qgesturerecognizer.cpp

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33 -

34 #include "qgesturerecognizer.h" -

35 -

36 #include "private/qgesture_p.h" -

37 #include "private/qgesturemanager_p.h" -

38 -

39 #ifndef QT_NO_GESTURES -

40 -

41 QT_BEGIN_NAMESPACE -

42 -

43 /*! -

44 \class QGestureRecognizer -

45 \since 4.6 -

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

47 \ingroup gestures -

48 \inmodule QtWidgets -

49 -

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

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

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

53 -

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

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

56 framework. -

57 -

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

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

60 -

61 \section1 Recognizing Gestures -

62 -

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

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

65 about the user's input. -

66 -

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

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

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

70 -

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

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

73 -

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

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

76 -

77 \section1 Supporting New Gestures -

78 -

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

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

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

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

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

84 -

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

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

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

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

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

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

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

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

93 object. -

94 -

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

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

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

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

99 -

100 \sa QGesture -

101 */ -

102 -

103 /*! -

104 \enum QGestureRecognizer::ResultFlag -

105 -

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

107 a gesture recognizer state machine. -

108 -

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

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

111 (ConsumeEventHint). -

112 -

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

114 -

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

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

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

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

119 -

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

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

122 QGestureEvent. -

123 -

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

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

126 QGestureEvent. -

127 -

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

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

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

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

132 -

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

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

135 -

136 \omitvalue ResultState_Mask -

137 \omitvalue ResultHint_Mask -

138 -

139 \sa QGestureRecognizer::recognize() -

140 */ -

141 -

142 /*! -

143 Constructs a new gesture recognizer object. -

144 */ -

145 QGestureRecognizer::QGestureRecognizer() -

146 { -

147 } -

148 -

149 /*! -

150 Destroys the gesture recognizer. -

151 */ -

152 QGestureRecognizer::~QGestureRecognizer() -

153 { -

154 } -

155 -

156 /*! -

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

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

159 -

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

161 object if necessary. -

162 -

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

164 */ -

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

166 { -

167 Q_UNUSED(target); -

168

return new QGesture;

never executed: return new QGesture;

169 } -

170 -

171 /*! -

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

173 -

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

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

176 need special handling when the gesture is reset. -

177 */ -

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

179 { -

180

if (gesture) {

gesture	Description
TRUE	never evaluated
FALSE	never evaluated

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

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

183 d->hotSpot = QPointF(); -

184 d->sceneHotSpot = QPointF(); -

185 d->isHotSpotSet = false; -

186

}

never executed: end of block

187

}

never executed: end of block

188 -

189 /*! -

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

191 -

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

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

194 -

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

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

197 -

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

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

200 -

201 \sa QGestureRecognizer::Result -

202 */ -

203 -

204 /*! -

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

206 for it. -

207 -

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

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

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

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

212 flag set. -

213 -

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

215 */ -

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

217 { -

218

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

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

219 } -

220 -

221 /*! -

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

223 -

224 \sa registerRecognizer() -

225 */ -

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

227 { -

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

229

}

never executed: end of block

230 -

231 QT_END_NAMESPACE -

232 -

233 #endif // QT_NO_GESTURES -

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