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1 /**************************************************************************** |
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2 ** |
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3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). |
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4 ** All rights reserved. |
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5 ** Contact: Nokia Corporation (qt-info@nokia.com) |
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6 ** |
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7 ** This file is part of the QtGui module of the Qt Toolkit. |
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8 ** |
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9 ** $QT_BEGIN_LICENSE:LGPL$ |
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10 ** No Commercial Usage |
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11 ** This file contains pre-release code and may not be distributed. |
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12 ** You may use this file in accordance with the terms and conditions |
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13 ** contained in the Technology Preview License Agreement accompanying |
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14 ** this package. |
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15 ** |
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16 ** GNU Lesser General Public License Usage |
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17 ** Alternatively, this file may be used under the terms of the GNU Lesser |
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18 ** General Public License version 2.1 as published by the Free Software |
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19 ** Foundation and appearing in the file LICENSE.LGPL included in the |
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20 ** packaging of this file. Please review the following information to |
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21 ** ensure the GNU Lesser General Public License version 2.1 requirements |
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22 ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. |
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23 ** |
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24 ** In addition, as a special exception, Nokia gives you certain additional |
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25 ** rights. These rights are described in the Nokia Qt LGPL Exception |
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26 ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. |
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28 ** If you have questions regarding the use of this file, please contact |
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29 ** Nokia at qt-info@nokia.com. |
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31 ** |
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32 ** |
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33 ** |
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34 ** |
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35 ** |
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36 ** |
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37 ** |
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38 ** $QT_END_LICENSE$ |
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39 ** |
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40 ****************************************************************************/ |
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41 |
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42 #include "qaccessible.h" |
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43 |
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44 #ifndef QT_NO_ACCESSIBILITY |
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45 |
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46 #include "qaccessibleplugin.h" |
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47 #include "qaccessiblewidget.h" |
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48 #include "qapplication.h" |
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49 #include "qhash.h" |
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50 #include "qmetaobject.h" |
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51 #include "qmutex.h" |
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52 #include <private/qfactoryloader_p.h> |
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53 |
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54 #include "qwidget.h" |
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55 |
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56 QT_BEGIN_NAMESPACE |
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57 |
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58 /*! |
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59 \class QAccessible |
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60 \brief The QAccessible class provides enums and static functions |
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61 relating to accessibility. |
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62 |
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63 \ingroup accessibility |
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64 |
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65 |
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66 Accessible applications can be used by people who are not able to |
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67 use applications by conventional means. |
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68 |
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69 The functions in this class are used for communication between |
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70 accessible applications (also called AT Servers) and |
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71 accessibility tools (AT Clients), such as screen readers and |
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72 braille displays. Clients and servers communicate in the following way: |
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73 |
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74 \list |
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75 \o \e{AT Servers} notify the clients about events through calls to the |
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76 updateAccessibility() function. |
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77 |
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78 \o \e{AT Clients} request information about the objects in the server. |
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79 The QAccessibleInterface class is the core interface, and encapsulates |
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80 this information in a pure virtual API. Implementations of the interface |
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81 are provided by Qt through the queryAccessibleInterface() API. |
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82 \endlist |
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83 |
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84 The communication between servers and clients is initialized by |
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85 the setRootObject() function. Function pointers can be installed |
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86 to replace or extend the default behavior of the static functions |
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87 in QAccessible. |
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88 |
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89 Qt supports Microsoft Active Accessibility (MSAA), Mac OS X |
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90 Accessibility, and the Unix/X11 AT-SPI standard. Other backends |
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91 can be supported using QAccessibleBridge. |
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92 |
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93 In addition to QAccessible's static functions, Qt offers one |
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94 generic interface, QAccessibleInterface, that can be used to wrap |
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95 all widgets and objects (e.g., QPushButton). This single |
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96 interface provides all the metadata necessary for the assistive |
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97 technologies. Qt provides implementations of this interface for |
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98 its built-in widgets as plugins. |
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99 |
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100 When you develop custom widgets, you can create custom subclasses |
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101 of QAccessibleInterface and distribute them as plugins (using |
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102 QAccessiblePlugin) or compile them into the application. |
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103 Likewise, Qt's predefined accessibility support can be built as |
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104 plugin (the default) or directly into the Qt library. The main |
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105 advantage of using plugins is that the accessibility classes are |
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106 only loaded into memory if they are actually used; they don't |
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107 slow down the common case where no assistive technology is being |
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108 used. |
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109 |
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110 Qt also includes two convenience classes, QAccessibleObject and |
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111 QAccessibleWidget, that inherit from QAccessibleInterface and |
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112 provide the lowest common denominator of metadata (e.g., widget |
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113 geometry, window title, basic help text). You can use them as |
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114 base classes when wrapping your custom QObject or QWidget |
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115 subclasses. |
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116 |
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117 \sa QAccessibleInterface |
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118 */ |
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119 |
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120 /*! |
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121 \enum QAccessible::Action |
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122 |
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123 This enum describes the possible types of action that can occur. |
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124 |
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125 \value DefaultAction |
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126 \value Press |
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127 \value SetFocus |
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128 \value Increase |
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129 \value Decrease |
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130 \value Accept |
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131 \value Cancel |
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132 \value Select |
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133 \value ClearSelection |
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134 \value RemoveSelection |
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135 \value ExtendSelection |
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136 \value AddToSelection |
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137 |
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138 \value FirstStandardAction |
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139 \value LastStandardAction |
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140 */ |
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141 |
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142 /*! |
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143 \enum QAccessible::Method |
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144 |
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145 This enum describes the possible types of methods that can be |
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146 invoked on an accessible object. |
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147 |
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148 \value ListSupportedMethods |
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149 \value SetCursorPosition |
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150 \value GetCursorPosition |
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151 |
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152 \omitvalue ForegroundColor |
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153 \omitvalue BackgroundColor |
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154 |
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155 \sa QAccessibleInterface::invokeMethod() |
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156 */ |
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157 |
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158 /*! |
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159 \fn QSet<Method> QAccessibleInterface::supportedMethods() |
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160 \since 4.3 |
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161 |
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162 Returns a QSet of \l{QAccessible::}{Method}s that are supported by this |
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163 accessible interface. |
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164 |
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165 \sa QAccessible::Method invokeMethod() |
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166 */ |
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167 |
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168 /*! |
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169 \enum QAccessible::StateFlag |
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170 |
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171 This enum type defines bit flags that can be combined to indicate |
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172 the state of an accessible object. The values are: |
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173 |
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174 \value Animated The object's appearance changes frequently. |
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175 \value Busy The object cannot accept input at the moment. |
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176 \value Checked The object's check box is checked. |
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177 \value Collapsed The object is collapsed, e.g. a closed listview item, or an iconified window. |
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178 \value DefaultButton The object represents the default button in a dialog. |
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179 \value Expanded The object is expandable, and currently the children are visible. |
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180 \value ExtSelectable The object supports extended selection. |
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181 \value Focusable The object can receive focus. Only objects in the active window can receive focus. |
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182 \value Focused The object has keyboard focus. |
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183 \value HasPopup The object opens a popup. |
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184 \value HotTracked The object's appearance is sensitive to the mouse cursor position. |
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185 \value Invisible The object is not visible to the user. |
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186 \value Linked The object is linked to another object, e.g. a hyperlink. |
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187 \value Marqueed The object displays scrolling contents, e.g. a log view. |
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188 \value Mixed The state of the object is not determined, e.g. a tri-state check box that is neither checked nor unchecked. |
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189 \value Modal The object blocks input from other objects. |
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190 \value Movable The object can be moved. |
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191 \value MultiSelectable The object supports multiple selected items. |
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192 \value Normal The normal state. |
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193 \value Offscreen The object is clipped by the visible area. Objects that are off screen are also invisible. |
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194 \value Pressed The object is pressed. |
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195 \value Protected The object is password protected, e.g. a line edit for entering a Password. |
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196 \value ReadOnly The object can usually be edited, but is explicitly set to read-only. |
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197 \value Selectable The object is selectable. |
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198 \value Selected The object is selected. |
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199 \value SelfVoicing The object describes itself through speech or sound. |
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200 \value Sizeable The object can be resized, e.g. top-level windows. |
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201 \value Traversed The object is linked and has been visited. |
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202 \value Unavailable The object is unavailable to the user, e.g. a disabled widget. |
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203 \omitvalue Moveable |
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204 \omitvalue HasInvokeExtension |
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205 |
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206 Implementations of QAccessibleInterface::state() return a combination |
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207 of these flags. |
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208 */ |
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209 |
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210 /*! |
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211 \enum QAccessible::Event |
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212 |
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213 This enum type defines accessible event types. |
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214 |
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215 \value AcceleratorChanged |
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216 \value Alert A system alert (e.g., a message from a QMessageBox) |
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217 \value ContextHelpEnd Context help (QWhatsThis) for an object is finished. |
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218 \value ContextHelpStart Context help (QWhatsThis) for an object is initiated. |
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219 \value DefaultActionChanged The default QAccessible::Action for the accessible object changed |
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220 \value DescriptionChanged The objects QAccessible::Description changed. |
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221 \value DialogEnd A dialog (QDialog) is been hidden |
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222 \value DialogStart A dialog (QDialog) has been set visible. |
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223 \value DragDropEnd A Drag & Drop operation is about to finished. |
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224 \value DragDropStart A Drag & Drop operation is about to be initiated. |
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225 \value Focus An object has gained keyboard focus. |
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226 \value ForegroundChanged A window has been activated (i.e., a new window has gained focus on the desktop) |
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227 \value HelpChanged The QAccessible::Help text property of an object has changed |
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228 \value LocationChanged An objects location on the screen changed |
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229 \value MenuCommand A menu item is triggered. |
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230 \value MenuEnd A menu has been closed (Qt uses PopupMenuEnd for all menus) |
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231 \value MenuStart A menu has been opened on the menubar (Qt uses PopupMenuStart for all menus) |
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232 \value NameChanged The QAccessible::Name property of an object has changed |
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233 \value ObjectCreated A new object is created. |
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234 \value ObjectDestroyed An object is deleted. |
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235 \value ObjectHide An object is hidden (i.e., with QWidget::hide()). Any children the object that is hidden has do not send this event. |
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236 It is not send when an object is hidden as it is being obcured by others. |
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237 \value ObjectReorder A layout or item view has added, removed, or moved an object (Qt does not use this event). |
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238 \value ObjectShow An object is displayed (i.e., with QWidget::show()). |
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239 \value ParentChanged An objects parent object changed. |
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240 \value PopupMenuEnd A popup menu has closed. |
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241 \value PopupMenuStart A popupmenu has opened. |
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242 \value ScrollingEnd A scrollbar scroll operation has ended (the mouse has released the slider handle) |
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243 \value ScrollingStart A scrollbar scroll operation is about to start (i.e., the mouse has pressed on the slider handle) |
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244 \value Selection The selection has changed in a menu or item view. |
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245 \value SelectionAdd An item has been added to the selection in an item view. |
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246 \value SelectionRemove An item has been removed from an item view selection. |
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247 \value SelectionWithin Several changes to a selection has occurred in an item view. |
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248 \value SoundPlayed A sound has been played by an object |
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249 \value StateChanged The QAccessible::State of an object has changed. |
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250 \value ValueChanged The QAccessible::Value of an object has changed. |
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251 */ |
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252 |
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253 /*! |
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254 \enum QAccessible::Role |
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255 |
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256 This enum defines the role of an accessible object. The roles are: |
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257 |
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258 \value AlertMessage An object that is used to alert the user. |
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259 \value Animation An object that displays an animation. |
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260 \value Application The application's main window. |
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261 \value Assistant An object that provids interactive help. |
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262 \value Border An object that represents a border. |
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263 \value ButtonDropDown A button that drops down a list of items. |
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264 \value ButtonDropGrid A button that drops down a grid. |
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265 \value ButtonMenu A button that drops down a menu. |
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266 \value Canvas An object that displays graphics that the user can interact with. |
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267 \value Caret An object that represents the system caret (text cursor). |
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268 \value Cell A cell in a table. |
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269 \value Chart An object that displays a graphical representation of data. |
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270 \value CheckBox An object that represents an option that can be checked or unchecked. Some options provide a "mixed" state, e.g. neither checked nor unchecked. |
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271 \value Client The client area in a window. |
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272 \value Clock A clock displaying time. |
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273 \value Column A column of cells, usually within a table. |
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274 \value ColumnHeader A header for a column of data. |
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275 \value ComboBox A list of choices that the user can select from. |
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276 \value Cursor An object that represents the mouse cursor. |
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277 \value Dial An object that represents a dial or knob. |
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278 \value Dialog A dialog box. |
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279 \value Document A document window, usually in an MDI environment. |
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280 \value EditableText Editable text |
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281 \value Equation An object that represents a mathematical equation. |
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282 \value Graphic A graphic or picture, e.g. an icon. |
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283 \value Grip A grip that the user can drag to change the size of widgets. |
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284 \value Grouping An object that represents a logical grouping of other objects. |
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285 \value HelpBalloon An object that displays help in a separate, short lived window. |
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286 \value HotkeyField A hotkey field that allows the user to enter a key sequence. |
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287 \value Indicator An indicator that represents a current value or item. |
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288 \value LayeredPane An object that can contain layered children, e.g. in a stack. |
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289 \value Link A link to something else. |
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290 \value List A list of items, from which the user can select one or more items. |
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291 \value ListItem An item in a list of items. |
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292 \value MenuBar A menu bar from which menus are opened by the user. |
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293 \value MenuItem An item in a menu or menu bar. |
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294 \value NoRole The object has no role. This usually indicates an invalid object. |
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295 \value PageTab A page tab that the user can select to switch to a different page in a dialog. |
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296 \value PageTabList A list of page tabs. |
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297 \value Pane A generic container. |
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298 \value PopupMenu A menu which lists options that the user can select to perform an action. |
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299 \value ProgressBar The object displays the progress of an operation in progress. |
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300 \value PropertyPage A property page where the user can change options and settings. |
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301 \value PushButton A button. |
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302 \value RadioButton An object that represents an option that is mutually exclusive with other options. |
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303 \value Row A row of cells, usually within a table. |
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304 \value RowHeader A header for a row of data. |
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305 \value ScrollBar A scroll bar, which allows the user to scroll the visible area. |
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306 \value Separator A separator that divides space into logical areas. |
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307 \value Slider A slider that allows the user to select a value within a given range. |
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308 \value Sound An object that represents a sound. |
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309 \value SpinBox A spin box widget that allows the user to enter a value within a given range. |
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310 \value Splitter A splitter distributing available space between its child widgets. |
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311 \value StaticText Static text, such as labels for other widgets. |
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312 \value StatusBar A status bar. |
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313 \value Table A table representing data in a grid of rows and columns. |
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314 \value TitleBar The title bar caption of a window. |
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315 \value ToolBar A tool bar, which groups widgets that the user accesses frequently. |
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316 \value ToolTip A tool tip which provides information about other objects. |
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317 \value Tree A list of items in a tree structure. |
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318 \value TreeItem An item in a tree structure. |
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319 \value UserRole The first value to be used for user defined roles. |
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320 \value Whitespace Blank space between other objects. |
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321 \value Window A top level window. |
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322 */ |
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323 |
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324 /*! |
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325 \enum QAccessible::RelationFlag |
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326 |
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327 This enum type defines bit flags that can be combined to indicate |
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328 the relationship between two accessible objects. |
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329 |
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330 \value Unrelated The objects are unrelated. |
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331 \value Self The objects are the same. |
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332 \value Ancestor The first object is a parent of the second object. |
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333 \value Child The first object is a direct child of the second object. |
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334 \value Descendent The first object is an indirect child of the second object. |
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335 \value Sibling The objects are siblings. |
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336 |
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337 \value Up The first object is above the second object. |
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338 \value Down The first object is below the second object. |
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339 \value Left The first object is left of the second object. |
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340 \value Right The first object is right of the second object. |
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341 \value Covers The first object covers the second object. |
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342 \value Covered The first object is covered by the second object. |
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343 |
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344 \value FocusChild The first object is the second object's focus child. |
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345 \value Label The first object is the label of the second object. |
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346 \value Labelled The first object is labelled by the second object. |
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347 \value Controller The first object controls the second object. |
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348 \value Controlled The first object is controlled by the second object. |
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349 |
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350 \omitvalue HierarchyMask |
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351 \omitvalue GeometryMask |
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352 \omitvalue LogicalMask |
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353 |
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354 Implementations of relationTo() return a combination of these flags. |
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355 Some values are mutually exclusive. |
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356 |
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357 Implementations of navigate() can accept only one distinct value. |
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358 */ |
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359 |
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360 /*! |
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361 \enum QAccessible::Text |
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362 |
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363 This enum specifies string information that an accessible object |
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364 returns. |
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365 |
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366 \value Name The name of the object. This can be used both |
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367 as an identifier or a short description by |
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368 accessible clients. |
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369 \value Description A short text describing the object. |
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370 \value Value The value of the object. |
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371 \value Help A longer text giving information about how to use the object. |
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372 \value Accelerator The keyboard shortcut that executes the object's default action. |
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373 \value UserText The first value to be used for user defined text. |
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374 */ |
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375 |
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376 /*! |
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377 \fn QAccessibleInterface::~QAccessibleInterface() |
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378 |
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379 Destroys the object. |
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380 */ |
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381 |
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382 /*! |
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383 \fn void QAccessible::initialize() |
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384 \internal |
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385 */ |
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386 |
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387 /*! |
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388 \fn void QAccessible::cleanup() |
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389 \internal |
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390 */ |
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391 |
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392 #if !defined(QT_NO_LIBRARY) && (!defined(QT_NO_SETTINGS) || !defined(Q_OS_WIN)) |
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393 Q_GLOBAL_STATIC_WITH_ARGS(QFactoryLoader, loader, |
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394 (QAccessibleFactoryInterface_iid, QLatin1String("/accessible"))) |
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395 #endif |
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396 |
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397 Q_GLOBAL_STATIC(QList<QAccessible::InterfaceFactory>, qAccessibleFactories) |
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398 |
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399 QAccessible::UpdateHandler QAccessible::updateHandler = 0; |
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400 QAccessible::RootObjectHandler QAccessible::rootObjectHandler = 0; |
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401 |
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402 static bool accessibility_active = false; |
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403 static bool cleanupAdded = false; |
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404 static void qAccessibleCleanup() |
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405 { |
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406 qAccessibleFactories()->clear(); |
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407 } |
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408 |
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409 /*! |
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410 \typedef QAccessible::InterfaceFactory |
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411 |
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412 A function pointer type. Use a function with this prototype to install |
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413 interface factories with installFactory(). |
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414 |
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415 The function receives a QObject pointer. If the QObject |
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416 provides a QAccessibleInterface, it sets the second parameter to |
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417 point to the corresponding QAccessibleInterface, and returns true; |
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418 otherwise returns false. |
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419 |
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420 Installed factories are called by queryAccessibilityInterface() until |
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421 one provides an interface. |
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422 */ |
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423 |
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424 /*! |
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425 \typedef QAccessible::UpdateHandler |
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426 |
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427 \internal |
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428 |
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429 A function pointer type. Use a function with this prototype to install |
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430 your own update function. |
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431 |
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432 The function is called by updateAccessibility(). |
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433 */ |
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434 |
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435 /*! |
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436 \typedef QAccessible::RootObjectHandler |
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437 |
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438 \internal |
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439 |
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440 A function pointer type. Use a function with this prototype to install |
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441 your own root object handler. |
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442 |
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443 The function is called by setRootObject(). |
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444 */ |
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445 |
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446 /*! |
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447 Installs the InterfaceFactory \a factory. The last factory added |
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448 is the first one used by queryAccessibleInterface(). |
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449 */ |
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450 void QAccessible::installFactory(InterfaceFactory factory) |
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451 { |
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452 if (!factory) |
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453 return; |
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454 |
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455 if (!cleanupAdded) { |
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456 qAddPostRoutine(qAccessibleCleanup); |
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457 cleanupAdded = true; |
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458 } |
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459 if (qAccessibleFactories()->contains(factory)) |
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460 return; |
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461 qAccessibleFactories()->append(factory); |
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462 } |
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463 |
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464 /*! |
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465 Removes \a factory from the list of installed InterfaceFactories. |
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466 */ |
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467 void QAccessible::removeFactory(InterfaceFactory factory) |
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468 { |
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469 qAccessibleFactories()->removeAll(factory); |
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470 } |
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471 |
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472 /*! |
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473 \internal |
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474 |
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475 Installs the given \a handler as the function to be used by |
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476 updateAccessibility(), and returns the previously installed |
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477 handler. |
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478 */ |
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479 QAccessible::UpdateHandler QAccessible::installUpdateHandler(UpdateHandler handler) |
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480 { |
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481 UpdateHandler old = updateHandler; |
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482 updateHandler = handler; |
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483 return old; |
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484 } |
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485 |
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486 /*! |
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487 Installs the given \a handler as the function to be used by setRootObject(), |
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488 and returns the previously installed handler. |
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489 */ |
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490 QAccessible::RootObjectHandler QAccessible::installRootObjectHandler(RootObjectHandler handler) |
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491 { |
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492 RootObjectHandler old = rootObjectHandler; |
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493 rootObjectHandler = handler; |
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494 return old; |
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495 } |
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496 |
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497 /*! |
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498 If a QAccessibleInterface implementation exists for the given \a object, |
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499 this function returns a pointer to the implementation; otherwise it |
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500 returns 0. |
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501 |
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502 The function calls all installed factory functions (from most |
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503 recently installed to least recently installed) until one is found |
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504 that provides an interface for the class of \a object. If no |
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505 factory can provide an accessibility implementation for the class |
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506 the function loads installed accessibility plugins, and tests if |
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507 any of the plugins can provide the implementation. |
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508 |
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509 If no implementation for the object's class is available, the |
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510 function tries to find an implementation for the object's parent |
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511 class, using the above strategy. |
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512 |
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513 \warning The caller is responsible for deleting the returned |
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514 interface after use. |
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515 */ |
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516 QAccessibleInterface *QAccessible::queryAccessibleInterface(QObject *object) |
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517 { |
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518 accessibility_active = true; |
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519 QAccessibleInterface *iface = 0; |
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520 if (!object) |
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521 return 0; |
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522 |
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523 QEvent e(QEvent::AccessibilityPrepare); |
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524 QApplication::sendEvent(object, &e); |
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525 |
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526 const QMetaObject *mo = object->metaObject(); |
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527 while (mo) { |
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528 const QLatin1String cn(mo->className()); |
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529 for (int i = qAccessibleFactories()->count(); i > 0; --i) { |
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530 InterfaceFactory factory = qAccessibleFactories()->at(i - 1); |
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531 iface = factory(cn, object); |
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532 if (iface) |
|
533 return iface; |
|
534 } |
|
535 #if !defined(QT_NO_LIBRARY) && (!defined(QT_NO_SETTINGS) || !defined(Q_OS_WIN)) |
|
536 QAccessibleFactoryInterface *factory = qobject_cast<QAccessibleFactoryInterface*>(loader()->instance(cn)); |
|
537 if (factory) { |
|
538 iface = factory->create(cn, object); |
|
539 if (iface) |
|
540 return iface; |
|
541 } |
|
542 #endif |
|
543 mo = mo->superClass(); |
|
544 } |
|
545 |
|
546 QWidget *widget = qobject_cast<QWidget*>(object); |
|
547 if (widget) |
|
548 return new QAccessibleWidget(widget); |
|
549 else if (object == qApp) |
|
550 return new QAccessibleApplication(); |
|
551 |
|
552 return 0; |
|
553 } |
|
554 |
|
555 /*! |
|
556 Returns true if an accessibility implementation has been requested |
|
557 during the runtime of the application; otherwise returns false. |
|
558 |
|
559 Use this function to prevent potentially expensive notifications via |
|
560 updateAccessibility(). |
|
561 */ |
|
562 bool QAccessible::isActive() |
|
563 { |
|
564 return accessibility_active; |
|
565 } |
|
566 |
|
567 /*! |
|
568 \fn void QAccessible::setRootObject(QObject *object) |
|
569 |
|
570 Sets the root accessible object of this application to \a object. |
|
571 All other accessible objects in the application can be reached by the |
|
572 client using object navigation. |
|
573 |
|
574 You should never need to call this function. Qt sets the QApplication |
|
575 object as the root object immediately before the event loop is entered |
|
576 in QApplication::exec(). |
|
577 |
|
578 Use QAccessible::installRootObjectHandler() to redirect the function |
|
579 call to a customized handler function. |
|
580 |
|
581 \sa queryAccessibleInterface() |
|
582 */ |
|
583 |
|
584 /*! |
|
585 \fn void QAccessible::updateAccessibility(QObject *object, int child, Event reason) |
|
586 |
|
587 Notifies accessibility clients about a change in \a object's |
|
588 accessibility information. |
|
589 |
|
590 \a reason specifies the cause of the change, for example, |
|
591 \c ValueChange when the position of a slider has been changed. \a |
|
592 child is the (1-based) index of the child element that has changed. |
|
593 When \a child is 0, the object itself has changed. |
|
594 |
|
595 Call this function whenever the state of your accessible object or |
|
596 one of its sub-elements has been changed either programmatically |
|
597 (e.g. by calling QLabel::setText()) or by user interaction. |
|
598 |
|
599 If there are no accessibility tools listening to this event, the |
|
600 performance penalty for calling this function is small, but if determining |
|
601 the parameters of the call is expensive you can test isActive() to |
|
602 avoid unnecessary computations. |
|
603 */ |
|
604 |
|
605 |
|
606 /*! |
|
607 \class QAccessibleInterface |
|
608 \brief The QAccessibleInterface class defines an interface that exposes information |
|
609 about accessible objects. |
|
610 |
|
611 \ingroup accessibility |
|
612 |
|
613 Accessibility tools (also called AT Clients), such as screen readers |
|
614 or braille displays, require high-level information about |
|
615 accessible objects in an application. Accessible objects provide |
|
616 specialized input and output methods, making it possible for users |
|
617 to use accessibility tools with enabled applications (AT Servers). |
|
618 |
|
619 Every element that the user needs to interact with or react to is |
|
620 an accessible object, and should provide this information. These |
|
621 are mainly visual objects, such as widgets and widget elements, but |
|
622 can also be content, such as sounds. |
|
623 |
|
624 The AT client uses three basic concepts to acquire information |
|
625 about any accessible object in an application: |
|
626 \list |
|
627 \i \e Properties The client can read information about |
|
628 accessible objects. In some cases the client can also modify these |
|
629 properties; such as text in a line edit. |
|
630 \i \e Actions The client can invoke actions like pressing a button |
|
631 or . |
|
632 \i \e{Relationships and Navigation} The client can traverse from one |
|
633 accessible object to another, using the relationships between objects. |
|
634 \endlist |
|
635 |
|
636 The QAccessibleInterface defines the API for these three concepts. |
|
637 |
|
638 \section1 Relationships and Navigation |
|
639 |
|
640 The functions childCount() and indexOfChild() return the number of |
|
641 children of an accessible object and the index a child object has |
|
642 in its parent. The childAt() function returns the index of a child |
|
643 at a given position. |
|
644 |
|
645 The relationTo() function provides information about how two |
|
646 different objects relate to each other, and navigate() allows |
|
647 traversing from one object to another object with a given |
|
648 relationship. |
|
649 |
|
650 \section1 Properties |
|
651 |
|
652 The central property of an accessible objects is what role() it |
|
653 has. Different objects can have the same role, e.g. both the "Add |
|
654 line" element in a scroll bar and the \c OK button in a dialog have |
|
655 the same role, "button". The role implies what kind of |
|
656 interaction the user can perform with the user interface element. |
|
657 |
|
658 An object's state() property is a combination of different state |
|
659 flags and can describe both how the object's state differs from a |
|
660 "normal" state, e.g. it might be unavailable, and also how it |
|
661 behaves, e.g. it might be selectable. |
|
662 |
|
663 The text() property provides textual information about the object. |
|
664 An object usually has a name, but can provide extended information |
|
665 such as a description, help text, or information about any |
|
666 keyboard accelerators it provides. Some objects allow changing the |
|
667 text() property through the setText() function, but this |
|
668 information is in most cases read-only. |
|
669 |
|
670 The rect() property provides information about the geometry of an |
|
671 accessible object. This information is usually only available for |
|
672 visual objects. |
|
673 |
|
674 \section1 Actions and Selection |
|
675 |
|
676 To enable the user to interact with an accessible object the |
|
677 object must expose information about the actions that it can |
|
678 perform. userActionCount() returns the number of actions supported by |
|
679 an accessible object, and actionText() returns textual information |
|
680 about those actions. doAction() invokes an action. |
|
681 |
|
682 Objects that support selections can define actions to change the selection. |
|
683 |
|
684 \section2 Objects and children |
|
685 |
|
686 A QAccessibleInterface provides information about the accessible |
|
687 object, and can also provide information for the children of that |
|
688 object if those children don't provide a QAccessibleInterface |
|
689 implementation themselves. This is practical if the object has |
|
690 many similar children (e.g. items in a list view), or if the |
|
691 children are an integral part of the object itself, for example, the |
|
692 different sections in a scroll bar. |
|
693 |
|
694 If an accessible object provides information about its children |
|
695 through one QAccessibleInterface, the children are referenced |
|
696 using indexes. The index is 1-based for the children, i.e. 0 |
|
697 refers to the object itself, 1 to the first child, 2 to the second |
|
698 child, and so on. |
|
699 |
|
700 All functions in QAccessibleInterface that take a child index |
|
701 relate to the object itself if the index is 0, or to the child |
|
702 specified. If a child provides its own interface implementation |
|
703 (which can be retrieved through navigation) asking the parent for |
|
704 information about that child will usually not succeed. |
|
705 |
|
706 \sa QAccessible |
|
707 */ |
|
708 |
|
709 /*! |
|
710 \fn bool QAccessibleInterface::isValid() const |
|
711 |
|
712 Returns true if all the data necessary to use this interface |
|
713 implementation is valid (e.g. all pointers are non-null); |
|
714 otherwise returns false. |
|
715 |
|
716 \sa object() |
|
717 */ |
|
718 |
|
719 /*! |
|
720 \fn QObject *QAccessibleInterface::object() const |
|
721 |
|
722 Returns a pointer to the QObject this interface implementation provides |
|
723 information for. |
|
724 |
|
725 \sa isValid() |
|
726 */ |
|
727 |
|
728 /*! |
|
729 \fn int QAccessibleInterface::childCount() const |
|
730 |
|
731 Returns the number of children that belong to this object. A child |
|
732 can provide accessibility information on its own (e.g. a child |
|
733 widget), or be a sub-element of this accessible object. |
|
734 |
|
735 All objects provide this information. |
|
736 |
|
737 \sa indexOfChild() |
|
738 */ |
|
739 |
|
740 /*! |
|
741 \fn int QAccessibleInterface::indexOfChild(const QAccessibleInterface *child) const |
|
742 |
|
743 Returns the 1-based index of the object \a child in this object's |
|
744 children list, or -1 if \a child is not a child of this object. 0 |
|
745 is not a possible return value. |
|
746 |
|
747 All objects provide this information about their children. |
|
748 |
|
749 \sa childCount() |
|
750 */ |
|
751 |
|
752 /*! |
|
753 \fn QAccessible::Relation QAccessibleInterface::relationTo(int child, |
|
754 const QAccessibleInterface *other, int otherChild) const |
|
755 |
|
756 Returns the relationship between this object's \a child and the \a |
|
757 other object's \a otherChild. If \a child is 0 the object's own relation |
|
758 is returned. |
|
759 |
|
760 The returned value indicates the relation of the called object to |
|
761 the \a other object, e.g. if this object is a child of \a other |
|
762 the return value will be \c Child. |
|
763 |
|
764 The return value is a combination of the bit flags in the |
|
765 QAccessible::Relation enumeration. |
|
766 |
|
767 All objects provide this information. |
|
768 |
|
769 \sa indexOfChild(), navigate() |
|
770 */ |
|
771 |
|
772 /*! |
|
773 \fn int QAccessibleInterface::childAt(int x, int y) const |
|
774 |
|
775 Returns the 1-based index of the child that contains the screen |
|
776 coordinates (\a x, \a y). This function returns 0 if the point is |
|
777 positioned on the object itself. If the tested point is outside |
|
778 the boundaries of the object this function returns -1. |
|
779 |
|
780 This function is only relyable for visible objects (invisible |
|
781 object might not be laid out correctly). |
|
782 |
|
783 All visual objects provide this information. |
|
784 |
|
785 \sa rect() |
|
786 */ |
|
787 |
|
788 /*! |
|
789 \fn int QAccessibleInterface::navigate(RelationFlag relation, int entry, QAccessibleInterface |
|
790 **target) const |
|
791 |
|
792 Navigates from this object to an object that has a relationship |
|
793 \a relation to this object, and returns the respective object in |
|
794 \a target. It is the caller's responsibility to delete *\a target |
|
795 after use. |
|
796 |
|
797 If an object is found, \a target is set to point to the object, and |
|
798 the index of the child of \a target is returned. The return value |
|
799 is 0 if \a target itself is the requested object. \a target is set |
|
800 to null if this object is the target object (i.e. the requested |
|
801 object is a handled by this object). |
|
802 |
|
803 If no object is found \a target is set to null, and the return |
|
804 value is -1. |
|
805 |
|
806 The \a entry parameter has two different meanings: |
|
807 \list |
|
808 \i \e{Hierarchical and Logical relationships} -- if multiple objects with |
|
809 the requested relationship exist \a entry specifies which one to |
|
810 return. \a entry is 1-based, e.g. use 1 to get the first (and |
|
811 possibly only) object with the requested relationship. |
|
812 |
|
813 The following code demonstrates how to use this function to |
|
814 navigate to the first child of an object: |
|
815 |
|
816 \snippet doc/src/snippets/code/src_gui_accessible_qaccessible.cpp 0 |
|
817 |
|
818 \i \e{Geometric relationships} -- the index of the child from |
|
819 which to start navigating in the specified direction. \a entry |
|
820 can be 0 to navigate to a sibling of this object, or non-null to |
|
821 navigate within contained children that don't provide their own |
|
822 accessible information. |
|
823 \endlist |
|
824 |
|
825 Note that the \c Descendent value for \a relation is not supported. |
|
826 |
|
827 All objects support navigation. |
|
828 |
|
829 \sa relationTo(), childCount() |
|
830 */ |
|
831 |
|
832 /*! |
|
833 \fn QString QAccessibleInterface::text(Text t, int child) const |
|
834 |
|
835 Returns the value of the text property \a t of the object, or of |
|
836 the object's child if \a child is not 0. |
|
837 |
|
838 The \l Name is a string used by clients to identify, find, or |
|
839 announce an accessible object for the user. All objects must have |
|
840 a name that is unique within their container. The name can be |
|
841 used differently by clients, so the name should both give a |
|
842 short description of the object and be unique. |
|
843 |
|
844 An accessible object's \l Description provides textual information |
|
845 about an object's visual appearance. The description is primarily |
|
846 used to provide greater context for vision-impaired users, but is |
|
847 also used for context searching or other applications. Not all |
|
848 objects have a description. An "OK" button would not need a |
|
849 description, but a tool button that shows a picture of a smiley |
|
850 would. |
|
851 |
|
852 The \l Value of an accessible object represents visual information |
|
853 contained by the object, e.g. the text in a line edit. Usually, |
|
854 the value can be modified by the user. Not all objects have a |
|
855 value, e.g. static text labels don't, and some objects have a |
|
856 state that already is the value, e.g. toggle buttons. |
|
857 |
|
858 The \l Help text provides information about the function and |
|
859 usage of an accessible object. Not all objects provide this |
|
860 information. |
|
861 |
|
862 The \l Accelerator is a keyboard shortcut that activates the |
|
863 object's default action. A keyboard shortcut is the underlined |
|
864 character in the text of a menu, menu item or widget, and is |
|
865 either the character itself, or a combination of this character |
|
866 and a modifier key like Alt, Ctrl or Shift. Command controls like |
|
867 tool buttons also have shortcut keys and usually display them in |
|
868 their tooltip. |
|
869 |
|
870 All objects provide a string for \l Name. |
|
871 |
|
872 \sa role(), state() |
|
873 */ |
|
874 |
|
875 /*! |
|
876 \fn void QAccessibleInterface::setText(Text t, int child, const QString &text) |
|
877 |
|
878 Sets the text property \a t of the object, or of the object's |
|
879 child if \a child is not 0, to \a text. |
|
880 |
|
881 Note that the text properties of most objects are read-only. |
|
882 |
|
883 \sa text() |
|
884 */ |
|
885 |
|
886 /*! |
|
887 \fn QRect QAccessibleInterface::rect(int child) const |
|
888 |
|
889 Returns the geometry of the object, or of the object's child if \a child |
|
890 is not 0. The geometry is in screen coordinates. |
|
891 |
|
892 This function is only reliable for visible objects (invisible |
|
893 objects might not be laid out correctly). |
|
894 |
|
895 All visual objects provide this information. |
|
896 |
|
897 \sa childAt() |
|
898 */ |
|
899 |
|
900 /*! |
|
901 \fn QAccessible::Role QAccessibleInterface::role(int child) const |
|
902 |
|
903 Returns the role of the object, or of the object's child if \a child |
|
904 is not 0. The role of an object is usually static. |
|
905 |
|
906 All accessible objects have a role. |
|
907 |
|
908 \sa text(), state() |
|
909 */ |
|
910 |
|
911 /*! |
|
912 \fn QAccessible::State QAccessibleInterface::state(int child) const |
|
913 |
|
914 Returns the current state of the object, or of the object's child if |
|
915 \a child is not 0. The returned value is a combination of the flags in |
|
916 the QAccessible::StateFlag enumeration. |
|
917 |
|
918 All accessible objects have a state. |
|
919 |
|
920 \sa text(), role() |
|
921 */ |
|
922 |
|
923 /*! |
|
924 \fn int QAccessibleInterface::userActionCount(int child) const |
|
925 |
|
926 Returns the number of custom actions of the object, or of the |
|
927 object's child if \a child is not 0. |
|
928 |
|
929 The \c Action type enumerates predefined actions: these |
|
930 are not included in the returned value. |
|
931 |
|
932 \sa actionText(), doAction() |
|
933 */ |
|
934 |
|
935 /*! |
|
936 \fn QString QAccessibleInterface::actionText(int action, Text t, int child) const |
|
937 |
|
938 Returns the text property \a t of the action \a action supported by |
|
939 the object, or of the object's child if \a child is not 0. |
|
940 |
|
941 \sa text(), userActionCount() |
|
942 */ |
|
943 |
|
944 /*! |
|
945 \fn bool QAccessibleInterface::doAction(int action, int child, const QVariantList ¶ms) |
|
946 |
|
947 Asks the object, or the object's \a child if \a child is not 0, to |
|
948 execute \a action using the parameters, \a params. Returns true if |
|
949 the action could be executed; otherwise returns false. |
|
950 |
|
951 \a action can be a predefined or a custom action. |
|
952 |
|
953 \sa userActionCount(), actionText() |
|
954 */ |
|
955 |
|
956 /*! |
|
957 \fn QColor QAccessibleInterface::backgroundColor() |
|
958 \internal |
|
959 */ |
|
960 |
|
961 /*! |
|
962 \fn QAccessibleEditableTextInterface *QAccessibleInterface::editableTextInterface() |
|
963 \internal |
|
964 */ |
|
965 |
|
966 /*! |
|
967 \fn QColor QAccessibleInterface::foregroundColor() |
|
968 \internal |
|
969 */ |
|
970 |
|
971 /*! |
|
972 \fn QAccessibleTextInterface *QAccessibleInterface::textInterface() |
|
973 \internal |
|
974 */ |
|
975 |
|
976 /*! |
|
977 \fn QAccessibleValueInterface *QAccessibleInterface::valueInterface() |
|
978 \internal |
|
979 */ |
|
980 |
|
981 /*! |
|
982 \fn QAccessibleTableInterface *QAccessibleInterface::tableInterface() |
|
983 \internal |
|
984 */ |
|
985 |
|
986 /*! |
|
987 \class QAccessibleEvent |
|
988 \brief The QAccessibleEvent class is used to query addition |
|
989 accessibility information about complex widgets. |
|
990 |
|
991 The event can be of type QEvent::AccessibilityDescription or |
|
992 QEvent::AccessibilityHelp. |
|
993 |
|
994 Some QAccessibleInterface implementations send QAccessibleEvents |
|
995 to the widget they wrap to obtain the description or help text of |
|
996 a widget or of its children. The widget can answer by calling |
|
997 setValue() with the requested information. |
|
998 |
|
999 The default QWidget::event() implementation simply sets the text |
|
1000 to be the widget's \l{QWidget::toolTip}{tooltip} (for \l |
|
1001 AccessibilityDescription event) or its |
|
1002 \l{QWidget::whatsThis}{"What's This?" text} (for \l |
|
1003 AccessibilityHelp event). |
|
1004 |
|
1005 \ingroup accessibility |
|
1006 \ingroup events |
|
1007 */ |
|
1008 |
|
1009 /*! |
|
1010 \fn QAccessibleEvent::QAccessibleEvent(Type type, int child) |
|
1011 |
|
1012 Constructs an accessibility event of the given \a type, which |
|
1013 must be QEvent::AccessibilityDescription or |
|
1014 QEvent::AccessibilityHelp. |
|
1015 |
|
1016 \a child is the (1-based) index of the child to which the request |
|
1017 applies. If \a child is 0, the request is for the widget itself. |
|
1018 |
|
1019 \sa child() |
|
1020 */ |
|
1021 |
|
1022 /*! |
|
1023 \fn int QAccessibleEvent::child() const |
|
1024 |
|
1025 Returns the (1-based) index of the child to which the request |
|
1026 applies. If the child is 0, the request is for the widget itself. |
|
1027 */ |
|
1028 |
|
1029 /*! |
|
1030 \fn QString QAccessibleEvent::value() const |
|
1031 |
|
1032 Returns the text set using setValue(). |
|
1033 |
|
1034 \sa setValue() |
|
1035 */ |
|
1036 |
|
1037 /*! |
|
1038 \fn void QAccessibleEvent::setValue(const QString &text) |
|
1039 |
|
1040 Set the description or help text for the given child() to \a |
|
1041 text, thereby answering the request. |
|
1042 |
|
1043 \sa value() |
|
1044 */ |
|
1045 |
|
1046 /*! |
|
1047 \since 4.2 |
|
1048 |
|
1049 Invokes a \a method on \a child with the given parameters \a params |
|
1050 and returns the result of the operation as QVariant. |
|
1051 |
|
1052 Note that the type of the returned QVariant depends on the action. |
|
1053 |
|
1054 Returns an invalid QVariant if the object doesn't support the action. |
|
1055 */ |
|
1056 QVariant QAccessibleInterface::invokeMethod(Method method, int child, const QVariantList ¶ms) |
|
1057 { |
|
1058 if (!(state(0) & HasInvokeExtension)) |
|
1059 return QVariant(); |
|
1060 |
|
1061 return static_cast<QAccessibleInterfaceEx *>(this)->invokeMethodEx(method, child, params); |
|
1062 } |
|
1063 |
|
1064 QVariant QAccessibleInterfaceEx::virtual_hook(const QVariant &) |
|
1065 { |
|
1066 return QVariant(); |
|
1067 } |
|
1068 |
|
1069 /*! \internal */ |
|
1070 QAccessible2Interface *QAccessibleInterface::cast_helper(QAccessible2::InterfaceType t) |
|
1071 { |
|
1072 if (state(0) & HasInvokeExtension) |
|
1073 return static_cast<QAccessibleInterfaceEx *>(this)->interface_cast(t); |
|
1074 return 0; |
|
1075 } |
|
1076 |
|
1077 QT_END_NAMESPACE |
|
1078 |
|
1079 #endif |