Brush up the qmlsurfacegallery example

- Use modern string literals
- Use member initialization
- Streamline the code a bit with algorithms

Task-number: QTBUG-110700
Change-Id: Iad834c22f4dc14858b0f5da4fc2a550de9906072
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>
(cherry picked from commit acdaea0c859ba7b78756011ea60ec2765b5a8f04)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 28 insertions, 30 deletions

diff --git a/examples/datavisualization/qmlsurfacegallery/datasource.cpp b/examples/datavisualization/qmlsurfacegallery/datasource.cpp
index 93073554..7aeea178 100644
--- a/examples/datavisualization/qmlsurfacegallery/datasource.cpp
+++ b/examples/datavisualization/qmlsurfacegallery/datasource.cpp
@@ -5,10 +5,10 @@
 #include <QtCore/qmath.h>
 #include <QtCore/qrandom.h>
 
+#include <algorithm>
+
 DataSource::DataSource(QObject *parent) :
-    QObject(parent),
-    m_index(-1),
-    m_resetArray(nullptr)
+    QObject(parent)
 {
     //! [3]
     qRegisterMetaType<QSurface3DSeries *>();
@@ -32,10 +32,10 @@ void DataSource::generateData(int cacheCount, int rowCount, int columnCount,
 
     // Re-create the cache array
     m_data.resize(cacheCount);
-    for (int i = 0; i < cacheCount; i++) {
+    for (int i = 0; i < cacheCount; ++i) {
         QSurfaceDataArray &array = m_data[i];
         array.reserve(rowCount);
-        for (int j = 0; j < rowCount; j++)
+        for (int j = 0; j < rowCount; ++j)
             array.append(new QSurfaceDataRow(columnCount));
     }
 
@@ -47,11 +47,12 @@ void DataSource::generateData(int cacheCount, int rowCount, int columnCount,
 
     //! [0]
     // Populate caches
-    for (int i = 0; i < cacheCount; i++) {
+    auto *generator = QRandomGenerator::global();
+    for (int i = 0; i < cacheCount; ++i) {
         QSurfaceDataArray &cache = m_data[i];
         float cacheXAdjustment = cacheStep * i;
         float cacheIndexAdjustment = cacheIndexStep * i;
-        for (int j = 0; j < rowCount; j++) {
+        for (int j = 0; j < rowCount; ++j) {
             QSurfaceDataRow &row = *(cache[j]);
             float rowMod = (float(j)) / float(rowCount);
             float yRangeMod = yRange * rowMod;
@@ -66,7 +67,7 @@ void DataSource::generateData(int cacheCount, int rowCount, int columnCount,
                 float colWave = float(qSin((2.0 * M_PI * colMod) - (1.0 / 2.0 * M_PI)) + 1.0);
                 float y = (colWave * ((float(qSin(rowColWaveAngleMul * colMod) + 1.0))))
                         * rowColWaveMul
-                        + QRandomGenerator::global()->bounded(0.15f) * yRangeMod;
+                        + generator->bounded(0.15f) * yRangeMod;
 
                 int index = k + cacheIndexAdjustment;
                 if (index >= columnCount) {
@@ -83,14 +84,13 @@ void DataSource::generateData(int cacheCount, int rowCount, int columnCount,
 
 void DataSource::update(QSurface3DSeries *series)
 {
-    if (series && m_data.size()) {
+    if (series && !m_data.isEmpty()) {
         //! [1]
         // Each iteration uses data from a different cached array
-        m_index++;
-        if (m_index > m_data.count() - 1)
+        if (++m_index >= m_data.size())
             m_index = 0;
 
-        QSurfaceDataArray array = m_data.at(m_index);
+        const QSurfaceDataArray &array = m_data.at(m_index);
         int newRowCount = array.size();
         int newColumnCount = array.at(0)->size();
 
@@ -100,16 +100,15 @@ void DataSource::update(QSurface3DSeries *series)
                 || series->dataProxy()->columnCount() != newColumnCount) {
             m_resetArray = new QSurfaceDataArray();
             m_resetArray->reserve(newRowCount);
-            for (int i = 0; i < newRowCount; i++)
+            for (int i = 0; i < newRowCount; ++i)
                 m_resetArray->append(new QSurfaceDataRow(newColumnCount));
         }
 
         // Copy items from our cache to the reset array
-        for (int i = 0; i < newRowCount; i++) {
+        for (int i = 0; i < newRowCount; ++i) {
             const QSurfaceDataRow &sourceRow = *(array.at(i));
             QSurfaceDataRow &row = *(*m_resetArray)[i];
-            for (int j = 0; j < newColumnCount; j++)
-                row[j].setPosition(sourceRow.at(j).position());
+            std::copy(sourceRow.cbegin(), sourceRow.cend(), row.begin());
         }
 
         // Notify the proxy that data has changed
@@ -120,10 +119,7 @@ void DataSource::update(QSurface3DSeries *series)
 
 void DataSource::clearData()
 {
-    for (int i = 0; i < m_data.size(); i++) {
-        QSurfaceDataArray &array = m_data[i];
-        for (int j = 0; j < array.size(); j++)
-            delete array[j];
-        array.clear();
-    }
+    for (auto &array : std::as_const(m_data))
+        qDeleteAll(array);
+    m_data.clear();
 }
diff --git a/examples/datavisualization/qmlsurfacegallery/datasource.h b/examples/datavisualization/qmlsurfacegallery/datasource.h
index 5cfebbd8..bac5eeb2 100644
--- a/examples/datavisualization/qmlsurfacegallery/datasource.h
+++ b/examples/datavisualization/qmlsurfacegallery/datasource.h
@@ -16,7 +16,7 @@ class DataSource : public QObject
     QML_ELEMENT
     //! [2]
 public:
-    explicit DataSource(QObject *parent = 0);
+    explicit DataSource(QObject *parent = nullptr);
     virtual ~DataSource();
 
     //! [1]
@@ -31,8 +31,8 @@ private:
     void clearData();
 
     QList<QSurfaceDataArray> m_data;
-    int m_index;
-    QSurfaceDataArray *m_resetArray;
+    int m_index = -1;
+    QSurfaceDataArray *m_resetArray = nullptr;
 };
 
 #endif
diff --git a/examples/datavisualization/qmlsurfacegallery/main.cpp b/examples/datavisualization/qmlsurfacegallery/main.cpp
index 24690ce9..cbd831b6 100644
--- a/examples/datavisualization/qmlsurfacegallery/main.cpp
+++ b/examples/datavisualization/qmlsurfacegallery/main.cpp
@@ -13,6 +13,8 @@
 #include "datasource.h"
 #endif
 
+using namespace Qt::StringLiterals;
+
 int main(int argc, char *argv[])
 {
     qputenv("QSG_RHI_BACKEND", "opengl");
@@ -32,17 +34,17 @@ int main(int argc, char *argv[])
     // The following are needed to make examples run without having to install the module
     // in desktop environments.
 #ifdef Q_OS_WIN
-    QString extraImportPath(QStringLiteral("%1/../../../../%2"));
+    QString extraImportPath(u"%1/../../../../%2"_s);
 #else
-    QString extraImportPath(QStringLiteral("%1/../../../%2"));
+    QString extraImportPath(u"%1/../../../%2"_s);
 #endif
     viewer.engine()->addImportPath(extraImportPath.arg(QGuiApplication::applicationDirPath(),
-                                                       QString::fromLatin1("qml")));
+                                                       u"qml"_s));
     QObject::connect(viewer.engine(), &QQmlEngine::quit, &viewer, &QWindow::close);
 
-    viewer.setTitle(QStringLiteral("Surface Graph Gallery"));
+    viewer.setTitle(u"Surface Graph Gallery"_s);
 
-    viewer.setSource(QUrl("qrc:/qml/qmlsurfacegallery/main.qml"));
+    viewer.setSource(QUrl(u"qrc:/qml/qmlsurfacegallery/main.qml"_s));
     viewer.setResizeMode(QQuickView::SizeRootObjectToView);
     viewer.show();