##// END OF EJS Templates
Optimize polar chart radius calculation a bit....
Optimize polar chart radius calculation a bit. Current algorithm still results in an occasional extra unneeded iteration, as it uses only crude approximation for radius reduction. However, any speedup gained by accurately calculating needed reduction would be very minor compared to approximations used, so it doesn't seem worth the effort to figure out the complex math. Change-Id: If670a1b058a85cd0305b93f62e6388b463bafd0d Reviewed-by: Tomi Korpipää <tomi.korpipaa@digia.com>

File last commit:

r2432:53927f716a3d
r2542:189023d9a551
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scroller.cpp
216 lines | 5.1 KiB | text/x-c | CppLexer
/****************************************************************************
**
** Copyright (C) 2013 Digia Plc
** All rights reserved.
** For any questions to Digia, please use contact form at http://qt.digia.com
**
** This file is part of the Qt Commercial Charts Add-on.
**
** $QT_BEGIN_LICENSE$
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia.
**
** If you have questions regarding the use of this file, please use
** contact form at http://qt.digia.com
** $QT_END_LICENSE$
**
****************************************************************************/
#include "scroller_p.h"
#include "qlegend.h"
#include <QGraphicsSceneMouseEvent>
#include <QDebug>
QTCOMMERCIALCHART_BEGIN_NAMESPACE
Scroller::Scroller()
: m_ticker(this),
m_timeTresholdMin(50),
m_timeTresholdMax(300),
m_state(Idle),
m_treshold(10)
{
}
Scroller::~Scroller()
{
}
void Scroller::move(const QPointF &delta)
{
switch (m_state) {
case Pressed:
m_timeStamp = QTime::currentTime();
break;
case Scroll:
stopTicker();
m_timeStamp = QTime::currentTime();
break;
default:
break;
}
setOffset(offset() - delta);
}
void Scroller::scrollTo(const QPointF &delta)
{
// Starts scrolling, if at least m_timeTresholdMin msecs has gone since timestamp
// current time is no more than m_timeTresholdMax from timestamp
if ((m_timeStamp.elapsed() > m_timeTresholdMin) && (m_timeStamp.msecsTo(QTime::currentTime()) < m_timeTresholdMax)) {
// Release was quick enough. Start scrolling.
qreal interval = 25;
qreal time = m_timeStamp.msecsTo(QTime::currentTime());
if (qFuzzyCompare(time, 0)) {
m_speed = delta / 5;
} else {
m_speed = delta * interval / time;
}
qreal fraction = qMax(qAbs(m_speed.x()), qAbs(m_speed.y()));
if (!qFuzzyCompare(fraction, 0)) {
m_fraction.setX(qAbs(m_speed.x() / fraction));
m_fraction.setY(qAbs(m_speed.y() / fraction));
} else {
m_fraction.setX(1);
m_fraction.setY(1);
}
startTicker(interval);
} else {
stopTicker(); // Stop ticker, if one is running.
}
}
void Scroller::handleMousePressEvent(QGraphicsSceneMouseEvent *event)
{
stopTicker();
m_pressPos = event->screenPos();
m_lastPos = m_pressPos;
m_state = Pressed;
event->accept();
}
void Scroller::handleMouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
QPointF delta = event->screenPos() - m_lastPos;
switch (m_state) {
case Pressed: {
// calculate treshold. If enough, change to move state and send out move deltas.
if (qAbs(delta.x()) > m_treshold || qAbs(delta.y()) > m_treshold) {
m_lastPos = event->screenPos();
move(delta);
m_state = Move;
}
event->accept();
break;
}
case Move: {
m_lastPos = event->screenPos();
move(delta);
event->accept();
break;
}
case Idle:
default: {
event->ignore();
break;
}
}
}
void Scroller::handleMouseReleaseEvent(QGraphicsSceneMouseEvent *event)
{
switch (m_state) {
case Move:
{
scrollTo(m_lastPos - m_pressPos);
event->accept();
break;
}
default:
{
m_state = Idle;
event->ignore();
break;
}
}
}
void Scroller::startTicker(int interval)
{
m_state = Scroll;
m_ticker.start(interval);
}
void Scroller::stopTicker()
{
m_state = Idle;
m_ticker.stop();
}
void Scroller::scrollTick()
{
switch (m_state) {
case Scroll:
lowerSpeed(m_speed);
setOffset(offset() - m_speed);
if (m_speed == QPointF(0, 0)) {
m_state = Idle;
m_ticker.stop();
}
break;
default:
qWarning() << __FUNCTION__ << "Scroller unexpected state" << m_state;
m_ticker.stop();
m_state = Idle;
break;
}
}
void Scroller::lowerSpeed(QPointF &speed, qreal maxSpeed)
{
qreal x = qBound(-maxSpeed, speed.x(), maxSpeed);
qreal y = qBound(-maxSpeed, speed.y(), maxSpeed);
x = (x == 0) ? x :
(x > 0) ? qMax(qreal(0), x - m_fraction.x()) : qMin(qreal(0), x + m_fraction.x());
y = (y == 0) ? y :
(y > 0) ? qMax(qreal(0), y - m_fraction.y()) : qMin(qreal(0), y + m_fraction.y());
speed.setX(x);
speed.setY(y);
}
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
ScrollTicker::ScrollTicker(Scroller *scroller, QObject *parent)
: QObject(parent),
m_scroller(scroller)
{
}
void ScrollTicker::start(int interval)
{
if (!m_timer.isActive())
m_timer.start(interval, this);
}
void ScrollTicker::stop()
{
m_timer.stop();
}
void ScrollTicker::timerEvent(QTimerEvent *event)
{
Q_UNUSED(event);
m_scroller->scrollTick();
}
#include "moc_scroller_p.cpp"
QTCOMMERCIALCHART_END_NAMESPACE