官方的这个例子比较有意思，在此记录下，方便以后查阅。

Hello Speak Example

这个例子主要是使用QTextToSpeech类将用户自定义输入的文本转换为口语，包括高低音、声音大小、读速。并且能够选择语言和声音。

包含的文件如下：

本篇博文，主要记录下如何使用QTextToSpeech将文字转换为口语。

QTextToSpeech Class

这里先来看下这个类，使用他需要在pro文件添加texttospeech。关于这个类的描述如下：

QTextToSpeech类提供了text-to-speech的引擎，这个引擎使用及其方便。

使用say()，就能将文字转换为口语，并且他能通过setLocale()指定语言，使用setVoice()选择声音。这里有点要注意这些语言和声音依赖于本地机器是否支持。

下面是关于QTextToSpeech::State

解析

下面主要是来看下，这个例子，是如何将文本转换为口语的。

关键.h文件：

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QtWidgets/qmainwindow.h>

#include "ui_mainwindow.h"

#include <QTextToSpeech>

class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    MainWindow(QWidget *parent = 0);

public slots:
    void speak();
    void stop();

    void setRate(int);
    void setPitch(int);
    void setVolume(int volume);

    void stateChanged(QTextToSpeech::State state);
    void engineSelected(int index);
    void languageSelected(int language);
    void voiceSelected(int index);

    void localeChanged(const QLocale &locale);

private:
    Ui::MainWindow ui;
    QTextToSpeech *m_speech;
    QVector<QVoice> m_voices;
};

#endif

关键.cpp文件

mainwindow.cpp

#include "mainwindow.h"
#include <QLoggingCategory>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent),
    m_speech(0)
{
    ui.setupUi(this);
    //QLoggingCategory::setFilterRules(QStringLiteral("qt.speech.tts=true \n qt.speech.tts.*=true"));

    // Populate engine selection list
    ui.engine->addItem("Default", QString("default"));
    foreach (QString engine, QTextToSpeech::availableEngines())
        ui.engine->addItem(engine, engine);
    ui.engine->setCurrentIndex(0);
    engineSelected(0);

    connect(ui.speakButton, &QPushButton::clicked, this, &MainWindow::speak);
    connect(ui.pitch, &QSlider::valueChanged, this, &MainWindow::setPitch);
    connect(ui.rate, &QSlider::valueChanged, this, &MainWindow::setRate);
    connect(ui.volume, &QSlider::valueChanged, this, &MainWindow::setVolume);
    connect(ui.engine, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged), this, &MainWindow::engineSelected);
}

void MainWindow::speak()
{
    m_speech->say(ui.plainTextEdit->toPlainText());
}
void MainWindow::stop()
{
    m_speech->stop();
}

void MainWindow::setRate(int rate)
{
    m_speech->setRate(rate / 10.0);
}

void MainWindow::setPitch(int pitch)
{
    m_speech->setPitch(pitch / 10.0);
}

void MainWindow::setVolume(int volume)
{
    m_speech->setVolume(volume / 100.0);
}

void MainWindow::stateChanged(QTextToSpeech::State state)
{
    if (state == QTextToSpeech::Speaking) {
        ui.statusbar->showMessage("Speech started...");
    } else if (state == QTextToSpeech::Ready)
        ui.statusbar->showMessage("Speech stopped...", 2000);
    else if (state == QTextToSpeech::Paused)
        ui.statusbar->showMessage("Speech paused...");
    else
        ui.statusbar->showMessage("Speech error!");

    ui.pauseButton->setEnabled(state == QTextToSpeech::Speaking);
    ui.resumeButton->setEnabled(state == QTextToSpeech::Paused);
    ui.stopButton->setEnabled(state == QTextToSpeech::Speaking || state == QTextToSpeech::Paused);
}

void MainWindow::engineSelected(int index)
{
    QString engineName = ui.engine->itemData(index).toString();
    delete m_speech;
    if (engineName == "default")
        m_speech = new QTextToSpeech(this);
    else
        m_speech = new QTextToSpeech(engineName, this);
    disconnect(ui.language, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged), this, &MainWindow::languageSelected);
    ui.language->clear();
    // Populate the languages combobox before connecting its signal.
    QVector<QLocale> locales = m_speech->availableLocales();
    QLocale current = m_speech->locale();
    foreach (const QLocale &locale, locales) {
        QString name(QString("%1 (%2)")
                     .arg(QLocale::languageToString(locale.language()))
                     .arg(QLocale::countryToString(locale.country())));
        QVariant localeVariant(locale);
        ui.language->addItem(name, localeVariant);
        if (locale.name() == current.name())
            current = locale;
    }
    setRate(ui.rate->value());
    setPitch(ui.pitch->value());
    setVolume(ui.volume->value());
    connect(ui.stopButton, &QPushButton::clicked, m_speech, &QTextToSpeech::stop);
    connect(ui.pauseButton, &QPushButton::clicked, m_speech, &QTextToSpeech::pause);
    connect(ui.resumeButton, &QPushButton::clicked, m_speech, &QTextToSpeech::resume);

    connect(m_speech, &QTextToSpeech::stateChanged, this, &MainWindow::stateChanged);
    connect(m_speech, &QTextToSpeech::localeChanged, this, &MainWindow::localeChanged);

    connect(ui.language, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged), this, &MainWindow::languageSelected);
    localeChanged(current);
}

void MainWindow::languageSelected(int language)
{
    QLocale locale = ui.language->itemData(language).toLocale();
    m_speech->setLocale(locale);
}

void MainWindow::voiceSelected(int index)
{
    m_speech->setVoice(m_voices.at(index));
}

void MainWindow::localeChanged(const QLocale &locale)
{
    QVariant localeVariant(locale);
    ui.language->setCurrentIndex(ui.language->findData(localeVariant));

    disconnect(ui.voice, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged), this, &MainWindow::voiceSelected);
    ui.voice->clear();

    m_voices = m_speech->availableVoices();
    QVoice currentVoice = m_speech->voice();
    foreach (const QVoice &voice, m_voices) {
        ui.voice->addItem(QString("%1 - %2 - %3").arg(voice.name())
                          .arg(QVoice::genderName(voice.gender()))
                          .arg(QVoice::ageName(voice.age())));
        if (voice.name() == currentVoice.name())
            ui.voice->setCurrentIndex(ui.voice->count() - 1);
    }
    connect(ui.voice, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged), this, &MainWindow::voiceSelected);
}

下面来跟一下这个m_speech是如何用的。

在.cpp中可以看到：

将engineName传入了QTextToSpeech的构造函数，而engineName的值来自于

QTextToSpeech::availableEngines()。

这里来看下，他是如何选择语言和音频的，

connect(ui.language, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged), this, &MainWindow::languageSelected);
connect(ui.voice, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged), this, &MainWindow::voiceSelected);

对应的槽函数分别为：

void MainWindow::languageSelected(int language)
{
    QLocale locale = ui.language->itemData(language).toLocale();
    m_speech->setLocale(locale);
}

void MainWindow::voiceSelected(int index)
{
    m_speech->setVoice(m_voices.at(index));
}

从中可以看到，这里封装好的，应用层调用的确是简单太多。

下面看下，他是如何播放、暂停、续播：

connect(ui.stopButton, &QPushButton::clicked, m_speech, &QTextToSpeech::stop);
connect(ui.pauseButton, &QPushButton::clicked, m_speech, &QTextToSpeech::pause);
connect(ui.resumeButton, &QPushButton::clicked, m_speech, &QTextToSpeech::resume);

关于设置音调，读速的相关代码如下：

void MainWindow::setRate(int rate)
{
    m_speech->setRate(rate / 10.0);
}

void MainWindow::setPitch(int pitch)
{
    m_speech->setPitch(pitch / 10.0);
}

void MainWindow::setVolume(int volume)
{
    m_speech->setVolume(volume / 100.0);
}