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-rw-r--r--examples/multimedia/spectrum/spectrograph.cpp202
1 files changed, 202 insertions, 0 deletions
diff --git a/examples/multimedia/spectrum/spectrograph.cpp b/examples/multimedia/spectrum/spectrograph.cpp
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+++ b/examples/multimedia/spectrum/spectrograph.cpp
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+// Copyright (C) 2017 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "spectrograph.h"
+
+#include <QDebug>
+#include <QMouseEvent>
+#include <QPainter>
+#include <QTimerEvent>
+
+const int NullTimerId = -1;
+const int NullIndex = -1;
+const int BarSelectionInterval = 2000;
+
+Spectrograph::Spectrograph(QWidget *parent)
+ : QWidget(parent),
+ m_barSelected(NullIndex),
+ m_timerId(NullTimerId),
+ m_lowFreq(0.0),
+ m_highFreq(0.0)
+{
+ setMinimumHeight(100);
+}
+
+Spectrograph::~Spectrograph() = default;
+
+void Spectrograph::setParams(int numBars, qreal lowFreq, qreal highFreq)
+{
+ Q_ASSERT(numBars > 0);
+ Q_ASSERT(highFreq > lowFreq);
+ m_bars.resize(numBars);
+ m_lowFreq = lowFreq;
+ m_highFreq = highFreq;
+ updateBars();
+}
+
+void Spectrograph::timerEvent(QTimerEvent *event)
+{
+ Q_ASSERT(event->timerId() == m_timerId);
+ Q_UNUSED(event); // suppress warnings in release builds
+ killTimer(m_timerId);
+ m_timerId = NullTimerId;
+ m_barSelected = NullIndex;
+ update();
+}
+
+void Spectrograph::paintEvent(QPaintEvent *event)
+{
+ Q_UNUSED(event);
+
+ QPainter painter(this);
+ painter.fillRect(rect(), Qt::black);
+
+ const int numBars = m_bars.count();
+
+ // Highlight region of selected bar
+ if (m_barSelected != NullIndex && numBars) {
+ QRect regionRect = rect();
+ regionRect.setLeft(m_barSelected * rect().width() / numBars);
+ regionRect.setWidth(rect().width() / numBars);
+ QColor regionColor(202, 202, 64);
+ painter.setBrush(Qt::DiagCrossPattern);
+ painter.fillRect(regionRect, regionColor);
+ painter.setBrush(Qt::NoBrush);
+ }
+
+ QColor barColor(51, 204, 102);
+ QColor clipColor(255, 255, 0);
+
+ // Draw the outline
+ const QColor gridColor = barColor.darker();
+ QPen gridPen(gridColor);
+ painter.setPen(gridPen);
+ painter.drawLine(rect().topLeft(), rect().topRight());
+ painter.drawLine(rect().topRight(), rect().bottomRight());
+ painter.drawLine(rect().bottomRight(), rect().bottomLeft());
+ painter.drawLine(rect().bottomLeft(), rect().topLeft());
+
+ QList<qreal> dashes;
+ dashes << 2 << 2;
+ gridPen.setDashPattern(dashes);
+ painter.setPen(gridPen);
+
+ // Draw vertical lines between bars
+ if (numBars) {
+ const int numHorizontalSections = numBars;
+ QLine line(rect().topLeft(), rect().bottomLeft());
+ for (int i = 1; i < numHorizontalSections; ++i) {
+ line.translate(rect().width() / numHorizontalSections, 0);
+ painter.drawLine(line);
+ }
+ }
+
+ // Draw horizontal lines
+ const int numVerticalSections = 10;
+ QLine line(rect().topLeft(), rect().topRight());
+ for (int i = 1; i < numVerticalSections; ++i) {
+ line.translate(0, rect().height() / numVerticalSections);
+ painter.drawLine(line);
+ }
+
+ barColor = barColor.lighter();
+ barColor.setAlphaF(0.75);
+ clipColor.setAlphaF(0.75);
+
+ // Draw the bars
+ if (numBars) {
+ // Calculate width of bars and gaps
+ const int widgetWidth = rect().width();
+ const int barPlusGapWidth = widgetWidth / numBars;
+ const int barWidth = 0.8 * barPlusGapWidth;
+ const int gapWidth = barPlusGapWidth - barWidth;
+ const int paddingWidth = widgetWidth - numBars * (barWidth + gapWidth);
+ const int leftPaddingWidth = (paddingWidth + gapWidth) / 2;
+ const int barHeight = rect().height() - 2 * gapWidth;
+
+ for (int i = 0; i < numBars; ++i) {
+ const qreal value = m_bars[i].value;
+ Q_ASSERT(value >= 0.0 && value <= 1.0);
+ QRect bar = rect();
+ bar.setLeft(rect().left() + leftPaddingWidth + (i * (gapWidth + barWidth)));
+ bar.setWidth(barWidth);
+ bar.setTop(rect().top() + gapWidth + (1.0 - value) * barHeight);
+ bar.setBottom(rect().bottom() - gapWidth);
+
+ QColor color = barColor;
+ if (m_bars[i].clipped)
+ color = clipColor;
+
+ painter.fillRect(bar, color);
+ }
+ }
+}
+
+void Spectrograph::mousePressEvent(QMouseEvent *event)
+{
+ const QPoint pos = event->pos();
+ const int index = m_bars.count() * (pos.x() - rect().left()) / rect().width();
+ selectBar(index);
+}
+
+void Spectrograph::reset()
+{
+ m_spectrum.reset();
+ spectrumChanged(m_spectrum);
+}
+
+void Spectrograph::spectrumChanged(const FrequencySpectrum &spectrum)
+{
+ m_spectrum = spectrum;
+ updateBars();
+}
+
+int Spectrograph::barIndex(qreal frequency) const
+{
+ Q_ASSERT(frequency >= m_lowFreq && frequency < m_highFreq);
+ const qreal bandWidth = (m_highFreq - m_lowFreq) / m_bars.count();
+ const int index = (frequency - m_lowFreq) / bandWidth;
+ if (index < 0 || index >= m_bars.count())
+ Q_ASSERT(false);
+ return index;
+}
+
+QPair<qreal, qreal> Spectrograph::barRange(int index) const
+{
+ Q_ASSERT(index >= 0 && index < m_bars.count());
+ const qreal bandWidth = (m_highFreq - m_lowFreq) / m_bars.count();
+ return QPair<qreal, qreal>(index * bandWidth, (index + 1) * bandWidth);
+}
+
+void Spectrograph::updateBars()
+{
+ m_bars.fill(Bar());
+ FrequencySpectrum::const_iterator i = m_spectrum.begin();
+ const FrequencySpectrum::const_iterator end = m_spectrum.end();
+ for (; i != end; ++i) {
+ const FrequencySpectrum::Element e = *i;
+ if (e.frequency >= m_lowFreq && e.frequency < m_highFreq) {
+ Bar &bar = m_bars[barIndex(e.frequency)];
+ bar.value = qMax(bar.value, e.amplitude);
+ bar.clipped |= e.clipped;
+ }
+ }
+ update();
+}
+
+void Spectrograph::selectBar(int index)
+{
+ const QPair<qreal, qreal> frequencyRange = barRange(index);
+ const QString message =
+ QStringLiteral("%1 - %2 Hz").arg(frequencyRange.first).arg(frequencyRange.second);
+ emit infoMessage(message, BarSelectionInterval);
+
+ if (NullTimerId != m_timerId)
+ killTimer(m_timerId);
+ m_timerId = startTimer(BarSelectionInterval);
+
+ m_barSelected = index;
+ update();
+}
+
+#include "moc_spectrograph.cpp"