Implemented QSwipeGesture recognizer using touch events.

Reviewed-by: Bradley T. Hughes

5 files changed, 176 insertions, 13 deletions

diff --git a/examples/gestures/imagegestures/imagewidget.cpp b/examples/gestures/imagegestures/imagewidget.cpp
index df8f56d..96400c4 100644
--- a/examples/gestures/imagegestures/imagewidget.cpp
+++ b/examples/gestures/imagegestures/imagewidget.cpp
@@ -103,12 +103,12 @@ void ImageWidget::mouseDoubleClickEvent(QMouseEvent *)
 //! [gesture event handler]
 bool ImageWidget::gestureEvent(QGestureEvent *event)
 {
-    if (QGesture *pan = event->gesture(Qt::PanGesture))
+    if (QGesture *swipe = event->gesture(Qt::SwipeGesture))
+        swipeTriggered(static_cast<QSwipeGesture *>(swipe));
+    else if (QGesture *pan = event->gesture(Qt::PanGesture))
         panTriggered(static_cast<QPanGesture *>(pan));
     if (QGesture *pinch = event->gesture(Qt::PinchGesture))
         pinchTriggered(static_cast<QPinchGesture *>(pinch));
-    if (QGesture *swipe = event->gesture(Qt::SwipeGesture))
-        swipeTriggered(static_cast<QSwipeGesture *>(swipe));
     return true;
 }
 //! [gesture event handler]
@@ -154,12 +154,14 @@ void ImageWidget::pinchTriggered(QPinchGesture *gesture)
 //! [swipe function]
 void ImageWidget::swipeTriggered(QSwipeGesture *gesture)
 {
-    if (gesture->horizontalDirection() == QSwipeGesture::Left
+    if (gesture->state() == Qt::GestureFinished) {
+        if (gesture->horizontalDirection() == QSwipeGesture::Left
             || gesture->verticalDirection() == QSwipeGesture::Up)
-        goPrevImage();
-    else
-        goNextImage();
-    update();
+            goPrevImage();
+        else
+            goNextImage();
+        update();
+    }
 }
 //! [swipe function]
 
diff --git a/src/gui/kernel/qgesture_p.h b/src/gui/kernel/qgesture_p.h
index ae2e287..a571bdb 100644
--- a/src/gui/kernel/qgesture_p.h
+++ b/src/gui/kernel/qgesture_p.h
@@ -136,13 +136,19 @@ public:
     QSwipeGesturePrivate()
         : horizontalDirection(QSwipeGesture::NoDirection),
           verticalDirection(QSwipeGesture::NoDirection),
-          swipeAngle(0)
+          swipeAngle(0),
+          started(false), speed(0)
     {
     }
 
     QSwipeGesture::SwipeDirection horizontalDirection;
     QSwipeGesture::SwipeDirection verticalDirection;
     qreal swipeAngle;
+
+    QPoint lastPositions[3];
+    bool started;
+    qreal speed;
+    QTime time;
 };
 
 QT_END_NAMESPACE
diff --git a/src/gui/kernel/qgesturemanager.cpp b/src/gui/kernel/qgesturemanager.cpp
index 628892d..662a64b 100644
--- a/src/gui/kernel/qgesturemanager.cpp
+++ b/src/gui/kernel/qgesturemanager.cpp
@@ -90,6 +90,7 @@ QGestureManager::QGestureManager(QObject *parent)
 #else
     registerGestureRecognizer(new QPanGestureRecognizer);
     registerGestureRecognizer(new QPinchGestureRecognizer);
+    registerGestureRecognizer(new QSwipeGestureRecognizer);
 #if defined(Q_OS_WIN)
     registerGestureRecognizer(new QWinNativePanGestureRecognizer);
 #endif
diff --git a/src/gui/kernel/qstandardgestures.cpp b/src/gui/kernel/qstandardgestures.cpp
index dfd49eb..79346ed 100644
--- a/src/gui/kernel/qstandardgestures.cpp
+++ b/src/gui/kernel/qstandardgestures.cpp
@@ -45,6 +45,7 @@
 #include "qevent.h"
 #include "qwidget.h"
 #include "qabstractscrollarea.h"
+#include "qdebug.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -66,7 +67,9 @@ QGesture *QPanGestureRecognizer::create(QObject *target)
     return new QPanGesture;
 }
 
-QGestureRecognizer::Result QPanGestureRecognizer::recognize(QGesture *state, QObject *, QEvent *event)
+QGestureRecognizer::Result QPanGestureRecognizer::recognize(QGesture *state,
+                                                            QObject *,
+                                                            QEvent *event)
 {
     QPanGesture *q = static_cast<QPanGesture *>(state);
     QPanGesturePrivate *d = q->d_func();
@@ -155,7 +158,9 @@ QGesture *QPinchGestureRecognizer::create(QObject *target)
     return new QPinchGesture;
 }
 
-QGestureRecognizer::Result QPinchGestureRecognizer::recognize(QGesture *state, QObject *, QEvent *event)
+QGestureRecognizer::Result QPinchGestureRecognizer::recognize(QGesture *state,
+                                                              QObject *,
+                                                              QEvent *event)
 {
     QPinchGesture *q = static_cast<QPinchGesture *>(state);
     QPinchGesturePrivate *d = q->d_func();
@@ -199,8 +204,9 @@ QGestureRecognizer::Result QPinchGestureRecognizer::recognize(QGesture *state, Q
             d->centerPoint = centerPoint;
             d->changeFlags |= QPinchGesture::CenterPointChanged;
 
-            const qreal scaleFactor = QLineF(p1.pos(), p2.pos()).length()
-                                      / QLineF(d->startPosition[0],  d->startPosition[1]).length();
+            const qreal scaleFactor =
+                    QLineF(p1.pos(), p2.pos()).length()
+                    / QLineF(d->startPosition[0],  d->startPosition[1]).length();
             if (d->isNewSequence) {
                 d->lastScaleFactor = scaleFactor;
             } else {
@@ -256,4 +262,143 @@ void QPinchGestureRecognizer::reset(QGesture *state)
     QGestureRecognizer::reset(state);
 }
 
+//
+// QSwipeGestureRecognizer
+//
+
+QSwipeGestureRecognizer::QSwipeGestureRecognizer()
+{
+}
+
+QGesture *QSwipeGestureRecognizer::create(QObject *target)
+{
+    if (target && target->isWidgetType()) {
+        static_cast<QWidget *>(target)->setAttribute(Qt::WA_AcceptTouchEvents);
+    }
+    return new QSwipeGesture;
+}
+
+QGestureRecognizer::Result QSwipeGestureRecognizer::recognize(QGesture *state,
+                                                              QObject *,
+                                                              QEvent *event)
+{
+    QSwipeGesture *q = static_cast<QSwipeGesture *>(state);
+    QSwipeGesturePrivate *d = q->d_func();
+
+    const QTouchEvent *ev = static_cast<const QTouchEvent *>(event);
+
+    QGestureRecognizer::Result result;
+
+    switch (event->type()) {
+    case QEvent::TouchBegin: {
+        d->speed = 1;
+        d->time = QTime::currentTime();
+        d->started = true;
+        result = QGestureRecognizer::MayBeGesture;
+        break;
+    }
+    case QEvent::TouchEnd: {
+        if (q->state() != Qt::NoGesture) {
+            result = QGestureRecognizer::FinishGesture;
+        } else {
+            result = QGestureRecognizer::CancelGesture;
+        }
+        break;
+    }
+    case QEvent::TouchUpdate: {
+        if (!d->started)
+            result = QGestureRecognizer::CancelGesture;
+        else if (ev->touchPoints().size() == 3) {
+            QTouchEvent::TouchPoint p1 = ev->touchPoints().at(0);
+            QTouchEvent::TouchPoint p2 = ev->touchPoints().at(1);
+            QTouchEvent::TouchPoint p3 = ev->touchPoints().at(2);
+
+            if (d->lastPositions[0].isNull()) {
+                d->lastPositions[0] = p1.startScreenPos().toPoint();
+                d->lastPositions[1] = p2.startScreenPos().toPoint();
+                d->lastPositions[2] = p3.startScreenPos().toPoint();
+            }
+            d->hotSpot = p1.screenPos();
+            d->isHotSpotSet = true;
+
+            int xDistance = (p1.screenPos().x() - d->lastPositions[0].x() +
+                             p2.screenPos().x() - d->lastPositions[1].x() +
+                             p3.screenPos().x() - d->lastPositions[2].x()) / 3;
+            int yDistance = (p1.screenPos().y() - d->lastPositions[0].y() +
+                             p2.screenPos().y() - d->lastPositions[1].y() +
+                             p3.screenPos().y() - d->lastPositions[2].y()) / 3;
+
+            const int distance = xDistance >= yDistance ? xDistance : yDistance;
+            int elapsedTime = d->time.msecsTo(QTime::currentTime());
+            if (!elapsedTime)
+                elapsedTime = 1;
+            d->speed = 0.9 * d->speed + distance / elapsedTime;
+            d->time = QTime::currentTime();
+            d->swipeAngle = QLineF(p1.startScreenPos(), p1.screenPos()).angle();
+
+            static const int MoveThreshold = 50;
+            if (xDistance > MoveThreshold || yDistance > MoveThreshold) {
+                // measure the distance to check if the direction changed
+                d->lastPositions[0] = p1.screenPos().toPoint();
+                d->lastPositions[1] = p2.screenPos().toPoint();
+                d->lastPositions[2] = p3.screenPos().toPoint();
+                QSwipeGesture::SwipeDirection horizontal =
+                        xDistance > 0 ? QSwipeGesture::Right : QSwipeGesture::Left;
+                QSwipeGesture::SwipeDirection vertical =
+                        yDistance > 0 ? QSwipeGesture::Down : QSwipeGesture::Up;
+                if (d->verticalDirection == QSwipeGesture::NoDirection)
+                    d->verticalDirection = vertical;
+                if (d->horizontalDirection == QSwipeGesture::NoDirection)
+                    d->horizontalDirection = horizontal;
+                if (d->verticalDirection != vertical || d->horizontalDirection != horizontal) {
+                    // the user has changed the direction!
+                    result = QGestureRecognizer::CancelGesture;
+                }
+                result = QGestureRecognizer::TriggerGesture;
+            } else {
+                if (q->state() != Qt::NoGesture)
+                    result = QGestureRecognizer::TriggerGesture;
+                else
+                    result = QGestureRecognizer::MayBeGesture;
+            }
+        } else if (ev->touchPoints().size() > 3) {
+            result = QGestureRecognizer::CancelGesture;
+        } else { // less than 3 touch points
+            if (d->started && (ev->touchPointStates() & Qt::TouchPointPressed))
+                result = QGestureRecognizer::CancelGesture;
+            else if (d->started)
+                result = QGestureRecognizer::Ignore;
+            else
+                result = QGestureRecognizer::MayBeGesture;
+        }
+        break;
+    }
+    case QEvent::MouseButtonPress:
+    case QEvent::MouseMove:
+    case QEvent::MouseButtonRelease:
+        result = QGestureRecognizer::Ignore;
+        break;
+    default:
+        result = QGestureRecognizer::Ignore;
+        break;
+    }
+    return result;
+}
+
+void QSwipeGestureRecognizer::reset(QGesture *state)
+{
+    QSwipeGesture *q = static_cast<QSwipeGesture *>(state);
+    QSwipeGesturePrivate *d = q->d_func();
+
+    d->verticalDirection = d->horizontalDirection = QSwipeGesture::NoDirection;
+    d->swipeAngle = 0;
+
+    d->lastPositions[0] = d->lastPositions[1] = d->lastPositions[2] = QPoint();
+    d->started = false;
+    d->speed = 0;
+    d->time = QTime();
+
+    QGestureRecognizer::reset(state);
+}
+
 QT_END_NAMESPACE
diff --git a/src/gui/kernel/qstandardgestures_p.h b/src/gui/kernel/qstandardgestures_p.h
index e6f346c..90f995d 100644
--- a/src/gui/kernel/qstandardgestures_p.h
+++ b/src/gui/kernel/qstandardgestures_p.h
@@ -74,7 +74,16 @@ public:
     QPinchGestureRecognizer();
 
     QGesture *create(QObject *target);
+    QGestureRecognizer::Result recognize(QGesture *state, QObject *watched, QEvent *event);
+    void reset(QGesture *state);
+};
 
+class QSwipeGestureRecognizer : public QGestureRecognizer
+{
+public:
+    QSwipeGestureRecognizer();
+
+    QGesture *create(QObject *target);
     QGestureRecognizer::Result recognize(QGesture *state, QObject *watched, QEvent *event);
     void reset(QGesture *state);
 };