7.qsqlquerymodel 与 qtableview使用

qtableview 委托

//设置单元格委托
void setItemDelegate(QAbstractItemDelegate *delegate);
QAbstractItemDelegate *itemDelegate() const;//设置列委托
void setItemDelegateForColumn(int column, QAbstractItemDelegate *delegate);
QAbstractItemDelegate *itemDelegateForColumn(int column) const;//设置行委托
void setItemDelegateForRow(int row, QAbstractItemDelegate *delegate);
QAbstractItemDelegate *itemDelegateForRow(int row) const;

QStyledItemDelegate

查看qtableview源码会发现itemdelegate默认就是QStyledItemDelegate
如果要自己写自定义的委托请尽量参考QStyledItemDelegate

显示事件

void QStyledItemDelegate::paint(QPainter *painter,const QStyleOptionViewItem &option, const QModelIndex &index) const
{Q_ASSERT(index.isValid());QStyleOptionViewItem opt = option;initStyleOption(&opt, index);const QWidget *widget = QStyledItemDelegatePrivate::widget(option);QStyle *style = widget ? widget->style() : QApplication::style();style->drawControl(QStyle::CE_ItemViewItem, &opt, painter, widget);
}

初始化绘制参数配置

void QStyledItemDelegate::initStyleOption(QStyleOptionViewItem *option,const QModelIndex &index) const
{QVariant value = index.data(Qt::FontRole);if (value.isValid() && !value.isNull()) {option->font = qvariant_cast<QFont>(value).resolve(option->font);option->fontMetrics = QFontMetrics(option->font);}value = index.data(Qt::TextAlignmentRole);if (value.isValid() && !value.isNull())option->displayAlignment = Qt::Alignment(value.toInt());value = index.data(Qt::ForegroundRole);if (value.canConvert<QBrush>())option->palette.setBrush(QPalette::Text, qvariant_cast<QBrush>(value));option->index = index;value = index.data(Qt::CheckStateRole);if (value.isValid() && !value.isNull()) {option->features |= QStyleOptionViewItem::HasCheckIndicator;option->checkState = static_cast<Qt::CheckState>(value.toInt());}value = index.data(Qt::DecorationRole);if (value.isValid() && !value.isNull()) {option->features |= QStyleOptionViewItem::HasDecoration;switch (value.type()) {case QVariant::Icon: {option->icon = qvariant_cast<QIcon>(value);QIcon::Mode mode;if (!(option->state & QStyle::State_Enabled))mode = QIcon::Disabled;else if (option->state & QStyle::State_Selected)mode = QIcon::Selected;elsemode = QIcon::Normal;QIcon::State state = option->state & QStyle::State_Open ? QIcon::On : QIcon::Off;QSize actualSize = option->icon.actualSize(option->decorationSize, mode, state);// For highdpi icons actualSize might be larger than decorationSize, which we don't want. Clamp it to decorationSize.option->decorationSize = QSize(qMin(option->decorationSize.width(), actualSize.width()),qMin(option->decorationSize.height(), actualSize.height()));break;}case QVariant::Color: {QPixmap pixmap(option->decorationSize);pixmap.fill(qvariant_cast<QColor>(value));option->icon = QIcon(pixmap);break;}case QVariant::Image: {QImage image = qvariant_cast<QImage>(value);option->icon = QIcon(QPixmap::fromImage(image));option->decorationSize = image.size() / image.devicePixelRatio();break;}case QVariant::Pixmap: {QPixmap pixmap = qvariant_cast<QPixmap>(value);option->icon = QIcon(pixmap);option->decorationSize = pixmap.size() / pixmap.devicePixelRatio();break;}default:break;}}value = index.data(Qt::DisplayRole);if (value.isValid() && !value.isNull()) {option->features |= QStyleOptionViewItem::HasDisplay;option->text = displayText(value, option->locale);}option->backgroundBrush = qvariant_cast<QBrush>(index.data(Qt::BackgroundRole));// disable style animations for checkboxes etc. within itemviews (QTBUG-30146)option->styleObject = 0;
}

当然有些列子https://blog.csdn.net/c1s2d3n4cs/article/details/143203486

行委托一般用来作为背景委托
列委托与单元格委托是一组，就是简单的优先级
列委托优先级》单元格委托

QAbstractItemDelegate

那么为了自定义qtableview 需要使用到这个QAbstractItemDelegate委托类

很遗憾，官方没给我们提供checkboxitemdelegate或者comboboxdelegate之类的委托
那么我们就需要自己去写一个
请参考https://blog.csdn.net/Gerald_Jones/article/details/106594052

CheckBoxItemDelegate

继承QItemDelegate需要实现一下几个虚函数

编辑模式，因为我们使用qsqlquerymodel 只读模型 所以可以不用写

// 创建编辑器virtual QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override;// 设置编辑器数据virtual void setEditorData(QWidget *editor, const QModelIndex &index) const override;// 更新编辑器集合属性virtual void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const override;// 设置模型数据virtual void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const override;

//如果是只读的组件那么我们只需要以下两个方法

CheckBoxItemDelegate.h

#ifndef CHECKBOXITEMDELEGATE_H
#define CHECKBOXITEMDELEGATE_H#include <QObject>
#include <QItemDelegate>
#include <QStyledItemDelegate>
#include <QCheckBox>
#include <QStylePainter>
#include <QDebug>
#include <QStyleOptionButton>class CheckBoxItemDelegate : public QItemDelegate
{Q_OBJECT
public:explicit CheckBoxItemDelegate(QObject *parent = nullptr);~CheckBoxItemDelegate();//---只读void paint(QPainter *painter,const QStyleOptionViewItem &option,const QModelIndex &index) const override;bool editorEvent(QEvent *event,QAbstractItemModel *model,const QStyleOptionViewItem &option,const QModelIndex &index) override;//---编辑模式// 创建编辑器 ---- 返回组件//     QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override;//    // 设置编辑器数据 ---- 初始化组件数据//     void setEditorData(QWidget *editor, const QModelIndex &index) const override;//    // 更新编辑器集合属性 --- 设置位置//     void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const override;//    // 设置模型数据 ---- 修改数据模型数据//     void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const override;signals:protected:void initStyleOption(QStyleOptionButton *option,const QStyleOptionViewItem *copy,const QModelIndex &index) const;private:bool m_checked = false;};#endif // CHECKBOXITEMDELEGATE_H

CheckBoxItemDelegate.cpp

#include "CheckBoxItemDelegate.h"
#include <QApplication>CheckBoxItemDelegate::CheckBoxItemDelegate(QObject *parent) : QItemDelegate(parent)
{qDebug()<< __FUNCTION__;
}CheckBoxItemDelegate::~CheckBoxItemDelegate()
{qDebug()<< __FUNCTION__;
}void CheckBoxItemDelegate::paint(QPainter *painter,const QStyleOptionViewItem &option,const QModelIndex &index) const
{QStyleOptionButton opt;initStyleOption(&opt, &option, index);const QWidget *widget = option.widget;QStyle *style = widget ? widget->style() : QApplication::style();style->drawControl(QStyle::CE_CheckBox, &opt, painter, widget);
}bool CheckBoxItemDelegate::editorEvent(QEvent *event,QAbstractItemModel *model,const QStyleOptionViewItem &option,const QModelIndex &index)
{//选中或者取消选中m_checked = true;return false;
}//QWidget *CheckBoxItemDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
//{//    return new QCheckBox(parent);
//}//void CheckBoxItemDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
//{
//    QCheckBox *cb = static_cast<QCheckBox *>(editor);
//    cb->setChecked(true);
//}//void CheckBoxItemDelegate::updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const
//{
//    editor->setGeometry(option.rect);
//}//void CheckBoxItemDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
//{
//    //    QCheckBox *cb = static_cast<QCheckBox *>(editor);
//    //    model->setData(index, cb->isChecked());
//}void CheckBoxItemDelegate::initStyleOption(QStyleOptionButton *option,const QStyleOptionViewItem *copy,const QModelIndex &index) const
{QRect boxRect = QApplication::style()->subElementRect(QStyle::SE_CheckBoxIndicator,option);option->rect = copy->rect;option->rect.setLeft(copy->rect.left()+(copy->rect.width()-boxRect.width())/2); //居中//option->rect.setTop(copy->rect.top()+(copy->rect.height()-option->rect.height())/2);option->state = m_checked? QStyle::State_On: QStyle::State_Off;
}

至于初始化选中状态由外部的section管理器来决定来决定
所以我们需要
实现一个选择管理器（支持单选，多选，跨页选）
我好想又看到qml有一个TableViewSelection.qml
至于c++有没有这个选择管理器还得自己去实现

使用

部分操作需要基于model之后，否则无效
如对行列隐藏，宽高设置等

qtableview控制列宽，行高，隐藏

    QTableView *view = new QTableView(this);view->setModel(model);view->move(0,400);//修改布局样式需要放到model之后设置CheckBoxItemDelegate* cb_delegate = new CheckBoxItemDelegate(this);view->setItemDelegateForColumn(0,cb_delegate);view->setColumnHidden(1,true);view->setColumnWidth(0,120);view->setRowHidden(0,true);view->setRowHeight(0,60);

而至于为什么view可以操作行列， 实际要查看Qheaderview.cpp
setColumnHidden -> setSectionHidden -> setVisualIndexHidden

    inline void setVisualIndexHidden(int visual, bool hidden) {sectionItems[visual].isHidden = hidden;}

而至于sectionItems怎么来的就跟我们上面的setmodel有关
他们之间有个信号槽，model 的信号 columnsInserted触发headerview中的sectionsInserted槽
sectionsInserted执行了sectionItems的添加操作

            QObject::connect(model, SIGNAL(columnsInserted(QModelIndex,int,int)),this, SLOT(sectionsInserted(QModelIndex,int,int)));

行的管理-------是同上的

拖拽行列

请参考https://blog.csdn.net/pyc_01/article/details/123346957

   view->setSelectionBehavior(QAbstractItemView::SelectRows); //选择方式：单元格选择、行选择、列选择view->setSelectionMode(QAbstractItemView::SingleSelection); //选择模式： 多选，单选view->horizontalHeader()->setSectionsMovable(true); //表头支持拖动view->setDragEnabled(true); //启用拖拽view->setAcceptDrops(true); //接受放置view->setDragDropMode(QAbstractItemView::InternalMove); //拖放范围：内部view->setEditTriggers(QAbstractItemView::NoEditTriggers); //禁用编辑功能view->setCursor(Qt::ClosedHandCursor);

//解下来需要重写拖放等相关事件，这需要重写一个DragTableView控件