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

Pick-to: 6.5
Task-number: QTBUG-110698
Change-Id: I70fed07a9850e2636e6085b9a9190f1e5a062a67
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>

1 files changed, 7 insertions, 6 deletions

diff --git a/examples/datavisualization/graphgallery/topographicseries.cpp b/examples/datavisualization/graphgallery/topographicseries.cpp
index ea0be77d..ea6767e0 100644
--- a/examples/datavisualization/graphgallery/topographicseries.cpp
+++ b/examples/datavisualization/graphgallery/topographicseries.cpp
@@ -30,20 +30,21 @@ void TopographicSeries::setTopographyFile(const QString file, float width, float
 
     QSurfaceDataArray *dataArray = new QSurfaceDataArray;
     dataArray->reserve(imageHeight);
-    for (int i = 0; i < imageHeight; i++) {
+    for (int i = 0; i < imageHeight; ++i) {
         int p = i * widthBits;
         float z = height - float(i) * stepZ;
-        QSurfaceDataRow *newRow = new QSurfaceDataRow(imageWidth);
-        for (int j = 0; j < imageWidth; j++) {
+        QSurfaceDataRow *newRow = new QSurfaceDataRow;
+        newRow->reserve(imageWidth);
+        for (int j = 0; j < imageWidth; ++j) {
             uchar aa = bits[p + 0];
             uchar rr = bits[p + 1];
             uchar gg = bits[p + 2];
             uint color = uint((gg << 16) + (rr << 8) + aa);
             float y = float(color) / packingFactor;
-            (*newRow)[j].setPosition(QVector3D(float(j) * stepX, y, z));
-            p = p + 4;
+            newRow->append(QSurfaceDataItem({float(j) * stepX, y, z}));
+            p += 4;
         }
-        *dataArray << newRow;
+        dataArray->append(newRow);
     }
 
     dataProxy()->resetArray(dataArray);