在QTableView中某列中添加Button的导致滚动条滚动的时候消失的问题

之前在项目上需要在表格中加入Button是按照以下两个文章的做法：

http://www.cnblogs.com/li-peng/p/3961843.html

http://www.cnblogs.com/li-peng/p/4029885.html

文章的做法是传统通过子类化QItemDelegate类来做的，通过paint函数在某列中画出QPushButton的Style。

但是这么做有一个问题，就是按钮画出来以后，但是拖动QTableView的滚动条的时候，会导致按钮所在的列的部分按钮又消失的问题。

没查到原因，但是最终还是在找到解决方案了。还是子类化QItemDelegate类，但是与之前的两个文章之前的做法有些不同，以下是正确的

代码：

Delegate头文件：

 #pragma once

 #include <QStyledItemDelegate>
 #include <QString>
 #include <QPersistentModelIndex>

 class QStyleOptionButton;
 class CTableWidget;
 class QPushButton;

 class AppRepoButtonDelegate : public QStyledItemDelegate
 {
     Q_OBJECT

 public:

     explicit AppRepoButtonDelegate(QObject *parent = Q_NULLPTR);
     ~AppRepoButtonDelegate();
 public:
     void setText(const QString& text);
     void setStyleSheet(const QString& qss);

 signals:
     void buttonClicked(const QModelIndex& index);
 public:

     QWidget* createEditor(QWidget *parent,
         const QStyleOptionViewItem &option,
         const QModelIndex &index) const override;
    void paint(QPainter *painter, const QStyleOptionViewItem &option,
         const QModelIndex &index) const override;
     void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const override;
 private slots:
     void cellEntered(const QModelIndex& index);
     void slotBtnClicked();
 private:
     CTableWidget * m_table_view;
     bool isOneCellInEditMode;
     QPushButton* m_btn;
     QPersistentModelIndex m_currentEditedCellIndex;
     QString m_btnText;
     QString m_btnQss;
 };

Delegate类的CPP实现文件：

 #include "AppRepoButtonDelegate.h"

 #include <QStyleOptionButton>
 #include <QPainter>
 #include <QApplication>
 #include <QMouseEvent>
 #include <QStandardItemModel>
 #include <QPushButton>
 #include <QTableView>

 #include "CTableWidget.h"

 AppRepoButtonDelegate::AppRepoButtonDelegate(QObject *parent)
     : QStyledItemDelegate(parent)
 {
     CTableWidget *tabView = qobject_cast<CTableWidget*>(parent);
     if (tabView)
     {
         m_table_view = tabView;
         m_btn = new QPushButton(QStringLiteral(""), m_table_view);
         m_btn->hide();
         m_table_view->setMouseTracking(true);
         connect(m_table_view, SIGNAL(entered(QModelIndex)),
             this, SLOT(cellEntered(QModelIndex)));
         isOneCellInEditMode = false;
     }
 }

 AppRepoButtonDelegate::~AppRepoButtonDelegate()
 {
 }

 void AppRepoButtonDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
 {
     int x, y, width, height;
     x = option.rect.left() + option.rect.width() /  - ;
     y = option.rect.top() + ;
     width = ;
     height = ;

     m_btn->setGeometry(QRect(x,y,width,height));
     m_btn->setText(m_btnText);
     m_btn->setStyleSheet(m_btnQss);
     if (option.state == QStyle::State_Selected)
         painter->fillRect(option.rect, option.palette.highlight());
     QPixmap map = QPixmap::grabWidget(m_btn);
     painter->drawPixmap(x, y, map);
 }

 QWidget* AppRepoButtonDelegate::createEditor(QWidget *parent,
     const QStyleOptionViewItem &option, const QModelIndex &index) const
 {
     QPushButton * btn = new QPushButton(parent);
     connect(btn, &QPushButton::clicked, this, &AppRepoButtonDelegate::slotBtnClicked);
     btn->setText(m_btnText);
     btn->setStyleSheet(m_btnQss);
     return btn;
 }

 void AppRepoButtonDelegate::cellEntered(const QModelIndex& index)
 {
     if (index.column() ==  || index.column() == )
     {
         if (isOneCellInEditMode)
         {
             m_table_view->closePersistentEditor(m_currentEditedCellIndex);
         }
         m_table_view->openPersistentEditor(index);
         isOneCellInEditMode = true;
         m_currentEditedCellIndex = index;
     }
     else {
         if (isOneCellInEditMode)
         {
             isOneCellInEditMode = false;
             m_table_view->closePersistentEditor(m_currentEditedCellIndex);
         }
     }
 }

 void AppRepoButtonDelegate::updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option,
     const QModelIndex &index) const
 {
     int x, y, width, height;
     x = option.rect.left() + option.rect.width() /  - ;
     y = option.rect.top() + ;
     width = ;
     height = ;
     editor->setGeometry(QRect(x, y, width, height));
 }

 void AppRepoButtonDelegate::setText(const QString& text)
 {
     m_btnText = text;
 }

 void AppRepoButtonDelegate::setStyleSheet(const QString& qss)
 {
     m_btnQss = qss;
 }

 void AppRepoButtonDelegate::slotBtnClicked()
 {
     emit buttonClicked(m_currentEditedCellIndex);
 }

用法：

  auto delegateBtn = new AppRepoButtonDelegate(ui->appTable);
         delegateBtn->setText(QStringLiteral("下载更新"));
         m_downloadUpdateDelegate = delegateBtn;
         connect(m_downloadUpdateDelegate, &AppRepoButtonDelegate::buttonClicked,
             this, &AppRepoPage::slotDownloadUpdateBtnClicked);
         ui->appTable->setItemDelegateForColumn(
             , m_downloadUpdateDelegate); //给第6列添加下载更新按钮的委托

references:

https://stackoverflow.com/questions/12360111/qpushbutton-in-qtableview
https://stackoverflow.com/questions/25337740/how-to-add-qpushbutton-in-qtableview-when-loading-database-by-c
http://www.qtcentre.org/threads/32394-Add-QPushButton-to-cell-in-QTableView
https://forum.qt.io/topic/53467/how-to-add-qpushbutton-in-qtableview

https://stackoverflow.com/questions/43082419/create-pushbuttons-in-qtableview-with-qstyleditemdelegate-subclass/43109044#43109044

https://qtadventures.wordpress.com/2012/02/04/adding-button-to-qviewtable/