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QPinchGesture Class Reference
[QtGui module]

The QPinchGesture class describes a pinch gesture made my the user. More...

 #include <QPinchGesture>

Inherits QGesture.

This class was introduced in Qt 4.6.

• List of all members, including inherited members

Public Types

Properties

• 5 properties inherited from QGesture
• 1 property inherited from QObject

Public Functions

• 8 public functions inherited from QGesture
• 29 public functions inherited from QObject

Additional Inherited Members

• 1 public slot inherited from QObject
• 1 signal inherited from QObject
• 5 static public members inherited from QObject
• 7 protected functions inherited from QObject

Detailed Description

The QPinchGesture class describes a pinch gesture made my the user.

A pinch gesture is a form of multitouch user input in which the user typically touches two points on the input device with a thumb and finger, before moving them closer together or further apart to change the scale factor, zoom, or level of detail of the user interface.

Instead of repeatedly applying the same pinching gesture, the user may continue to touch the input device in one place, and apply a second touch to a new point, continuing the gesture. When this occurs, gesture events will continue to be delivered to the target object, containing an instance of QPinchGesture in the Qt::GestureUpdated state.

See also Gestures Programming, QPanGesture, and QSwipeGesture.

Member Type Documentation

enum QPinchGesture::ChangeFlag
flags QPinchGesture::ChangeFlags

This enum describes the changes that can occur to the properties of the gesture object.

The ChangeFlags type is a typedef for QFlags<ChangeFlag>. It stores an OR combination of ChangeFlag values.

See also changeFlags and totalChangeFlags.

Property Documentation

centerPoint : QPointF

This property holds the current center point.

The center point is the midpoint between the two input points in the gesture.

Access functions:

See also startCenterPoint and lastCenterPoint.

changeFlags : ChangeFlags

This property holds the property of the gesture that has changed in the current step.

This property indicates which of the other properties has changed since the previous gesture event included information about this gesture. You can use this information to determine which aspect of your user interface needs to be updated.

Access functions:

See also totalChangeFlags, scaleFactor, rotationAngle, and centerPoint.

lastCenterPoint : QPointF

This property holds the last position of the center point recorded for this gesture.

Access functions:

See also centerPoint and startCenterPoint.

lastRotationAngle : qreal

This property holds the last reported angle covered by the gesture motion.

The last rotation angle is the angle as reported in the rotationAngle property when a previous gesture event was delivered for this gesture.

Access functions:

See also rotationAngle and totalRotationAngle.

lastScaleFactor : qreal

This property holds the last scale factor recorded for this gesture.

The last scale factor contains the scale factor reported in the scaleFactor property when a previous gesture event included information about this gesture.

If no previous event was delivered with information about this gesture (i.e., this gesture object contains information about the first movement in the gesture) then this property contains zero.

Access functions:

See also scaleFactor and totalScaleFactor.

rotationAngle : qreal

This property holds the angle covered by the gesture motion.

Access functions:

See also totalRotationAngle and lastRotationAngle.

scaleFactor : qreal

This property holds the current scale factor.

The scale factor measures the scale factor associated with the distance between two of the user's inputs on a multitouch device.

Access functions:

See also totalScaleFactor and lastScaleFactor.

startCenterPoint : QPointF

This property holds the starting position of the center point.

Access functions:

See also centerPoint and lastCenterPoint.

totalChangeFlags : ChangeFlags

This property holds the property of the gesture that has change.

This property indicates which of the other properties has changed since the gesture has started. You can use this information to determine which aspect of your user interface needs to be updated.

Access functions:

See also changeFlags, scaleFactor, rotationAngle, and centerPoint.

totalRotationAngle : qreal

This property holds the total angle covered by the gesture.

This total angle measures the complete angle covered by the gesture. Usually, this is equal to the value held by the rotationAngle property, except in the case where the user performs multiple rotations by removing and repositioning one of the touch points, as described above. In this case, the total angle will be the sum of the rotation angles for the multiple stages of the gesture.

Access functions:

See also rotationAngle and lastRotationAngle.

totalScaleFactor : qreal

This property holds the total scale factor.

The total scale factor measures the total change in scale factor from the original value to the current scale factor.

Access functions:

See also scaleFactor and lastScaleFactor.