Optimize barcharts painting

Previously, bar charts used to recreate the bar chart visuals from
scratch whenever any change to the bar data occurred.
The following changes were made:
- Graphics items are generated only for visible bars and labels
- Graphics items are reused if layout or data changes
- Labels are not generated unless they are visible
- Only newly added bars are animated from scratch; existing bars
  will retain their size, making things more visually pleasing.

With these optimizations, the size of the bar series is irrelevant
to the painting performance, only thing that matters is how many
bars and labels are actually within visible range.

Task-number: QTBUG-52442
Change-Id: If3199a86e6819ef6219d2eb5f06d729c0bdbd2ae
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>

5 files changed, 444 insertions, 1 deletions

diff --git a/tests/manual/barcharttester/barcharttester.pro b/tests/manual/barcharttester/barcharttester.pro
new file mode 100644
index 00000000..09b28bba
--- /dev/null
+++ b/tests/manual/barcharttester/barcharttester.pro
@@ -0,0 +1,9 @@
+QT += core gui charts widgets
+
+TARGET = barcharttester
+TEMPLATE = app
+
+SOURCES += main.cpp\
+           chart-widget.cpp
+
+HEADERS  += chart-widget.h
diff --git a/tests/manual/barcharttester/chart-widget.cpp b/tests/manual/barcharttester/chart-widget.cpp
new file mode 100644
index 00000000..a2f15b42
--- /dev/null
+++ b/tests/manual/barcharttester/chart-widget.cpp
@@ -0,0 +1,319 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the Qt Charts module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 or (at your option) any later version
+** approved by the KDE Free Qt Foundation. The licenses are as published by
+** the Free Software Foundation and appearing in the file LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "chart-widget.h"
+
+#include <QtCharts/QLineSeries>
+#include <QtCharts/QLegend>
+#include <QtCharts/QCategoryAxis>
+#include <QtCharts/QValueAxis>
+#include <QtCharts/QLogValueAxis>
+#include <QtCharts/QBarSet>
+#include <QtCharts/QHorizontalBarSeries>
+#include <QtCharts/QHorizontalPercentBarSeries>
+#include <QtCharts/QHorizontalStackedBarSeries>
+#include <QtCharts/QPercentBarSeries>
+#include <QtCharts/QStackedBarSeries>
+#include <QtCore/QTime>
+#include <QElapsedTimer>
+#include <QDebug>
+
+const int initialCount = 20;
+const int visibleCount = 40;
+const int storeCount = 100000000;
+const int interval = 600;
+const int initialSetCount = 3;
+const int maxSetCount = 3;
+const bool removeSets = true;
+const int extraSetFrequency = 30;
+const bool initialLabels = false;
+const int labelsTrigger = -1;
+const int visibleTrigger = -1;
+const int appendFrequency = 1;
+const int animationTrigger = -1;
+const bool sameNumberOfBars = false;
+const bool animation = true;
+const int animationDuration = 500;
+
+const bool horizontal = false;
+const bool percent = false;
+const bool stacked = false;
+
+// Negative indexes are counted from end of the set.
+const bool doReplace = false;
+const bool doRemove = false;
+const bool doInsert = false;
+const bool singleReplace = false;
+const bool singleRemove = false;
+const bool singleInsert = false;
+const int removeIndex = -7;
+const int replaceIndex = -3;
+const int insertIndex = -5;
+
+const bool logarithmic = false;
+// Note: reverse axes are not fully supported for bars (animation and label positioning break a bit)
+const bool reverseBar = false;
+const bool reverseValue = false;
+
+static int counter = 1;
+static const QString nameTemplate = QStringLiteral("Set %1");
+
+ChartWidget::ChartWidget(QWidget *parent) :
+    QWidget(parent),
+    m_chart(new QChart()),
+    m_chartView(new QChartView(this)),
+    m_barAxis(new QValueAxis()),
+    m_series(nullptr),
+    m_setCount(initialSetCount)
+{
+    m_elapsedTimer.start();
+
+    if (logarithmic) {
+        QLogValueAxis *logAxis = new QLogValueAxis;
+        logAxis->setBase(2);
+        m_valueAxis = logAxis;
+    } else {
+        m_valueAxis = new QValueAxis;
+    }
+
+    m_barAxis->setReverse(reverseBar);
+    m_valueAxis->setReverse(reverseValue);
+
+    if (horizontal) {
+        if (percent)
+            m_series = new QHorizontalPercentBarSeries;
+        else if (stacked)
+            m_series = new QHorizontalStackedBarSeries;
+        else
+            m_series = new QHorizontalBarSeries;
+    } else {
+        if (percent)
+            m_series = new QPercentBarSeries;
+        else if (stacked)
+            m_series = new QStackedBarSeries;
+        else
+            m_series = new QBarSeries;
+    }
+
+    qsrand((uint) QTime::currentTime().msec());
+
+    resize(800, 300);
+    m_horizontalLayout = new QHBoxLayout(this);
+    m_horizontalLayout->setSpacing(6);
+    m_horizontalLayout->setContentsMargins(11, 11, 11, 11);
+    m_horizontalLayout->addWidget(m_chartView);
+
+    qDebug() << "UI setup time:"<< m_elapsedTimer.restart();
+
+    m_chartView->setRenderHint(QPainter::Antialiasing);
+
+    createChart();
+    qDebug() << "Chart creation time:"<< m_elapsedTimer.restart();
+
+    QObject::connect(&m_timer, SIGNAL(timeout()), this, SLOT(handleTimeout()));
+
+    m_timer.setInterval(interval);
+    m_timer.start();
+}
+
+ChartWidget::~ChartWidget()
+{
+}
+
+void ChartWidget::handleTimeout()
+{
+    qDebug() << "Intervening time:" << m_elapsedTimer.restart();
+
+    qDebug() << "----------" << counter << "----------";
+
+    bool doScroll = false;
+
+    if (counter % appendFrequency == 0) {
+        for (int i = 0; i < maxSetCount; i++) {
+            QBarSet *set = m_sets.at(i);
+            qreal value = (counter % 100) / qreal(i+1);
+            set->append(value);
+            if (set->count() > storeCount)
+                set->remove(5, set->count() - storeCount);
+            if (set->count() > visibleCount)
+                doScroll = true;
+        }
+        qDebug() << "Append time:" << m_elapsedTimer.restart();
+    }
+
+    if (doScroll) {
+        doScroll = false;
+        if (horizontal)
+            m_chart->scroll(0, m_chart->plotArea().height() / visibleCount);
+        else
+            m_chart->scroll(m_chart->plotArea().width() / visibleCount, 0);
+        qDebug() << "Scroll time:" << m_elapsedTimer.restart();
+    }
+
+    if (doRemove || doReplace || doInsert) {
+        for (int i = 0; i < m_setCount; i++) {
+            QBarSet *set = m_sets.at(i);
+            qreal value = ((counter + 20) % 100) / qreal(i+1);
+            if (doReplace && (!singleReplace || i == 0)) {
+                int index = replaceIndex < 0 ? set->count() + replaceIndex : replaceIndex;
+                set->replace(index, value);
+            }
+            if (doRemove && (!singleRemove || i == 0)) {
+                int index = removeIndex < 0 ? set->count() + removeIndex : removeIndex;
+                set->remove(index, 1);
+            }
+            if (doInsert && (!singleInsert || i == 0)) {
+                int index = insertIndex < 0 ? set->count() + insertIndex : insertIndex;
+                set->insert(index, value);
+            }
+        }
+        qDebug() << "R/R    time:" << m_elapsedTimer.restart();
+    }
+
+//    if (counter % 5 == 0) {
+//        m_sets.at(0)->setPen(QPen(QColor(counter % 255, counter % 255, counter % 255), 2));
+//    }
+
+    if (counter % extraSetFrequency == 0) {
+        if (m_setCount <= maxSetCount) {
+            qDebug() << "Adjusting setcount, current count:" << m_setCount;
+            static int setCountAdder = 1;
+            if (m_setCount == maxSetCount) {
+                if (removeSets)
+                    setCountAdder = -1;
+                else
+                    setCountAdder = 0;
+            } else if (m_setCount == 0) {
+                setCountAdder = 1;
+            }
+            if (setCountAdder < 0) {
+                int barCount = m_sets.at(m_setCount - 1)->count();
+                m_series->remove(m_sets.at(m_setCount - 1));
+                // Since remove deletes the set, recreate it in our list
+                QBarSet *set = new QBarSet(nameTemplate.arg(m_setCount - 1));
+                m_sets[m_setCount - 1] = set;
+                set->setLabelBrush(QColor("black"));
+                set->setPen(QPen(QColor("black"), 0.3));
+                QList<qreal> valueList;
+                valueList.reserve(barCount);
+                for (int j = 0; j < barCount; ++j)
+                    valueList.append(counter % 100);
+                set->append(valueList);
+
+            } else if (m_setCount < maxSetCount) {
+                m_series->append(m_sets.at(m_setCount));
+            }
+            m_setCount += setCountAdder;
+        }
+    }
+
+    if (labelsTrigger > 0 && counter % labelsTrigger == 0) {
+        m_series->setLabelsVisible(!m_series->isLabelsVisible());
+        qDebug() << "Label visibility changed";
+    }
+
+    if (visibleTrigger > 0 && counter % visibleTrigger == 0) {
+        m_series->setVisible(!m_series->isVisible());
+        qDebug() << "Series visibility changed";
+    }
+
+    if (animationTrigger > 0 && counter % animationTrigger == 0) {
+        if (m_chart->animationOptions() == QChart::SeriesAnimations)
+            m_chart->setAnimationOptions(QChart::NoAnimation);
+        else
+            m_chart->setAnimationOptions(QChart::SeriesAnimations);
+        qDebug() << "Series animation changed";
+    }
+
+    qDebug() << "Restof time:" << m_elapsedTimer.restart();
+
+    qDebug() << "Item Count:" << m_chart->scene()->items().size();
+    counter++;
+}
+
+void ChartWidget::createChart()
+{
+    qDebug() << "Initial bar count:" << initialCount;
+
+    QList<qreal> valueList;
+    valueList.reserve(initialCount);
+    for (int j = 0; j < initialCount; ++j)
+        valueList.append(counter++ % 100);
+
+    for (int i = 0; i < maxSetCount; i++) {
+        QBarSet *set = new QBarSet(nameTemplate.arg(i));
+        m_sets.append(set);
+        set->setLabelBrush(QColor("black"));
+        set->setPen(QPen(QColor("black"), 0.3));
+        if (sameNumberOfBars) {
+            set->append(valueList);
+        } else {
+            QList<qreal> tempList = valueList;
+            for (int j = 0; j < i; j++) {
+                tempList.removeLast();
+                tempList.removeLast();
+                tempList.removeLast();
+            }
+            set->append(tempList);
+        }
+    }
+
+    m_series->setName("bar");
+    for (int i = 0; i < initialSetCount; i++)
+        m_series->append(m_sets.at(i));
+
+    m_series->append(m_sets.at(0));
+    m_series->setLabelsPosition(QAbstractBarSeries::LabelsInsideEnd);
+    m_series->setLabelsVisible(initialLabels);
+    m_series->setBarWidth(0.9);
+
+    m_chart->addSeries(m_series);
+    m_chart->setTitle("Chart");
+    if (animation) {
+        m_chart->setAnimationOptions(QChart::SeriesAnimations);
+        m_chart->setAnimationDuration(animationDuration);
+    }
+
+    if (horizontal) {
+        m_chart->setAxisX(m_valueAxis, m_series);
+        m_chart->setAxisY(m_barAxis, m_series);
+    } else {
+        m_chart->setAxisX(m_barAxis, m_series);
+        m_chart->setAxisY(m_valueAxis, m_series);
+    }
+    m_barAxis->setTickCount(11);
+    if (initialCount > visibleCount)
+        m_barAxis->setRange(initialCount - visibleCount, initialCount);
+    else
+        m_barAxis->setRange(0, visibleCount);
+
+    m_valueAxis->setRange(logarithmic ? 1 : 0, stacked ? 200 : 100);
+
+    m_chartView->setChart(m_chart);
+}
diff --git a/tests/manual/barcharttester/chart-widget.h b/tests/manual/barcharttester/chart-widget.h
new file mode 100644
index 00000000..989c48a9
--- /dev/null
+++ b/tests/manual/barcharttester/chart-widget.h
@@ -0,0 +1,72 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the Qt Charts module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 or (at your option) any later version
+** approved by the KDE Free Qt Foundation. The licenses are as published by
+** the Free Software Foundation and appearing in the file LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef CHARTWIDGET_H
+#define CHARTWIDGET_H
+
+#include <QtWidgets/QHBoxLayout>
+#include <QtCharts/QChart>
+#include <QtCharts/QChartView>
+#include <QtCharts/QValueAxis>
+#include <QtCharts/QBarSeries>
+#include <QtCharts/QBarSet>
+#include <QtCore/QTimer>
+#include <QtCore/QElapsedTimer>
+
+QT_CHARTS_USE_NAMESPACE
+
+
+class ChartWidget : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit ChartWidget(QWidget *parent = 0);
+    ~ChartWidget();
+
+public slots:
+    void handleTimeout();
+
+private:
+    void createChart();
+
+private:
+    QChart *m_chart;
+    QChartView *m_chartView;
+    QValueAxis *m_barAxis;
+    QAbstractAxis *m_valueAxis;
+    QAbstractBarSeries *m_series;
+    QVector<QBarSet *> m_sets;
+    QTimer m_timer;
+    QElapsedTimer m_elapsedTimer;
+    QHBoxLayout *m_horizontalLayout;
+    int m_setCount;
+};
+
+#endif // CHARTWIDGET_H
diff --git a/tests/manual/barcharttester/main.cpp b/tests/manual/barcharttester/main.cpp
new file mode 100644
index 00000000..eb4cd99f
--- /dev/null
+++ b/tests/manual/barcharttester/main.cpp
@@ -0,0 +1,42 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the Qt Charts module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 or (at your option) any later version
+** approved by the KDE Free Qt Foundation. The licenses are as published by
+** the Free Software Foundation and appearing in the file LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "chart-widget.h"
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+
+    ChartWidget w;
+    w.resize(1200, 800);
+    w.show();
+
+    return a.exec();
+}
diff --git a/tests/manual/manual.pro b/tests/manual/manual.pro
index 0e02e8c2..507fd47c 100644
--- a/tests/manual/manual.pro
+++ b/tests/manual/manual.pro
@@ -3,7 +3,8 @@ SUBDIRS += \
     presenterchart \
     polarcharttest \
     boxplottester \
-    candlesticktester
+    candlesticktester \
+    barcharttester
 
 contains(QT_CONFIG, opengl) {
     SUBDIRS +=  chartwidgettest \