datasource.cpp Example File | Qt Data Visualization 5.9

Qt 5.9 | Qt Data Visualization | Qt Quick 2 Oscilloscope Example | datasource.cpp Example File

Qt 5.9.6 Reference Documentation

# datasource.cpp Example File

qmloscilloscope/datasource.cpp

      /****************************************************************************
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      ** Copyright (C) 2016 The Qt Company Ltd.
      ** Contact: https://www.qt.io/licensing/
      **
      ** This file is part of the Qt Data Visualization module of the Qt Toolkit.
      **
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      ** Alternatively, this file may be used under the terms of the GNU
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      ** the Free Software Foundation and appearing in the file LICENSE.GPL3
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      #include "datasource.h"
      #include <QtCore/qmath.h>

      using namespace QtDataVisualization;

      Q_DECLARE_METATYPE(QSurface3DSeries *)

      DataSource::DataSource(QObject *parent) :
          QObject(parent),
          m_index(-1),
          m_resetArray(nullptr)
      {
          qRegisterMetaType<QSurface3DSeries *>();
      }

      DataSource::~DataSource()
      {
          clearData();
      }

      void DataSource::generateData(int cacheCount, int rowCount, int columnCount,
                                    float xMin, float xMax, float yMin, float yMax,
                                    float zMin, float zMax)
      {
          if (!cacheCount || !rowCount || !columnCount)
              return;

          clearData();
          // Re-create the cache array
          m_data.resize(cacheCount);
          for (int i(0); i < cacheCount; i++) {
              QSurfaceDataArray &array = m_data[i];
              array.reserve(rowCount);
              for (int j(0); j < rowCount; j++)
                  array.append(new QSurfaceDataRow(columnCount));
          }

          float xRange = xMax - xMin;
          float yRange = yMax - yMin;
          float zRange = zMax - zMin;
          int cacheIndexStep = columnCount / cacheCount;
          float cacheStep = float(cacheIndexStep) * xRange / float(columnCount);

          // Populate caches
          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++) {
                  QSurfaceDataRow &row = *(cache[j]);
                  float rowMod = (float(j)) / float(rowCount);
                  float yRangeMod = yRange * rowMod;
                  float zRangeMod = zRange * rowMod;
                  float z = zRangeMod + zMin;
                  qreal rowColWaveAngleMul = M_PI * M_PI * rowMod;
                  float rowColWaveMul = yRangeMod * 0.2f;
                  for (int k(0); k < columnCount; k++) {
                      float colMod = (float(k)) / float(columnCount);
                      float xRangeMod = xRange * colMod;
                      float x = xRangeMod + xMin + cacheXAdjustment;
                      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
                              + (0.15f * float(qrand()) / float(RAND_MAX)) * yRangeMod;

                      int index = k + cacheIndexAdjustment;
                      if (index >= columnCount) {
                          // Wrap over
                          index -= columnCount;
                          x -= xRange;
                      }
                      row[index] = QVector3D(x, y, z);
                  }
              }
          }
      }

      void DataSource::update(QSurface3DSeries *series)
      {
          if (series && m_data.size()) {
              // Each iteration uses data from a different cached array
              m_index++;
              if (m_index > m_data.count() - 1)
                  m_index = 0;

              QSurfaceDataArray array = m_data.at(m_index);
              int newRowCount = array.size();
              int newColumnCount = array.at(0)->size();

              // If the first time or the dimensions of the cache array have changed,
              // reconstruct the reset array
              if (!m_resetArray || series->dataProxy()->rowCount() != newRowCount
                      || series->dataProxy()->columnCount() != newColumnCount) {
                  m_resetArray = new QSurfaceDataArray();
                  m_resetArray->reserve(newRowCount);
                  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++) {
                  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());
              }

              // Notify the proxy that data has changed
              series->dataProxy()->resetArray(m_resetArray);
          }
      }

      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();
          }
      }