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kernel/qgesturerecognizer.cpp

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41 -

42 #include "qgesturerecognizer.h" -

43 -

44 #include "private/qgesture_p.h" -

45 #include "private/qgesturemanager_p.h" -

46 -

47 #ifndef QT_NO_GESTURES -

48 -

49 QT_BEGIN_NAMESPACE -

50 -

51 /*! -

52 \class QGestureRecognizer -

53 \since 4.6 -

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

55 \ingroup gestures -

56 \inmodule QtWidgets -

57 -

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

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

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

61 -

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

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

64 framework. -

65 -

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

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

68 -

69 \section1 Recognizing Gestures -

70 -

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

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

73 about the user's input. -

74 -

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

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

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

78 -

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

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

81 -

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

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

84 -

85 \section1 Supporting New Gestures -

86 -

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

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

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

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

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

92 -

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

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

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

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

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

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

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

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

101 object. -

102 -

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

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

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

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

107 -

108 \sa QGesture -

109 */ -

110 -

111 /*! -

112 \enum QGestureRecognizer::ResultFlag -

113 -

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

115 a gesture recognizer state machine. -

116 -

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

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

119 (ConsumeEventHint). -

120 -

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

122 -

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

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

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

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

127 -

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

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

130 QGestureEvent. -

131 -

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

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

134 QGestureEvent. -

135 -

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

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

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

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

140 -

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

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

143 -

144 \omitvalue ResultState_Mask -

145 \omitvalue ResultHint_Mask -

146 -

147 \sa QGestureRecognizer::recognize() -

148 */ -

149 -

150 /*! -

151 Constructs a new gesture recognizer object. -

152 */ -

153 QGestureRecognizer::QGestureRecognizer() -

154 { -

155 } -

156 -

157 /*! -

158 Destroys the gesture recognizer. -

159 */ -

160 QGestureRecognizer::~QGestureRecognizer() -

161 { -

162 } -

163 -

164 /*! -

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

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

167 -

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

169 object if necessary. -

170 -

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

172 */ -

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

174 { -

175

Q_UNUSED(target);

never executed (the execution status of this line is deduced): (void)target;;

176

return new QGesture;

never executed: return new QGesture;

177 } -

178 -

179 /*! -

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

181 -

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

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

184 need special handling when the gesture is reset. -

185 */ -

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

187 { -

188

if (gesture) {

partially evaluated: gesture

TRUE	FALSE
yes Evaluation Count:87	no Evaluation Count:0

0-87

189

QGesturePrivate *d = gesture->d_func();

executed (the execution status of this line is deduced): QGesturePrivate *d = gesture->d_func();

190

d->state = Qt::NoGesture;

executed (the execution status of this line is deduced): d->state = Qt::NoGesture;

191

d->hotSpot = QPointF();

executed (the execution status of this line is deduced): d->hotSpot = QPointF();

192

d->sceneHotSpot = QPointF();

executed (the execution status of this line is deduced): d->sceneHotSpot = QPointF();

193

d->isHotSpotSet = false;

executed (the execution status of this line is deduced): d->isHotSpotSet = false;

194

}

executed: }

Execution Count:87

195

}

executed: }

Execution Count:87

196 -

197 /*! -

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

199 -

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

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

202 -

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

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

205 -

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

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

208 -

209 \sa QGestureRecognizer::Result -

210 */ -

211 -

212 /*! -

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

214 for it. -

215 -

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

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

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

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

220 flag set. -

221 -

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

223 */ -

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

225 { -

226

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

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

Execution Count:19

227 } -

228 -

229 /*! -

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

231 -

232 \sa registerRecognizer() -

233 */ -

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

235 { -

236

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

executed (the execution status of this line is deduced): QGestureManager::instance()->unregisterGestureRecognizer(type);

237

}

executed: }

Execution Count:21

238 -

239 QT_END_NAMESPACE -

240 -

241 #endif // QT_NO_GESTURES -

242 -

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