1/****************************************************************************
2**
3** Copyright (C) 2017 The Qt Company Ltd.
4** Contact: https://www.qt.io/licensing/
5**
6** This file is part of the examples of the Qt Toolkit.
7**
8** $QT_BEGIN_LICENSE:BSD$
9** Commercial License Usage
10** Licensees holding valid commercial Qt licenses may use this file in
11** accordance with the commercial license agreement provided with the
12** Software or, alternatively, in accordance with the terms contained in
13** a written agreement between you and The Qt Company. For licensing terms
14** and conditions see https://www.qt.io/terms-conditions. For further
15** information use the contact form at https://www.qt.io/contact-us.
16**
17** BSD License Usage
18** Alternatively, you may use this file under the terms of the BSD license
19** as follows:
20**
21** "Redistribution and use in source and binary forms, with or without
22** modification, are permitted provided that the following conditions are
23** met:
24** * Redistributions of source code must retain the above copyright
25** notice, this list of conditions and the following disclaimer.
26** * Redistributions in binary form must reproduce the above copyright
27** notice, this list of conditions and the following disclaimer in
28** the documentation and/or other materials provided with the
29** distribution.
30** * Neither the name of The Qt Company Ltd nor the names of its
31** contributors may be used to endorse or promote products derived
32** from this software without specific prior written permission.
33**
34**
35** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
36** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
37** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
38** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
39** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
40** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
41** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
42** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
43** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
44** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
45** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
46**
47** $QT_END_LICENSE$
48**
49****************************************************************************/
50
51#include "spectrograph.h"
52#include <QDebug>
53#include <QMouseEvent>
54#include <QPainter>
55#include <QTimerEvent>
56
57const int NullTimerId = -1;
58const int NullIndex = -1;
59const int BarSelectionInterval = 2000;
60
61Spectrograph::Spectrograph(QWidget *parent)
62 : QWidget(parent)
63 , m_barSelected(NullIndex)
64 , m_timerId(NullTimerId)
65 , m_lowFreq(0.0)
66 , m_highFreq(0.0)
67{
68 setMinimumHeight(100);
69}
70
71Spectrograph::~Spectrograph()
72{
73
74}
75
76void Spectrograph::setParams(int numBars, qreal lowFreq, qreal highFreq)
77{
78 Q_ASSERT(numBars > 0);
79 Q_ASSERT(highFreq > lowFreq);
80 m_bars.resize(asize: numBars);
81 m_lowFreq = lowFreq;
82 m_highFreq = highFreq;
83 updateBars();
84}
85
86void Spectrograph::timerEvent(QTimerEvent *event)
87{
88 Q_ASSERT(event->timerId() == m_timerId);
89 Q_UNUSED(event) // suppress warnings in release builds
90 killTimer(id: m_timerId);
91 m_timerId = NullTimerId;
92 m_barSelected = NullIndex;
93 update();
94}
95
96void Spectrograph::paintEvent(QPaintEvent *event)
97{
98 Q_UNUSED(event)
99
100 QPainter painter(this);
101 painter.fillRect(r: rect(), c: Qt::black);
102
103 const int numBars = m_bars.count();
104
105 // Highlight region of selected bar
106 if (m_barSelected != NullIndex && numBars) {
107 QRect regionRect = rect();
108 regionRect.setLeft(m_barSelected * rect().width() / numBars);
109 regionRect.setWidth(rect().width() / numBars);
110 QColor regionColor(202, 202, 64);
111 painter.setBrush(Qt::DiagCrossPattern);
112 painter.fillRect(regionRect, color: regionColor);
113 painter.setBrush(Qt::NoBrush);
114 }
115
116 QColor barColor(51, 204, 102);
117 QColor clipColor(255, 255, 0);
118
119 // Draw the outline
120 const QColor gridColor = barColor.darker();
121 QPen gridPen(gridColor);
122 painter.setPen(gridPen);
123 painter.drawLine(p1: rect().topLeft(), p2: rect().topRight());
124 painter.drawLine(p1: rect().topRight(), p2: rect().bottomRight());
125 painter.drawLine(p1: rect().bottomRight(), p2: rect().bottomLeft());
126 painter.drawLine(p1: rect().bottomLeft(), p2: rect().topLeft());
127
128 QVector<qreal> dashes;
129 dashes << 2 << 2;
130 gridPen.setDashPattern(dashes);
131 painter.setPen(gridPen);
132
133 // Draw vertical lines between bars
134 if (numBars) {
135 const int numHorizontalSections = numBars;
136 QLine line(rect().topLeft(), rect().bottomLeft());
137 for (int i=1; i<numHorizontalSections; ++i) {
138 line.translate(adx: rect().width()/numHorizontalSections, ady: 0);
139 painter.drawLine(line);
140 }
141 }
142
143 // Draw horizontal lines
144 const int numVerticalSections = 10;
145 QLine line(rect().topLeft(), rect().topRight());
146 for (int i=1; i<numVerticalSections; ++i) {
147 line.translate(adx: 0, ady: rect().height()/numVerticalSections);
148 painter.drawLine(line);
149 }
150
151 barColor = barColor.lighter();
152 barColor.setAlphaF(0.75);
153 clipColor.setAlphaF(0.75);
154
155 // Draw the bars
156 if (numBars) {
157 // Calculate width of bars and gaps
158 const int widgetWidth = rect().width();
159 const int barPlusGapWidth = widgetWidth / numBars;
160 const int barWidth = 0.8 * barPlusGapWidth;
161 const int gapWidth = barPlusGapWidth - barWidth;
162 const int paddingWidth = widgetWidth - numBars * (barWidth + gapWidth);
163 const int leftPaddingWidth = (paddingWidth + gapWidth) / 2;
164 const int barHeight = rect().height() - 2 * gapWidth;
165
166 for (int i=0; i<numBars; ++i) {
167 const qreal value = m_bars[i].value;
168 Q_ASSERT(value >= 0.0 && value <= 1.0);
169 QRect bar = rect();
170 bar.setLeft(rect().left() + leftPaddingWidth + (i * (gapWidth + barWidth)));
171 bar.setWidth(barWidth);
172 bar.setTop(rect().top() + gapWidth + (1.0 - value) * barHeight);
173 bar.setBottom(rect().bottom() - gapWidth);
174
175 QColor color = barColor;
176 if (m_bars[i].clipped)
177 color = clipColor;
178
179 painter.fillRect(bar, color);
180 }
181 }
182}
183
184void Spectrograph::mousePressEvent(QMouseEvent *event)
185{
186 const QPoint pos = event->pos();
187 const int index = m_bars.count() * (pos.x() - rect().left()) / rect().width();
188 selectBar(index);
189}
190
191void Spectrograph::reset()
192{
193 m_spectrum.reset();
194 spectrumChanged(spectrum: m_spectrum);
195}
196
197void Spectrograph::spectrumChanged(const FrequencySpectrum &spectrum)
198{
199 m_spectrum = spectrum;
200 updateBars();
201}
202
203int Spectrograph::barIndex(qreal frequency) const
204{
205 Q_ASSERT(frequency >= m_lowFreq && frequency < m_highFreq);
206 const qreal bandWidth = (m_highFreq - m_lowFreq) / m_bars.count();
207 const int index = (frequency - m_lowFreq) / bandWidth;
208 if (index <0 || index >= m_bars.count())
209 Q_ASSERT(false);
210 return index;
211}
212
213QPair<qreal, qreal> Spectrograph::barRange(int index) const
214{
215 Q_ASSERT(index >= 0 && index < m_bars.count());
216 const qreal bandWidth = (m_highFreq - m_lowFreq) / m_bars.count();
217 return QPair<qreal, qreal>(index * bandWidth, (index+1) * bandWidth);
218}
219
220void Spectrograph::updateBars()
221{
222 m_bars.fill(from: Bar());
223 FrequencySpectrum::const_iterator i = m_spectrum.begin();
224 const FrequencySpectrum::const_iterator end = m_spectrum.end();
225 for ( ; i != end; ++i) {
226 const FrequencySpectrum::Element e = *i;
227 if (e.frequency >= m_lowFreq && e.frequency < m_highFreq) {
228 Bar &bar = m_bars[barIndex(frequency: e.frequency)];
229 bar.value = qMax(a: bar.value, b: e.amplitude);
230 bar.clipped |= e.clipped;
231 }
232 }
233 update();
234}
235
236void Spectrograph::selectBar(int index) {
237 const QPair<qreal, qreal> frequencyRange = barRange(index);
238 const QString message = QString("%1 - %2 Hz")
239 .arg(a: frequencyRange.first)
240 .arg(a: frequencyRange.second);
241 emit infoMessage(message, intervalMs: BarSelectionInterval);
242
243 if (NullTimerId != m_timerId)
244 killTimer(id: m_timerId);
245 m_timerId = startTimer(interval: BarSelectionInterval);
246
247 m_barSelected = index;
248 update();
249}
250
251
252

source code of qtmultimedia/examples/multimedia/spectrum/app/spectrograph.cpp