1 files changed, 69 insertions, 0 deletions
diff --git a/src/quicktemplates/qquickvelocitycalculator.cpp b/src/quicktemplates/qquickvelocitycalculator.cpp
new file mode 100644
index 0000000000..8c7dbd7d6c
--- /dev/null
+++ b/src/quicktemplates/qquickvelocitycalculator.cpp
@@ -0,0 +1,69 @@
+// Copyright (C) 2017 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#include "qquickvelocitycalculator_p_p.h"
+
+#include <QtCore/qdebug.h>
+
+QT_BEGIN_NAMESPACE
+
+/*
+    Usage:
+
+    QQuickVelocityCalculator velocityCalculator;
+
+    // ...
+
+    velocityCalcular.startMeasuring(event->pos(), event->timestamp());
+    velocityCalcular.stopMeasuring(event->pos(), event->timestamp());
+
+    // ...
+
+    if (velocityCalculator.velocity().x() > someAmount)
+        doSomething();
+    else if (velocityCalculator.velocity().x() < -someAmount)
+        doSomethingElse();
+*/
+
+void QQuickVelocityCalculator::startMeasuring(const QPointF &point1, qint64 timestamp)
+{
+    m_point1 = point1;
+
+    if (timestamp != 0)
+        m_point1Timestamp = timestamp;
+    else
+        m_timer.start();
+}
+
+void QQuickVelocityCalculator::stopMeasuring(const QPointF &point2, qint64 timestamp)
+{
+    if (timestamp == 0 && !m_timer.isValid()) {
+        qWarning() << "QQuickVelocityCalculator: a call to stopMeasuring() must be preceded by a call to startMeasuring()";
+        return;
+    }
+
+    m_point2 = point2;
+    m_point2Timestamp = timestamp != 0 ? timestamp : m_timer.elapsed();
+    m_timer.invalidate();
+}
+
+void QQuickVelocityCalculator::reset()
+{
+    m_point1 = QPointF();
+    m_point2 = QPointF();
+    m_point1Timestamp = 0;
+    m_point2Timestamp = 0;
+    m_timer.invalidate();
+}
+
+QPointF QQuickVelocityCalculator::velocity() const
+{
+    if ((m_point2Timestamp == 0 || m_point1Timestamp == m_point2Timestamp) && !m_timer.isValid())
+        return QPointF();
+
+    const qreal secondsElapsed = (m_point2Timestamp != 0 ? m_point2Timestamp - m_point1Timestamp : m_timer.elapsed()) / 1000.0;
+    const QPointF distance = m_point2 - m_point1;
+    return distance / secondsElapsed;
+}
+
+QT_END_NAMESPACE