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| ** |
| ** Copyright (C) 2016 The Qt Company Ltd. |
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| ** This file is part of the Qt Data Visualization module of the Qt Toolkit. |
| ** |
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| |
| #include "audiolevelsiodevice.h" |
| #include <QtCore/QDebug> |
| |
| using namespace QtDataVisualization; |
| |
| //! [1] |
| static const int resolution = 8; |
| static const int rowSize = 800; |
| static const int rowCount = 7; // Must be odd number |
| static const int middleRow = rowCount / 2; |
| //! [1] |
| |
| AudioLevelsIODevice::AudioLevelsIODevice(QBarDataProxy *proxy, QObject *parent) |
| : QIODevice(parent), |
| m_proxy(proxy), |
| m_array(new QBarDataArray) |
| { |
| // We reuse the existing array for maximum performance, so construct the array here |
| //! [0] |
| m_array->reserve(rowCount); |
| for (int i = 0; i < rowCount; i++) |
| m_array->append(new QBarDataRow(rowSize)); |
| //! [0] |
| |
| qDebug() << "Total of" << (rowSize * rowCount) << "items in the array."; |
| } |
| |
| // Implementation required for this pure virtual function |
| qint64 AudioLevelsIODevice::readData(char *data, qint64 maxSize) |
| { |
| Q_UNUSED(data) |
| Q_UNUSED(maxSize) |
| return -1; |
| } |
| |
| //! [2] |
| qint64 AudioLevelsIODevice::writeData(const char *data, qint64 maxSize) |
| { |
| // The amount of new data available. |
| int newDataSize = maxSize / resolution; |
| |
| // If we get more data than array size, we need to adjust the start index for new data. |
| int newDataStartIndex = qMax(0, (newDataSize - rowSize)); |
| |
| // Move the old data ahead in the rows (only do first half of rows + middle one now). |
| // If the amount of new data was larger than row size, skip copying. |
| if (!newDataStartIndex) { |
| for (int i = 0; i <= middleRow; i++) { |
| QBarDataItem *srcPos = m_array->at(i)->data(); |
| QBarDataItem *dstPos = srcPos + newDataSize; |
| memmove((void *)dstPos, (void *)srcPos, (rowSize - newDataSize) * sizeof(QBarDataItem)); |
| } |
| } |
| |
| // Insert data in reverse order, so that newest data is always at the front of the row. |
| int index = 0; |
| for (int i = newDataSize - 1; i >= newDataStartIndex; i--) { |
| // Add 0.01 to the value to avoid gaps in the graph (i.e. zero height bars). |
| // Also, scale to 0...100 |
| float value = float(quint8(data[resolution * i]) - 128) / 1.28f + 0.01f; |
| (*m_array->at(middleRow))[index].setValue(value); |
| // Insert a fractional value into front half of the rows. |
| for (int j = 1; j <= middleRow; j++) { |
| float fractionalValue = value / float(j + 1); |
| (*m_array->at(middleRow - j))[index].setValue(fractionalValue); |
| } |
| index++; |
| } |
| |
| // Copy the front half of rows to the back half for symmetry. |
| index = 0; |
| for (int i = rowCount - 1; i > middleRow; i--) { |
| QBarDataItem *srcPos = m_array->at(index++)->data(); |
| QBarDataItem *dstPos = m_array->at(i)->data(); |
| memcpy((void *)dstPos, (void *)srcPos, rowSize * sizeof(QBarDataItem)); |
| } |
| |
| // Reset the proxy array now that data has been updated to trigger a redraw. |
| m_proxy->resetArray(m_array); |
| |
| return maxSize; |
| } |
| //! [2] |
| |
| |