Qt Charts_Audio实践

这里完全是照搬帮助文档中的代码生成的程序

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工程文件代码

#-------------------------------------------------
#
# Project created by QtCreator 2017-02-06T13:52:31
#
#-------------------------------------------------

QT       += core gui
QT       += charts multimedia

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = qchart_Audio_Project
TEMPLATE = app

DEFINES += QT_DEPRECATED_WARNINGS

SOURCES += main.cpp\
        widget.cpp \
    xyseriesiodevice.cpp

HEADERS  += widget.h \
    xyseriesiodevice.h

FORMS    += widget.ui

target.path = $$[QT_INSTALL_EXAMPLES]/charts/audio
INSTALLS += target

widget.h文件代码

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QtCharts/QChartGlobal>

namespace Ui {
class Widget;
}

QT_CHARTS_BEGIN_NAMESPACE
class QLineSeries;
class QChart;
QT_CHARTS_END_NAMESPACE

QT_CHARTS_USE_NAMESPACE

class XYSeriesIODevice;

class QAudioInput;

class Widget : public QWidget
{
    Q_OBJECT

public:
    explicit Widget(QWidget *parent = 0);
    ~Widget();

private:
    Ui::Widget *ui;

    XYSeriesIODevice *m_device;
    QChart *m_chart;
    QLineSeries *m_series;
    QAudioInput *m_audioInput;
};

#endif // WIDGET_H

widget.cpp代码

#include "widget.h"
#include <QtMultimedia/QAudioDeviceInfo>
#include <QtMultimedia/QAudioInput>
#include <QtMultimedia/QAudioFormat>
#include <QtCharts/QChartView>
#include <QtCharts/QLineSeries>
#include <QtCharts/QChart>
#include <QtWidgets/QVBoxLayout>
#include <QtCharts/QValueAxis>
#include "xyseriesiodevice.h"
#include "ui_widget.h"

QT_CHARTS_USE_NAMESPACE

Widget::Widget(QWidget *parent) :
    QWidget(parent),m_device(0),
    m_chart(0),
    m_series(0),
    m_audioInput(0),
    ui(new Ui::Widget)
{
    ui->setupUi(this);

    m_chart = new QChart;
    QChartView *chartView = new QChartView(m_chart);
    chartView->setMinimumSize(800, 600);
    m_series = new QLineSeries;
    m_chart->addSeries(m_series);
    QValueAxis *axisX = new QValueAxis;
    axisX->setRange(0, 2000);
    axisX->setLabelFormat("%g");
    axisX->setTitleText("Samples");
    QValueAxis *axisY = new QValueAxis;
    axisY->setRange(-1, 1);
    axisY->setTitleText("Audio level");
    m_chart->setAxisX(axisX, m_series);
    m_chart->setAxisY(axisY, m_series);
    m_chart->legend()->hide();
    m_chart->setTitle("Data from the microphone");

    QVBoxLayout *mainLayout = new QVBoxLayout;
    mainLayout->addWidget(chartView);
    setLayout(mainLayout);

    QAudioFormat formatAudio;
    formatAudio.setSampleRate(8000);
    formatAudio.setChannelCount(1);
    formatAudio.setSampleSize(8);
    formatAudio.setCodec("audio/pcm");
    formatAudio.setByteOrder(QAudioFormat::LittleEndian);
    formatAudio.setSampleType(QAudioFormat::UnSignedInt);

    QAudioDeviceInfo inputDevices = QAudioDeviceInfo::defaultInputDevice();
    m_audioInput = new QAudioInput(inputDevices,formatAudio, this);

    m_device = new XYSeriesIODevice(m_series, this);
    m_device->open(QIODevice::WriteOnly);

    m_audioInput->start(m_device);
}

Widget::~Widget()
{
    m_audioInput->stop();
    m_device->close();
    delete ui;
}

xyseriesiodevice.h代码

#ifndef XYSERIESIODEVICE_H
#define XYSERIESIODEVICE_H

#include <QtCore/QIODevice>
#include <QtCharts/QChartGlobal>

QT_CHARTS_BEGIN_NAMESPACE
class QXYSeries;
QT_CHARTS_END_NAMESPACE

QT_CHARTS_USE_NAMESPACE

class XYSeriesIODevice : public QIODevice
{
    Q_OBJECT
public:
    explicit XYSeriesIODevice(QXYSeries * series, QObject *parent = 0);

protected:
    qint64 readData(char * data, qint64 maxSize);
    qint64 writeData(const char * data, qint64 maxSize);

private:
    QXYSeries *m_series;
};

#endif // XYSERIESIODEVICE_H

xyseriesiodevice.cpp代码

#include "xyseriesiodevice.h"
#include <QtCharts/QXYSeries>

XYSeriesIODevice::XYSeriesIODevice(QXYSeries * series, QObject *parent) :
    QIODevice(parent),
    m_series(series)
{
}

qint64 XYSeriesIODevice::readData(char * data, qint64 maxSize)
{
    Q_UNUSED(data)
    Q_UNUSED(maxSize)
    return -1;
}

qint64 XYSeriesIODevice::writeData(const char * data, qint64 maxSize)
{
    qint64 range = 2000;
    QVector<QPointF> oldPoints = m_series->pointsVector();
    QVector<QPointF> points;
    int resolution = 4;

    if (oldPoints.count() < range) {
        points = m_series->pointsVector();
    } else {
        for (int i = maxSize/resolution; i < oldPoints.count(); i++)
            points.append(QPointF(i - maxSize/resolution, oldPoints.at(i).y()));
    }

    qint64 size = points.count();
    for (int k = 0; k < maxSize/resolution; k++)
        points.append(QPointF(k + size, ((quint8)data[resolution * k] - 128)/128.0));

    m_series->replace(points);
    return maxSize;
}