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29 | |
30 | #include "audiolevelsiodevice.h" |
31 | #include <QtCore/QDebug> |
32 | |
33 | using namespace QtDataVisualization; |
34 | |
35 | //! [1] |
36 | static const int resolution = 8; |
37 | static const int rowSize = 800; |
38 | static const int rowCount = 7; // Must be odd number |
39 | static const int middleRow = rowCount / 2; |
40 | //! [1] |
41 | |
42 | AudioLevelsIODevice::AudioLevelsIODevice(QBarDataProxy *proxy, QObject *parent) |
43 | : QIODevice(parent), |
44 | m_proxy(proxy), |
45 | m_array(new QBarDataArray) |
46 | { |
47 | // We reuse the existing array for maximum performance, so construct the array here |
48 | //! [0] |
49 | m_array->reserve(alloc: rowCount); |
50 | for (int i = 0; i < rowCount; i++) |
51 | m_array->append(t: new QBarDataRow(rowSize)); |
52 | //! [0] |
53 | |
54 | qDebug() << "Total of" << (rowSize * rowCount) << "items in the array." ; |
55 | } |
56 | |
57 | // Implementation required for this pure virtual function |
58 | qint64 AudioLevelsIODevice::readData(char *data, qint64 maxSize) |
59 | { |
60 | Q_UNUSED(data) |
61 | Q_UNUSED(maxSize) |
62 | return -1; |
63 | } |
64 | |
65 | //! [2] |
66 | qint64 AudioLevelsIODevice::writeData(const char *data, qint64 maxSize) |
67 | { |
68 | // The amount of new data available. |
69 | int newDataSize = maxSize / resolution; |
70 | |
71 | // If we get more data than array size, we need to adjust the start index for new data. |
72 | int newDataStartIndex = qMax(a: 0, b: (newDataSize - rowSize)); |
73 | |
74 | // Move the old data ahead in the rows (only do first half of rows + middle one now). |
75 | // If the amount of new data was larger than row size, skip copying. |
76 | if (!newDataStartIndex) { |
77 | for (int i = 0; i <= middleRow; i++) { |
78 | QBarDataItem *srcPos = m_array->at(i)->data(); |
79 | QBarDataItem *dstPos = srcPos + newDataSize; |
80 | memmove(dest: (void *)dstPos, src: (void *)srcPos, n: (rowSize - newDataSize) * sizeof(QBarDataItem)); |
81 | } |
82 | } |
83 | |
84 | // Insert data in reverse order, so that newest data is always at the front of the row. |
85 | int index = 0; |
86 | for (int i = newDataSize - 1; i >= newDataStartIndex; i--) { |
87 | // Add 0.01 to the value to avoid gaps in the graph (i.e. zero height bars). |
88 | // Also, scale to 0...100 |
89 | float value = float(quint8(data[resolution * i]) - 128) / 1.28f + 0.01f; |
90 | (*m_array->at(i: middleRow))[index].setValue(value); |
91 | // Insert a fractional value into front half of the rows. |
92 | for (int j = 1; j <= middleRow; j++) { |
93 | float fractionalValue = value / float(j + 1); |
94 | (*m_array->at(i: middleRow - j))[index].setValue(fractionalValue); |
95 | } |
96 | index++; |
97 | } |
98 | |
99 | // Copy the front half of rows to the back half for symmetry. |
100 | index = 0; |
101 | for (int i = rowCount - 1; i > middleRow; i--) { |
102 | QBarDataItem *srcPos = m_array->at(i: index++)->data(); |
103 | QBarDataItem *dstPos = m_array->at(i)->data(); |
104 | memcpy(dest: (void *)dstPos, src: (void *)srcPos, n: rowSize * sizeof(QBarDataItem)); |
105 | } |
106 | |
107 | // Reset the proxy array now that data has been updated to trigger a redraw. |
108 | m_proxy->resetArray(newArray: m_array); |
109 | |
110 | return maxSize; |
111 | } |
112 | //! [2] |
113 | |
114 | |
115 | |