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1 /**************************************************************************** |
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2 ** |
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3 ** Copyright (C) 2010 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 Qt Mobility Components. |
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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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27 ** |
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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 #include "qabstractvideosurface_p.h" |
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43 |
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44 QT_BEGIN_NAMESPACE |
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45 |
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46 /*! |
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47 \class QAbstractVideoSurface |
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48 \brief The QAbstractVideoSurface class is a base class for video presentation surfaces. |
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49 \since 4.6 |
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50 |
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51 The QAbstractVideoSurface class defines the standard interface that video producers use to |
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52 inter-operate with video presentation surfaces. It is not supposed to be instantiated directly. |
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53 Instead, you should subclass it to create new video surfaces. |
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54 |
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55 A video surface presents a continuous stream of identically formatted frames, where the format |
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56 of each frame is compatible with a stream format supplied when starting a presentation. |
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57 |
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58 A list of pixel formats a surface can present is given by the supportedPixelFormats() function, |
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59 and the isFormatSupported() function will test if a video surface format is supported. If a |
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60 format is not supported the nearestFormat() function may be able to suggest a similar format. |
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61 For example if a surface supports fixed set of resolutions it may suggest the smallest |
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62 supported resolution that contains the proposed resolution. |
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63 |
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64 The start() function takes a supported format and enables a video surface. Once started a |
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65 surface will begin displaying the frames it receives in the present() function. Surfaces may |
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66 hold a reference to the buffer of a presented video frame until a new frame is presented or |
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67 streaming is stopped. The stop() function will disable a surface and a release any video |
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68 buffers it holds references to. |
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69 */ |
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70 |
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71 /*! |
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72 \enum QAbstractVideoSurface::Error |
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73 This enum describes the errors that may be returned by the error() function. |
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74 |
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75 \value NoError No error occurred. |
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76 \value UnsupportedFormatError A video format was not supported. |
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77 \value IncorrectFormatError A video frame was not compatible with the format of the surface. |
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78 \value StoppedError The surface has not been started. |
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79 \value ResourceError The surface could not allocate some resource. |
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80 */ |
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81 |
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82 /*! |
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83 Constructs a video surface with the given \a parent. |
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84 */ |
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85 |
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86 QAbstractVideoSurface::QAbstractVideoSurface(QObject *parent) |
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87 : QObject(*new QAbstractVideoSurfacePrivate, parent) |
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88 { |
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89 } |
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90 |
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91 /*! |
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92 \internal |
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93 */ |
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94 |
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95 QAbstractVideoSurface::QAbstractVideoSurface(QAbstractVideoSurfacePrivate &dd, QObject *parent) |
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96 : QObject(dd, parent) |
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97 { |
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98 } |
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99 |
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100 /*! |
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101 Destroys a video surface. |
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102 */ |
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103 |
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104 QAbstractVideoSurface::~QAbstractVideoSurface() |
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105 { |
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106 } |
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107 |
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108 /*! |
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109 \fn QAbstractVideoSurface::supportedPixelFormats(QAbstractVideoBuffer::HandleType type) const |
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110 |
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111 Returns a list of pixel formats a video surface can present for a given handle \a type. |
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112 |
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113 The pixel formats returned for the QAbstractVideoBuffer::NoHandle type are valid for any buffer |
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114 that can be mapped in read-only mode. |
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115 |
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116 Types that are first in the list can be assumed to be faster to render. |
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117 */ |
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118 |
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119 /*! |
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120 Tests a video surface \a format to determine if a surface can accept it. |
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121 |
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122 Returns true if the format is supported by the surface, and false otherwise. |
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123 */ |
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124 |
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125 bool QAbstractVideoSurface::isFormatSupported(const QVideoSurfaceFormat &format) const |
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126 { |
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127 return supportedPixelFormats(format.handleType()).contains(format.pixelFormat()); |
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128 } |
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129 |
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130 /*! |
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131 Returns a supported video surface format that is similar to \a format. |
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132 |
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133 A similar surface format is one that has the same \l {QVideoSurfaceFormat::pixelFormat()}{pixel |
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134 format} and \l {QVideoSurfaceFormat::handleType()}{handle type} but differs in some of the other |
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135 properties. For example if there are restrictions on the \l {QVideoSurfaceFormat::frameSize()} |
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136 {frame sizes} a video surface can accept it may suggest a format with a larger frame size and |
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137 a \l {QVideoSurfaceFormat::viewport()}{viewport} the size of the original frame size. |
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138 |
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139 If the format is already supported it will be returned unchanged, or if there is no similar |
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140 supported format an invalid format will be returned. |
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141 */ |
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142 |
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143 QVideoSurfaceFormat QAbstractVideoSurface::nearestFormat(const QVideoSurfaceFormat &format) const |
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144 { |
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145 return isFormatSupported(format) |
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146 ? format |
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147 : QVideoSurfaceFormat(); |
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148 } |
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149 |
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150 /*! |
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151 \fn QAbstractVideoSurface::supportedFormatsChanged() |
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152 |
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153 Signals that the set of formats supported by a video surface has changed. |
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154 |
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155 \sa supportedPixelFormats(), isFormatSupported() |
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156 */ |
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157 |
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158 /*! |
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159 Returns the format of a video surface. |
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160 */ |
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161 |
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162 QVideoSurfaceFormat QAbstractVideoSurface::surfaceFormat() const |
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163 { |
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164 return d_func()->format; |
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165 } |
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166 |
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167 /*! |
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168 \fn QAbstractVideoSurface::surfaceFormatChanged(const QVideoSurfaceFormat &format) |
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169 |
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170 Signals that the configured \a format of a video surface has changed. |
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171 |
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172 \sa surfaceFormat(), start() |
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173 */ |
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174 |
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175 /*! |
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176 Starts a video surface presenting \a format frames. |
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177 |
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178 Returns true if the surface was started, and false if an error occurred. |
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179 |
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180 \sa isActive(), stop() |
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181 */ |
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182 |
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183 bool QAbstractVideoSurface::start(const QVideoSurfaceFormat &format) |
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184 { |
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185 Q_D(QAbstractVideoSurface); |
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186 |
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187 bool wasActive = d->active; |
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188 |
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189 d->active = true; |
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190 d->format = format; |
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191 d->error = NoError; |
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192 |
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193 emit surfaceFormatChanged(d->format); |
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194 |
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195 if (!wasActive) |
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196 emit activeChanged(true); |
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197 |
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198 return true; |
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199 } |
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200 |
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201 /*! |
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202 Stops a video surface presenting frames and releases any resources acquired in start(). |
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203 |
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204 \sa isActive(), start() |
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205 */ |
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206 |
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207 void QAbstractVideoSurface::stop() |
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208 { |
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209 Q_D(QAbstractVideoSurface); |
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210 |
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211 if (d->active) { |
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212 d->format = QVideoSurfaceFormat(); |
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213 d->active = false; |
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214 |
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215 emit activeChanged(false); |
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216 emit surfaceFormatChanged(d->format); |
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217 } |
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218 } |
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219 |
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220 /*! |
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221 Indicates whether a video surface has been started. |
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222 |
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223 Returns true if the surface has been started, and false otherwise. |
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224 */ |
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225 |
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226 bool QAbstractVideoSurface::isActive() const |
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227 { |
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228 return d_func()->active; |
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229 } |
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230 |
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231 /*! |
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232 \fn QAbstractVideoSurface::activeChanged(bool active) |
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233 |
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234 Signals that the \a active state of a video surface has changed. |
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235 |
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236 \sa isActive(), start(), stop() |
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237 */ |
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238 |
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239 /*! |
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240 \fn QAbstractVideoSurface::present(const QVideoFrame &frame) |
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241 |
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242 Presents a video \a frame. |
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243 |
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244 Returns true if the frame was presented, and false if an error occurred. |
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245 |
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246 Not all surfaces will block until the presentation of a frame has completed. Calling present() |
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247 on a non-blocking surface may fail if called before the presentation of a previous frame has |
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248 completed. In such cases the surface may not return to a ready state until it's had an |
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249 opportunity to process events. |
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250 |
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251 If present() fails for any other reason the surface will immediately enter the stopped state |
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252 and an error() value will be set. |
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253 |
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254 A video surface must be in the started state for present() to succeed, and the format of the |
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255 video frame must be compatible with the current video surface format. |
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256 |
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257 \sa error() |
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258 */ |
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259 |
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260 /*! |
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261 Returns the last error that occurred. |
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262 |
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263 If a surface fails to start(), or stops unexpectedly this function can be called to discover |
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264 what error occurred. |
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265 */ |
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266 |
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267 QAbstractVideoSurface::Error QAbstractVideoSurface::error() const |
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268 { |
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269 return d_func()->error; |
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270 } |
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271 |
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272 /*! |
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273 Sets the value of error() to \a error. |
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274 */ |
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275 |
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276 void QAbstractVideoSurface::setError(Error error) |
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277 { |
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278 Q_D(QAbstractVideoSurface); |
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279 |
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280 d->error = error; |
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281 } |
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282 |
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283 QT_END_NAMESPACE |