C++ Qt 学习（九）：模型视图代理

1. Qt 模型视图代理

• Qt 模型视图代理，也可以称为 MVD 模式
  • 模型(model)、视图(view)、代理(delegate)
  • 主要用来显示编辑数据

1.1 模型

• 模型 (Model) 是视图与原始数据之间的接口
  • 原始数据可以是：数据库的一个数据表、内存中的一个 StringList，磁盘文件结构等
  • QAbstractItemModel 是所有模型的祖宗类，其它 model 类都派生于它

1.2 视图

• 视图 (View) 是显示和编辑数据的界面组件
  • 主要的视图组件有 QListView、QTreeView 和 QTableView
  • QListWidget、QTreeWidget 和 QTableWidget 是视图类的简化版
    • 它们不使用数据模型，而是将数据直接存储在组件的每个项里
  • QAbstractItemView 是所有视图的祖宗类，其它 view 类都派生于它

1.3 代理

• 代理 (Delegate) 为视图组件提供数据编辑器
  • 如在表格组件中，编辑一个单元格的数据时，缺省是使用一个 QLineEdit 编辑框
  • 代理负责从数据模型获取相应的数据，然后显示在编辑器里，修改数据后，又将其保存到数据模型中

2. QTableView 应用

• tableView.pro

  QT       += core gui// 使用 QAxObject 需添加下行
  // The QAxObject class provides a QObject that wraps a COM object.
  greaterThan(QT_MAJOR_VERSION, 4): QT += widgets axcontainer
  

2.1 widget.ui

2.2 主窗口

2.2.1 widget.h

#ifndef WIDGET_H
#define WIDGET_H#include <QWidget>
#include <QStandardItemModel>
#include <QItemSelectionModel>
#include "cintspindelegate.h"
#include "cfloatspindelegate.h"
#include "ccomboboxdelegate.h"QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACEclass Widget : public QWidget {Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();private slots:void on_btnOpenExcel_clicked();void on_btnReshowData_clicked();void OnCurrentChanged(const QModelIndex &current, const QModelIndex &previous);void on_btnAppendLast_clicked();void on_btnAppend_clicked();void on_btnDeleteSelectedLine_clicked();private:Ui::Widget *ui;QStandardItemModel  *m_pItemModel;        // 数据模型QItemSelectionModel *m_pSelectionModel;   // Item 选择模型CIntSpinDelegate    m_intSpinDelegate;    // 整型数 spinbox 代理CFloatSpinDelegate  m_floatSpinDelegate;  // 浮点数 spinbox 代理CComboBoxDelegate   m_comboBoxDelegate;   // combobox 代理
};
#endif // WIDGET_H

2.2.2 widget.cpp

#include "widget.h"
#include "ui_widget.h"
#include <QAxObject>
#include <QFileDialog>
#include <QStandardPaths>static const int COLUMN_COUNT = 7;Widget::Widget(QWidget *parent) : QWidget(parent), ui(new Ui::Widget) {ui->setupUi(this);showMaximized();m_pItemModel = new QStandardItemModel(1, COLUMN_COUNT, this);m_pSelectionModel = new QItemSelectionModel(m_pItemModel);  // Item 选择模型// 选择当前单元格变化时的信号与槽connect(m_pSelectionModel, &QItemSelectionModel::currentChanged, this, &Widget::OnCurrentChanged);ui->tableView->setModel(m_pItemModel);                // 设置数据模型ui->tableView->setSelectionModel(m_pSelectionModel);  // 设置选择模型ui->tableView->setSelectionMode(QAbstractItemView::ExtendedSelection);ui->tableView->setSelectionBehavior(QAbstractItemView::SelectItems);// 给第 3，4，5 列设置自定义代理组件ui->tableView->setItemDelegateForColumn(3, &m_floatSpinDelegate);ui->tableView->setItemDelegateForColumn(4, &m_intSpinDelegate);ui->tableView->setItemDelegateForColumn(5, &m_comboBoxDelegate);
}Widget::~Widget() {delete ui;
}// 打开 excel
void Widget::on_btnOpenExcel_clicked() {QAxObject *excel = new QAxObject(this);excel->setControl("Excel.Application");excel->setProperty("Visible", false);  // 显示窗体看效果，选择 ture 将会看到 excel 表格被打开excel->setProperty("DisplayAlerts", true);QAxObject *workbooks = excel->querySubObject("WorkBooks");  // 获取工作簿(excel文件)集合QString str = QFileDialog::getOpenFileName(this, u8"打开excel","D:/MyQtCreatorProject/9_2_tableView",u8"Excel 文件(*.xls *.xlsx)");// 打开刚才选定的 excelworkbooks->dynamicCall("Open(const QString&)", str);QAxObject *workbook = excel->querySubObject("ActiveWorkBook");QAxObject *worksheet = workbook->querySubObject("WorkSheets(int)",1);QAxObject *usedRange = worksheet->querySubObject("UsedRange");   // 获取表格中的数据范围QVariant var = usedRange->dynamicCall("Value");  // 将所有的数据读取到 QVariant 容器中保存QList<QList<QVariant>> excel_list;               // 用于将 QVariant 转换为 Qlist 的二维数组QVariantList varRows = var.toList();if (varRows.isEmpty()) {return;}const int row_count = varRows.size();QVariantList rowData;for (int i = 0; i < row_count; ++i) {rowData = varRows[i].toList();excel_list.push_back(rowData);}// 将每一行的内容放到 contentListQList<QStringList> contentList;for (int i = 0; i < row_count; i++) {QList<QVariant> curList = excel_list.at(i);int curRowCount = curList.size();QStringList oneLineStrlist;for (int j = 0; j < curRowCount; j++) {QString content = curList.at(j).toString();oneLineStrlist << content;}contentList << oneLineStrlist;}workbook->dynamicCall("Close(Boolean)", false);excel->dynamicCall("Quit(void)");delete excel;// 解析 contentList，填充 tableViewint rowCounts = contentList.size();QStandardItem *aItem;// 遍历行for (int i = 0; i < rowCounts; i++) {QStringList tmpList = contentList[i];if(i == 0) {// 设置表头m_pItemModel->setHorizontalHeaderLabels(tmpList);} else {int j;for (j = 0; j < COLUMN_COUNT - 1; j++) {// 不包含最后一列aItem = new QStandardItem(tmpList.at(j));m_pItemModel->setItem(i-1, j, aItem);       // 为模型的某个行列位置设置 Item}// 设置最后一列aItem = new QStandardItem(contentList[0].at(j));  // 获取最后一列的指针aItem->setCheckable(true);  // 设置可以使用 check 控件if (tmpList.at(j) == "0")aItem->setCheckState(Qt::Unchecked);  // 根据数据设置 check 状态elseaItem->setCheckState(Qt::Checked);m_pItemModel->setItem(i-1 , j, aItem);    // 设置最后一列}}
}// 选择单元格变化时的响应
void Widget::OnCurrentChanged(const QModelIndex &current, const QModelIndex &previous) {Q_UNUSED(previous);if (current.isValid()) {  // 当前模型索引有效ui->textEdit->clear();ui->textEdit->append(QString::asprintf(u8"当前单元格：%d行，%d列",current.row(),current.column()));  // 显示模型索引的行和列号QStandardItem *aItem;aItem = m_pItemModel->itemFromIndex(current);           // 从模型索引获得 itemui->textEdit->append(u8"单元格内容：" + aItem->text());  // 显示 item 的文字内容}
}// 在表格最后一行添加
void Widget::on_btnAppendLast_clicked() {QList<QStandardItem*> aItemList;QStandardItem *aItem;for (int i = 0; i < COLUMN_COUNT - 1; i++) {  // 不包含最后 1 列aItem = new QStandardItem(u8"自定义");aItemList << aItem;}// 获取最后一列的表头文字QString str = m_pItemModel->headerData(m_pItemModel->columnCount()-1, Qt::Horizontal, Qt::DisplayRole).toString();aItem = new QStandardItem(str);aItem->setCheckable(true);aItemList<<aItem;   // 添加到容器m_pItemModel->insertRow(m_pItemModel->rowCount(), aItemList);  // 插入一行，需要每个 Cell 的 ItemQModelIndex curIndex = m_pItemModel->index(m_pItemModel->rowCount()-1, 0);  // 创建最后一行的 ModelIndex// 如果之前点击了表格，清空选择项m_pSelectionModel->clearSelection();// 设置刚插入的行为当前选择行m_pSelectionModel->setCurrentIndex(curIndex, QItemSelectionModel::Select);
}void Widget::on_btnAppend_clicked() {QList<QStandardItem*> aItemList;QStandardItem *aItem;for(int i = 0; i < COLUMN_COUNT-1; i++) {aItem = new QStandardItem(u8"自定义");aItemList << aItem;}// 获取表头文字QString str = m_pItemModel->headerData(m_pItemModel->columnCount()-1, Qt::Horizontal, Qt::DisplayRole).toString();aItem = new QStandardItem(str);aItem->setCheckable(true);aItemList<<aItem;QModelIndex curIndex = m_pSelectionModel->currentIndex();  // 获取当前选中项的模型索引m_pItemModel->insertRow(curIndex.row(), aItemList);  // 在当前行的前面插入一行m_pSelectionModel->clearSelection();                // 清除已有选择m_pSelectionModel->setCurrentIndex(curIndex, QItemSelectionModel::Select);
}// 删除选择的行
void Widget::on_btnDeleteSelectedLine_clicked() {QModelIndex curIndex = m_pSelectionModel->currentIndex();  // 获取当前选择单元格的模型索引if (curIndex.row() == m_pItemModel->rowCount() - 1) {  // 如果是最后一行m_pItemModel->removeRow(curIndex.row());           // 删除最后一行} else {m_pItemModel->removeRow(curIndex.row());           // 删除一行，并重新设置当前选择行m_pSelectionModel->setCurrentIndex(curIndex, QItemSelectionModel::Select);}
}// 将 tableView 的数据显示在 textEdit
void Widget::on_btnReshowData_clicked() {ui->textEdit->clear();  // 清空QStandardItem *aItem;QString str;// 获取表头文字int i, j;for (i = 0; i < m_pItemModel->columnCount(); i++) {aItem = m_pItemModel->horizontalHeaderItem(i);  // 获取表头的一个项数据str = str + aItem->text() + "\t";  // 用 tab 间隔文字}ui->textEdit->append(str);  // 添加为文本框的一行//获取数据区的每行for (i = 0; i < m_pItemModel->rowCount(); i++) {str = "";for (j = 0; j<m_pItemModel->columnCount()-1; j++) {aItem = m_pItemModel->item(i,j);str = str + aItem->text() + QString::asprintf("\t");  //以 tab 分隔}aItem = m_pItemModel->item(i, j);  // 最后一行if (aItem->checkState() == Qt::Checked)str = str + "1";elsestr = str + "0";ui->textEdit->append(str);}
}

2.3 整型数 spinbox 代理

2.3.1 cintspindelegate.h

#ifndef CINTSPINDELEGATE_H
#define CINTSPINDELEGATE_H#include <QStyledItemDelegate>class CIntSpinDelegate : public QStyledItemDelegate {Q_OBJECT
public:CIntSpinDelegate(QObject *parent=0);// 自定义代理组件必须继承以下 4 个函数// 创建编辑组件QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option,const QModelIndex &index) const Q_DECL_OVERRIDE;// 从数据模型获取数据，显示到代理组件中void setEditorData(QWidget *editor, const QModelIndex &index) const Q_DECL_OVERRIDE;// 将代理组件的数据，保存到数据模型中void setModelData(QWidget *editor, QAbstractItemModel *model,const QModelIndex &index) const Q_DECL_OVERRIDE;// 更新代理编辑组件的大小void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option,const QModelIndex &index) const Q_DECL_OVERRIDE;
};#endif // CINTSPINDELEGATE_H

2.3.2 cintspindelegate.cpp

#include "cintspindelegate.h"
#include <QSpinBox>CIntSpinDelegate::CIntSpinDelegate(QObject *parent) : QStyledItemDelegate(parent) {}QWidget *CIntSpinDelegate::createEditor(QWidget *parent,const QStyleOptionViewItem &option, const QModelIndex &index) const {// 创建代理编辑组件Q_UNUSED(option);Q_UNUSED(index);QSpinBox *editor = new QSpinBox(parent);  // 创建一个 QSpinBoxeditor->setFrame(false);  // 设置为无边框editor->setMinimum(0);editor->setMaximum(120);return editor;  // 返回此编辑器
}void CIntSpinDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const {// 从数据模型获取数据，显示到代理组件中// 获取数据模型的模型索引指向的单元的数据int value = index.model()->data(index, Qt::EditRole).toInt();QSpinBox *spinBox = static_cast<QSpinBox*>(editor);  // 强制类型转换spinBox->setValue(value);  // 设置编辑器的数值
}void CIntSpinDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const {// 将代理组件的数据，保存到数据模型中QSpinBox *spinBox = static_cast<QSpinBox*>(editor);  // 强制类型转换spinBox->interpretText();      // 解释数据，如果数据被修改后，就触发信号int value = spinBox->value();  // 获取 spinBox 的值model->setData(index, value, Qt::EditRole); //更新到数据模型
}void CIntSpinDelegate::updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const {// 设置组件大小Q_UNUSED(index);editor->setGeometry(option.rect);
}

2.4 浮点数 spinbox 代理

2.4.1 cfloatspindelegate.h

#ifndef CFLOATSPINDELEGATE_H
#define CFLOATSPINDELEGATE_H#include <QObject>
#include <QWidget>
#include <QStyledItemDelegate>class CFloatSpinDelegate : public QStyledItemDelegate {Q_OBJECT
public:CFloatSpinDelegate(QObject *parent=0);// 自定义代理组件必须继承以下4个函数// 创建编辑组件QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option,const QModelIndex &index) const Q_DECL_OVERRIDE;void setEditorData(QWidget *editor, const QModelIndex &index) const Q_DECL_OVERRIDE;void setModelData(QWidget *editor, QAbstractItemModel *model,const QModelIndex &index) const Q_DECL_OVERRIDE;void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option,const QModelIndex &index) const Q_DECL_OVERRIDE;
};#endif // CFLOATSPINDELEGATE_H

2.4.2 cfloatspindelegate.cpp

#include "cfloatspindelegate.h"
#include <QDoubleSpinBox>CFloatSpinDelegate::CFloatSpinDelegate(QObject *parent):QStyledItemDelegate(parent) {}QWidget *CFloatSpinDelegate::createEditor(QWidget *parent,const QStyleOptionViewItem &option, const QModelIndex &index) const {Q_UNUSED(option);Q_UNUSED(index);QDoubleSpinBox *editor = new QDoubleSpinBox(parent);editor->setFrame(false);editor->setMinimum(0);editor->setDecimals(2);editor->setMaximum(100);return editor;
}void CFloatSpinDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const {float value = index.model()->data(index, Qt::EditRole).toFloat();QDoubleSpinBox *spinBox = static_cast<QDoubleSpinBox*>(editor);spinBox->setValue(value);
}void CFloatSpinDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const {QDoubleSpinBox *spinBox = static_cast<QDoubleSpinBox*>(editor);spinBox->interpretText();float value = spinBox->value();QString str = QString::asprintf("%.2f", value);model->setData(index, str, Qt::EditRole);
}void CFloatSpinDelegate::updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const {editor->setGeometry(option.rect);
}

2.5 combobox 代理

2.5.1 ccomboboxdelegate.h

#ifndef CCOMBOBOXDELEGATE_H
#define CCOMBOBOXDELEGATE_H#include <QItemDelegate>class CComboBoxDelegate : public QItemDelegate {Q_OBJECTpublic:CComboBoxDelegate(QObject *parent=0);// 自定义代理组件必须继承以下4个函数QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option,const QModelIndex &index) const Q_DECL_OVERRIDE;void setEditorData(QWidget *editor, const QModelIndex &index) const Q_DECL_OVERRIDE;void setModelData(QWidget *editor, QAbstractItemModel *model,const QModelIndex &index) const Q_DECL_OVERRIDE;void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option,const QModelIndex &index) const Q_DECL_OVERRIDE;
};#endif // CCOMBOBOXDELEGATE_H

2.5.2 ccomboboxdelegate.cpp

#include "ccomboboxdelegate.h"
#include <QComboBox>CComboBoxDelegate::CComboBoxDelegate(QObject *parent) : QItemDelegate(parent) {}QWidget *CComboBoxDelegate::createEditor(QWidget *parent,const QStyleOptionViewItem &option, const QModelIndex &index) const {QComboBox *editor = new QComboBox(parent);editor->addItem(u8"优");editor->addItem(u8"良");editor->addItem(u8"一般");return editor;
}void CComboBoxDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const {QString str = index.model()->data(index, Qt::EditRole).toString();QComboBox *comboBox = static_cast<QComboBox*>(editor);comboBox->setCurrentText(str);
}void CComboBoxDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const {QComboBox *comboBox = static_cast<QComboBox*>(editor);QString str = comboBox->currentText();model->setData(index, str, Qt::EditRole);
}void CComboBoxDelegate::updateEditorGeometry(QWidget *editor,const QStyleOptionViewItem &option, const QModelIndex &index) const {editor->setGeometry(option.rect);
}

3. QListView 应用

3.1 widget.h

#ifndef WIDGET_H
#define WIDGET_H#include <QWidget>
#include <QStringListModel>
#include <QMenu>QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACEclass Widget : public QWidget {Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();private:void initMenu();private slots:void on_btnAddItem_clicked();void on_btnDeleteItem_clicked();void on_btnInsert_clicked();void on_btnClearAllData_clicked();void on_btnReshow_clicked();void on_showRightMenu(const QPoint& pos);void OnActionDelete();// 链接 listview 的 clicked 信号void on_listView_clicked(const QModelIndex &index);private:Ui::Widget *ui;QStringListModel* m_pStringListModel;QMenu *m_pMenu;
};
#endif // WIDGET_H

3.2 widget.cpp

#include "widget.h"
#include "ui_widget.h"
#include <QMenu>Widget::Widget(QWidget *parent) : QWidget(parent), ui(new Ui::Widget) {ui->setupUi(this);this->setWindowTitle(u8"QListView使用教程");QStringList strList;strList << u8"北京" << u8"上海" << u8"深圳" << u8"广东"<< u8"南京" << u8"苏州" << u8"西安";// 创建数据模型m_pStringListModel = new QStringListModel(this);// 为模型设置 StringList，会导入 StringList 的内容m_pStringListModel->setStringList(strList);// 为 listView 设置数据模型ui->listView->setModel(m_pStringListModel);// 设置 listview 编辑属性// 双击与选择//ui->listView->setEditTriggers(QAbstractItemView::DoubleClicked | QAbstractItemView::SelectedClicked);initMenu();// listview 右键菜单ui->listView->setContextMenuPolicy(Qt::CustomContextMenu);connect(ui->listView, &QListView::customContextMenuRequested, this, &Widget::on_showRightMenu);
}Widget::~Widget() {delete ui;
}// 添加 item
void Widget::on_btnAddItem_clicked() {// 在尾部插入一空行, 不添加就把最后一行给替换了m_pStringListModel->insertRow(m_pStringListModel->rowCount());// 获取最后一行QModelIndex index = m_pStringListModel->index(m_pStringListModel->rowCount() - 1, 0);m_pStringListModel->setData(index,"new item", Qt::DisplayRole);  // 设置显示文字// 设置新添加的行选中ui->listView->setCurrentIndex(index);
}// 删除选中的项
void Widget::on_btnDeleteItem_clicked() {// 获取当前选中的 modelIndexQModelIndex index = ui->listView->currentIndex();// 删除当前行m_pStringListModel->removeRow(index.row());
}// 插入一项
void Widget::on_btnInsert_clicked() {// 获取选中 model IndexQModelIndex index=ui->listView->currentIndex();// 在当前行的前面插入一行m_pStringListModel->insertRow(index.row());m_pStringListModel->setData(index, "inserted item", Qt::DisplayRole);ui->listView->setCurrentIndex(index);
}// 回显 listview数据
void Widget::on_btnReshow_clicked() {// 获取数据模型的 StringListQStringList tmpList = m_pStringListModel->stringList();ui->textEdit->clear();  // 文本框清空for (int i = 0; i < tmpList.count(); i++) {// 显示数据模型的 StringList()返回的内容ui->textEdit->append(tmpList.at(i));}
}// 清除所有数据
void Widget::on_btnClearAllData_clicked() {m_pStringListModel->removeRows(0, m_pStringListModel->rowCount());
}void Widget::initMenu() {m_pMenu = new QMenu(ui->listView);QAction *pAc1 = new QAction(u8"删除", ui->listView);QAction *pAc2 = new QAction(u8"插入", ui->listView);QAction *pAc3 = new QAction(u8"置顶", ui->listView);QAction *pAc4 = new QAction(u8"排到最后", ui->listView);m_pMenu->addAction(pAc1);m_pMenu->addAction(pAc2);m_pMenu->addAction(pAc3);m_pMenu->addAction(pAc4);// 注意在 exec 前链接信号槽，因为 exec 会阻塞主线程，// 如果 connect 写在 exec 代码之后，信号槽将无法链接connect(pAc1, &QAction::triggered, this, &Widget::OnActionDelete);
}void Widget::on_showRightMenu(const QPoint& pos) {if (!((ui->listView->selectionModel()->selectedIndexes()).empty())) {m_pMenu->exec(QCursor::pos());  // 在当前鼠标位置显示}
}void Widget::OnActionDelete() {// 获取当前 modelIndexQModelIndex index = ui->listView->currentIndex();// 删除当前行m_pStringListModel->removeRow(index.row());
}void Widget::on_listView_clicked(const QModelIndex &index) {ui->textEdit->clear();  // 文本框清空// 显示 QModelIndex 的行、列号ui->textEdit->append(QString::asprintf(u8"当前项:row=%d, column=%d",index.row(), index.column()));
}