Mercurial > hg > svgui
view widgets/WheelCounter.h @ 1368:38f35c2e03c4
Merge branch waverevision
author | Chris Cannam |
---|---|
date | Thu, 01 Nov 2018 10:12:12 +0000 |
parents | 13f5f84fbfad |
children |
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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */ /* Sonic Visualiser An audio file viewer and annotation editor. Centre for Digital Music, Queen Mary, University of London. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. See the file COPYING included with this distribution for more information. */ #ifndef SV_WHEEL_COUNTER_H #define SV_WHEEL_COUNTER_H #include <QWheelEvent> /** * Manage the little bit of tedious book-keeping associated with * translating vertical wheel events into up/down notch counts */ class WheelCounter { public: WheelCounter() : m_pendingWheelAngle(0) { } ~WheelCounter() { } int count(QWheelEvent *e) { e->accept(); int delta = e->angleDelta().y(); if (delta == 0) { return 0; } if (e->phase() == Qt::ScrollBegin || std::abs(delta) >= 120 || (delta > 0 && m_pendingWheelAngle < 0) || (delta < 0 && m_pendingWheelAngle > 0)) { m_pendingWheelAngle = delta; } else { m_pendingWheelAngle += delta; } if (abs(m_pendingWheelAngle) >= 600) { // Sometimes on Linux we're seeing absurdly extreme angles // on the first wheel event -- discard those entirely m_pendingWheelAngle = 0; return 0; } int count = m_pendingWheelAngle / 120; m_pendingWheelAngle -= count * 120; return count; } private: int m_pendingWheelAngle; }; #endif