Added a property to QPinchGesture to specify what exactly changed.

Added QPinchGesture::whatChanged() which specifies which property in the pinch
gesture changed - the scale factor or rotation angle or both.

Reviewed-by: Bradley T. Hughes

4 files changed, 34 insertions, 3 deletions

diff --git a/examples/gestures/imageviewer/imagewidget.cpp b/examples/gestures/imageviewer/imagewidget.cpp
index a4ea238d05..c71c461a75 100644
--- a/examples/gestures/imageviewer/imagewidget.cpp
+++ b/examples/gestures/imageviewer/imagewidget.cpp
@@ -123,9 +123,9 @@ void ImageWidget::panTriggered()
 void ImageWidget::pinchTriggered()
 {
     QPinchGesture *pg = qobject_cast<QPinchGesture*>(sender());
-    if (pg->rotationAngle() != 0.0)
+    if (pg->whatChanged() & QPinchGesture::RotationAngleChanged)
         rotationAngle += pg->rotationAngle() - pg->lastRotationAngle();
-    if (pg->scaleFactor() != 1.0)
+    if (pg->whatChanged() & QPinchGesture::ScaleFactorChanged)
         scaleFactor += pg->scaleFactor() - pg->lastScaleFactor();
     update();
 }
diff --git a/src/gui/kernel/qstandardgestures.cpp b/src/gui/kernel/qstandardgestures.cpp
index 783c1d3e28..8e76715ba7 100644
--- a/src/gui/kernel/qstandardgestures.cpp
+++ b/src/gui/kernel/qstandardgestures.cpp
@@ -413,6 +413,7 @@ bool QPinchGesture::eventFilter(QObject *receiver, QEvent *event)
             // next we might receive the first gesture update event, so we
             // prepare for it.
             d->state = Qt::NoGesture;
+            d->changes = 0;
             d->totalScaleFactor = d->scaleFactor = d->lastScaleFactor = 1.;
             d->totalRotationAngle = d->rotationAngle = d->lastRotationAngle = 0.;
             d->startCenterPoint = d->centerPoint = d->lastCenterPoint = QPointF();
@@ -460,6 +461,7 @@ bool QPinchGesture::eventFilter(QObject *receiver, QEvent *event)
             if (!windowsRotateWorkaround)
                 nextState = Qt::GestureUpdated;
 #endif
+            d->changes = QPinchGesture::RotationAngleChanged;
             event->accept();
             break;
         }
@@ -484,6 +486,7 @@ bool QPinchGesture::eventFilter(QObject *receiver, QEvent *event)
             d->scaleFactor += ev->percentage;
 #endif
             nextState = Qt::GestureUpdated;
+            d->changes = QPinchGesture::ScaleFactorChanged;
             event->accept();
             break;
         case QNativeGestureEvent::GestureEnd:
@@ -498,6 +501,8 @@ bool QPinchGesture::eventFilter(QObject *receiver, QEvent *event)
             d->startCenterPoint = d->centerPoint;
         d->lastCenterPoint = d->centerPoint;
         d->centerPoint = static_cast<QWidget*>(receiver)->mapFromGlobal(ev->position);
+        if (d->lastCenterPoint != d->centerPoint)
+            d->changes |= QPinchGesture::CenterPointChanged;
         updateState(nextState);
         return true;
     }
@@ -523,6 +528,7 @@ bool QPinchGesture::filterEvent(QEvent *event)
 void QPinchGesture::reset()
 {
     Q_D(QPinchGesture);
+    d->changes = 0;
     d->totalScaleFactor = d->scaleFactor = d->lastScaleFactor = 1.;
     d->totalRotationAngle = d->rotationAngle = d->lastRotationAngle = 0.;
     d->startCenterPoint = d->centerPoint = d->lastCenterPoint = QPointF();
@@ -530,6 +536,16 @@ void QPinchGesture::reset()
 }
 
 /*!
+    \property QPinchGesture::whatChanged
+
+    Specifies which values were changed in the gesture.
+*/
+QPinchGesture::WhatChanged QPinchGesture::whatChanged() const
+{
+    return d_func()->changes;
+}
+
+/*!
     \property QPinchGesture::totalScaleFactor
 
     Specifies a total scale factor of the pinch gesture since the gesture
diff --git a/src/gui/kernel/qstandardgestures.h b/src/gui/kernel/qstandardgestures.h
index c6dfa925eb..53c4416abf 100644
--- a/src/gui/kernel/qstandardgestures.h
+++ b/src/gui/kernel/qstandardgestures.h
@@ -89,6 +89,16 @@ class Q_GUI_EXPORT QPinchGesture : public QGesture
     Q_OBJECT
     Q_DECLARE_PRIVATE(QPinchGesture)
 
+public:
+    enum WhatChange {
+        ScaleFactorChanged = 0x1,
+        RotationAngleChanged = 0x2,
+        CenterPointChanged = 0x4
+    };
+    Q_DECLARE_FLAGS(WhatChanged, WhatChange)
+
+    Q_PROPERTY(WhatChanged whatChanged READ whatChanged)
+
     Q_PROPERTY(qreal totalScaleFactor READ totalScaleFactor)
     Q_PROPERTY(qreal lastScaleFactor READ lastScaleFactor)
     Q_PROPERTY(qreal scaleFactor READ scaleFactor)
@@ -102,11 +112,14 @@ class Q_GUI_EXPORT QPinchGesture : public QGesture
     Q_PROPERTY(QPointF centerPoint READ centerPoint)
 
 public:
+
     QPinchGesture(QWidget *gestureTarget, QObject *parent = 0);
 
     bool filterEvent(QEvent *event);
     void reset();
 
+    WhatChanged whatChanged() const;
+
     QPointF startCenterPoint() const;
     QPointF lastCenterPoint() const;
     QPointF centerPoint() const;
diff --git a/src/gui/kernel/qstandardgestures_p.h b/src/gui/kernel/qstandardgestures_p.h
index 9e235155cf..354ebeeaa7 100644
--- a/src/gui/kernel/qstandardgestures_p.h
+++ b/src/gui/kernel/qstandardgestures_p.h
@@ -89,7 +89,7 @@ class QPinchGesturePrivate : public QGesturePrivate
 
 public:
     QPinchGesturePrivate()
-        : totalScaleFactor(0.), lastScaleFactor(0.), scaleFactor(0.),
+        : changes(0), totalScaleFactor(0.), lastScaleFactor(0.), scaleFactor(0.),
           totalRotationAngle(0.), lastRotationAngle(0.), rotationAngle(0.)
 #ifdef Q_WS_WIN
           ,initialDistance(0), lastSequenceId(0)
@@ -99,6 +99,8 @@ public:
 
     void setupGestureTarget(QObject *o);
 
+    QPinchGesture::WhatChanged changes;
+
     qreal totalScaleFactor; // total scale factor, excluding the current sequence.
     qreal lastScaleFactor;
     qreal scaleFactor; // scale factor in the current sequence.