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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 documentation 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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30 ** |
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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 /*! |
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43 \class QDesktopWidget |
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44 \brief The QDesktopWidget class provides access to screen information on multi-head systems. |
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45 |
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46 \ingroup advanced |
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47 \ingroup desktop |
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48 |
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49 Systems with more than one graphics card and monitor can manage the |
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50 physical screen space available either as multiple desktops, or as a |
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51 large virtual desktop. |
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52 |
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53 This class provides information about the user's desktop, such as its |
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54 total size, number of screens, the geometry of each screen, and whether |
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55 they are configured as separate desktops or a single virtual desktop. |
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56 |
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57 Widgets provided by Qt use this class to place tooltips, menus and |
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58 dialog boxes on the correct screen for their parent or application |
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59 widgets. Applications can use this class to obtain information that |
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60 can be used to save window positions, or to place child widgets and |
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61 dialogs on one particular screen. |
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62 |
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63 \section1 Obtaining a Desktop Widget |
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64 |
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65 The QApplication::desktop() function is used to get an instance of |
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66 QDesktopWidget. |
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67 |
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68 The widget's screenGeometry() function provides information about the |
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69 geometry of the available screens with. The number of screens |
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70 available is returned by screenCount, and the screenCountChanged() |
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71 signal is emitted when screens are added or removed. |
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72 The screen number that a particular point or widget is located in |
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73 is returned by screenNumber(). |
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74 |
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75 \section1 Screen Geometry |
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76 |
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77 To obtain the dimensions of a particular screen, call the screenGeometry() |
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78 function. On some desktop environments, not all of the screen is |
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79 available for applications to use; for example, an application dock or |
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80 menu bar may take up some space. Use the availableGeometry() function |
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81 to obtain the available area for applications. |
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82 |
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83 QDesktopWidget also inherits the QWidget properties, width() and |
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84 height(), which specify the size of the desktop. However, for |
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85 desktops with multiple screens, the size of the desktop is the union |
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86 of all the screen sizes, so width() and height() should \e not be |
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87 used for computing the size of a widget to be placed on one of the |
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88 screens. |
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89 |
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90 On systems that are configured to use the available screens as a |
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91 single, large virtual desktop, the virtualDesktop property will be |
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92 set to true. In this case, the widget's size is usually the size of |
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93 the bounding rectangle of all the screens. |
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94 |
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95 \section1 Use of the Primary Screen |
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96 |
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97 For an application, the screen where the main widget resides is the |
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98 primary screen. This is stored in the primaryScreen property. |
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99 All windows opened in the context of the application should be |
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100 constrained to the boundaries of the primary screen; for example, |
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101 it would be inconvenient if a dialog box popped up on a different |
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102 screen, or split over two screens. |
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103 |
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104 \image qdesktopwidget.png Managing Multiple Screens |
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105 |
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106 In the illustration above, Application One's primary screen is |
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107 screen 0, and App Two's primary screen is screen 1. |
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108 |
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109 \sa QApplication, QApplication::desktop(), QX11Info::appRootWindow() |
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110 */ |
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111 |
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112 /*! |
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113 \fn QDesktopWidget::QDesktopWidget() |
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114 |
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115 \internal |
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116 |
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117 Creates the desktop widget. |
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118 |
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119 If the system supports a virtual desktop, this widget will have |
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120 the size of the virtual desktop; otherwise this widget will have |
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121 the size of the primary screen. |
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122 |
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123 Instead of using QDesktopWidget directly, use QApplication::desktop(). |
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124 */ |
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125 |
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126 /*! |
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127 \fn QDesktopWidget::~QDesktopWidget() |
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128 |
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129 \internal |
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130 |
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131 Destroys the desktop widget and frees any allocated resources. |
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132 */ |
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133 |
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134 /*! |
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135 \fn int QDesktopWidget::numScreens() const |
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136 |
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137 Returns the number of available screens. |
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138 |
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139 \obsolete |
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140 |
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141 This function is deprecated. Use screenCount instead. |
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142 |
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143 \sa primaryScreen |
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144 */ |
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145 |
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146 /*! |
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147 \fn QWidget *QDesktopWidget::screen(int screen) |
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148 |
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149 Returns a widget that represents the screen with index \a screen |
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150 (a value of -1 means the default screen). |
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151 |
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152 If the system uses a virtual desktop, the returned widget will |
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153 have the geometry of the entire virtual desktop; i.e., bounding |
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154 every \a screen. |
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155 |
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156 \sa primaryScreen, screenCount, virtualDesktop |
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157 */ |
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158 |
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159 /*! |
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160 \fn const QRect QDesktopWidget::availableGeometry(int screen) const |
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161 |
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162 Returns the available geometry of the screen with index \a screen. What |
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163 is available will be subrect of screenGeometry() based on what the |
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164 platform decides is available (for example excludes the dock and menu bar |
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165 on Mac OS X, or the task bar on Windows). The default screen is used if |
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166 \a screen is -1. |
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167 |
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168 \sa screenNumber(), screenGeometry() |
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169 */ |
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170 |
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171 /*! |
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172 \fn const QRect QDesktopWidget::availableGeometry(const QWidget *widget) const |
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173 \overload |
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174 |
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175 Returns the available geometry of the screen which contains \a widget. |
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176 |
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177 \sa screenGeometry() |
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178 */ |
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179 |
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180 /*! |
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181 \fn const QRect QDesktopWidget::availableGeometry(const QPoint &p) const |
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182 \overload |
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183 |
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184 Returns the available geometry of the screen which contains \a p. |
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185 |
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186 \sa screenGeometry() |
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187 */ |
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188 |
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189 |
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190 /*! |
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191 \fn const QRect QDesktopWidget::screenGeometry(int screen) const |
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192 |
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193 Returns the geometry of the screen with index \a screen. The default |
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194 screen is used if \a screen is -1. |
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195 |
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196 \sa screenNumber() |
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197 */ |
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198 |
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199 /*! |
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200 \fn const QRect QDesktopWidget::screenGeometry(const QWidget *widget) const |
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201 \overload |
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202 |
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203 Returns the geometry of the screen which contains \a widget. |
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204 */ |
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205 |
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206 /*! |
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207 \fn const QRect QDesktopWidget::screenGeometry(const QPoint &p) const |
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208 \overload |
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209 |
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210 Returns the geometry of the screen which contains \a p. |
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211 */ |
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212 |
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213 |
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214 /*! |
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215 \fn int QDesktopWidget::screenNumber(const QWidget *widget) const |
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216 |
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217 Returns the index of the screen that contains the largest |
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218 part of \a widget, or -1 if the widget not on a screen. |
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219 |
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220 \sa primaryScreen |
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221 */ |
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222 |
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223 /*! |
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224 \fn int QDesktopWidget::screenNumber(const QPoint &point) const |
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225 |
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226 \overload |
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227 Returns the index of the screen that contains the \a point, or the |
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228 screen which is the shortest distance from the \a point. |
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229 |
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230 \sa primaryScreen |
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231 */ |
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232 |
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233 /*! |
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234 \fn void QDesktopWidget::resizeEvent(QResizeEvent *event) |
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235 \reimp |
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236 */ |
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237 |
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238 /*! |
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239 \fn void QDesktopWidget::resized(int screen) |
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240 |
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241 This signal is emitted when the size of \a screen changes. |
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242 */ |
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243 |
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244 /*! |
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245 \fn void QDesktopWidget::workAreaResized(int screen) |
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246 |
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247 This signal is emitted when the work area available on \a screen changes. |
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248 */ |
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249 |
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250 /*! |
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251 \property QDesktopWidget::screenCount |
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252 \brief the number of screens currently available on the system. |
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253 |
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254 \since 4.6 |
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255 |
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256 \sa screenCountChanged() |
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257 */ |
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258 |
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259 /*! |
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260 \property QDesktopWidget::primaryScreen |
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261 \brief the index of the screen that is configured to be the primary screen |
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262 on the system. |
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263 */ |
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264 |
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265 /*! |
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266 \property QDesktopWidget::virtualDesktop |
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267 |
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268 \brief if the system manages the available screens in a virtual desktop. |
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269 |
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270 For virtual desktops, screen() will always return the same widget. |
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271 The size of the virtual desktop is the size of this desktop |
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272 widget. |
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273 */ |
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274 |
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275 /*! |
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276 \fn void QDesktopWidget::screenCountChanged(int newCount) |
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277 |
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278 \since 4.6 |
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279 |
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280 This signal is emitted when the number of screens changes to \a newCount. |
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281 |
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282 \sa screenCount |
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283 */ |