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如何让这个Qt状态机工作?

qstatemachine state-machine qt c++

Ton van den Heuvel · 技术社区 · 15 年前

我有两个可以检查的小部件,一个数字输入字段应该包含一个大于零的值。每当两个小部件都被选中,并且数字输入字段包含大于零的值时,应该启用一个按钮。我正在努力为这种情况定义一个合适的状态机。到目前为止,我有以下几点:

QStateMachine *machine = new QStateMachine(this);

QState *buttonDisabled = new QState(QState::ParallelStates);
buttonDisabled->assignProperty(ui_->button, "enabled", false);

QState *a = new QState(buttonDisabled);
QState *aUnchecked = new QState(a);
QFinalState *aChecked = new QFinalState(a);
aUnchecked->addTransition(wa, SIGNAL(checked()), aChecked);
a->setInitialState(aUnchecked);

QState *b = new QState(buttonDisabled);
QState *bUnchecked = new QState(b);
QFinalState *bChecked = new QFinalState(b);
employeeUnchecked->addTransition(wb, SIGNAL(checked()), bChecked);
b->setInitialState(bUnchecked);

QState *weight = new QState(buttonDisabled);
QState *weightZero = new QState(weight);
QFinalState *weightGreaterThanZero = new QFinalState(weight);
weightZero->addTransition(this, SIGNAL(validWeight()), weightGreaterThanZero);
weight->setInitialState(weightZero);

QState *buttonEnabled = new QState();
buttonEnabled->assignProperty(ui_->registerButton, "enabled", true);

buttonDisabled->addTransition(buttonDisabled, SIGNAL(finished()), buttonEnabled);
buttonEnabled->addTransition(this, SIGNAL(invalidWeight()), weightZero);

machine->addState(registerButtonDisabled);
machine->addState(registerButtonEnabled);
machine->setInitialState(registerButtonDisabled);
machine->start();

这里的问题是以下转换:

buttonEnabled->addTransition(this, SIGNAL(invalidWeight()), weightZero);

导致 registerButtonDisabled 要恢复到初始状态的状态。这是不受欢迎的行为,因为我希望 a b

我如何确保 A. 和 B 保持相同的状态?有没有其他/更好的方法可以使用状态机来解决这个问题?

注意

5 回复 | 直到 14 年前

Harald Scheirich 15 年前

在阅读了您的需求以及这里的答案和评论之后,我认为merula的解决方案或类似的解决方案是唯一的纯状态机解决方案。

正如我们所注意到的那样,平行状态引发了 finished() 所有被禁用的状态都必须是最终状态,但这并不是他们真正应该的状态,因为有人可以取消选中其中一个复选框,然后你就必须离开最终状态。您不能这样做,因为FinalState不接受任何转换。使用FinalState退出并行状态也会导致并行状态在重新进入时重新启动。

class AndGateTransition : public QAbstractTransition
{
    Q_OBJECT

public:

    AndGateTransition(QAbstractState* sourceState) : QAbstractTransition(sourceState)
        m_isSet(false), m_triggerOnSet(true), m_triggerOnUnset(false)

    void setTriggerSet(bool val)
    {
        m_triggerSet = val;
    }

    void setTriggerOnUnset(bool val)
    {
        m_triggerOnUnset = val;
    }

    addState(QState* state)
    {
        m_states[state] = false;
        connect(m_state, SIGNAL(entered()), this, SLOT(stateActivated());
        connect(m_state, SIGNAL(exited()), this, SLOT(stateDeactivated());
    }

public slots:
    void stateActivated()
    {
        QObject sender = sender();
        if (sender == 0) return;
        m_states[sender] = true;
        checkTrigger();
    }

    void stateDeactivated()
    {
        QObject sender = sender();
        if (sender == 0) return;
        m_states[sender] = false;
        checkTrigger();
    }

    void checkTrigger()
    {
        bool set = true;
        QHashIterator<QObject*, bool> it(m_states)
        while (it.hasNext())
        {
            it.next();
            set = set&&it.value();
            if (! set) break;
        }

        if (m_triggerOnSet && set && !m_isSet)
        {
            m_isSet = set;
            emit (triggered());

        }
        elseif (m_triggerOnUnset && !set && m_isSet)
        {
            m_isSet = set;
            emit (triggered());
        }
    }

pivate:
    QHash<QObject*, bool> m_states;
    bool m_triggerOnSet;
    bool m_triggerOnUnset;
    bool m_isSet;

}

没有编译这个,甚至没有测试它,但它应该证明的原则

merula 15 年前

我将使用具有四个子状态(无有效输入、一个有效输入、两个有效输入、三个有效输入)的状态机。很明显你一开始没有有效的输入。每个小部件都可以从“无”转换为“后”(2和3的计数相同)。当输入3时,所有小部件都有效(按钮已启用)。对于所有其他状态,进入状态时必须禁用按钮。

我编写了一个示例应用程序。主窗口包含两个qcheckbox一个QSpinBox和一个QPushButton。主窗口中有信号,便于记录状态的转换。当窗口小部件的状态发生更改时,会触发。

主窗口.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QtGui>

namespace Ui
{
    class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
    bool m_editValid;

    bool isEditValid() const;
    void setEditValid(bool value);

private slots:
    void on_checkBox1_stateChanged(int state);
    void on_checkBox2_stateChanged(int state);
    void on_spinBox_valueChanged (int i);
signals:
    void checkBox1Checked();
    void checkBox1Unchecked();
    void checkBox2Checked();
    void checkBox2Unchecked();
    void editValid();
    void editInvalid();
};

#endif // MAINWINDOW_H

主窗口.cpp

#include "MainWindow.h"
#include "ui_MainWindow.h"

MainWindow::MainWindow(QWidget *parent)
  : QMainWindow(parent), ui(new Ui::MainWindow), m_editValid(false)
{
  ui->setupUi(this);

  QStateMachine* stateMachine = new QStateMachine(this);
  QState* noneValid = new QState(stateMachine);
  QState* oneValid = new QState(stateMachine);
  QState* twoValid = new QState(stateMachine);
  QState* threeValid = new QState(stateMachine);

  noneValid->addTransition(this, SIGNAL(checkBox1Checked()), oneValid);
  oneValid->addTransition(this, SIGNAL(checkBox1Checked()), twoValid);
  twoValid->addTransition(this, SIGNAL(checkBox1Checked()), threeValid);
  threeValid->addTransition(this, SIGNAL(checkBox1Unchecked()), twoValid);
  twoValid->addTransition(this, SIGNAL(checkBox1Unchecked()), oneValid);
  oneValid->addTransition(this, SIGNAL(checkBox1Unchecked()), noneValid);

  noneValid->addTransition(this, SIGNAL(checkBox2Checked()), oneValid);
  oneValid->addTransition(this, SIGNAL(checkBox2Checked()), twoValid);
  twoValid->addTransition(this, SIGNAL(checkBox2Checked()), threeValid);
  threeValid->addTransition(this, SIGNAL(checkBox2Unchecked()), twoValid);
  twoValid->addTransition(this, SIGNAL(checkBox2Unchecked()), oneValid);
  oneValid->addTransition(this, SIGNAL(checkBox2Unchecked()), noneValid);

  noneValid->addTransition(this, SIGNAL(editValid()), oneValid);
  oneValid->addTransition(this, SIGNAL(editValid()), twoValid);
  twoValid->addTransition(this, SIGNAL(editValid()), threeValid);
  threeValid->addTransition(this, SIGNAL(editInvalid()), twoValid);
  twoValid->addTransition(this, SIGNAL(editInvalid()), oneValid);
  oneValid->addTransition(this, SIGNAL(editInvalid()), noneValid);

  threeValid->assignProperty(ui->pushButton, "enabled", true);
  twoValid->assignProperty(ui->pushButton, "enabled", false);
  oneValid->assignProperty(ui->pushButton, "enabled", false);
  noneValid->assignProperty(ui->pushButton, "enabled", false);

  stateMachine->setInitialState(noneValid);

  stateMachine->start();
}

MainWindow::~MainWindow()
{
  delete ui;
}

bool MainWindow::isEditValid() const
{
  return m_editValid;
}

void MainWindow::setEditValid(bool value)
{
  if (value == m_editValid)
  {
    return;
  }
  m_editValid = value;
  if (value)
  {
    emit editValid();
  } else {
    emit editInvalid();
  }
}

void MainWindow::on_checkBox1_stateChanged(int state)
{
  if (state == Qt::Checked)
  {
    emit checkBox1Checked();
  } else {
    emit checkBox1Unchecked();
  }
}

void MainWindow::on_checkBox2_stateChanged(int state)
{
  if (state == Qt::Checked)
  {
    emit checkBox2Checked();
  } else {
    emit checkBox2Unchecked();
  }
}

void MainWindow::on_spinBox_valueChanged (int i)
{
  setEditValid(i > 0);
}

Amos 15 年前

有时,单击按钮后,还需要更改按钮状态。

[编辑]:我确信有一些方法可以使用状态机来实现这一点,您是只在两个复选框都选中并且添加了无效权重的情况下进行还原,还是只需要在选中一个复选框的情况下进行还原?如果是前者,那么你可以建立一个 RestoreProperties 允许您还原为复选框状态的状态。否则,是否有某种方法可以在检查重量是否有效之前保存状态,还原所有复选框,然后还原状态。

PiedPiper 15 年前

设置你的重量输入小部件,这样就不可能输入小于零的重量。那你就不需要了 invalidWeight()

CapelliC 10 年前

编辑

我重新打开了这个测试,愿意使用它,添加到.pro

CONFIG += C++11

我发现lambda语法已经改变了。。。捕获列表不能引用成员变量。这是正确的代码

auto cs = [/*button, check1, check2, edit, */this](QState *s, QState *t, bool on_off) {
    s->assignProperty(button, "enabled", !on_off);
    s->addTransition(new QSignalTransition(check1, SIGNAL(clicked())));
    s->addTransition(new QSignalTransition(check2, SIGNAL(clicked())));
    s->addTransition(new QSignalTransition(edit, SIGNAL(textChanged(QString))));
    Transition *p = new Transition(this, on_off);
    p->setTargetState(t);
    s->addTransition(p);
};

结束编辑

#include "mainwindow.h"
#include <QLayout>
#include <QFrame>
#include <QSignalTransition>

struct MainWindow::Transition : QAbstractTransition {
    Transition(MainWindow *main_w, bool on_off) :
        main_w(main_w),
        on_off(on_off)
    {}

    virtual bool eventTest(QEvent *) {
        bool ok_int, ok_cond =
            main_w->check1->isChecked() &&
            main_w->check2->isChecked() &&
            main_w->edit->text().toInt(&ok_int) > 0 && ok_int;
        if (on_off)
            return ok_cond;
        else
            return !ok_cond;
    }

    virtual void onTransition(QEvent *) {}

    MainWindow *main_w;
    bool on_off;
};

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    QFrame *f = new QFrame(this);
    QVBoxLayout *l = new QVBoxLayout;

    l->addWidget(check1 = new QCheckBox("Ok &1"));
    l->addWidget(check2 = new QCheckBox("Ok &2"));
    l->addWidget(edit = new QLineEdit());

    l->addWidget(button = new QPushButton("Enable &Me"));

    f->setLayout(l);
    setCentralWidget(f);

    QState *s1, *s2;
    sm = new QStateMachine(this);
    sm->addState(s1 = new QState());
    sm->addState(s2 = new QState());
    sm->setInitialState(s1);

    auto cs = [button, check1, check2, edit, this](QState *s, QState *t, bool on_off) {
        s->assignProperty(button, "enabled", !on_off);
        s->addTransition(new QSignalTransition(check1, SIGNAL(clicked())));
        s->addTransition(new QSignalTransition(check2, SIGNAL(clicked())));
        s->addTransition(new QSignalTransition(edit, SIGNAL(textChanged(QString))));
        Transition *tr = new Transition(this, on_off);
        tr->setTargetState(t);
        s->addTransition(tr);
    };
    cs(s1, s2, true);
    cs(s2, s1, false);

    sm->start();
}