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1 /* |
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2 * Copyright 2000-2007 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 package sun.awt; |
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27 |
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28 import java.awt.ScrollPane; |
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29 import java.awt.Insets; |
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30 import java.awt.Adjustable; |
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31 import java.awt.event.MouseWheelEvent; |
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32 |
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33 import java.util.logging.*; |
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34 |
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35 /* |
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36 * ScrollPaneWheelScroller is a helper class for implmenenting mouse wheel |
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37 * scrolling on a java.awt.ScrollPane. It contains only static methods. |
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38 * No objects of this class may be instantiated, thus it is declared abstract. |
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39 */ |
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40 public abstract class ScrollPaneWheelScroller { |
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41 |
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42 private static final Logger log = Logger.getLogger("sun.awt.ScrollPaneWheelScroller"); |
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43 |
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44 private ScrollPaneWheelScroller() {} |
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45 |
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46 /* |
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47 * Called from ScrollPane.processMouseWheelEvent() |
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48 */ |
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49 public static void handleWheelScrolling(ScrollPane sp, MouseWheelEvent e) { |
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50 if (log.isLoggable(Level.FINER)) { |
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51 log.log(Level.FINER, "x = " + e.getX() + ", y = " + e.getY() + ", src is " + e.getSource()); |
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52 } |
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53 int increment = 0; |
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54 |
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55 if (sp != null && e.getScrollAmount() != 0) { |
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56 Adjustable adj = getAdjustableToScroll(sp); |
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57 if (adj != null) { |
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58 increment = getIncrementFromAdjustable(adj, e); |
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59 if (log.isLoggable(Level.FINER)) { |
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60 log.log(Level.FINER, "increment from adjustable(" + adj.getClass() + ") : " + increment); |
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61 } |
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62 scrollAdjustable(adj, increment); |
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63 } |
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64 } |
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65 } |
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66 |
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67 /* |
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68 * Given a ScrollPane, determine which Scrollbar should be scrolled by the |
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69 * mouse wheel, if any. |
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70 */ |
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71 public static Adjustable getAdjustableToScroll(ScrollPane sp) { |
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72 int policy = sp.getScrollbarDisplayPolicy(); |
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73 |
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74 // if policy is display always or never, use vert |
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75 if (policy == ScrollPane.SCROLLBARS_ALWAYS || |
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76 policy == ScrollPane.SCROLLBARS_NEVER) { |
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77 if (log.isLoggable(Level.FINER)) { |
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78 log.log(Level.FINER, "using vertical scrolling due to scrollbar policy"); |
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79 } |
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80 return sp.getVAdjustable(); |
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81 |
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82 } |
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83 else { |
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84 |
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85 Insets ins = sp.getInsets(); |
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86 int vertScrollWidth = sp.getVScrollbarWidth(); |
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87 |
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88 if (log.isLoggable(Level.FINER)) { |
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89 log.log(Level.FINER, "insets: l = " + ins.left + ", r = " + ins.right + |
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90 ", t = " + ins.top + ", b = " + ins.bottom); |
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91 log.log(Level.FINER, "vertScrollWidth = " + vertScrollWidth); |
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92 } |
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93 |
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94 // Check if scrollbar is showing by examining insets of the |
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95 // ScrollPane |
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96 if (ins.right >= vertScrollWidth) { |
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97 if (log.isLoggable(Level.FINER)) { |
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98 log.log(Level.FINER, "using vertical scrolling because scrollbar is present"); |
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99 } |
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100 return sp.getVAdjustable(); |
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101 } |
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102 else { |
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103 int horizScrollHeight = sp.getHScrollbarHeight(); |
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104 if (ins.bottom >= horizScrollHeight) { |
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105 if (log.isLoggable(Level.FINER)) { |
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106 log.log(Level.FINER, "using horiz scrolling because scrollbar is present"); |
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107 } |
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108 return sp.getHAdjustable(); |
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109 } |
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110 else { |
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111 if (log.isLoggable(Level.FINER)) { |
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112 log.log(Level.FINER, "using NO scrollbar becsause neither is present"); |
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113 } |
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114 return null; |
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115 } |
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116 } |
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117 } |
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118 } |
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119 |
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120 /* |
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121 * Given the info in a MouseWheelEvent and an Adjustable to scroll, return |
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122 * the amount by which the Adjustable should be adjusted. This value may |
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123 * be positive or negative. |
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124 */ |
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125 public static int getIncrementFromAdjustable(Adjustable adj, |
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126 MouseWheelEvent e) { |
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127 if (log.isLoggable(Level.FINE)) { |
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128 if (adj == null) { |
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129 log.log(Level.FINE, "Assertion (adj != null) failed"); |
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130 } |
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131 } |
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132 |
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133 int increment = 0; |
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134 |
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135 if (e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL) { |
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136 increment = e.getUnitsToScroll() * adj.getUnitIncrement(); |
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137 } |
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138 else if (e.getScrollType() == MouseWheelEvent.WHEEL_BLOCK_SCROLL) { |
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139 increment = adj.getBlockIncrement() * e.getWheelRotation(); |
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140 } |
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141 return increment; |
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142 } |
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143 |
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144 /* |
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145 * Scroll the given Adjustable by the given amount. Checks the Adjustable's |
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146 * bounds and sets the new value to the Adjustable. |
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147 */ |
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148 public static void scrollAdjustable(Adjustable adj, int amount) { |
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149 if (log.isLoggable(Level.FINE)) { |
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150 if (adj == null) { |
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151 log.log(Level.FINE, "Assertion (adj != null) failed"); |
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152 } |
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153 if (amount == 0) { |
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154 log.log(Level.FINE, "Assertion (amount != 0) failed"); |
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155 } |
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156 } |
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157 |
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158 int current = adj.getValue(); |
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159 int upperLimit = adj.getMaximum() - adj.getVisibleAmount(); |
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160 if (log.isLoggable(Level.FINER)) { |
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161 log.log(Level.FINER, "doScrolling by " + amount); |
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162 } |
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163 |
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164 if (amount > 0 && current < upperLimit) { // still some room to scroll |
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165 // down |
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166 if (current + amount < upperLimit) { |
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167 adj.setValue(current + amount); |
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168 return; |
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169 } |
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170 else { |
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171 adj.setValue(upperLimit); |
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172 return; |
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173 } |
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174 } |
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175 else if (amount < 0 && current > adj.getMinimum()) { // still some room |
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176 // to scroll up |
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177 if (current + amount > adj.getMinimum()) { |
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178 adj.setValue(current + amount); |
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179 return; |
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180 } |
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181 else { |
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182 adj.setValue(adj.getMinimum()); |
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183 return; |
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184 } |
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185 } |
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186 } |
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187 } |