释放 QPushbutton 时未检测到插槽

Question

我目前正在制作一个游戏的主菜单，但是当点击按钮时它似乎没有调用相关的插槽（按钮没有做任何事情）。我试图将按钮移动到一个线程以确保没有任何东西阻止它立即进入运行。我已经编写了一个按钮工作的更简单的程序，所以看起来问题不在于按钮或信号本身。因此它一定是有什么东西阻止了它运行？源文件给出为：

    #include <QGraphicsScene>
    #include <QGraphicsView>
    #include <QObject>
    #include <QBrush>
    #include"game.h"
    #include <QMediaPlayer>
    #include <QImage>
    #include<QGraphicsPixmapItem>
    #include <QPixmap>
    #include<QGraphicsItem>
    #include <QPushButton>
    #include <QLineEdit>
    #include <QPalette>
    #include <QMessageBox>
    #include <QLabel>
    #include <QComboBox>

    Game::Game(QWidget*parent)
    {
    //adding the background

    QGraphicsScene *scene=new QGraphicsScene();//to create a new graphics scene
    scene->setSceneRect( 0,0,1366,768);
    setBackgroundBrush(QBrush(QImage(":/images/Back_1_withlogo.jpg")));
    setScene(scene);
    show();
    setFixedSize(1366,768);

    //adding logo
        //setPixmap(QPixmap(":/images/Logo.png"));
    //adding the soundtrack

    music=new QMediaPlayer();
    music->moveToThread(&MusicThread);
    music->setMedia(QUrl("qrc:/sounds/Surreal-Game-Menu.mp3"));
    music->play();
    MusicThread.start();


    //add GUI
    this->setFixedSize(1366,768);
    this->move(-7,-5);
    //start button and username edit box
    btnStart = new QPushButton(this);
    btnStart->moveToThread(&btnThread);

    UserName = new QLineEdit(this);
    UserName->setFixedSize(100,25);
    UserName->move(300,300);
    UserName->show();
    UserName->setMaxLength(12);

    btnStart->setText("Start");
    btnStart->setFixedSize(100,30);
    btnStart->show();
    btnStart->move(300,600);
    connect(btnStart, SIGNAL (released()),this, SLOT (btnStart_clicked()));
    btnThread.start();

    //label for username edit box
    QLabel *LblUsername= new QLabel(this);
    LblUsername->setStyleSheet("QLabel { color : white; }");
    LblUsername->setFixedSize(100,30);
    LblUsername->move(230,300);
    LblUsername->setText("Username:");
    LblUsername->show();

    QLabel *lblGameMode = new QLabel(this);
    lblGameMode->setStyleSheet("QLabel { color : white; }");
    lblGameMode->setFixedSize(100,30);
    lblGameMode->move(190,450);
    lblGameMode->setText("Select Game mode:");
    lblGameMode->show();

    //combobox to select players
    GameMode=new QComboBox(this);
    GameMode->move(300,450);
    GameMode->setFixedSize(100,30);
    QStringList Modelist=(QStringList()<<"singleplayer"<<"co-op"<<"multiplayer (3 players)");
    GameMode->addItems(Modelist);
    GameMode->show();
    }

    void Game::btnStart_clicked()
     {
     if (UserName->text()==NULL)
     {
         QMessageBox messageBox;
         messageBox.critical(0,"Error","Please insert username!");
         messageBox.setFixedSize(500,200);
     }
     else
     {
         numPlayers = GameMode->currentIndex();
         SUsername= UserName->text();
         UserName->setText("works");
     }
     }

header 代码如下：

    #ifndef GAME_H
    #define GAME_H

    #include <QGraphicsScene>
    #include <QGraphicsView>
    #include <QWidget>
    #include <QPushButton>
    #include <QLineEdit>
    #include <QMediaPlayer>
    #include <QThread>
    #include <QComboBox>


    class Game:public QGraphicsView
    {
    public:
        Game(QWidget*parent=0);
        QGraphicsScene*scene;
    private slots:
        void btnStart_clicked();
    private:
        QPushButton *btnStart;
        QLineEdit *UserName;
        QMediaPlayer *music;
        QThread MusicThread;
        QString SUsername;
        QThread btnThread;
        QComboBox *GameMode;
        int numPlayers;

    };
    #endif // GAME_H

我收到以下错误：

    QObject::connect: No such slot QGraphicsView::btnStart_clicked() in game.cpp:57

Answer 1

添加一个Q_OBJECT宏，如下所示：

class Game:public QGraphicsView
    {
    Q_OBJECT
    public:
        Game(QWidget*parent=0);
        QGraphicsScene*scene;
    private slots:
        void btnStart_clicked();
    private:
        QPushButton *btnStart;
        QLineEdit *UserName;
        QMediaPlayer *music;
        QThread MusicThread;
        QString SUsername;
        QThread btnThread;
        QComboBox *GameMode;
        int numPlayers;

    };

这个宏帮助编译器确定 class 正在使用信号和槽机制。基本上它在 MOC（元对象编译器）文件中创建一个已定义信号和槽的条目。通过下面 link 了解信息： http://www.bogotobogo.com/Qt/Qt5_Q_OBJECT_Macro_Meta_Object.php

Answer 2

QObject::connect (btnStart, &QPushButton::clicked, this, &Game::btnStart_clicked);可能有效...如果您想使用释放事件，请尝试覆盖 virtual void mouseRelease 或 eventFilter。

当然还有……Q_OBJECT marco。

释放 QPushbutton 时未检测到插槽

Slot is not detected when QPushbutton is released

qt

qthread

slots

qt-signals

qpushbutton