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1 /*******************************************************************************
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2 * Copyright (c) 2000, 2006 IBM Corporation and others.
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3 * All rights reserved. This program and the accompanying materials
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4 * are made available under the terms of the Eclipse Public License v1.0
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5 * which accompanies this distribution, and is available at
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6 * http://www.eclipse.org/legal/epl-v10.html
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7 *
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8 * Contributors:
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9 * IBM Corporation - initial API and implementation
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10 * Port to the D programming language:
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11 * Frank Benoit <benoit@tionex.de>
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12 *******************************************************************************/
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13 module dwt.events.TraverseEvent;
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14
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15
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16 import dwt.widgets.Event;
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17 import dwt.events.KeyEvent;
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18
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19 import tango.text.convert.Format;
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20 /**
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21 * Instances of this class are sent as a result of
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22 * widget traversal actions.
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23 * <p>
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24 * The traversal event allows fine control over keyboard traversal
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25 * in a control both to implement traversal and override the default
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26 * traversal behavior defined by the system. This is achieved using
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27 * two fields, <code>detail</code> and <code>doit</code>.
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28 * </p><p>
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29 * When a control is traversed, a traverse event is sent. The detail
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30 * describes the type of traversal and the doit field indicates the default
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31 * behavior of the system. For example, when a right arrow key is pressed
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32 * in a text control, the detail field is <code>TRAVERSE_ARROW_NEXT</code>
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33 * and the doit field is <code>false</code>, indicating that the system
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34 * will not traverse to the next tab item and the arrow key will be
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35 * delivered to the text control. If the same key is pressed in a radio
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36 * button, the doit field will be <code>true</code>, indicating that
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37 * traversal is to proceed to the next tab item, possibly another radio
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38 * button in the group and that the arrow key is not to be delivered
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39 * to the radio button.
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40 * </p><p>
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41 * How can the traversal event be used to implement traversal?
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42 * When a tab key is pressed in a canvas, the detail field will be
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43 * <code>TRAVERSE_TAB_NEXT</code> and the doit field will be
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44 * <code>false</code>. The default behavior of the system is to
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45 * provide no traversal for canvas controls. This means that by
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46 * default in a canvas, a key listener will see every key that the
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47 * user types, including traversal keys. To understand why this
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48 * is so, it is important to understand that only the widget implementor
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49 * can decide which traversal is appropriate for the widget. Returning
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50 * to the <code>TRAVERSE_TAB_NEXT</code> example, a text widget implemented
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51 * by a canvas would typically want to use the tab key to insert a
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52 * tab character into the widget. A list widget implementation, on the
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53 * other hand, would like the system default traversal behavior. Using
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54 * only the doit flag, both implementations are possible. The text widget
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55 * implementor sets doit to <code>false</code>, ensuring that the system
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56 * will not traverse and that the tab key will be delivered to key listeners.
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57 * The list widget implementor sets doit to <code>true</code>, indicating
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58 * that the system should perform tab traversal and that the key should not
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59 * be delivered to the list widget.
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60 * </p><p>
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61 * How can the traversal event be used to override system traversal?
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62 * When the return key is pressed in a single line text control, the
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63 * detail field is <code>TRAVERSE_RETURN</code> and the doit field
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64 * is <code>true</code>. This means that the return key will be processed
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65 * by the default button, not the text widget. If the text widget has
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66 * a default selection listener, it will not run because the return key
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67 * will be processed by the default button. Imagine that the text control
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68 * is being used as an in-place editor and return is used to dispose the
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69 * widget. Setting doit to <code>false</code> will stop the system from
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70 * activating the default button but the key will be delivered to the text
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71 * control, running the key and selection listeners for the text. How
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72 * can <code>TRAVERSE_RETURN</code> be implemented so that the default button
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73 * will not be activated and the text widget will not see the return key?
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74 * This is achieved by setting doit to <code>true</code>, and the detail
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75 * to <code>TRAVERSE_NONE</code>.
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76 * </p><p>
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77 * Note: A widget implementor will typically implement traversal using
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78 * only the doit flag to either enable or disable system traversal.
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79 * </p>
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80 *
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81 * @see TraverseListener
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82 */
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83
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84 public final class TraverseEvent : KeyEvent {
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85
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86 /**
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87 * The traversal type.
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88 * <p><ul>
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89 * <li>{@link dwt.DWT#TRAVERSE_NONE}</li>
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90 * <li>{@link dwt.DWT#TRAVERSE_ESCAPE}</li>
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91 * <li>{@link dwt.DWT#TRAVERSE_RETURN}</li>
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92 * <li>{@link dwt.DWT#TRAVERSE_TAB_NEXT}</li>
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93 * <li>{@link dwt.DWT#TRAVERSE_TAB_PREVIOUS}</li>
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94 * <li>{@link dwt.DWT#TRAVERSE_ARROW_NEXT}</li>
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95 * <li>{@link dwt.DWT#TRAVERSE_ARROW_PREVIOUS}</li>
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96 * <li>{@link dwt.DWT#TRAVERSE_MNEMONIC}</li>
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97 * <li>{@link dwt.DWT#TRAVERSE_PAGE_NEXT}</li>
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98 * <li>{@link dwt.DWT#TRAVERSE_PAGE_PREVIOUS}</li>
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99 * </ul></p>
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100 *
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101 * Setting this field will change the type of traversal.
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102 * For example, setting the detail to <code>TRAVERSE_NONE</code>
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103 * causes no traversal action to be taken.
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104 *
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105 * When used in conjunction with the <code>doit</code> field, the
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106 * traversal detail field can be useful when overriding the default
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107 * traversal mechanism for a control. For example, setting the doit
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108 * field to <code>false</code> will cancel the operation and allow
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109 * the traversal key stroke to be delivered to the control. Setting
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110 * the doit field to <code>true</code> indicates that the traversal
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111 * described by the detail field is to be performed.
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112 */
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113 public int detail;
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114
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115 //static final long serialVersionUID = 3257565105301239349L;
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116
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117 /**
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118 * Constructs a new instance of this class based on the
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119 * information in the given untyped event.
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120 *
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121 * @param e the untyped event containing the information
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122 */
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123 public this(Event e) {
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124 super(e);
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125 this.detail = e.detail;
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126 }
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127
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128 /**
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129 * Returns a string containing a concise, human-readable
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130 * description of the receiver.
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131 *
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132 * @return a string representation of the event
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133 */
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134 public char[] toString() {
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135 return Format( "{} detail={}}", super.toString[ 0 .. $-2 ], detail );
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136 }
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137 }
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