| /**************************************************************************** |
| ** |
| ** Copyright (C) 2017 The Qt Company Ltd. |
| ** Contact: http://www.qt.io/licensing/ |
| ** |
| ** This file is part of the Qt Quick Templates 2 module of the Qt Toolkit. |
| ** |
| ** $QT_BEGIN_LICENSE:LGPL3$ |
| ** Commercial License Usage |
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| ** |
| ** GNU Lesser General Public License Usage |
| ** Alternatively, this file may be used under the terms of the GNU Lesser |
| ** General Public License version 3 as published by the Free Software |
| ** Foundation and appearing in the file LICENSE.LGPLv3 included in the |
| ** packaging of this file. Please review the following information to |
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| ** |
| ** GNU General Public License Usage |
| ** Alternatively, this file may be used under the terms of the GNU |
| ** General Public License version 2.0 or later as published by the Free |
| ** Software Foundation and appearing in the file LICENSE.GPL included in |
| ** the packaging of this file. Please review the following information to |
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| ****************************************************************************/ |
| |
| #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 |