QT-自定义 模型/视图（Tree） 结构代码分析

问题描述

         本文通过代码示例，加深对模型视图结构的理解，具体如下

解决方案

         模型视图最简单的理解：（源数据）通过（模型）存储，通过（代理）在（视图）中显示，用户通过在视图中操作，反向逐一修改数据。（本例中不涉及代理信息）

         首先附上一张代码框架图示

根据上图，可以大致了解本案例的框架，及核心数据的存储方式，采用的数据结构等，便于理解代码，同时也反应了模型视图结构的信息在图中。

代码如下

main.cpp

#include "mainwindow.h"
#include 

int main(int argc, char *argv[])
{
    Q_INIT_RESOURCE(editabletreemodel);

    QApplication app(argc, argv);
    MainWindow window;
    window.show();
    return app.exec();
}

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include "ui_mainwindow.h"

#include 

class MainWindow : public QMainWindow, private Ui::MainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);

public slots:
    void updateActions();

private slots:
    void insertChild();
    bool insertColumn();
    void insertRow();
    bool removeColumn();
    void removeRow();
};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "treemodel.h"

#include 

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    setupUi(this);

    const QStringList headers({tr("Title"), tr("Description")});

    QFile file(":/default.txt");
    file.open(QIODevice::ReadOnly);
    TreeModel *model = new TreeModel(headers, file.readAll());
    file.close();

    view->setModel(model);
    for (int column = 0; column < model->columnCount(); ++column)
        view->resizeColumnToContents(column);

    connect(exitAction, &QAction::triggered, qApp, &QCoreApplication::quit);

    connect(view->selectionModel(), &QItemSelectionModel::selectionChanged,
            this, &MainWindow::updateActions);

    connect(actionsMenu, &QMenu::aboutToShow, this, &MainWindow::updateActions);
    connect(insertRowAction, &QAction::triggered, this, &MainWindow::insertRow);
    connect(insertColumnAction, &QAction::triggered, this, &MainWindow::insertColumn);
    connect(removeRowAction, &QAction::triggered, this, &MainWindow::removeRow);
    connect(removeColumnAction, &QAction::triggered, this, &MainWindow::removeColumn);
    connect(insertChildAction, &QAction::triggered, this, &MainWindow::insertChild);

    updateActions();
}

void MainWindow::insertChild()
{
    const QModelIndex index = view->selectionModel()->currentIndex();
    QAbstractItemModel *model = view->model();

    if (model->columnCount(index) == 0) {
        if (!model->insertColumn(0, index))
            return;
    }

    if (!model->insertRow(0, index))
        return;

    for (int column = 0; column < model->columnCount(index); ++column) {
        const QModelIndex child = model->index(0, column, index);
        model->setData(child, QVariant(tr("[No data]")), Qt::EditRole);
        if (!model->headerData(column, Qt::Horizontal).isValid())
            model->setHeaderData(column, Qt::Horizontal, QVariant(tr("[No header]")), Qt::EditRole);
    }

    view->selectionModel()->setCurrentIndex(model->index(0, 0, index),
                                            QItemSelectionModel::ClearAndSelect);
    updateActions();
}

bool MainWindow::insertColumn()
{
    QAbstractItemModel *model = view->model();
    int column = view->selectionModel()->currentIndex().column();

    // Insert a column in the parent item.
    bool changed = model->insertColumn(column + 1);
    if (changed)
        model->setHeaderData(column + 1, Qt::Horizontal, QVariant("[No header]"), Qt::EditRole);

    updateActions();

    return changed;
}

void MainWindow::insertRow()
{
    const QModelIndex index = view->selectionModel()->currentIndex();
    QAbstractItemModel *model = view->model();

    if (!model->insertRow(index.row()+1, index.parent()))
        return;

    updateActions();

    for (int column = 0; column < model->columnCount(index.parent()); ++column) {
        const QModelIndex child = model->index(index.row() + 1, column, index.parent());
        model->setData(child, QVariant(tr("[No data]")), Qt::EditRole);
    }
}

bool MainWindow::removeColumn()
{
    QAbstractItemModel *model = view->model();
    const int column = view->selectionModel()->currentIndex().column();

    // Insert columns in each child of the parent item.
    const bool changed = model->removeColumn(column);
    if (changed)
        updateActions();

    return changed;
}

void MainWindow::removeRow()
{
    const QModelIndex index = view->selectionModel()->currentIndex();
    QAbstractItemModel *model = view->model();
    if (model->removeRow(index.row(), index.parent()))
        updateActions();
}

void MainWindow::updateActions()
{
    const bool hasSelection = !view->selectionModel()->selection().isEmpty();
    removeRowAction->setEnabled(hasSelection);
    removeColumnAction->setEnabled(hasSelection);

    const bo