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/***************************************************************************
* Copyright (C) 2011 by Peter Penz <[email protected]> *
* *
* 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. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with this program; if not, write to the *
* Free Software Foundation, Inc., *
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA *
***************************************************************************/
#include "kitemlistsmoothscroller_p.h"
#include <QEvent>
#include <QPropertyAnimation>
#include <QScrollBar>
#include <QWheelEvent>
#include <KDebug>
KItemListSmoothScroller::KItemListSmoothScroller(QScrollBar* scrollBar,
QObject* parent) :
QObject(parent),
m_scrollBarPressed(false),
m_smoothScrolling(true),
m_scrollBar(scrollBar),
m_animation(0)
{
m_animation = new QPropertyAnimation(this);
m_animation->setDuration(300);
connect(m_animation, SIGNAL(stateChanged(QAbstractAnimation::State,QAbstractAnimation::State)),
this, SLOT(slotAnimationStateChanged(QAbstractAnimation::State,QAbstractAnimation::State)));
m_scrollBar->installEventFilter(this);
}
KItemListSmoothScroller::~KItemListSmoothScroller()
{
}
void KItemListSmoothScroller::setScrollBar(QScrollBar *scrollBar)
{
m_scrollBar = scrollBar;
}
QScrollBar* KItemListSmoothScroller::scrollBar() const
{
return m_scrollBar;
}
void KItemListSmoothScroller::setTargetObject(QObject* target)
{
m_animation->setTargetObject(target);
}
QObject* KItemListSmoothScroller::targetObject() const
{
return m_animation->targetObject();
}
void KItemListSmoothScroller::setPropertyName(const QByteArray& propertyName)
{
m_animation->setPropertyName(propertyName);
}
QByteArray KItemListSmoothScroller::propertyName() const
{
return m_animation->propertyName();
}
void KItemListSmoothScroller::scrollContentsBy(qreal distance)
{
QObject* target = targetObject();
if (!target) {
return;
}
const QByteArray name = propertyName();
const qreal currentOffset = target->property(name).toReal();
if (static_cast<int>(currentOffset) == m_scrollBar->value()) {
// The current offset is already synchronous to the scrollbar
return;
}
const bool animRunning = (m_animation->state() == QAbstractAnimation::Running);
if (animRunning) {
// Stopping a running animation means skipping the range from the current offset
// until the target offset. To prevent skipping of the range the difference
// is added to the new target offset.
const qreal oldEndOffset = m_animation->endValue().toReal();
distance += (currentOffset - oldEndOffset);
}
const qreal endOffset = currentOffset - distance;
if (m_smoothScrolling || animRunning) {
qreal startOffset = currentOffset;
if (animRunning) {
// If the animation was running and has been interrupted by assigning a new end-offset
// one frame must be added to the start-offset to keep the animation smooth. This also
// assures that animation proceeds even in cases where new end-offset are triggered
// within a very short timeslots.
startOffset += (endOffset - currentOffset) * 1000 / (m_animation->duration() * 60);
}
m_animation->stop();
m_animation->setStartValue(startOffset);
m_animation->setEndValue(endOffset);
m_animation->setEasingCurve(animRunning ? QEasingCurve::OutQuad : QEasingCurve::InOutQuad);
m_animation->start();
target->setProperty(name, startOffset);
} else {
target->setProperty(name, endOffset);
}
}
void KItemListSmoothScroller::scrollTo(qreal position)
{
m_smoothScrolling = true;
m_scrollBar->setValue(position);
}
bool KItemListSmoothScroller::requestScrollBarUpdate(int newMaximum)
{
if (m_animation->state() == QAbstractAnimation::Running) {
if (newMaximum == m_scrollBar->maximum()) {
// The value has been changed by the animation, no update
// of the scrollbars is required as their target state will be
// reached with the end of the animation.
return false;
}
// The maximum has been changed which indicates that the content
// of the view has been changed. Stop the animation in any case and
// update the scrollbars immediately.
m_animation->stop();
}
return true;
}
bool KItemListSmoothScroller::eventFilter(QObject* obj, QEvent* event)
{
Q_ASSERT(obj == m_scrollBar);
switch (event->type()) {
case QEvent::MouseButtonPress:
m_scrollBarPressed = true;
m_smoothScrolling = true;
break;
case QEvent::MouseButtonRelease:
m_scrollBarPressed = false;
m_smoothScrolling = false;
break;
case QEvent::Wheel:
handleWheelEvent(static_cast<QWheelEvent*>(event));
break;
default:
break;
}
return QObject::eventFilter(obj, event);
}
void KItemListSmoothScroller::slotAnimationStateChanged(QAbstractAnimation::State newState,
QAbstractAnimation::State oldState)
{
Q_UNUSED(oldState);
if (newState == QAbstractAnimation::Stopped && m_smoothScrolling && !m_scrollBarPressed) {
m_smoothScrolling = false;
}
}
void KItemListSmoothScroller::handleWheelEvent(QWheelEvent* event)
{
const int numDegrees = event->delta() / 8;
const int numSteps = numDegrees / 15;
const bool previous = m_smoothScrolling;
m_smoothScrolling = true;
const int value = m_scrollBar->value();
const int pageStep = m_scrollBar->pageStep();
m_scrollBar->setValue(value - numSteps * pageStep);
m_smoothScrolling = previous;
event->accept();
}
#include "kitemlistsmoothscroller_p.moc"
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