From 249071e508d1758a0968a7d89a3d264c75cd104d 2012-03-16 07:53:49
From: Jani Honkonen <jani.honkonen@digia.com>
Date: 2012-03-16 07:53:49
Subject: [PATCH] Add animations to pie. Works but has some visual issues when adding slices.

---

diff --git a/demos/piechartcustomization/main.cpp b/demos/piechartcustomization/main.cpp
index 973fc30..13d9b17 100644
--- a/demos/piechartcustomization/main.cpp
+++ b/demos/piechartcustomization/main.cpp
@@ -287,6 +287,7 @@ public:
         // create chart
         m_chartView =  new QChartView();
         m_chartView->setChartTitle("Piechart customization");
+        m_chartView->setAnimationOptions(QChart::AllAnimations);
 
         // create series
         m_series = new QPieSeries();
@@ -349,12 +350,15 @@ public:
         m_endAngle->setValue(m_series->pieEndAngle());
         m_endAngle->setSingleStep(1);
 
+        QPushButton *addSlice = new QPushButton("Add slice");
+
         QFormLayout* seriesSettingsLayout = new QFormLayout();
         seriesSettingsLayout->addRow("Horizontal position", m_hPosition);
         seriesSettingsLayout->addRow("Vertical position", m_vPosition);
         seriesSettingsLayout->addRow("Size factor", m_sizeFactor);
         seriesSettingsLayout->addRow("Start angle", m_startAngle);
         seriesSettingsLayout->addRow("End angle", m_endAngle);
+        seriesSettingsLayout->addRow(addSlice);
         QGroupBox* seriesSettings = new QGroupBox("Series");
         seriesSettings->setLayout(seriesSettingsLayout);
 
@@ -363,6 +367,7 @@ public:
         connect(m_sizeFactor, SIGNAL(valueChanged(double)), this, SLOT(updateSerieSettings()));
         connect(m_startAngle, SIGNAL(valueChanged(double)), this, SLOT(updateSerieSettings()));
         connect(m_endAngle, SIGNAL(valueChanged(double)), this, SLOT(updateSerieSettings()));
+        connect(addSlice, SIGNAL(clicked()), this, SLOT(addSlice()));
 
         // slice settings
         m_sliceName = new QLabel("<click a slice>");
@@ -381,6 +386,7 @@ public:
         m_font = new QPushButton();
         m_labelArmPen = new QPushButton();
         m_labelArmPenTool = new PenTool("Label arm pen", this);
+        QPushButton *removeSlice = new QPushButton("Remove slice");
 
         QFormLayout* sliceSettingsLayout = new QFormLayout();
         sliceSettingsLayout->addRow("Selected", m_sliceName);
@@ -393,6 +399,7 @@ public:
         sliceSettingsLayout->addRow("Label arm length", m_sliceLabelArmFactor);
         sliceSettingsLayout->addRow("Exploded", m_sliceExploded);
         sliceSettingsLayout->addRow("Explode distance", m_sliceExplodedFactor);
+        sliceSettingsLayout->addRow(removeSlice);
         QGroupBox* sliceSettings = new QGroupBox("Slice");
         sliceSettings->setLayout(sliceSettingsLayout);
 
@@ -409,6 +416,7 @@ public:
         connect(m_sliceLabelArmFactor, SIGNAL(valueChanged(double)), this, SLOT(updateSliceSettings()));
         connect(m_sliceExploded, SIGNAL(toggled(bool)), this, SLOT(updateSliceSettings()));
         connect(m_sliceExplodedFactor, SIGNAL(valueChanged(double)), this, SLOT(updateSliceSettings()));
+        connect(removeSlice, SIGNAL(clicked()), this, SLOT(removeSlice()));
 
         // create main layout
         QVBoxLayout *settingsLayout = new QVBoxLayout();
@@ -513,6 +521,20 @@ public Q_SLOTS:
         m_font->setText(dialog.currentFont().toString());
     }
 
+    void addSlice()
+    {
+        *m_series << new CustomSlice(10.0, "Slice " + QString::number(m_series->count()));
+    }
+
+    void removeSlice()
+    {
+        if (!m_slice)
+            return;
+
+        m_series->remove(m_slice);
+        m_slice = 0;
+    }
+
 private:
     QComboBox *m_themeComboBox;
     QCheckBox *m_aaCheckBox;
diff --git a/src/animations/animations.pri b/src/animations/animations.pri
index 124acee..5b0d655 100644
--- a/src/animations/animations.pri
+++ b/src/animations/animations.pri
@@ -4,10 +4,14 @@ DEPENDPATH += $$PWD
 SOURCES += \
     $$PWD/axisanimation.cpp \
     $$PWD/chartanimator.cpp \
-    $$PWD/xyanimation.cpp
+    $$PWD/xyanimation.cpp \
+    $$PWD/pieanimation.cpp \
+    $$PWD/piesliceanimation.cpp
 
 PRIVATE_HEADERS += \
     $$PWD/axisanimation_p.h \
     $$PWD/chartanimator_p.h \
     $$PWD/chartanimation_p.h \
-    $$PWD/xyanimation_p.h
\ No newline at end of file
+    $$PWD/xyanimation_p.h \
+    $$PWD/pieanimation_p.h \
+    $$PWD/piesliceanimation_p.h
diff --git a/src/animations/chartanimator.cpp b/src/animations/chartanimator.cpp
index aa176c8..7ef3645 100644
--- a/src/animations/chartanimator.cpp
+++ b/src/animations/chartanimator.cpp
@@ -2,6 +2,7 @@
 #include "axisanimation_p.h"
 #include "xyanimation_p.h"
 #include "xychartitem_p.h"
+#include "pieanimation_p.h"
 #include "areachartitem_p.h"
 #include <QTimer>
 
@@ -44,6 +45,18 @@ void ChartAnimator::addAnimation(XYChartItem*  item)
     item->setAnimator(this);
 }
 
+void ChartAnimator::addAnimation(PieChartItem* item)
+{
+    ChartAnimation* animation = m_animations.value(item);
+
+    if(!animation) {
+        animation = new PieAnimation(item);
+        m_animations.insert(item,animation);
+    }
+
+    item->setAnimator(this);
+}
+
 void ChartAnimator::removeAnimation(ChartItem* item)
 {
     item->setAnimator(0);
@@ -171,6 +184,20 @@ void ChartAnimator::updateLayout(XYChartItem* item, QVector<QPointF>& newPoints)
     QTimer::singleShot(0,animation,SLOT(start()));
 }
 
+void ChartAnimator::applyLayout(PieChartItem* item, QVector<PieSliceLayout> &layout)
+{
+    PieAnimation* animation = static_cast<PieAnimation*>(m_animations.value(item));
+    Q_ASSERT(animation);
+    animation->setValues(layout);
+}
+
+void ChartAnimator::updateLayout(PieChartItem* item, PieSliceLayout &layout)
+{
+    PieAnimation* animation = static_cast<PieAnimation*>(m_animations.value(item));
+    Q_ASSERT(animation);
+    animation->updateValue(layout);
+}
+
 void ChartAnimator::setState(State state,const QPointF& point)
 {
 	m_state=state;
diff --git a/src/animations/chartanimator_p.h b/src/animations/chartanimator_p.h
index dc430a7..cb28d53 100644
--- a/src/animations/chartanimator_p.h
+++ b/src/animations/chartanimator_p.h
@@ -2,6 +2,7 @@
 #define CHARTANIMATOR_P_H_
 #include "qchartglobal.h"
 #include "chartanimation_p.h"
+#include "piechartitem_p.h"
 #include <QPointF>
 
 QTCOMMERCIALCHART_BEGIN_NAMESPACE
@@ -22,6 +23,7 @@ public:
 
     void addAnimation(AxisItem* item);
     void addAnimation(XYChartItem* item);
+    void addAnimation(PieChartItem* item);
 
     void removeAnimation(ChartItem* item);
 
@@ -30,6 +32,9 @@ public:
     void updateLayout(XYChartItem* item, QVector<QPointF>& layout);
     void applyLayout(AxisItem* item, QVector<qreal>& layout);
 
+    void applyLayout(PieChartItem* item, QVector<PieSliceLayout> &layout);
+    void updateLayout(PieChartItem* item, PieSliceLayout &layout);
+
     void setState(State state,const QPointF& point = QPointF());
 
 private:
diff --git a/src/animations/pieanimation.cpp b/src/animations/pieanimation.cpp
new file mode 100644
index 0000000..367c782
--- /dev/null
+++ b/src/animations/pieanimation.cpp
@@ -0,0 +1,94 @@
+#include "PieAnimation_p.h"
+#include "piesliceanimation_p.h"
+#include "piechartitem_p.h"
+#include <QParallelAnimationGroup>
+#include <QTimer>
+
+QTCOMMERCIALCHART_BEGIN_NAMESPACE
+
+PieAnimation::PieAnimation(PieChartItem *item)
+    :ChartAnimation(item),
+    m_item(item)
+{
+}
+
+PieAnimation::~PieAnimation()
+{
+}
+
+void PieAnimation::setValues(QVector<PieSliceLayout>& newValues)
+{
+    PieSliceAnimation *animation = 0;
+
+    foreach (PieSliceLayout endLayout, newValues) {
+        animation = m_animations.value(endLayout.m_data);
+        if (animation) {
+            // existing slice
+            animation->stop();
+            animation->updateValue(endLayout);
+        } else {
+            // new slice
+            animation = new PieSliceAnimation(m_item);
+            m_animations.insert(endLayout.m_data, animation);
+            PieSliceLayout startLayout = endLayout;
+            startLayout.m_radius = 0;
+            //startLayout.m_startAngle = 0;
+            //startLayout.m_angleSpan = 0;
+            animation->setValue(startLayout, endLayout);
+        }
+        animation->setDuration(1000);
+        animation->setEasingCurve(QEasingCurve::OutQuart);
+        QTimer::singleShot(0, animation, SLOT(start())); // TODO: use sequential animation?
+    }
+
+    foreach (QPieSlice *s, m_animations.keys()) {
+        bool isFound = false;
+        foreach (PieSliceLayout layout, newValues) {
+            if (s == layout.m_data)
+                isFound = true;
+        }
+        if (!isFound) {
+            // slice has been deleted
+            animation = m_animations.value(s);
+            animation->stop();
+            PieSliceLayout endLayout = m_animations.value(s)->currentSliceValue();
+            endLayout.m_radius = 0;
+            // TODO: find the actual angle where this slice disappears
+            endLayout.m_startAngle = endLayout.m_startAngle + endLayout.m_angleSpan;
+            endLayout.m_angleSpan = 0;
+            animation->updateValue(endLayout);
+            animation->setDuration(1000);
+            animation->setEasingCurve(QEasingCurve::OutQuart);
+            connect(animation, SIGNAL(finished()), this, SLOT(destroySliceAnimationComplete()));
+            QTimer::singleShot(0, animation, SLOT(start()));
+        }
+    }
+}
+
+void PieAnimation::updateValue(PieSliceLayout& endLayout)
+{
+    PieSliceAnimation *animation = m_animations.value(endLayout.m_data);
+    Q_ASSERT(animation);
+    animation->stop();
+    animation->updateValue(endLayout);
+    animation->setDuration(1000);
+    animation->setEasingCurve(QEasingCurve::OutQuart);
+    QTimer::singleShot(0, animation, SLOT(start()));
+}
+
+void PieAnimation::updateCurrentValue(const QVariant &)
+{
+    // nothing to do...
+}
+
+void PieAnimation::destroySliceAnimationComplete()
+{
+    PieSliceAnimation *animation = static_cast<PieSliceAnimation*>(sender());
+    QPieSlice *slice = m_animations.key(animation);
+    m_item->destroySlice(slice);
+    delete m_animations.take(slice);
+}
+
+#include "moc_pieanimation_p.cpp"
+
+QTCOMMERCIALCHART_END_NAMESPACE
diff --git a/src/animations/pieanimation_p.h b/src/animations/pieanimation_p.h
new file mode 100644
index 0000000..4e70469
--- /dev/null
+++ b/src/animations/pieanimation_p.h
@@ -0,0 +1,35 @@
+#ifndef PIEANIMATION_P_H_
+#define PIEANIMATION_P_H_
+
+#include "chartanimation_p.h"
+#include "piechartitem_p.h"
+#include "piesliceanimation_p.h"
+
+QTCOMMERCIALCHART_BEGIN_NAMESPACE
+
+class PieChartItem;
+
+class PieAnimation : public ChartAnimation
+{
+    Q_OBJECT
+
+public:
+    PieAnimation(PieChartItem *item);
+    ~PieAnimation();
+    void setValues(QVector<PieSliceLayout>& newValues);
+    void updateValue(PieSliceLayout& newValue);
+
+public: // from QVariantAnimation
+    void updateCurrentValue(const QVariant &value);
+
+public Q_SLOTS:
+    void destroySliceAnimationComplete();
+
+private:
+    PieChartItem *m_item;
+    QHash<QPieSlice*, PieSliceAnimation*> m_animations;
+};
+
+QTCOMMERCIALCHART_END_NAMESPACE
+
+#endif
diff --git a/src/animations/piesliceanimation.cpp b/src/animations/piesliceanimation.cpp
new file mode 100644
index 0000000..47e5189
--- /dev/null
+++ b/src/animations/piesliceanimation.cpp
@@ -0,0 +1,77 @@
+#include "PieSliceAnimation_p.h"
+#include "piechartitem_p.h"
+#include "qpieslice.h"
+
+Q_DECLARE_METATYPE(QtCommercialChart::PieSliceLayout)
+
+QTCOMMERCIALCHART_BEGIN_NAMESPACE
+
+qreal linearPos(qreal start, qreal end, qreal pos)
+{
+    return start + ((end - start) * pos);
+}
+
+QPointF linearPos(QPointF start, QPointF end, qreal pos)
+{
+    qreal x = linearPos(start.x(), end.x(), pos);
+    qreal y = linearPos(start.y(), end.y(), pos);
+    return QPointF(x, y);
+}
+
+PieSliceAnimation::PieSliceAnimation(PieChartItem *item)
+    :QVariantAnimation(item),
+    m_item(item)
+{
+}
+
+PieSliceAnimation::~PieSliceAnimation()
+{
+}
+
+void PieSliceAnimation::setValue(PieSliceLayout& startValue, PieSliceLayout& endValue)
+{
+    if (state() != QAbstractAnimation::Stopped)
+        stop();
+
+    setKeyValueAt(0.0, qVariantFromValue(startValue));
+    setKeyValueAt(1.0, qVariantFromValue(endValue));
+}
+
+void PieSliceAnimation::updateValue(PieSliceLayout& endValue)
+{
+    if (state() != QAbstractAnimation::Stopped)
+        stop();
+
+    //qDebug() << "PieSliceAnimation::updateValue()" << endValue.m_data->label() << currentSliceValue().m_startAngle << endValue.m_startAngle;
+
+    setKeyValueAt(0.0, qVariantFromValue(currentSliceValue()));
+    setKeyValueAt(1.0, qVariantFromValue(endValue));
+}
+
+PieSliceLayout PieSliceAnimation::currentSliceValue()
+{
+    return qVariantValue<PieSliceLayout>(currentValue());
+}
+
+QVariant PieSliceAnimation::interpolated(const QVariant &start, const QVariant &end, qreal progress) const
+{
+    PieSliceLayout startValue = qVariantValue<PieSliceLayout>(start);
+    PieSliceLayout endValue = qVariantValue<PieSliceLayout>(end);
+
+    PieSliceLayout result;
+    result = endValue;
+    result.m_center = linearPos(startValue.m_center, endValue.m_center, progress);
+    result.m_radius = linearPos(startValue.m_radius, endValue.m_radius, progress);
+    result.m_startAngle = linearPos(startValue.m_startAngle, endValue.m_startAngle, progress);
+    result.m_angleSpan = linearPos(startValue.m_angleSpan, endValue.m_angleSpan, progress);
+
+    return qVariantFromValue(result);
+}
+
+void PieSliceAnimation::updateCurrentValue(const QVariant &value)
+{
+    if (state() != QAbstractAnimation::Stopped) //workaround
+        m_item->setLayout(qVariantValue<PieSliceLayout>(value));
+}
+
+QTCOMMERCIALCHART_END_NAMESPACE
diff --git a/src/animations/piesliceanimation_p.h b/src/animations/piesliceanimation_p.h
new file mode 100644
index 0000000..5afff87
--- /dev/null
+++ b/src/animations/piesliceanimation_p.h
@@ -0,0 +1,30 @@
+#ifndef PIESLICEANIMATION_P_H_
+#define PIESLICEANIMATION_P_H_
+
+#include "piechartitem_p.h"
+#include <QVariantAnimation>
+
+QTCOMMERCIALCHART_BEGIN_NAMESPACE
+
+class PieChartItem;
+
+class PieSliceAnimation : public QVariantAnimation
+{
+public:
+    PieSliceAnimation(PieChartItem *item);
+    ~PieSliceAnimation();
+    void setValue(PieSliceLayout& startValue, PieSliceLayout& endValue);
+    void updateValue(PieSliceLayout& endValue);
+    PieSliceLayout currentSliceValue();
+
+protected:
+    QVariant interpolated(const QVariant &start, const QVariant &end, qreal progress) const;
+    void updateCurrentValue(const QVariant &value);
+
+private:
+    PieChartItem *m_item;
+};
+
+QTCOMMERCIALCHART_END_NAMESPACE
+
+#endif
diff --git a/src/chartpresenter.cpp b/src/chartpresenter.cpp
index 5f416bd..88e06e4 100644
--- a/src/chartpresenter.cpp
+++ b/src/chartpresenter.cpp
@@ -224,7 +224,7 @@ void ChartPresenter::handleSeriesAdded(QSeries* series,Domain* domain)
         QPieSeries *pieSeries = static_cast<QPieSeries *>(series);
         PieChartItem* pie = new PieChartItem(m_chart, pieSeries);
         if(m_options.testFlag(QChart::SeriesAnimations)) {
-           // m_animator->addAnimation(pie);
+            m_animator->addAnimation(pie);
         }
         m_chartTheme->decorate(pieSeries, m_dataset->seriesIndex(series));
         QObject::connect(this,SIGNAL(geometryChanged(const QRectF&)),pie,SLOT(handleGeometryChanged(const QRectF&)));
diff --git a/src/piechart/piechartitem.cpp b/src/piechart/piechartitem.cpp
index bf4e4cd..0fd7ba7 100644
--- a/src/piechart/piechartitem.cpp
+++ b/src/piechart/piechartitem.cpp
@@ -3,6 +3,7 @@
 #include "qpieslice.h"
 #include "qpieseries.h"
 #include "chartpresenter_p.h"
+#include "chartanimator_p.h"
 #include <QDebug>
 #include <QPainter>
 
@@ -36,16 +37,24 @@ void PieChartItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *, QW
 
 void PieChartItem::handleSeriesChanged()
 {
-    QVector<PieSliceLayout> sliceLayout = calculateLayout();
-    applyLayout(sliceLayout);
+    QVector<PieSliceLayout> layout = calculateLayout();
+    applyLayout(layout);
     update();
 }
 
 void PieChartItem::handleSliceChanged()
 {
-    // TODO: optimize don't need to handle all slices
-    QVector<PieSliceLayout> sliceLayout = calculateLayout();
-    applyLayout(sliceLayout);
+    QPieSlice* slice = qobject_cast<QPieSlice *>(sender());
+    Q_ASSERT(m_slices.contains(slice));
+
+    //qDebug() << "PieChartItem::handleSliceChanged" << slice->label();
+
+    // TODO: Optimize. No need to calculate everything.
+    QVector<PieSliceLayout> layout = calculateLayout();
+    foreach (PieSliceLayout sl, layout) {
+        if (sl.m_data == slice)
+            updateLayout(sl);
+    }
     update();
 }
 
@@ -93,15 +102,23 @@ QVector<PieSliceLayout> PieChartItem::calculateLayout()
     return layout;
 }
 
-void PieChartItem::applyLayout(const QVector<PieSliceLayout> &layout)
+void PieChartItem::applyLayout(QVector<PieSliceLayout> &layout)
 {
-    //if(m_animator)
-    //        m_animator->applyLayout(this,points);
-    //else
-    setLayout(layout);
+    if (m_animator)
+        m_animator->applyLayout(this, layout);
+    else
+        setLayout(layout);
 }
 
-void PieChartItem::setLayout(const QVector<PieSliceLayout> &layout)
+void PieChartItem::updateLayout(PieSliceLayout &layout)
+{
+    if (m_animator)
+        m_animator->updateLayout(this, layout);
+    else
+        setLayout(layout);
+}
+
+void PieChartItem::setLayout(QVector<PieSliceLayout> &layout)
 {
     foreach (PieSliceLayout l, layout) {
 
@@ -135,8 +152,32 @@ void PieChartItem::setLayout(const QVector<PieSliceLayout> &layout)
         }
 
         if (!found)
-            delete m_slices.take(s);
+            destroySlice(s);
+    }
+}
+
+void PieChartItem::setLayout(PieSliceLayout &layout)
+{
+    // find slice
+    PieSlice *slice = m_slices.value(layout.m_data);
+    if (!slice) {
+        slice = new PieSlice(this);
+        m_slices.insert(layout.m_data, slice);
+        connect(layout.m_data, SIGNAL(changed()), this, SLOT(handleSliceChanged()));
+        connect(slice, SIGNAL(clicked()), layout.m_data, SIGNAL(clicked()));
+        connect(slice, SIGNAL(hoverEnter()), layout.m_data, SIGNAL(hoverEnter()));
+        connect(slice, SIGNAL(hoverLeave()), layout.m_data, SIGNAL(hoverLeave()));
     }
+    slice->setLayout(layout);
+    if (m_series->m_slices.contains(layout.m_data)) // Slice has been deleted if not found. Animations ongoing...
+        slice->updateData(layout.m_data);
+    slice->updateGeometry();
+    slice->update();
+}
+
+void PieChartItem::destroySlice(QPieSlice *slice)
+{
+    delete m_slices.take(slice);
 }
 
 #include "moc_piechartitem_p.cpp"
diff --git a/src/piechart/piechartitem_p.h b/src/piechart/piechartitem_p.h
index 253348a..6ea55c7 100644
--- a/src/piechart/piechartitem_p.h
+++ b/src/piechart/piechartitem_p.h
@@ -28,10 +28,13 @@ public Q_SLOTS:
     void handleDomainChanged(qreal, qreal, qreal, qreal);
     void handleGeometryChanged(const QRectF& rect);
 
-private:
+public:
     QVector<PieSliceLayout> calculateLayout();
-    void applyLayout(const QVector<PieSliceLayout> &layout);
-    void setLayout(const QVector<PieSliceLayout> &layout);
+    void applyLayout(QVector<PieSliceLayout> &layout);
+    void updateLayout(PieSliceLayout &layout);
+    void setLayout(QVector<PieSliceLayout> &layout);
+    void setLayout(PieSliceLayout &layout);
+    void destroySlice(QPieSlice *slice);
 
 private:
     friend class PieSlice;
diff --git a/src/piechart/pieslice.cpp b/src/piechart/pieslice.cpp
index fb55ef9..20f576c 100644
--- a/src/piechart/pieslice.cpp
+++ b/src/piechart/pieslice.cpp
@@ -22,8 +22,6 @@ QPointF offset(qreal angle, qreal length)
 
 PieSlice::PieSlice(QGraphicsItem* parent)
     :QGraphicsObject(parent),
-    m_startAngle(0),
-    m_angleSpan(0),
     m_isExploded(false),
     m_explodeDistanceFactor(0),
     m_labelVisible(false),
@@ -41,7 +39,7 @@ PieSlice::~PieSlice()
 
 QRectF PieSlice::boundingRect() const
 {
-    return m_slicePath.boundingRect();
+    return m_slicePath.boundingRect().united(m_labelTextRect);
 }
 
 QPainterPath PieSlice::shape() const
@@ -90,7 +88,6 @@ void PieSlice::mousePressEvent(QGraphicsSceneMouseEvent* /*event*/)
 void PieSlice::setLayout(PieSliceLayout layout)
 {
     m_layout = layout;
-    updateData(layout.m_data);
 }
 
 void PieSlice::updateGeometry()
@@ -103,7 +100,7 @@ void PieSlice::updateGeometry()
     // update slice path
     qreal centerAngle;
     QPointF armStart;
-    m_slicePath = slicePath(m_layout.m_center, m_layout.m_radius, m_startAngle, m_angleSpan, &centerAngle, &armStart);
+    m_slicePath = slicePath(m_layout.m_center, m_layout.m_radius, m_layout.m_startAngle, m_layout.m_angleSpan, &centerAngle, &armStart);
 
     // update text rect
     m_labelTextRect = labelTextRect(m_labelFont, m_labelText);
@@ -122,8 +119,6 @@ void PieSlice::updateData(const QPieSlice* sliceData)
 {
     // TODO: compare what has changes to avoid unneccesary geometry updates
 
-    m_startAngle = sliceData->startAngle();
-    m_angleSpan = sliceData->m_angleSpan;
     m_isExploded = sliceData->isExploded();
     m_explodeDistanceFactor = sliceData->explodeDistanceFactor();
     m_slicePen = sliceData->slicePen();
diff --git a/src/piechart/pieslice_p.h b/src/piechart/pieslice_p.h
index 953ce35..ec50820 100644
--- a/src/piechart/pieslice_p.h
+++ b/src/piechart/pieslice_p.h
@@ -19,7 +19,7 @@ class QPieSlice;
 class PieSliceLayout
 {
 public:
-    QPieSlice* m_data;
+    QPieSlice* m_data; // TODO: get rid of this
     QPointF m_center;
     qreal m_radius;
     qreal m_startAngle;
@@ -60,8 +60,6 @@ private:
     PieSliceLayout m_layout;
 
     QPainterPath m_slicePath;
-    qreal m_startAngle;
-    qreal m_angleSpan;
     bool m_isExploded;
     qreal m_explodeDistanceFactor;
     bool m_labelVisible;
diff --git a/src/piechart/qpieseries.cpp b/src/piechart/qpieseries.cpp
index 4b22081..46f2833 100644
--- a/src/piechart/qpieseries.cpp
+++ b/src/piechart/qpieseries.cpp
@@ -511,6 +511,8 @@ void QPieSeries::updateDerivativeData()
     foreach (QPieSlice* s, m_slices)
         m_total += s->value();
 
+    // TODO: emit totalChanged?
+
     // we must have some values
     if (m_total == 0) {
         qDebug() << "QPieSeries::updateDerivativeData() total == 0";
@@ -520,31 +522,35 @@ void QPieSeries::updateDerivativeData()
     // update slice attributes
     qreal sliceAngle = m_pieStartAngle;
     qreal pieSpan = m_pieEndAngle - m_pieStartAngle;
+    QVector<QPieSlice*> changed;
     foreach (QPieSlice* s, m_slices) {
 
-        bool changed = false;
+        bool isChanged = false;
 
         qreal percentage = s->value() / m_total;
         if (s->m_percentage != percentage) {
             s->m_percentage = percentage;
-            changed = true;
+            isChanged = true;
         }
 
         qreal sliceSpan = pieSpan * percentage;
         if (s->m_angleSpan != sliceSpan) {
             s->m_angleSpan = sliceSpan;
-            changed = true;
+            isChanged = true;
         }
 
         if (s->m_startAngle != sliceAngle) {
             s->m_startAngle = sliceAngle;
-            changed = true;
+            isChanged = true;
         }
         sliceAngle += sliceSpan;
 
-        if (changed)
-            emit s->changed();
+        if (isChanged)
+            changed << s;
     }
+
+    foreach (QPieSlice* s, changed)
+        emit s->changed();
 }
 
 bool QPieSeries::setModel(QAbstractItemModel* model)
diff --git a/src/piechart/qpieseries.h b/src/piechart/qpieseries.h
index bd4e34c..1924f73 100644
--- a/src/piechart/qpieseries.h
+++ b/src/piechart/qpieseries.h
@@ -124,6 +124,7 @@ private:
     // TODO: use PIML
     friend class PieChartItem;
     friend class PieSlice;
+    friend class QPieSlice;
 
     QList<QPieSlice*> m_slices;
     qreal m_pieRelativeHorPos;
diff --git a/src/piechart/qpieslice.cpp b/src/piechart/qpieslice.cpp
index 80ce8a6..91a713b 100644
--- a/src/piechart/qpieslice.cpp
+++ b/src/piechart/qpieslice.cpp
@@ -1,4 +1,5 @@
 #include "qpieslice.h"
+#include "qpieseries.h"
 
 QTCOMMERCIALCHART_BEGIN_NAMESPACE
 
@@ -266,7 +267,12 @@ void QPieSlice::setValue(qreal value)
 {
     if (m_value != value) {
         m_value = value;
-        emit changed();
+
+        QPieSeries *series = qobject_cast<QPieSeries*>(parent());
+        if (series)
+            series->updateDerivativeData(); // will emit changed()
+        else
+            emit changed();
     }
 }
 
diff --git a/src/piechart/qpieslice.h b/src/piechart/qpieslice.h
index abaf88c..48f169a 100644
--- a/src/piechart/qpieslice.h
+++ b/src/piechart/qpieslice.h
@@ -8,6 +8,7 @@
 #include <QFont>
 
 QTCOMMERCIALCHART_BEGIN_NAMESPACE
+class QPieSeries;
 
 class QTCOMMERCIALCHART_EXPORT QPieSlice : public QObject
 {
@@ -29,8 +30,6 @@ public:
     bool isLabelVisible() const;
     void setExploded(bool exploded);
     bool isExploded() const;
-    void setExplodeDistanceFactor(qreal factor);
-    qreal explodeDistanceFactor() const;
 
     // generated data
     qreal percentage() const;
@@ -48,10 +47,8 @@ public:
     QFont labelFont() const;
     void setLabelArmLengthFactor(qreal factor);
     qreal labelArmLengthFactor() const;
-
-    // TODO: label position in general
-    // setLabelFlags(inside|outside|labelArmOn|labelArmOff|???)
-    // setLabelOrientation(horizontal|vertical|same as slice center angle|???)
+    void setExplodeDistanceFactor(qreal factor);
+    qreal explodeDistanceFactor() const;
 
 Q_SIGNALS:
     void clicked();