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List:       kde-commits
Subject:    [kde-baseapps] dolphin/src: Implement smooth-scrolling for
From:       Peter Penz <peter.penz19 () gmail ! com>
Date:       2011-09-30 21:29:28
Message-ID: 20110930212928.05753A60A6 () git ! kde ! org
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Git commit acd03f45d56d80ea519ca96c382ea5b69352c05c by Peter Penz.
Committed on 30/09/2011 at 23:22.
Pushed by ppenz into branch 'master'.

Implement smooth-scrolling for horizontal and vertical scrollbars

Currently only a smoothscrolling was provided into the
scroll-direction, but not in case of the details-view where a
horizontal scrollbar might be shown too.

Some minor adjustments of the private KItemListSmoothScroller interface
will be done later...

M  +1    -0    dolphin/src/CMakeLists.txt
M  +95   -166  dolphin/src/kitemviews/kitemlistcontainer.cpp
M  +5    -5    dolphin/src/kitemviews/kitemlistcontainer.h
A  +201  -0    dolphin/src/kitemviews/kitemlistsmoothscroller.cpp     [License: GPL \
(v2+)] A  +103  -0    dolphin/src/kitemviews/kitemlistsmoothscroller_p.h     \
[License: GPL (v2+)] M  +10   -0    dolphin/src/kitemviews/kitemlistview.cpp
M  +2    -0    dolphin/src/kitemviews/kitemlistview.h
M  +3    -1    dolphin/src/views/dolphinview.cpp

http://commits.kde.org/kde-baseapps/acd03f45d56d80ea519ca96c382ea5b69352c05c

diff --git a/dolphin/src/CMakeLists.txt b/dolphin/src/CMakeLists.txt
index 0eedece..93225c5 100644
--- a/dolphin/src/CMakeLists.txt
+++ b/dolphin/src/CMakeLists.txt
@@ -30,6 +30,7 @@ set(dolphinprivate_LIB_SRCS
     kitemviews/kitemlistrubberband.cpp
     kitemviews/kitemlistselectionmanager.cpp
     kitemviews/kitemlistsizehintresolver.cpp
+    kitemviews/kitemlistsmoothscroller.cpp
     kitemviews/kitemliststyleoption.cpp
     kitemviews/kitemlistview.cpp
     kitemviews/kitemlistviewanimation.cpp
diff --git a/dolphin/src/kitemviews/kitemlistcontainer.cpp \
b/dolphin/src/kitemviews/kitemlistcontainer.cpp index 45db700..926e13b 100644
--- a/dolphin/src/kitemviews/kitemlistcontainer.cpp
+++ b/dolphin/src/kitemviews/kitemlistcontainer.cpp
@@ -23,6 +23,7 @@
 #include "kitemlistcontainer.h"
 
 #include "kitemlistcontroller.h"
+#include "kitemlistsmoothscroller_p.h"
 #include "kitemlistview.h"
 #include "kitemmodelbase.h"
 
@@ -35,33 +36,42 @@
 
 #include <KDebug>
 
+/**
+ * Replaces the default viewport of KItemListContainer by a
+ * non-scrollable viewport. The scrolling is done in an optimized
+ * way by KItemListView internally.
+ */
 class KItemListContainerViewport : public QGraphicsView
 {
 public:
-    KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent)
-        : QGraphicsView(scene, parent)
-    {
-        setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
-        setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
-        setViewportMargins(0, 0, 0, 0);
-        setFrameShape(QFrame::NoFrame);
-    }
-
-    void scrollContentsBy(int dx, int dy)
-    {
-        Q_UNUSED(dx);
-        Q_UNUSED(dy);
-        // Do nothing. This prevents that e.g. the wheel-event
-        // results in a moving of the scene items.
-    }
+    KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent);
+protected:
+    virtual void wheelEvent(QWheelEvent* event);
 };
 
+KItemListContainerViewport::KItemListContainerViewport(QGraphicsScene* scene, \
QWidget* parent) : +    QGraphicsView(scene, parent)
+{
+    setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+    setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+    setViewportMargins(0, 0, 0, 0);
+    setFrameShape(QFrame::NoFrame);
+}
+
+void KItemListContainerViewport::wheelEvent(QWheelEvent* event)
+{
+    // Assure that the wheel-event gets forwarded to the parent
+    // and not handled at all by QGraphicsView.
+    event->ignore();
+}
+
+
+
 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* \
parent) :  QAbstractScrollArea(parent),
     m_controller(controller),
-    m_scrollBarPressed(false),
-    m_smoothScrolling(false),
-    m_smoothScrollingAnimation(0)
+    m_horizontalSmoothScroller(0),
+    m_verticalSmoothScroller(0)
 {
     Q_ASSERT(controller);
     controller->setParent(this);
@@ -71,9 +81,8 @@ KItemListContainer::KItemListContainer(KItemListController* \
controller, QWidget*  KItemListContainer::KItemListContainer(QWidget* parent) :
     QAbstractScrollArea(parent),
     m_controller(0),
-    m_scrollBarPressed(false),
-    m_smoothScrolling(false),
-    m_smoothScrollingAnimation(0)
+    m_horizontalSmoothScroller(0),
+    m_verticalSmoothScroller(0)
 {
     initialize();
 }
@@ -115,86 +124,8 @@ void KItemListContainer::resizeEvent(QResizeEvent* event)
 
 void KItemListContainer::scrollContentsBy(int dx, int dy)
 {
-    KItemListView* view = m_controller->view();
-    if (!view) {
-        return;
-    }
-
-    const QScrollBar* scrollBar = (view->scrollOrientation() == Qt::Vertical)
-                                  ? verticalScrollBar() : horizontalScrollBar();
-    const qreal currentOffset = view->scrollOffset();
-    if (static_cast<int>(currentOffset) == scrollBar->value()) {
-        // The current offset is already synchronous to the scrollbar
-        return;
-    }
-
-    qreal offsetDiff = (view->scrollOrientation() == Qt::Vertical) ? dy : dx;
-
-    const bool animRunning = (m_smoothScrollingAnimation->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_smoothScrollingAnimation->endValue().toReal();
-        offsetDiff += (currentOffset - oldEndOffset);
-    }
-
-    const qreal endOffset = currentOffset - offsetDiff;
-
-    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_smoothScrollingAnimation->duration() * 60);
-        }
-
-        m_smoothScrollingAnimation->stop();
-        m_smoothScrollingAnimation->setStartValue(startOffset);
-        m_smoothScrollingAnimation->setEndValue(endOffset);
-        m_smoothScrollingAnimation->setEasingCurve(animRunning ? \
                QEasingCurve::OutQuad : QEasingCurve::InOutQuad);
-        m_smoothScrollingAnimation->start();
-        view->setScrollOffset(startOffset);
-    } else {
-        view->setScrollOffset(endOffset);
-    }
-}
-
-bool KItemListContainer::eventFilter(QObject* obj, QEvent* event)
-{
-    Q_ASSERT(obj == horizontalScrollBar() || obj == verticalScrollBar());
-
-    // Check whether the scrollbar has been adjusted by a mouse-event
-    // triggered by the user and remember this in m_scrollBarPressed.
-    // The smooth scrolling will only get active if m_scrollBarPressed
-    // is true (see scrollContentsBy()).
-    const bool scrollVertical = (m_controller->view()->scrollOrientation() == \
                Qt::Vertical);
-    const bool checkEvent = ( scrollVertical && obj == verticalScrollBar()) ||
-                            (!scrollVertical && obj == horizontalScrollBar());
-    if (checkEvent) {
-        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:
-            wheelEvent(static_cast<QWheelEvent*>(event));
-            break;
-
-        default:
-            break;
-        }
-    }
-
-    return QAbstractScrollArea::eventFilter(obj, event);
+    m_horizontalSmoothScroller->scrollContentsBy(dx);
+    m_verticalSmoothScroller->scrollContentsBy(dy);
 }
 
 void KItemListContainer::wheelEvent(QWheelEvent* event)
@@ -205,28 +136,31 @@ void KItemListContainer::wheelEvent(QWheelEvent* event)
     }
 
     KItemListView* view = m_controller->view();
-
-    if (!view || event->orientation() != view->scrollOrientation()) {
+    if (!view) {
+        event->ignore();
         return;
     }
 
+    const bool scrollHorizontally = (event->orientation() == Qt::Horizontal) ||
+                                    (event->orientation() == Qt::Vertical && \
!verticalScrollBar()->isVisible()); +    KItemListSmoothScroller* smoothScroller = \
scrollHorizontally ? +                                              \
m_horizontalSmoothScroller : m_verticalSmoothScroller; +
     const int numDegrees = event->delta() / 8;
     const int numSteps = numDegrees / 15;
 
-    const bool previous = m_smoothScrolling;
-    m_smoothScrolling = true;
-    if (view->scrollOrientation() == Qt::Vertical) {
-        const int value = verticalScrollBar()->value();
-        verticalScrollBar()->setValue(value - numSteps * view->size().height());
-    } else {
-        const int value = horizontalScrollBar()->value();
-        horizontalScrollBar()->setValue(value - numSteps * view->size().width());
-    }
-    m_smoothScrolling = previous;
+    const QScrollBar* scrollBar = smoothScroller->scrollBar();
+    smoothScroller->scrollTo(scrollBar->value() - numSteps * scrollBar->pageStep());
 
     event->accept();
 }
 
+void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, \
Qt::Orientation previous) +{
+    Q_UNUSED(previous);
+    updateSmoothScrollers(current);
+}
+
 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* \
previous)  {
     Q_UNUSED(current);
@@ -238,45 +172,39 @@ void KItemListContainer::slotViewChanged(KItemListView* \
                current, KItemListView*
     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
     if (previous) {
         scene->removeItem(previous);
+        disconnect(current, \
SIGNAL(scrollOrientationChanged(Qt::Orientation,Qt::Orientation)), this, \
                SLOT(slotScrollOrientationChanged(Qt::Orientation,Qt::Orientation)));
         disconnect(previous, SIGNAL(scrollOffsetChanged(qreal,qreal)),        this, \
                SLOT(updateScrollOffsetScrollBar()));
         disconnect(previous, SIGNAL(maximumScrollOffsetChanged(qreal,qreal)), this, \
                SLOT(updateScrollOffsetScrollBar()));
         disconnect(previous, SIGNAL(itemOffsetChanged(qreal,qreal)),          this, \
                SLOT(updateItemOffsetScrollBar()));
         disconnect(previous, SIGNAL(maximumItemOffsetChanged(qreal,qreal)),   this, \
                SLOT(updateItemOffsetScrollBar()));
         disconnect(previous, SIGNAL(scrollTo(qreal)),                         this, \
                SLOT(scrollTo(qreal)));
-        m_smoothScrollingAnimation->setTargetObject(0);
+        m_horizontalSmoothScroller->setTargetObject(0);
+        m_verticalSmoothScroller->setTargetObject(0);
     }
     if (current) {
         scene->addItem(current);
+        connect(current, \
SIGNAL(scrollOrientationChanged(Qt::Orientation,Qt::Orientation)), this, \
                SLOT(slotScrollOrientationChanged(Qt::Orientation,Qt::Orientation)));
         connect(current, SIGNAL(scrollOffsetChanged(qreal,qreal)),        this, \
                SLOT(updateScrollOffsetScrollBar()));
         connect(current, SIGNAL(maximumScrollOffsetChanged(qreal,qreal)), this, \
                SLOT(updateScrollOffsetScrollBar()));
         connect(current, SIGNAL(itemOffsetChanged(qreal,qreal)),          this, \
                SLOT(updateItemOffsetScrollBar()));
         connect(current, SIGNAL(maximumItemOffsetChanged(qreal,qreal)),   this, \
                SLOT(updateItemOffsetScrollBar()));
         connect(current, SIGNAL(scrollTo(qreal)),                         this, \
                SLOT(scrollTo(qreal)));
-        m_smoothScrollingAnimation->setTargetObject(current);
-    }
-}
-
-void KItemListContainer::slotAnimationStateChanged(QAbstractAnimation::State \
                newState,
-                                                   QAbstractAnimation::State \
                oldState)
-{
-    Q_UNUSED(oldState);
-    if (newState == QAbstractAnimation::Stopped && m_smoothScrolling && \
                !m_scrollBarPressed) {
-        m_smoothScrolling = false;
+        m_horizontalSmoothScroller->setTargetObject(current);
+        m_verticalSmoothScroller->setTargetObject(current);
+        updateSmoothScrollers(current->scrollOrientation());
     }
 }
 
-
 void KItemListContainer::scrollTo(qreal offset)
 {
     const KItemListView* view = m_controller->view();
-    if (!view) {
-        return;
+    if (view) {
+        if (view->scrollOrientation() == Qt::Vertical) {
+            m_verticalSmoothScroller->scrollTo(offset);
+        } else {
+            m_horizontalSmoothScroller->scrollTo(offset);
+        }
     }
-
-    m_smoothScrolling = true;
-    QScrollBar* scrollBar = (view->scrollOrientation() == Qt::Vertical)
-                            ? verticalScrollBar() : horizontalScrollBar();
-    scrollBar->setValue(offset);
 }
 
 void KItemListContainer::updateScrollOffsetScrollBar()
@@ -286,14 +214,17 @@ void KItemListContainer::updateScrollOffsetScrollBar()
         return;
     }
 
+    KItemListSmoothScroller* smoothScroller = 0;
     QScrollBar* scrollOffsetScrollBar = 0;
     int singleStep = 0;
     int pageStep = 0;
     if (view->scrollOrientation() == Qt::Vertical) {
+        smoothScroller = m_verticalSmoothScroller;
         scrollOffsetScrollBar = verticalScrollBar();
         singleStep = view->itemSize().height();
         pageStep = view->size().height();
     } else {
+        smoothScroller = m_horizontalSmoothScroller;
         scrollOffsetScrollBar = horizontalScrollBar();
         singleStep = view->itemSize().width();
         pageStep = view->size().width();
@@ -301,25 +232,13 @@ void KItemListContainer::updateScrollOffsetScrollBar()
 
     const int value = view->scrollOffset();
     const int maximum = qMax(0, int(view->maximumScrollOffset() - pageStep));
-    if (m_smoothScrollingAnimation->state() == QAbstractAnimation::Running) {
-        if (maximum == scrollOffsetScrollBar->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;
-        }
-
-        // 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_smoothScrollingAnimation->stop();
+    if (smoothScroller->requestScrollBarUpdate(maximum)) {
+        scrollOffsetScrollBar->setSingleStep(singleStep);
+        scrollOffsetScrollBar->setPageStep(pageStep);
+        scrollOffsetScrollBar->setMinimum(0);
+        scrollOffsetScrollBar->setMaximum(maximum);
+        scrollOffsetScrollBar->setValue(value);
     }
-
-    scrollOffsetScrollBar->setSingleStep(singleStep);
-    scrollOffsetScrollBar->setPageStep(pageStep);
-    scrollOffsetScrollBar->setMinimum(0);
-    scrollOffsetScrollBar->setMaximum(maximum);
-    scrollOffsetScrollBar->setValue(value);
 }
 
 void KItemListContainer::updateItemOffsetScrollBar()
@@ -329,27 +248,31 @@ void KItemListContainer::updateItemOffsetScrollBar()
         return;
     }
 
+    KItemListSmoothScroller* smoothScroller = 0;
     QScrollBar* itemOffsetScrollBar = 0;
     int singleStep = 0;
     int pageStep = 0;
     if (view->scrollOrientation() == Qt::Vertical) {
+        smoothScroller = m_horizontalSmoothScroller;
         itemOffsetScrollBar = horizontalScrollBar();
-        singleStep = view->itemSize().width() / 10;
+        singleStep = view->size().width() / 10;
         pageStep = view->size().width();
     } else {
+        smoothScroller = m_verticalSmoothScroller;
         itemOffsetScrollBar = verticalScrollBar();
-        singleStep = view->itemSize().height() / 10;
+        singleStep = view->size().height() / 10;
         pageStep = view->size().height();
     }
 
     const int value = view->itemOffset();
     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
-
-    itemOffsetScrollBar->setSingleStep(singleStep);
-    itemOffsetScrollBar->setPageStep(pageStep);
-    itemOffsetScrollBar->setMinimum(0);
-    itemOffsetScrollBar->setMaximum(maximum);
-    itemOffsetScrollBar->setValue(value);
+    if (smoothScroller->requestScrollBarUpdate(maximum)) {
+        itemOffsetScrollBar->setSingleStep(singleStep);
+        itemOffsetScrollBar->setPageStep(pageStep);
+        itemOffsetScrollBar->setMinimum(0);
+        itemOffsetScrollBar->setMaximum(maximum);
+        itemOffsetScrollBar->setValue(value);
+    }
 }
 
 void KItemListContainer::updateGeometries()
@@ -378,6 +301,17 @@ void KItemListContainer::updateGeometries()
     }
 }
 
+void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
+{
+    if (orientation == Qt::Vertical) {
+        m_verticalSmoothScroller->setPropertyName("scrollOffset");
+        m_horizontalSmoothScroller->setPropertyName("itemOffset");
+    } else {
+        m_horizontalSmoothScroller->setPropertyName("scrollOffset");
+        m_verticalSmoothScroller->setPropertyName("itemOffset");
+    }
+}
+
 void KItemListContainer::initialize()
 {
     if (!m_controller) {
@@ -392,13 +326,8 @@ void KItemListContainer::initialize()
     QGraphicsView* graphicsView = new KItemListContainerViewport(new \
QGraphicsScene(this), this);  setViewport(graphicsView);
 
-    m_smoothScrollingAnimation = new QPropertyAnimation(this, "scrollOffset");
-    m_smoothScrollingAnimation->setDuration(300);
-    connect(m_smoothScrollingAnimation, \
                SIGNAL(stateChanged(QAbstractAnimation::State,QAbstractAnimation::State)),
                
-            this, SLOT(slotAnimationStateChanged(QAbstractAnimation::State,QAbstractAnimation::State)));
                
-
-    horizontalScrollBar()->installEventFilter(this);
-    verticalScrollBar()->installEventFilter(this);
+    m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), \
this); +    m_verticalSmoothScroller = new \
KItemListSmoothScroller(verticalScrollBar(), this);  }
 
 #include "kitemlistcontainer.moc"
diff --git a/dolphin/src/kitemviews/kitemlistcontainer.h \
b/dolphin/src/kitemviews/kitemlistcontainer.h index 36ac975..4d6eadb 100644
--- a/dolphin/src/kitemviews/kitemlistcontainer.h
+++ b/dolphin/src/kitemviews/kitemlistcontainer.h
@@ -29,6 +29,7 @@
 #include <QAbstractScrollArea>
 
 class KItemListController;
+class KItemListSmoothScroller;
 class KItemListView;
 class KItemModelBase;
 class QPropertyAnimation;
@@ -54,13 +55,12 @@ protected:
     virtual void showEvent(QShowEvent* event);
     virtual void resizeEvent(QResizeEvent* event);
     virtual void scrollContentsBy(int dx, int dy);
-    virtual bool eventFilter(QObject* obj, QEvent* event);
     virtual void wheelEvent(QWheelEvent* event);
 
 private slots:
+    void slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation \
                previous);
     void slotModelChanged(KItemModelBase* current, KItemModelBase* previous);
     void slotViewChanged(KItemListView* current, KItemListView* previous);
-    void slotAnimationStateChanged(QAbstractAnimation::State newState, \
QAbstractAnimation::State oldState);  void scrollTo(qreal offset);
     void updateScrollOffsetScrollBar();
     void updateItemOffsetScrollBar();
@@ -68,13 +68,13 @@ private slots:
 private:
     void initialize();
     void updateGeometries();
+    void updateSmoothScrollers(Qt::Orientation orientation);
 
 private:
     KItemListController* m_controller;
 
-    bool m_scrollBarPressed;
-    bool m_smoothScrolling;
-    QPropertyAnimation* m_smoothScrollingAnimation;
+    KItemListSmoothScroller* m_horizontalSmoothScroller;
+    KItemListSmoothScroller* m_verticalSmoothScroller;
 };
 
 #endif
diff --git a/dolphin/src/kitemviews/kitemlistsmoothscroller.cpp \
b/dolphin/src/kitemviews/kitemlistsmoothscroller.cpp new file mode 100644
index 0000000..5c1bf3c
--- /dev/null
+++ b/dolphin/src/kitemviews/kitemlistsmoothscroller.cpp
@@ -0,0 +1,201 @@
+/***************************************************************************
+ *   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"
diff --git a/dolphin/src/kitemviews/kitemlistsmoothscroller_p.h \
b/dolphin/src/kitemviews/kitemlistsmoothscroller_p.h new file mode 100644
index 0000000..252c966
--- /dev/null
+++ b/dolphin/src/kitemviews/kitemlistsmoothscroller_p.h
@@ -0,0 +1,103 @@
+/***************************************************************************
+ *   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            *
+ ***************************************************************************/
+
+#ifndef KITEMLISTSMOOTHSCROLLER_H
+#define KITEMLISTSMOOTHSCROLLER_H
+
+#include <libdolphin_export.h>
+
+#include <QAbstractAnimation>
+#include <QObject>
+
+class QPropertyAnimation;
+class QScrollBar;
+class QWheelEvent;
+
+/**
+ * @brief Helper class for KItemListContainer to have a smooth
+ *        scrolling when adjusting the scrollbars.
+ */
+class LIBDOLPHINPRIVATE_EXPORT KItemListSmoothScroller : public QObject
+{
+    Q_OBJECT
+
+public:
+    KItemListSmoothScroller(QScrollBar* scrollBar,
+                            QObject* parent = 0);
+    virtual ~KItemListSmoothScroller();
+
+    void setScrollBar(QScrollBar* scrollBar);
+    QScrollBar* scrollBar() const;
+
+    void setTargetObject(QObject* target);
+    QObject* targetObject() const;
+
+    void setPropertyName(const QByteArray& propertyName);
+    QByteArray propertyName() const;
+
+    /**
+     * Adjusts the position of the target by \p distance
+     * pixels. Is invoked in the context of QAbstractScrollArea::scrollContentsBy()
+     * where the scrollbars already have the new position but the content
+     * has not been scrolled yet.
+     */
+    void scrollContentsBy(qreal distance);
+
+    /**
+     * Does a smooth-scrolling to the position \p position
+     * on the target and also adjusts the corresponding scrollbar
+     * to the new position.
+     */
+    void scrollTo(qreal position);
+
+    /**
+     * Must be invoked before the scrollbar should get updated to have a new
+     * maximum. True is returned if the new maximum can be applied. If false
+     * is returned the maximum has already been reached and the value will
+     * be reached at the end of the animation.
+     */
+    // TODO: This interface is tricky to understand. Try to make this more
+    // generic/readable if the corresponding code in KItemListContainer got
+    // stable.
+    bool requestScrollBarUpdate(int newMaximum);
+
+protected:
+    virtual bool eventFilter(QObject* obj, QEvent* event);
+
+private slots:
+    void slotAnimationStateChanged(QAbstractAnimation::State newState,
+                                   QAbstractAnimation::State oldState);
+
+private:
+    /**
+     * Results into a smooth-scrolling of the target dependent on the direction
+     * of the wheel event.
+     */
+    void handleWheelEvent(QWheelEvent* event);
+
+private:
+    bool m_scrollBarPressed;
+    bool m_smoothScrolling;
+    QScrollBar* m_scrollBar;
+    QPropertyAnimation* m_animation;
+};
+
+#endif
+
+
diff --git a/dolphin/src/kitemviews/kitemlistview.cpp \
b/dolphin/src/kitemviews/kitemlistview.cpp index 63315b6..f9c2fca 100644
--- a/dolphin/src/kitemviews/kitemlistview.cpp
+++ b/dolphin/src/kitemviews/kitemlistview.cpp
@@ -119,7 +119,9 @@ void KItemListView::setScrollOrientation(Qt::Orientation \
orientation)  m_animation->setScrollOrientation(orientation);
     m_sizeHintResolver->clearCache();
     updateLayout();
+
     onScrollOrientationChanged(orientation, previousOrientation);
+    emit scrollOrientationChanged(orientation, previousOrientation);
 }
 
 Qt::Orientation KItemListView::scrollOrientation() const
@@ -189,6 +191,13 @@ qreal KItemListView::maximumScrollOffset() const
 void KItemListView::setItemOffset(qreal offset)
 {
     m_layouter->setItemOffset(offset);
+    if (m_header) {
+        m_header->setPos(-offset, 0);
+    }
+    if (!m_layoutTimer->isActive()) {
+        doLayout(NoAnimation, 0, 0);
+        update();
+    }
 }
 
 qreal KItemListView::itemOffset() const
@@ -1505,6 +1514,7 @@ void KItemListView::updateStretchedVisibleRolesSizes()
 
     if (m_header) {
         m_header->setVisibleRolesWidths(headerRolesWidths());
+        m_header->resize(dynamicItemSize.width(), m_header->size().height());
     }
 
     // Update the role sizes for all visible widgets
diff --git a/dolphin/src/kitemviews/kitemlistview.h \
b/dolphin/src/kitemviews/kitemlistview.h index e49dbe4..3ddfabd 100644
--- a/dolphin/src/kitemviews/kitemlistview.h
+++ b/dolphin/src/kitemviews/kitemlistview.h
@@ -66,6 +66,7 @@ class LIBDOLPHINPRIVATE_EXPORT KItemListView : public \
QGraphicsWidget  Q_OBJECT
 
     Q_PROPERTY(qreal scrollOffset READ scrollOffset WRITE setScrollOffset)
+    Q_PROPERTY(qreal itemOffset READ itemOffset WRITE setItemOffset)
 
 public:
     KItemListView(QGraphicsWidget* parent = 0);
@@ -199,6 +200,7 @@ public:
     virtual void paint(QPainter* painter, const QStyleOptionGraphicsItem* option, \
QWidget* widget = 0);  
 signals:
+    void scrollOrientationChanged(Qt::Orientation current, Qt::Orientation \
previous);  void scrollOffsetChanged(qreal current, qreal previous);
     void maximumScrollOffsetChanged(qreal current, qreal previous);
     void itemOffsetChanged(qreal current, qreal previous);
diff --git a/dolphin/src/views/dolphinview.cpp b/dolphin/src/views/dolphinview.cpp
index fe45541..a82008d 100644
--- a/dolphin/src/views/dolphinview.cpp
+++ b/dolphin/src/views/dolphinview.cpp
@@ -719,8 +719,10 @@ void DolphinView::wheelEvent(QWheelEvent* event)
         const int numSteps = numDegrees / 15;
 
         setZoomLevel(zoomLevel() + numSteps);
+        event->accept();
+    } else {
+        event->ignore();
     }
-    event->accept();
 }
 
 void DolphinView::activate()


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