+/***************************************************************************
+ * Copyright (C) 2011 by Peter Penz <peter.penz19@gmail.com> *
+ * *
+ * 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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