使用QStateMachine在菜单屏幕之间转换

Question

我正在考虑使用QStateMachine在游戏的菜单屏幕之间转换。然而，我不确定如何在状态之间发生转换时启动某些代码（例如show()和QWidget）。我可以用简单的旧信号很容易地做到这一点（请参阅注释掉的代码），但我认为我可能可以在使用转换切换屏幕时做一些花哨的动画。

这是我的代码：

编辑：根据Koying的建议更新。

ApplicationWindow.h：

#include <QtGui>
#include <QStateMachine>
#include "MainMenu.h"
#include "LoadGameMenu.h"
class ApplicationWindow : public QMainWindow
{
    Q_OBJECT
public:
    ApplicationWindow();
private slots:
    void mainMenuButtonClicked();
    void loadGameMenuButtonClicked();
private:
    MainMenu* mainMenu;
    LoadGameMenu* loadGameMenu;
    QStateMachine stateMachine;
    QStackedWidget* stack;
};

ApplicationWindow.cpp：

ApplicationWindow::ApplicationWindow()
{
    resize(800, 600);
    stack = new QStackedWidget(this);
    mainMenu = new MainMenu();
    setCentralWidget(mainMenu);
    loadGameMenu = new LoadGameMenu();
    QState* mainMenuState = new QState();
    QState* loadGameMenuState = new QState();
    QAbstractTransition* loadTransition = mainMenuState->addTransition(
        mainMenu, SIGNAL(loadGameClicked()), loadGameMenuState);
    connect(loadTransition, SIGNAL(triggered()), this, SLOT(loadGameMenuButtonClicked()));
    QAbstractTransition* mainMenuTransition = loadGameMenuState->addTransition(
        loadGameMenu, SIGNAL(backToMainMenuClicked()), mainMenuState);
    connect(mainMenuTransition, SIGNAL(triggered()), this, SLOT(mainMenuButtonClicked()));
    stateMachine.addState(mainMenuState);
    stateMachine.addState(loadGameMenuState);
    stateMachine.setInitialState(mainMenuState);
    stateMachine.start();
}
void ApplicationWindow::mainMenuButtonClicked()
{
    setCentralWidget(mainMenu);
}
void ApplicationWindow::loadGameMenuButtonClicked()
{
    setCentralWidget(loadGameMenu);
}

加载游戏菜单.h:

#include <QtGui>
class LoadGameMenu : public QWidget
{
    Q_OBJECT
public:
    LoadGameMenu();
signals:
    void backToMainMenuClicked();
private:
    QPushButton* loadGameButton;
    QPushButton* backToMainMenuButton;
};

LoadGameMenu.cpp:

#include "LoadGameMenu.h"
LoadGameMenu::LoadGameMenu()
{
    loadGameButton = new QPushButton(tr("Load"));
    backToMainMenuButton = new QPushButton(tr("Main Menu"));
    QObject::connect(backToMainMenuButton, SIGNAL(clicked()),
        this, SIGNAL(backToMainMenuClicked()));
    QVBoxLayout* layout = new QVBoxLayout();
    layout->addWidget(loadGameButton);
    layout->addWidget(backToMainMenuButton);
    layout->setContentsMargins(300, 400, 300, 200);
    setLayout(layout);
}

主菜单.h:

#include <QtGui>
class MainMenu : public QWidget
{
    Q_OBJECT
public:
    MainMenu();
signals:
    void newGameClicked();
    void loadGameClicked();
private slots:
    void exit();
private:
    QPushButton* newGameButton;
    QPushButton* loadGameButton;
    QPushButton* exitGameButton;
    QMenu* fileMenu;
};

主菜单.cpp：

#include "MainMenu.h"
MainMenu::MainMenu()
{
    newGameButton = new QPushButton(tr("New Game"), this);
    loadGameButton = new QPushButton(tr("Load Game"));
    exitGameButton = new QPushButton(tr("Exit"));
    QObject::connect(newGameButton, SIGNAL(clicked()), this, SIGNAL(newGameClicked()));
    QObject::connect(loadGameButton, SIGNAL(clicked()), this, SIGNAL(loadGameClicked()));
    QObject::connect(exitGameButton, SIGNAL(clicked()), qApp, SLOT(quit()));
    QVBoxLayout* layout = new QVBoxLayout();
    layout->addWidget(newGameButton);
    layout->addWidget(loadGameButton);
    layout->addWidget(exitGameButton);
    layout->setContentsMargins(300, 200, 300, 200);
    setLayout(layout);
}
void MainMenu::exit()
{
    if( QMessageBox::question(
        this,
        tr("Exit?"),
        tr("Do you really want to exit the game?"),
        QMessageBox::Yes | QMessageBox::No,
        QMessageBox::No
        ) == QMessageBox::Yes
    )
    {
        qApp->quit();
    }
}

main.cpp：

#include <QtGui>
#include "ApplicationWindow.h"
int main(int argv, char **args)
{
    QApplication app(argv, args);
    ApplicationWindow window;
    window.show();
    return app.exec();
}

那么，当过渡发生时，我该如何触发一些行为或动作呢？

干杯。

Answer 1

要在状态转换中实际执行某些操作，必须连接到转换的triggered()信号，例如

QAbstractTransition* trMainLoad = mainMenuState->addTransition(mainMenu, SIGNAL(loadGameClicked()), loadGameMenuState);
connect(trMainLoad , SIGNAL(triggered()), SLOT(...));