Improved the gesture api.

Made properties in QPanGesture and QPinchGesture more consistent - all of them
have value, lastValue and totalValue. Documented that totalValue means the
value from the beginning of the gesture, while the 'value' - from the beginning
of the current sequence. This is especially useful on Windows when you zoom
with two fingers and then release one finger and touch again to continue
zooming.

Also added a workaround for native Rotate gesture on Windows which contain a
'bad' value in the first WM_GESTURE message in every gesture sequence.

Reviewed-by: Bradley T. Hughes

5 files changed, 150 insertions, 43 deletions

diff --git a/examples/gestures/imageviewer/imagewidget.cpp b/examples/gestures/imageviewer/imagewidget.cpp
index 7dbd084..a4ea238 100644
--- a/examples/gestures/imageviewer/imagewidget.cpp
+++ b/examples/gestures/imageviewer/imagewidget.cpp
@@ -123,8 +123,10 @@ void ImageWidget::panTriggered()
 void ImageWidget::pinchTriggered()
 {
     QPinchGesture *pg = qobject_cast<QPinchGesture*>(sender());
-    rotationAngle += pg->rotationAngle();
-    scaleFactor += pg->scaleFactor();
+    if (pg->rotationAngle() != 0.0)
+        rotationAngle += pg->rotationAngle() - pg->lastRotationAngle();
+    if (pg->scaleFactor() != 1.0)
+        scaleFactor += pg->scaleFactor() - pg->lastScaleFactor();
     update();
 }
 
diff --git a/src/gui/kernel/qstandardgestures.cpp b/src/gui/kernel/qstandardgestures.cpp
index f6534d1..783c1d3 100644
--- a/src/gui/kernel/qstandardgestures.cpp
+++ b/src/gui/kernel/qstandardgestures.cpp
@@ -47,6 +47,7 @@
 #include <private/qapplication_p.h>
 #include <private/qevent_p.h>
 #include <private/qwidget_p.h>
+#include <qmath.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -172,11 +173,12 @@ bool QPanGesture::eventFilter(QObject *receiver, QEvent *event)
             return false;
         }
         if (state() == Qt::NoGesture) {
-            d->lastOffset = d->totalOffset = QSize();
+            d->lastOffset = d->totalOffset = d->offset = QSize();
         } else {
-            d->lastOffset = QSize(ev->position.x() - d->lastPosition.x(),
-                                  ev->position.y() - d->lastPosition.y());
-            d->totalOffset += d->lastOffset;
+            d->lastOffset = d->offset;
+            d->offset = QSize(ev->position.x() - d->lastPosition.x(),
+                              ev->position.y() - d->lastPosition.y());
+            d->totalOffset += d->offset;
         }
         d->lastPosition = ev->position;
         updateState(nextState);
@@ -201,16 +203,17 @@ bool QPanGesture::filterEvent(QEvent *event)
     if (event->type() == QEvent::TouchBegin) {
         QTouchEvent::TouchPoint p = ev->touchPoints().at(0);
         d->lastPosition = p.pos().toPoint();
-        d->lastOffset = d->totalOffset = QSize();
+        d->lastOffset = d->totalOffset = d->offset = QSize();
     } else if (event->type() == QEvent::TouchEnd) {
         if (state() != Qt::NoGesture) {
             if (ev->touchPoints().size() == 2) {
                 QTouchEvent::TouchPoint p1 = ev->touchPoints().at(0);
                 QTouchEvent::TouchPoint p2 = ev->touchPoints().at(1);
-                d->lastOffset =
+                d->lastOffset = d->offset;
+                d->offset =
                         QSize(p1.pos().x() - p1.lastPos().x() + p2.pos().x() - p2.lastPos().x(),
                               p1.pos().y() - p1.lastPos().y() + p2.pos().y() - p2.lastPos().y()) / 2;
-                d->totalOffset += d->lastOffset;
+                d->totalOffset += d->offset;
             }
             updateState(Qt::GestureFinished);
         }
@@ -219,10 +222,11 @@ bool QPanGesture::filterEvent(QEvent *event)
         if (ev->touchPoints().size() == 2) {
             QTouchEvent::TouchPoint p1 = ev->touchPoints().at(0);
             QTouchEvent::TouchPoint p2 = ev->touchPoints().at(1);
-            d->lastOffset =
+            d->lastOffset = d->offset;
+            d->offset =
                     QSize(p1.pos().x() - p1.lastPos().x() + p2.pos().x() - p2.lastPos().x(),
                           p1.pos().y() - p1.lastPos().y() + p2.pos().y() - p2.lastPos().y()) / 2;
-            d->totalOffset += d->lastOffset;
+            d->totalOffset += d->offset;
             if (d->totalOffset.width() > 10  || d->totalOffset.height() > 10 ||
                 d->totalOffset.width() < -10 || d->totalOffset.height() < -10) {
                 updateState(Qt::GestureUpdated);
@@ -264,8 +268,9 @@ bool QPanGesture::filterEvent(QEvent *event)
                 QPointF mousePos = QCursor::pos();
                 QPointF dist = mousePos - d->lastPosition;
                 d->lastPosition = mousePos;
-                d->lastOffset = QSizeF(dist.x(), dist.y());
-                d->totalOffset += d->lastOffset;
+                d->lastOffset = d->offset;
+                d->offset = QSizeF(dist.x(), dist.y());
+                d->totalOffset += d->offset;
                 updateState(Qt::GestureUpdated);
             }
         } else if (state() == Qt::NoGesture) {
@@ -285,7 +290,7 @@ bool QPanGesture::filterEvent(QEvent *event)
 void QPanGesture::reset()
 {
     Q_D(QPanGesture);
-    d->lastOffset = d->totalOffset = QSize(0, 0);
+    d->lastOffset = d->totalOffset = d->offset = QSize(0, 0);
     d->lastPosition = QPoint(0, 0);
 
 #if defined(QT_MAC_USE_COCOA)
@@ -310,8 +315,7 @@ QSizeF QPanGesture::totalOffset() const
 /*!
     \property QPanGesture::lastOffset
 
-    Specifies a pan offset since the last time the gesture was
-    triggered.
+    Specifies a pan offset the last time the gesture was triggered.
 */
 QSizeF QPanGesture::lastOffset() const
 {
@@ -319,6 +323,18 @@ QSizeF QPanGesture::lastOffset() const
     return d->lastOffset;
 }
 
+/*!
+    \property QPanGesture::offset
+
+    Specifies the current pan offset since the last time the gesture was
+    triggered.
+*/
+QSizeF QPanGesture::offset() const
+{
+    Q_D(const QPanGesture);
+    return d->offset;
+}
+
 //////////////////////////////////////////////////////////////////////////////
 
 /*!
@@ -397,37 +413,75 @@ 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->scaleFactor = d->lastScaleFactor = 1;
-            d->rotationAngle = d->lastRotationAngle = 0;
+            d->totalScaleFactor = d->scaleFactor = d->lastScaleFactor = 1.;
+            d->totalRotationAngle = d->rotationAngle = d->lastRotationAngle = 0.;
             d->startCenterPoint = d->centerPoint = d->lastCenterPoint = QPointF();
 #if defined(Q_WS_WIN)
             d->initialDistance = 0;
+            d->lastSequenceId = ev->sequenceId;
 #endif
             return false;
-        case QNativeGestureEvent::Rotate:
-            d->scaleFactor = 0;
+        case QNativeGestureEvent::Rotate: {
+            d->lastScaleFactor = d->scaleFactor;
             d->lastRotationAngle = d->rotationAngle;
-#if defined(Q_WS_WIN)
-            d->rotationAngle = -1 * GID_ROTATE_ANGLE_FROM_ARGUMENT(ev->argument);
-#elif defined(Q_WS_MAC)
-            d->rotationAngle = ev->percentage;
-#endif
+#if defined(Q_WS_MAC)
+            d->rotationAngle += ev->percentage;
             nextState = Qt::GestureUpdated;
+#elif defined(Q_WS_WIN)
+            // This is a workaround for an issue with the native rotation
+            // gesture on Windows 7. For some reason the rotation angle in the
+            // first WM_GESTURE message in a sequence contains value that is
+            // off a little bit and causes the rotating item to "jump", so
+            // we just ignore the first WM_GESTURE in every sequence.
+            bool windowsRotateWorkaround = false;
+            if (!d->lastSequenceId) {
+                windowsRotateWorkaround = true;
+                d->lastSequenceId = ev->sequenceId;
+            }
+            if (d->lastSequenceId > 0 && d->lastSequenceId != (ulong)-1 && ev->sequenceId != d->lastSequenceId) {
+                // this is the first WM_GESTURE message in a sequence.
+                d->totalRotationAngle += d->rotationAngle;
+                windowsRotateWorkaround = true;
+                // a magic value to mark that the next WM_GESTURE message is
+                // the second message in a sequence and we should clear the
+                // lastRotationAngle
+                d->lastSequenceId = (ulong)-1;
+            }
+            if (!windowsRotateWorkaround) {
+                d->rotationAngle = -1 * GID_ROTATE_ANGLE_FROM_ARGUMENT(ev->argument) * 180. / M_PI;
+                if (d->lastSequenceId == (ulong)-1) {
+                    // a special case since we need to set the lastRotationAngle to
+                    // rotationAngle when the first WM_GESTURE is received in each
+                    // sequence.
+                    d->lastRotationAngle = d->rotationAngle;
+                }
+                d->lastSequenceId = ev->sequenceId;
+            }
+            if (!windowsRotateWorkaround)
+                nextState = Qt::GestureUpdated;
+#endif
             event->accept();
             break;
+        }
         case QNativeGestureEvent::Zoom:
-            d->rotationAngle = 0;
+            d->lastRotationAngle = d->rotationAngle;
+            d->lastScaleFactor = d->scaleFactor;
 #if defined(Q_WS_WIN)
             if (d->initialDistance != 0) {
-                d->lastScaleFactor = d->scaleFactor;
                 int distance = int(qint64(ev->argument));
-                d->scaleFactor = (qreal) distance / d->initialDistance;
+                if (d->lastSequenceId && ev->sequenceId != d->lastSequenceId) {
+                    d->totalScaleFactor *= d->scaleFactor;
+                    d->initialDistance = int(qint64(ev->argument));
+                    d->lastScaleFactor = d->scaleFactor = (qreal) distance / d->initialDistance;
+                } else {
+                    d->scaleFactor = (qreal) distance / d->initialDistance;
+                }
+                d->lastSequenceId = ev->sequenceId;
             } else {
                 d->initialDistance = int(qint64(ev->argument));
             }
 #elif defined(Q_WS_MAC)
-            d->lastScaleFactor = d->scaleFactor;
-            d->scaleFactor = ev->percentage;
+            d->scaleFactor += ev->percentage;
 #endif
             nextState = Qt::GestureUpdated;
             event->accept();
@@ -469,16 +523,33 @@ bool QPinchGesture::filterEvent(QEvent *event)
 void QPinchGesture::reset()
 {
     Q_D(QPinchGesture);
-    d->scaleFactor = d->lastScaleFactor = 0;
-    d->rotationAngle = d->lastRotationAngle = 0;
+    d->totalScaleFactor = d->scaleFactor = d->lastScaleFactor = 1.;
+    d->totalRotationAngle = d->rotationAngle = d->lastRotationAngle = 0.;
     d->startCenterPoint = d->centerPoint = d->lastCenterPoint = QPointF();
     QGesture::reset();
 }
 
 /*!
+    \property QPinchGesture::totalScaleFactor
+
+    Specifies a total scale factor of the pinch gesture since the gesture
+    started.
+*/
+qreal QPinchGesture::totalScaleFactor() const
+{
+    Q_D(const QPinchGesture);
+    return d->totalScaleFactor * d->scaleFactor;
+}
+
+/*!
     \property QPinchGesture::scaleFactor
 
     Specifies a scale factor of the pinch gesture.
+
+    If the gesture consists of several pinch sequences (i.e. zoom and rotate
+    sequences), then this property specifies the scale factor in the current
+    sequence. When pinching changes the rotation angle only, the value of this
+    property is 1.
 */
 qreal QPinchGesture::scaleFactor() const
 {
@@ -496,9 +567,29 @@ qreal QPinchGesture::lastScaleFactor() const
 }
 
 /*!
+    \property QPinchGesture::totalRotationAngle
+
+    Specifies a total rotation angle of the gesture since the gesture started.
+
+    The angle is specified in degrees.
+*/
+qreal QPinchGesture::totalRotationAngle() const
+{
+    Q_D(const QPinchGesture);
+    return d->totalRotationAngle + d->rotationAngle;
+}
+
+/*!
     \property QPinchGesture::rotationAngle
 
     Specifies a rotation angle of the gesture.
+
+    If the gesture consists of several pinch sequences (i.e. zoom and rotate
+    sequences), then this property specifies the rotation angle in the current
+    sequence. When pinching changes the scale factor only, the value of this
+    property is 0.
+
+    The angle is specified in degrees.
 */
 qreal QPinchGesture::rotationAngle() const
 {
@@ -509,6 +600,8 @@ qreal QPinchGesture::rotationAngle() const
     \property QPinchGesture::lastRotationAngle
 
     Specifies a previous rotation angle of the gesture.
+
+    The angle is specified in degrees.
 */
 qreal QPinchGesture::lastRotationAngle() const
 {
diff --git a/src/gui/kernel/qstandardgestures.h b/src/gui/kernel/qstandardgestures.h
index 33166fe..c6dfa92 100644
--- a/src/gui/kernel/qstandardgestures.h
+++ b/src/gui/kernel/qstandardgestures.h
@@ -61,6 +61,7 @@ class Q_GUI_EXPORT QPanGesture : public QGesture
 
     Q_PROPERTY(QSizeF totalOffset READ totalOffset)
     Q_PROPERTY(QSizeF lastOffset READ lastOffset)
+    Q_PROPERTY(QSizeF offset READ offset)
 
 public:
     QPanGesture(QWidget *gestureTarget, QObject *parent = 0);
@@ -69,6 +70,7 @@ public:
 
     QSizeF totalOffset() const;
     QSizeF lastOffset() const;
+    QSizeF offset() const;
 
 protected:
     void reset();
@@ -87,11 +89,13 @@ class Q_GUI_EXPORT QPinchGesture : public QGesture
     Q_OBJECT
     Q_DECLARE_PRIVATE(QPinchGesture)
 
-    Q_PROPERTY(qreal scaleFactor READ scaleFactor)
+    Q_PROPERTY(qreal totalScaleFactor READ totalScaleFactor)
     Q_PROPERTY(qreal lastScaleFactor READ lastScaleFactor)
+    Q_PROPERTY(qreal scaleFactor READ scaleFactor)
 
-    Q_PROPERTY(qreal rotationAngle READ rotationAngle)
+    Q_PROPERTY(qreal totalRotationAngle READ totalRotationAngle)
     Q_PROPERTY(qreal lastRotationAngle READ lastRotationAngle)
+    Q_PROPERTY(qreal rotationAngle READ rotationAngle)
 
     Q_PROPERTY(QPointF startCenterPoint READ startCenterPoint)
     Q_PROPERTY(QPointF lastCenterPoint READ lastCenterPoint)
@@ -107,11 +111,13 @@ public:
     QPointF lastCenterPoint() const;
     QPointF centerPoint() const;
 
-    qreal scaleFactor() const;
+    qreal totalScaleFactor() const;
     qreal lastScaleFactor() const;
+    qreal scaleFactor() const;
 
-    qreal rotationAngle() const;
+    qreal totalRotationAngle() const;
     qreal lastRotationAngle() const;
+    qreal rotationAngle() const;
 
 private:
     bool event(QEvent *event);
diff --git a/src/gui/kernel/qstandardgestures_p.h b/src/gui/kernel/qstandardgestures_p.h
index 270f307..9e23515 100644
--- a/src/gui/kernel/qstandardgestures_p.h
+++ b/src/gui/kernel/qstandardgestures_p.h
@@ -74,6 +74,7 @@ public:
 
     QSizeF totalOffset;
     QSizeF lastOffset;
+    QSizeF offset;
     QPointF lastPosition;
 
 #if defined(QT_MAC_USE_COCOA)
@@ -88,25 +89,30 @@ class QPinchGesturePrivate : public QGesturePrivate
 
 public:
     QPinchGesturePrivate()
-        : scaleFactor(0), lastScaleFactor(0),
-          rotationAngle(0), lastRotationAngle(0)
+        : totalScaleFactor(0.), lastScaleFactor(0.), scaleFactor(0.),
+          totalRotationAngle(0.), lastRotationAngle(0.), rotationAngle(0.)
 #ifdef Q_WS_WIN
-          ,initialDistance(0)
+          ,initialDistance(0), lastSequenceId(0)
 #endif
     {
     }
 
     void setupGestureTarget(QObject *o);
 
-    qreal scaleFactor;
+    qreal totalScaleFactor; // total scale factor, excluding the current sequence.
     qreal lastScaleFactor;
-    qreal rotationAngle;
+    qreal scaleFactor; // scale factor in the current sequence.
+
+    qreal totalRotationAngle; // total rotation angle, excluding the current sequence.
     qreal lastRotationAngle;
+    qreal rotationAngle; // rotation angle in the current sequence.
+
     QPointF startCenterPoint;
     QPointF lastCenterPoint;
     QPointF centerPoint;
 #ifdef Q_WS_WIN
     int initialDistance;
+    ulong lastSequenceId;
 #endif
 };
 
diff --git a/tests/manual/gestures/pinch/pinchwidget.cpp b/tests/manual/gestures/pinch/pinchwidget.cpp
index aa11f8d..cc16443 100644
--- a/tests/manual/gestures/pinch/pinchwidget.cpp
+++ b/tests/manual/gestures/pinch/pinchwidget.cpp
@@ -104,8 +104,8 @@ void PinchWidget::onPinchTriggered()
     QPoint transformCenter = worldTransform.map(QPoint(width()/2, height()/2));
     currentPinchTransform = QTransform()
         .translate(transformCenter.x(), transformCenter.y())
-        .scale(pinch->scaleFactor(), pinch->scaleFactor())
-        .rotateRadians(pinch->rotationAngle())
+        .scale(pinch->totalScaleFactor(), pinch->totalScaleFactor())
+        .rotate(pinch->totalRotationAngle())
         .translate(-transformCenter.x(), -transformCenter.y());
     update();
 }