graphgallery example: Streamline the code a bit

- Populate the data rows using reserve()/append() instead
  of resize() / assign.
- Use prefix increment
- Use QStringView when splitting the data file lines

Task-number: QTBUG-110698
Change-Id: I70fed07a9850e2636e6085b9a9190f1e5a062a67
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>
(cherry picked from commit ed80c940b659455e2bd98700157f5fc78a17b41c)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 17 insertions, 22 deletions

diff --git a/examples/datavisualization/graphgallery/scatterdatamodifier.cpp b/examples/datavisualization/graphgallery/scatterdatamodifier.cpp
index f018c81b..575515a4 100644
--- a/examples/datavisualization/graphgallery/scatterdatamodifier.cpp
+++ b/examples/datavisualization/graphgallery/scatterdatamodifier.cpp
@@ -71,24 +71,21 @@ void ScatterDataModifier::addData()
 
     //! [4]
     QScatterDataArray *dataArray = new QScatterDataArray;
-    dataArray->resize(m_itemCount);
-    QScatterDataItem *ptrToDataArray = &dataArray->first();
+    dataArray->reserve(m_itemCount);
     //! [4]
 
 #ifdef RANDOM_SCATTER
-    for (int i = 0; i < m_itemCount; i++) {
-        ptrToDataArray->setPosition(randVector());
-        ptrToDataArray++;
-    }
+    for (int i = 0; i < m_itemCount; ++i)
+        dataArray->append(QScatterDataItem(randVector()));
 #else
     //! [5]
-    float limit = qSqrt(m_itemCount) / 2.0f;
-    for (int i = -limit; i < limit; i++) {
-        for (int j = -limit; j < limit; j++) {
-            ptrToDataArray->setPosition(QVector3D(float(i) + 0.5f,
-                                                  qCos(qDegreesToRadians(float(i * j) / m_curveDivider)),
-                                                  float(j) + 0.5f));
-            ptrToDataArray++;
+    const float limit = qSqrt(m_itemCount) / 2.0f;
+    for (int i = -limit; i < limit; ++i) {
+        for (int j = -limit; j < limit; ++j) {
+            const float x = float(i) + 0.5f;
+            const float y = qCos(qDegreesToRadians(float(i * j) / m_curveDivider));
+            const float z = float(j) + 0.5f;
+            dataArray->append(QScatterDataItem({x, y, z}));
         }
     }
     //! [5]
@@ -148,12 +145,12 @@ void ScatterDataModifier::changeShadowQuality(int quality)
 
 void ScatterDataModifier::setBackgroundEnabled(int enabled)
 {
-    m_graph->activeTheme()->setBackgroundEnabled((bool)enabled);
+    m_graph->activeTheme()->setBackgroundEnabled(enabled == Qt::Checked);
 }
 
 void ScatterDataModifier::setGridEnabled(int enabled)
 {
-    m_graph->activeTheme()->setGridEnabled((bool)enabled);
+    m_graph->activeTheme()->setGridEnabled(enabled == Qt::Checked);
 }
 
 void ScatterDataModifier::toggleItemCount()
@@ -186,11 +183,9 @@ void ScatterDataModifier::toggleRanges()
 
 QVector3D ScatterDataModifier::randVector()
 {
-    return QVector3D(
-                (float)(QRandomGenerator::global()->bounded(100)) / 2.0f -
-                (float)(QRandomGenerator::global()->bounded(100)) / 2.0f,
-                (float)(QRandomGenerator::global()->bounded(100)) / 100.0f -
-                (float)(QRandomGenerator::global()->bounded(100)) / 100.0f,
-                (float)(QRandomGenerator::global()->bounded(100)) / 2.0f -
-                (float)(QRandomGenerator::global()->bounded(100)) / 2.0f);
+    auto *generator = QRandomGenerator::global();
+    const auto x = float(generator->bounded(100)) / 2.0f - float(generator->bounded(100)) / 2.0f;
+    const auto y = float(generator->bounded(100)) / 100.0f - float(generator->bounded(100)) / 100.0f;
+    const auto z = float(generator->bounded(100)) / 2.0f - float(generator->bounded(100)) / 2.0f;
+    return {x, y, z};
 }