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qgesturerecognizer.cpp

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39 -

40 #include "qgesturerecognizer.h" -

41 -

42 #include "private/qgesture_p.h" -

43 #include "private/qgesturemanager_p.h" -

44 -

45 #ifndef QT_NO_GESTURES -

46 -

47 QT_BEGIN_NAMESPACE -

48 -

49 /*! -

50 \class QGestureRecognizer -

51 \since 4.6 -

52 \brief The QGestureRecognizer class provides the infrastructure for gesture recognition. -

53 \ingroup gestures -

54 \inmodule QtWidgets -

55 -

56 Gesture recognizers are responsible for creating and managing QGesture objects and -

57 monitoring input events sent to QWidget and QGraphicsObject subclasses. -

58 QGestureRecognizer is the base class for implementing custom gestures. -

59 -

60 Developers that only need to provide gesture recognition for standard gestures do not -

61 need to use this class directly. Instances will be created behind the scenes by the -

62 framework. -

63 -

64 For an overview of gesture handling in Qt and information on using gestures -

65 in your applications, see the \l{Gestures in Widgets and Graphics View} document. -

66 -

67 \section1 Recognizing Gestures -

68 -

69 The process of recognizing gestures involves filtering input events sent to specific -

70 objects, and modifying the associated QGesture objects to include relevant information -

71 about the user's input. -

72 -

73 Gestures are created when the framework calls create() to handle user input -

74 for a particular instance of a QWidget or QGraphicsObject subclass. A QGesture object -

75 is created for each widget or item that is configured to use gestures. -

76 -

77 Once a QGesture has been created for a target object, the gesture recognizer will -

78 receive events for it in its recognize() handler function. -

79 -

80 When a gesture is canceled, the reset() function is called, giving the recognizer the -

81 chance to update the appropriate properties in the corresponding QGesture object. -

82 -

83 \section1 Supporting New Gestures -

84 -

85 To add support for new gestures, you need to derive from QGestureRecognizer to create -

86 a custom recognizer class, construct an instance of this class, and register it with -

87 the application by calling QGestureRecognizer::registerRecognizer(). You can also -

88 subclass QGesture to create a custom gesture class, or rely on dynamic properties -

89 to express specific details of the gesture you want to handle. -

90 -

91 Your custom QGestureRecognizer subclass needs to reimplement the recognize() -

92 function to handle and filter the incoming input events for QWidget and -

93 QGraphicsObject subclasses. Although the logic for gesture recognition is -

94 implemented in this function, you can store persistent information about the -

95 state of the recognition process in the QGesture object supplied. The -

96 recognize() function must return a value of QGestureRecognizer::Result that -

97 indicates the state of recognition for a given gesture and target object. -

98 This determines whether or not a gesture event will be delivered to a target -

99 object. -

100 -

101 If you choose to represent a gesture by a custom QGesture subclass, you will need to -

102 reimplement the create() function to construct instances of your gesture class. -

103 Similarly, you may need to reimplement the reset() function if your custom gesture -

104 objects need to be specially handled when a gesture is canceled. -

105 -

106 \sa QGesture -

107 */ -

108 -

109 /*! -

110 \enum QGestureRecognizer::ResultFlag -

111 -

112 This enum describes the result of the current event filtering step in -

113 a gesture recognizer state machine. -

114 -

115 The result consists of a state value (one of Ignore, MayBeGesture, -

116 TriggerGesture, FinishGesture, CancelGesture) and an optional hint -

117 (ConsumeEventHint). -

118 -

119 \value Ignore The event does not change the state of the recognizer. -

120 -

121 \value MayBeGesture The event changed the internal state of the recognizer, -

122 but it isn't clear yet if it is a gesture or not. The recognizer needs to -

123 filter more events to decide. Gesture recognizers in the MayBeGesture state -

124 may be reset automatically if they take too long to recognize gestures. -

125 -

126 \value TriggerGesture The gesture has been triggered and the appropriate -

127 QGesture object will be delivered to the target as a part of a -

128 QGestureEvent. -

129 -

130 \value FinishGesture The gesture has been finished successfully and the -

131 appropriate QGesture object will be delivered to the target as a part of a -

132 QGestureEvent. -

133 -

134 \value CancelGesture The event made it clear that it is not a gesture. If -

135 the gesture recognizer was in GestureTriggered state before, then the -

136 gesture is canceled and the appropriate QGesture object will be delivered -

137 to the target as a part of a QGestureEvent. -

138 -

139 \value ConsumeEventHint This hint specifies that the gesture framework -

140 should consume the filtered event and not deliver it to the receiver. -

141 -

142 \omitvalue ResultState_Mask -

143 \omitvalue ResultHint_Mask -

144 -

145 \sa QGestureRecognizer::recognize() -

146 */ -

147 -

148 /*! -

149 Constructs a new gesture recognizer object. -

150 */ -

151 QGestureRecognizer::QGestureRecognizer() -

152 { -

153 } -

154 -

155 /*! -

156 Destroys the gesture recognizer. -

157 */ -

158 QGestureRecognizer::~QGestureRecognizer() -

159 { -

160 } -

161 -

162 /*! -

163 This function is called by Qt to create a new QGesture object for the -

164 given \a target (QWidget or QGraphicsObject). -

165 -

166 Reimplement this function to create a custom QGesture-derived gesture -

167 object if necessary. -

168 -

169 The application takes ownership of the created gesture object. -

170 */ -

171 QGesture *QGestureRecognizer::create(QObject *target) -

172 { -

173 Q_UNUSED(target); -

174

return new QGesture;

never executed: return new QGesture;

175 } -

176 -

177 /*! -

178 This function is called by the framework to reset a given \a gesture. -

179 -

180 Reimplement this function to implement additional requirements for custom QGesture -

181 objects. This may be necessary if you implement a custom QGesture whose properties -

182 need special handling when the gesture is reset. -

183 */ -

184 void QGestureRecognizer::reset(QGesture *gesture) -

185 { -

186

if (gesture) {

gesture	Description
TRUE	never evaluated
FALSE	never evaluated

187 QGesturePrivate *d = gesture->d_func(); -

188 d->state = Qt::NoGesture; -

189 d->hotSpot = QPointF(); -

190 d->sceneHotSpot = QPointF(); -

191 d->isHotSpotSet = false; -

192

}

never executed: end of block

193

}

never executed: end of block

194 -

195 /*! -

196 \fn QGestureRecognizer::recognize(QGesture *gesture, QObject *watched, QEvent *event) -

197 -

198 Handles the given \a event for the \a watched object, updating the state of the \a gesture -

199 object as required, and returns a suitable result for the current recognition step. -

200 -

201 This function is called by the framework to allow the recognizer to filter input events -

202 dispatched to QWidget or QGraphicsObject instances that it is monitoring. -

203 -

204 The result reflects how much of the gesture has been recognized. The state of the -

205 \a gesture object is set depending on the result. -

206 -

207 \sa QGestureRecognizer::Result -

208 */ -

209 -

210 /*! -

211 Registers the given \a recognizer in the gesture framework and returns a gesture ID -

212 for it. -

213 -

214 The application takes ownership of the \a recognizer and returns the gesture type -

215 ID associated with it. For gesture recognizers which handle custom QGesture -

216 objects (i.e., those which return Qt::CustomGesture in a QGesture::gestureType() -

217 function) the return value is a generated gesture ID with the Qt::CustomGesture -

218 flag set. -

219 -

220 \sa unregisterRecognizer(), QGestureRecognizer::create(), QGesture -

221 */ -

222 Qt::GestureType QGestureRecognizer::registerRecognizer(QGestureRecognizer *recognizer) -

223 { -

224

return QGestureManager::instance()->registerGestureRecognizer(recognizer);

never executed: return QGestureManager::instance()->registerGestureRecognizer(recognizer);

225 } -

226 -

227 /*! -

228 Unregisters all gesture recognizers of the specified \a type. -

229 -

230 \sa registerRecognizer() -

231 */ -

232 void QGestureRecognizer::unregisterRecognizer(Qt::GestureType type) -

233 { -

234 QGestureManager::instance()->unregisterGestureRecognizer(type); -

235

}

never executed: end of block

236 -

237 QT_END_NAMESPACE -

238 -

239 #endif // QT_NO_GESTURES -

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