简单使用，数据不是单例且只能选择那个位置不可编辑

QItemDelegate只能在编辑的时候显示。
.h

#ifndef TABLEVIEW_H
#define TABLEVIEW_H

#include <QItemDelegate>
#include <QWidget>

namespace Ui {
class Tableview;
}

class Tableview : public QWidget
{
    Q_OBJECT

public:
    explicit Tableview(QWidget *parent = 0);
    ~Tableview();
private:
    Ui::Tableview *ui;
};
class ItemDelegate :public QItemDelegate
{
public:
    ItemDelegate(QObject *parent = nullptr);

    // QAbstractItemDelegate interface
public:
    virtual QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override;
    virtual void setEditorData(QWidget *editor, const QModelIndex &index) const override;
    virtual void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const override;
    virtual void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const override;
};
#endif // TABLEVIEW_H

.cpp

#include "Tableview.h"
#include "ui_Tableview.h"

#include <QLineEdit>
#include <QStandardItemModel>
#include<qdebug.h>
Tableview::Tableview(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Tableview)
{
    ui->setupUi(this);
    ui->tableView->horizontalHeader()->setStyleSheet("QHeaderView::section {"
                                                     "color: black;border: 1px solid #6c6c6c;}");
//允许鼠标事件
   ui->tableView->setMouseTracking(true);
    //设置选中时为整行选中
    ui->tableView->setSelectionBehavior(QAbstractItemView::SelectRows);
    //铺满整个窗口
    ui->tableView->horizontalHeader()->setSectionResizeMode(QHeaderView::Stretch);
    ui->tableView->verticalHeader()->setVisible(false);
    QStandardItemModel *itemModel = new QStandardItemModel(this);
    ui->tableView->setModel(itemModel);
    itemModel->setRowCount(2);
    QStringList header;header<<"1"<<"2"<<"3"<<"4"<<"5";
    itemModel->setHorizontalHeaderLabels(header);
    QStringList data;data<<"1"<<"2"<<"3"<<"4"<<"5";
    for(int i = 0;i<data.size();i++)
    {
        QStandardItem *item = new QStandardItem(data.at(i));
        item->setEditable(false);
        item->setTextAlignment(Qt::AlignHCenter | Qt::AlignVCenter);
        itemModel->setItem(0,i,item);
    }
    ui->tableView->setItemDelegateForRow(1,new ItemDelegate(this));
    for(int i = 0;i<data.size();i++)
    {
        QStandardItem *item = new QStandardItem;
        item->setTextAlignment(Qt::AlignHCenter | Qt::AlignVCenter);
        itemModel->setItem(1,i,item);
    }
    //获取数据
    connect(ui->pushButton,&QPushButton::clicked,this,[=](){
        for(int i = 0;i<data.size();i++)
        {
            qDebug()<<itemModel->index(1,i).data().toString();
        }
    });
//指定位置添加控件，未编辑也显示
    QPushButton *button_1 = new QPushButton(this);
    button_1->setText("123");
    ui->tableView->setIndexWidget(itemModel->index(2,2),button_1);
}

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

ItemDelegate::ItemDelegate(QObject *parent):QItemDelegate(parent)
{

}

QWidget *ItemDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    Q_UNUSED(option)
    Q_UNUSED(index)
    QLineEdit *editor = new QLineEdit(parent);
    editor->setAlignment(Qt::AlignCenter);
    QRegExp regx("[0-9]+$");
    QValidator *validator=new QRegExpValidator(regx,editor);
    editor->setValidator(validator);
    return editor;
}

void ItemDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
    QString value = index.model()->data(index, Qt::EditRole).toInt();
    QLineEdit *currentEditor = static_cast<QLineEdit*>(editor);
    currentEditor->setText(value);
}

void ItemDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{
    QLineEdit *currentEditor = static_cast<QLineEdit*>(editor);
    QString value= currentEditor->text();
    //设置模型的数据
    model->setData(index, value, Qt::EditRole);
}

void ItemDelegate::updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    //根据option,设置编辑框位置
    Q_UNUSED(index)
    editor->setGeometry(option.rect);
}

未编辑也显示控件，不过要为单元格分类，除非指定行或者列全是代理。
.h

class ItemDelegate :public QItemDelegate
{
public:
    ItemDelegate(QObject *parent = nullptr);
    // QAbstractItemDelegate interface
    virtual void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const override;
    virtual bool editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index) override;
private:
    QPushButton *m_boutton;
};

ItemDelegate::ItemDelegate(QObject *parent):QItemDelegate(parent)
{
ItemDelegate::ItemDelegate(QObject *parent):QItemDelegate(parent)
{
     m_boutton = new QPushButton;
     m_boutton->setProperty("IsDelegateButton",true);
     m_boutton->setToolTip("ok");
     m_boutton->setStyleSheet("QPushButton {border-radius:0px;background:transparent; border-image: url(:/image/image/size.png);}");
}

void ItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    //ItemDelegate::paint(painter, option, index);
    painter->save();
    painter->restore();
    if (index.column() == 4)
   {
        QStyleOptionButton styleButton;                   //设置参数
        styleButton.rect=option.rect;
        styleButton.state  = QStyle::State_Enabled;
        if (option.state & QStyle::State_Selected) {
            painter->fillRect(option.rect, option.palette.highlight());
        }
        QWidget *widget = m_boutton;
        widget->style()->drawControl(QStyle::CE_PushButton,&styleButton,painter,widget);
    }
    else
    {
        //否则调用默认委托
        QItemDelegate::paint(painter, option, index);
    }
}

bool ItemDelegate::editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index)
{
    if(event->type() == QEvent::MouseButtonDblClick)     //禁止双击编辑
    {
            return true;
    }
    return QItemDelegate::editorEvent(event,model,option,index);
}
}

void ItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    if (index.column() == 5&&index.row() == 1)
   {
        //按钮的风格选项
        //获取项风格设置
        QString value = index.model()->data(index, Qt::DisplayRole).toString();
        QStyleOptionComboBox comboBoxOption;
        comboBoxOption.rect=option.rect;
        comboBoxOption.state = option.state;
        comboBoxOption.state |= QStyle::State_Selected;
        comboBoxOption.editable = false;
        comboBoxOption.currentText=value;
       //绘制QCheckBox
       QApplication::style()->drawComplexControl(QStyle::CC_ComboBox,&comboBoxOption,painter);
       QApplication::style()->drawControl(QStyle::CE_ComboBoxLabel, &comboBoxOption, painter);
    }
   else
   {
       //否则调用默认委托
       QItemDelegate::paint(painter, option, index);
    }
}

QWidget *ItemDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    Q_UNUSED(option)
    if (index.column() == 5&&index.row() == 1)//需要分类，这个cell为下拉框，不是的话为编辑框，这里没写编辑框。
    {
        QComboBox *editor = new QComboBox(parent);
        editor->addItem("q",0);
        editor->addItem("w",1);
        editor->setCurrentIndex(0);
        return editor;
    }
    return QItemDelegate::createEditor(parent, option, index);
}

void ItemDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
{
    if (!(index.column() == 5&&index.row() == 1))return;
    QComboBox *currentComboBox = static_cast<QComboBox*>(editor);
    QString value = index.model()->data(index, Qt::DisplayRole).toString();
    int data = index.model()->data(index, Qt::UserRole + 1).toInt();

    qDebug()<<"text="<<value<<",data="<<data;

    int idx = currentComboBox->findData(data);
    if (idx > -1 ) {
        currentComboBox->setCurrentIndex(idx);
    }
}

void ItemDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{
    QComboBox *currentComboBox = static_cast<QComboBox*>(editor);
    QString displayData = currentComboBox->currentText();
    QVariant value = currentComboBox->currentData();
    model->setData(index, displayData, Qt::DisplayRole);
    model->setData( index, value, Qt::UserRole + 1 );
}

void ItemDelegate::updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    editor->setGeometry(option.rect);
}

双击事件

   connect(ui->tableView,&QTableView::doubleClicked,this,[](const QModelIndex &index){
       if(index.isValid())
       {
         qDebug()<<index.model()->data(index, Qt::DisplayRole).toString();
       }
   });

鼠标进入单元格事件

   connect(ui->tableView,&QTableView::entered,this,[=](const QModelIndex &index){
       if(index.isValid())
       {
         qDebug()<<index.model()->data(index, Qt::DisplayRole).toString();
         itemModel->item(index.row(),index.column())->setBackground(QBrush(QColor(255, 0, 0)));
       }
   });