c++ - Qt5 连接导致 Unhandled Exception 或 HEAP CORRUPTION

Question

我在 VS2010SP1 上使用 Qt5.5。我在停靠小部件中有一个 QCheckBox，它控制同一停靠小部件中的 QTableView(提示为 ConsoleWindowView)是否自动滚动。

问题一:

当我将 QCheckBox::stateChanged 信号连接到 QTableView 的插槽(autoScroll)时，一切似乎都很好，除非我更改 QCheckBox 的状态并退出。在退出时我收到错误:

Debug Error! Program: QtTests.exe HEAP CORRUPTION DETECTED: after Normal block (#4613) at 0x02B63850. CRT detected that the application wrote to memory after end of heap buffer.

如果我没有激活QCheckBox就退出了，退出是正常的。

问题2:

认为这可能与销毁顺序有关，我试图在 QTableView 析构函数中“记住”连接和断开连接，但是当我尝试将 QObject::connect 的返回值分配给 QMetaObject::Connection 成员变量时，我得到:

Unhandled exception at 0x669859c2 in QtTests.exe: 0xC0000005: Access violation writing location 0xabababc7

代码如下，后跟相关的 ui 文件。

崩溃的区域在 Gui.h 中，方法 connectControls。对于问题 1，配置为:

QObject::connect(AutoScrollCheckBox, &QCheckBox::stateChanged, this, &ConsoleWindowView::autoScroll); // CRASH1: Debug Error! Program: QtTests.exe HEAP CORRUPTION DETECTED: after Normal block (#4613) at 0x02B63850. CRT detected that the application wrote to memory after end of heap buffer.
//QMetaObject::Connection NewConnection = QObject::connect(AutoScrollCheckBox, &QCheckBox::stateChanged, this, &ConsoleWindowView::autoScroll);
//AutoScrollConnection = NewConnection; // CRASH2: Unhandled exception at 0x669859c2 in QtTests.exe: 0xC0000005: Access violation writing location 0xabababc7

对于问题 2，配置为:

//QObject::connect(AutoScrollCheckBox, &QCheckBox::stateChanged, this, &ConsoleWindowView::autoScroll); // CRASH1: Debug Error! Program: QtTests.exe HEAP CORRUPTION DETECTED: after Normal block (#4613) at 0x02B63850. CRT detected that the application wrote to memory after end of heap buffer.
QMetaObject::Connection NewConnection = QObject::connect(AutoScrollCheckBox, &QCheckBox::stateChanged, this, &ConsoleWindowView::autoScroll);
AutoScrollConnection = NewConnection; // CRASH2: Unhandled exception at 0x669859c2 in QtTests.exe: 0xC0000005: Access violation writing location 0xabababc7

主.cpp

#include <QtWidgets/QApplication>

#include "Gui.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Gui w;
    w.show();
    return a.exec();
}

贵.h

#ifndef QTTESTS_H
#define QTTESTS_H

#include <iostream>

#include <QTimer>
#include <QHeaderView>
#include <QCheckBox>
#include <QObject>

#include "ui_Gui.h"

class ConsoleWindowModelClass : public QAbstractTableModel
{
    Q_OBJECT
public:
    ConsoleWindowModelClass(QObject *parent)
        : QAbstractTableModel(parent)
        , RowCount(0)
    {
        //
        ControllerTimer = new QTimer(this);
        connect(ControllerTimer, SIGNAL(timeout()), this, SLOT(updateController()));
        ControllerTimer->start(2000);
    }
    int rowCount(const QModelIndex &parent = QModelIndex()) const Q_DECL_OVERRIDE
    {
        return RowCount;
    }
    int columnCount(const QModelIndex &parent = QModelIndex()) const Q_DECL_OVERRIDE
    {
        return 2;
    }
    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const Q_DECL_OVERRIDE
    {
        if (role == Qt::DisplayRole)
        {
            return QString("Row%1, Column%2")
                .arg(index.row() + 1)
                .arg(index.column() +1);
        }
        return QVariant();
    }
    QVariant headerData(int section, Qt::Orientation orientation, int role) const Q_DECL_OVERRIDE
    {
        if (orientation == Qt::Horizontal)
        {
            if (role == Qt::DisplayRole)
            {
                switch(section)
                {
                case 0:
                    return "Stamp";
                    break;
                case 1:
                    return "Text";
                    break;
                default:
                    return QString("Column %1").arg(section + 1);
                    break;
                }
            }
        }
        else if (orientation == Qt::Vertical)
        {
            if (role == Qt::DisplayRole)
            {
                return QString("%1").arg(section + 1);
            }
        }
        return QVariant();
    }
protected:
    unsigned int RowCount;
    QTimer *ControllerTimer;
    private slots:
        // GUI triggered
        // Timer triggered
        void updateController()
        {
            beginInsertRows(QModelIndex(), RowCount, RowCount);
            RowCount++;
            endInsertRows();
        }
};

class ConsoleWindowView : public QTableView
{
    Q_OBJECT

public:
    ConsoleWindowView(QWidget *parent = 0)
        : QTableView(parent)
        , AutoScroll(true)
    {
    }
    virtual ~ConsoleWindowView()
    {
        //disconnect(AutoScrollConnection);
    }
    void setTheModel(QAbstractItemModel *TheModel)
    {
        QTableView::setModel(TheModel);
        connect(model(), &QAbstractItemModel::rowsInserted, this, &ConsoleWindowView::modelRowsInserted);
    }
    void connectControls(QCheckBox *AutoScrollCheckBox, QCheckBox *ReverseList, QPushButton *MarkerA, QPushButton *MarkerB, QPushButton *MarkerC, QPushButton *MarkerD)
    {
        try
        {
            //QObject::connect(AutoScrollCheckBox, &QCheckBox::stateChanged, this, &ConsoleWindowView::autoScroll); // CRASH1: Debug Error! Program: QtTests.exe HEAP CORRUPTION DETECTED: after Normal block (#4613) at 0x02B63850. CRT detected that the application wrote to memory after end of heap buffer.
            QMetaObject::Connection NewConnection = QObject::connect(AutoScrollCheckBox, &QCheckBox::stateChanged, this, &ConsoleWindowView::autoScroll);
            AutoScrollConnection = NewConnection; // CRASH2: Unhandled exception at 0x669859c2 in QtTests.exe: 0xC0000005: Access violation writing location 0xabababc7
        }
        catch (const std::exception &Exception)
        {
            std::cerr << "ConsoleWindowView::connectControls: " << Exception.what() << std::endl;
        }
    }

    public slots:
        void modelRowsInserted(const QModelIndex & parent, int start, int end)
        {
            if (model() != nullptr)
            {
                if (AutoScroll)
                {
                    scrollTo(model()->index(start, 0));
                }
            }
        }
        void autoScroll(int State)
        {
            if (State == 0)
            {
                AutoScroll = false;
            }
            else
            {
                AutoScroll = true;
            }
        }

signals:

protected:
    bool AutoScroll;
    QMetaObject::Connection AutoScrollConnection;
private:
};

class Gui : public QMainWindow
{
    Q_OBJECT

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

protected:
    ConsoleWindowModelClass *ConsoleWindowModel;

private:
    Ui::Gui ui;
    void createConsoleWindow();

    //
private slots:
    // GUI triggered

};

#endif // QTTESTS_H

gui.cpp

#include <iostream>

#include <QTimer>
#include <QHeaderView>
#include <QCheckBox>
#include <QObject>

// Qt model handling the BusSimLowRateTx message from BusSim to DataSwitch.

#include <QAbstractTableModel>

#include "Gui.h"

Gui::Gui(QWidget *parent)
    : QMainWindow(parent)
{
    // create UI
    ui.setupUi(this);
    //
    ui.actionExit->setShortcuts(QKeySequence::Quit);
    ui.actionExit->setStatusTip(tr("Exit the application"));
    connect(ui.actionExit, SIGNAL(triggered()), this, SLOT(close()));
    // create models
    ConsoleWindowModel = new ConsoleWindowModelClass(this); // should be deleted as part of QMainWindow destructor, by specifying this as the parent.
    //
    // connect ConsoleWindowModel to the View(s)
    createConsoleWindow();
}

Gui::~Gui()
{
    // ConsoleWindowModel - should be deleted as part of QMainWindow destructor.
    //ConsoleWindowView *View = static_cast<ConsoleWindowView *>(ui.ConsoleOutputTable);
    //disconnect(ui.AutoScroll, &QCheckBox::stateChanged, View, &ConsoleWindowView::autoScroll);
}

void Gui::createConsoleWindow()
{
    ConsoleWindowView *View = static_cast<ConsoleWindowView *>(ui.ConsoleOutputTable);
    View->setTheModel(ConsoleWindowModel);
    for (int c = 1; c < View->horizontalHeader()->count(); ++c)
    {
        View->horizontalHeader()->setSectionResizeMode(c, QHeaderView::Stretch);
    }
    // connect the other ConsoleWindow Controls to the model
    View->connectControls(ui.AutoScroll, ui.NewestAtTop, ui.MarkerA, ui.MarkerB, ui.MarkerC, ui.MarkerD);
}

贵.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>Gui</class>
 <widget class="QMainWindow" name="Gui">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>593</width>
    <height>652</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>Gui Tests</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <property name="sizePolicy">
    <sizepolicy hsizetype="Maximum" vsizetype="Preferred">
     <horstretch>0</horstretch>
     <verstretch>0</verstretch>
    </sizepolicy>
   </property>
   <layout class="QGridLayout" name="gridLayout_7"/>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>593</width>
     <height>21</height>
    </rect>
   </property>
   <widget class="QMenu" name="menuFile">
    <property name="title">
     <string>File</string>
    </property>
    <addaction name="actionExit"/>
   </widget>
   <widget class="QMenu" name="menuView">
    <property name="title">
     <string>View</string>
    </property>
   </widget>
   <addaction name="menuFile"/>
   <addaction name="menuView"/>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
  <widget class="QDockWidget" name="ConsoleOutput">
   <property name="windowTitle">
    <string>Console Output</string>
   </property>
   <attribute name="dockWidgetArea">
    <number>8</number>
   </attribute>
   <widget class="QWidget" name="ConsoleOutputDock">
    <layout class="QGridLayout" name="gridLayout_4">
     <item row="0" column="0">
      <layout class="QGridLayout" name="gridLayout">
       <item row="0" column="0">
        <layout class="QHBoxLayout" name="horizontalLayout">
         <item>
          <widget class="QCheckBox" name="AutoScroll">
           <property name="text">
            <string>Auto Scroll</string>
           </property>
           <property name="checked">
            <bool>true</bool>
           </property>
          </widget>
         </item>
         <item>
          <widget class="QCheckBox" name="NewestAtTop">
           <property name="text">
            <string>Newest At Top</string>
           </property>
          </widget>
         </item>
         <item>
          <widget class="QPushButton" name="MarkerA">
           <property name="styleSheet">
            <string notr="true">background-color: rgb(255, 0, 0);</string>
           </property>
           <property name="text">
            <string>Marker A</string>
           </property>
          </widget>
         </item>
         <item>
          <widget class="QPushButton" name="MarkerB">
           <property name="styleSheet">
            <string notr="true">background-color: rgb(0, 255, 0);</string>
           </property>
           <property name="text">
            <string>Marker B</string>
           </property>
          </widget>
         </item>
         <item>
          <widget class="QPushButton" name="MarkerC">
           <property name="styleSheet">
            <string notr="true">background-color: rgb(255, 255, 0);</string>
           </property>
           <property name="text">
            <string>Marker C</string>
           </property>
          </widget>
         </item>
         <item>
          <widget class="QPushButton" name="MarkerD">
           <property name="styleSheet">
            <string notr="true">background-color: rgb(0, 0, 255);
color: rgb(255, 255, 255);</string>
           </property>
           <property name="text">
            <string>Marker D</string>
           </property>
          </widget>
         </item>
        </layout>
       </item>
       <item row="1" column="0">
        <widget class="QTableView" name="ConsoleOutputTable"/>
       </item>
      </layout>
     </item>
    </layout>
   </widget>
  </widget>
  <action name="actionExit">
   <property name="text">
    <string>Exit</string>
   </property>
  </action>
  <action name="actionECIO_Outputs">
   <property name="text">
    <string>Enlightenment Monitor</string>
   </property>
  </action>
  <action name="actionECIO_Inputs">
   <property name="text">
    <string>Enlightenment Control</string>
   </property>
  </action>
  <action name="actionSHM_Control">
   <property name="text">
    <string>SHM Input</string>
   </property>
  </action>
  <action name="actionSHM_Output">
   <property name="text">
    <string>SHM Output</string>
   </property>
  </action>
  <zorder>ConsoleOutput</zorder>
 </widget>
 <resources/>
 <connections/>
</ui>

Answer 1

您正在静态转换 QTableView 的实例至ConsoleWindowView .它不起作用，因为它不是 ConsoleWindowView .你期待什么？你为什么要static_cast它？

如果您不确定静态转换是否有效，请使用 qobject_cast .它会失败，产生一个 nullptr 结果，你会知道你必须停下来弄清楚为什么你没有得到正确的类实例。你不是因为你的 UI 文件被破坏了——你必须在 UI 文件中有正确类型的实例。

修复您的 UI 文件以实例化正确的类:

在设计 View 中右键单击 ConsoleOutputTable。

点击推广到....

输入 ConsoleWindowView在升级类名中:。

输入 gui.h在头文件中:.

单击添加。

点击推广。

在任何情况下，您都不需要手动跟踪对象连接。

其他观点/咆哮:

如果你想要一个计时器实例，只需放一个 QTimer那里的成员 - 使用指针并通过间接引用和额外的堆分配过早地悲观有什么意义？让您的生活轻松。

抽象项目 View 已经有一个名为 autoScroll 的属性。 .你把一个新属性(property)的同名弄乱了，让每个人的生活都变得糟糕透顶。将其命名为其他名称，例如 scrollToNewest .

你的自动滚动 TableView 应该有一个属性来控制它的行为。然后，您可以将该属性连接到一个有助于了解源控件(如复选框)的位置的控件。将 View 紧密绑定(bind)到一些随机控件是一个坏主意。观点应该是一般的。您使用它的表单了解其他控件，并且知道如何将 View 绑定(bind)到这些控件。

setModel是一种虚方法。覆盖它，不要创建自己的。

变量名以大写字母开头会让你感到很困惑。不要那样做。类以大写字母开头，变量和成员以小写字母开头。

使用signals和 slots仅当信号和/或插槽在逻辑上相关并且其中有很多时才应使用节宏 - 太多了，使用 Q_SIGNAL或 Q_SLOT前缀会有点多。在大多数情况下，您有少量信号/插槽，您应该使用前缀。然后，您可以轻松地将信号和槽声明与其他相关方法分组，以便声明分组遵循函数，而不是实现细节。

在 Qt 5 中，您不需要 Q_SLOT前缀，任何方法都可以是带有新 connect 的插槽句法。您只需要 Q_SLOT或 Q_INVOKABLE如果您希望方法的元数据在运行时可用，则为前缀。

考虑到上述情况，这就是 ConsoleWindowView类应该看起来:

class ConsoleWindowView : public QTableView
{
   Q_OBJECT
   Q_PROPERTY(bool scrollToNewest READ scrollToNewest WRITE setScrollToNewest)
   bool m_scrollToNewest;
   void modelRowsInserted(const QModelIndex &, int start, int end) {
      Q_UNUSED(end)
      if (model() && m_scrollToNewest) scrollTo(model()->index(start, 0));
   }
public:
   ConsoleWindowView(QWidget *parent = 0) : QTableView(parent), m_scrollToNewest(true)
   {}
   void setModel(QAbstractItemModel *TheModel) Q_DECL_OVERRIDE
   {
      QTableView::setModel(TheModel);
      connect(model(), &QAbstractItemModel::rowsInserted, this, &ConsoleWindowView::modelRowsInserted);
   }
   Q_SLOT void setScrollToNewest(bool s) { m_scrollToNewest = s; }
   bool scrollToNewest() const { return m_scrollToNewest; }
};

Gui类，在将控制台 View 与用于调整它的具体控件解耦之后:

class Gui : public QMainWindow
{
   Q_OBJECT
   Ui::Gui ui;
   ConsoleWindowModel consoleWindowModel;
   void connectConsoleWindow() {
      auto view = ui.ConsoleOutputTable;
      view->setModel(&consoleWindowModel);
      for (int c = 1; c < view->horizontalHeader()->count(); ++c)
         view->horizontalHeader()->setSectionResizeMode(c, QHeaderView::Stretch);

      connect(ui.AutoScroll, &QCheckBox::toggled, view, &ConsoleWindowView::setScrollToNewest);
   }

public:
   Gui(QWidget *parent = 0) : QMainWindow(parent) {
      ui.setupUi(this);
      ui.actionExit->setShortcuts(QKeySequence::Quit);
      ui.actionExit->setStatusTip(tr("Exit the application"));
      connect(ui.actionExit, &QAction::triggered, this, &QWidget::close);
      connectConsoleWindow();
   }
};

请注意，我们只是将 connectConsoleWindow 命名为方法根据它的作用。您已将其命名为 错了如 createConsoleWindow然后 评论 关于它的行为——也就是说，它不创造任何东西，而只是连接东西。 这是一个可怕的反模式，必须被视为即时代码审查失败 .在可行的情况下，根据他们所做的事情命名(在此处)。使代码自记录。

最后，这就是您应该如何实例化诸如计时器等长生命周期成员的方式 - 不使用原始指针和易受人为错误影响的显式内存分配:

class ConsoleWindowModel : public QAbstractTableModel
{
   Q_OBJECT
   unsigned int m_rowCount;
   QTimer m_controllerTimer;
   void updateController()
   {
      beginInsertRows(QModelIndex(), m_rowCount, m_rowCount);
      m_rowCount++;
      endInsertRows();
   }
public:
   ConsoleWindowModel(QObject *parent = 0)
      : QAbstractTableModel(parent)
      , m_rowCount(0) {
      connect(&m_controllerTimer, &QTimer::timeout, this, &ConsoleWindowModel::updateController);
      m_controllerTimer.start(2000);
   }
   [...]