constructor |
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402 */ |
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403 public void layoutContainer(Container target) { |
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404 checkContainer(target); |
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405 int nChildren = target.getComponentCount(); |
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406 int[] xOffsets = new int[nChildren]; |
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407 int[] xSpans = new int[nChildren]; |
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408 int[] yOffsets = new int[nChildren]; |
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409 int[] ySpans = new int[nChildren]; |
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410 |
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411 Dimension alloc = target.getSize(); |
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412 Insets in = target.getInsets(); |
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413 alloc.width -= in.left + in.right; |
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414 alloc.height -= in.top + in.bottom; |
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415 |
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416 // Resolve axis to an absolute value (either X_AXIS or Y_AXIS) |
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417 ComponentOrientation o = target.getComponentOrientation(); |
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418 int absoluteAxis = resolveAxis( axis, o ); |
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419 boolean ltr = (absoluteAxis != axis) ? o.isLeftToRight() : true; |
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420 |
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421 |
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422 // determine the child placements |
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423 synchronized(this) { |
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424 checkRequests(); |
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425 |
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426 if (absoluteAxis == X_AXIS) { |
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427 SizeRequirements.calculateTiledPositions(alloc.width, xTotal, |
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428 xChildren, xOffsets, |
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429 xSpans, ltr); |
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430 SizeRequirements.calculateAlignedPositions(alloc.height, yTotal, |
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431 yChildren, yOffsets, |
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432 ySpans); |
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433 } else { |
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434 SizeRequirements.calculateAlignedPositions(alloc.width, xTotal, |
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435 xChildren, xOffsets, |
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436 xSpans, ltr); |
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437 SizeRequirements.calculateTiledPositions(alloc.height, yTotal, |
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438 yChildren, yOffsets, |
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439 ySpans); |
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440 } |
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441 } |
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442 |
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443 // flush changes to the container |
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444 for (int i = 0; i < nChildren; i++) { |
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445 Component c = target.getComponent(i); |
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446 c.setBounds((int) Math.min((long) in.left + (long) xOffsets[i], Integer.MAX_VALUE), |
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447 (int) Math.min((long) in.top + (long) yOffsets[i], Integer.MAX_VALUE), |
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448 xSpans[i], ySpans[i]); |
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449 |
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450 } |
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451 if (dbg != null) { |
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452 for (int i = 0; i < nChildren; i++) { |
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453 Component c = target.getComponent(i); |
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454 dbg.println(c.toString()); |
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455 dbg.println("X: " + xChildren[i]); |
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456 dbg.println("Y: " + yChildren[i]); |
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457 } |
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458 } |
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459 |
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460 } |
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461 |
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462 void checkContainer(Container target) { |
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463 if (this.target != target) { |
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464 throw new AWTError("BoxLayout can't be shared"); |
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465 } |
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466 } |
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467 |
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468 void checkRequests() { |
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469 if (xChildren == null || yChildren == null) { |
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470 // The requests have been invalidated... recalculate |
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471 // the request information. |
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472 int n = target.getComponentCount(); |
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473 xChildren = new SizeRequirements[n]; |
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474 yChildren = new SizeRequirements[n]; |
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475 for (int i = 0; i < n; i++) { |
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476 Component c = target.getComponent(i); |
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477 if (!c.isVisible()) { |
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478 xChildren[i] = new SizeRequirements(0,0,0, c.getAlignmentX()); |
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479 yChildren[i] = new SizeRequirements(0,0,0, c.getAlignmentY()); |
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480 continue; |
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481 } |
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482 Dimension min = c.getMinimumSize(); |
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483 Dimension typ = c.getPreferredSize(); |
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484 Dimension max = c.getMaximumSize(); |
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485 xChildren[i] = new SizeRequirements(min.width, typ.width, |
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486 max.width, |
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487 c.getAlignmentX()); |
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488 yChildren[i] = new SizeRequirements(min.height, typ.height, |
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489 max.height, |
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490 c.getAlignmentY()); |
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491 } |
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492 |
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493 // Resolve axis to an absolute value (either X_AXIS or Y_AXIS) |
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494 int absoluteAxis = resolveAxis(axis,target.getComponentOrientation()); |
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495 |
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496 if (absoluteAxis == X_AXIS) { |
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497 xTotal = SizeRequirements.getTiledSizeRequirements(xChildren); |
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498 yTotal = SizeRequirements.getAlignedSizeRequirements(yChildren); |
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499 } else { |
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500 xTotal = SizeRequirements.getAlignedSizeRequirements(xChildren); |
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501 yTotal = SizeRequirements.getTiledSizeRequirements(yChildren); |
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502 } |
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503 } |
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504 } |
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505 |
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506 /** |
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507 * Given one of the 4 axis values, resolve it to an absolute axis. |
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508 * The relative axis values, PAGE_AXIS and LINE_AXIS are converted |
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509 * to their absolute couterpart given the target's ComponentOrientation |
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510 * value. The absolute axes, X_AXIS and Y_AXIS are returned unmodified. |
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511 * |
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512 * @param axis the axis to resolve |
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513 * @param o the ComponentOrientation to resolve against |
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514 * @return the resolved axis |
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515 */ |
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516 private int resolveAxis( int axis, ComponentOrientation o ) { |
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517 int absoluteAxis; |
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518 if( axis == LINE_AXIS ) { |
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519 absoluteAxis = o.isHorizontal() ? X_AXIS : Y_AXIS; |
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520 } else if( axis == PAGE_AXIS ) { |
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521 absoluteAxis = o.isHorizontal() ? Y_AXIS : X_AXIS; |
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522 } else { |
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523 absoluteAxis = axis; |
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524 } |
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525 return absoluteAxis; |
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526 } |
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527 |
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528 |
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529 private int axis; |
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530 private Container target; |
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531 |
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532 private transient SizeRequirements[] xChildren; |
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533 private transient SizeRequirements[] yChildren; |
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534 private transient SizeRequirements xTotal; |
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535 private transient SizeRequirements yTotal; |
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536 |
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537 private transient PrintStream dbg; |
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538 } |