(四)Qt實作自定義模型基于QAbstractTableModel

目錄：

(一) Qt Model/View 的簡單說明 、預定義模型

(二)使用預定義模型 QstringListModel例子

(三)使用預定義模型QDirModel的例子

(四)Qt實作自定義模型基于QAbstractTableModel

(五)Qt實作自定義模型基于QAbstractItemModel 

(六) Qt實作自定義委托 QDelegate

Qt實作自定義模型基于QAbstractTableModel

兩個例子

例子1代碼

Main.cpp

#include <QtGui>

#include "currencymodel.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    //資料源
    QMap<QString, double> currencyMap;
    currencyMap.insert("AUD", 1.3259);
    currencyMap.insert("CHF", 1.2970);
    currencyMap.insert("CZK", 24.510);
    currencyMap.insert("DKK", 6.2168);
    currencyMap.insert("EUR", 0.8333);
    currencyMap.insert("GBP", 0.5661);
    currencyMap.insert("HKD", 7.7562);
    currencyMap.insert("JPY", 112.92);
    currencyMap.insert("NOK", 6.5200);
    currencyMap.insert("NZD", 1.4697);
    currencyMap.insert("SEK", 7.8180);
    currencyMap.insert("SGD", 1.6901);
    currencyMap.insert("USD", 1.0000);

    //自定義表模型
    CurrencyModel currencyModel;
    currencyModel.setCurrencyMap(currencyMap);
    //表視圖
    QTableView tableView;
    //設定視圖模型
    tableView.setModel(&currencyModel);
    //設定交替顔色
    tableView.setAlternatingRowColors(true);

    tableView.setWindowTitle(QObject::tr("Currencies"));
    tableView.show();

    return app.exec();
}
           

currencymodel.h

#ifndef CURRENCYMODEL_H
#define CURRENCYMODEL_H

#include <QAbstractTableModel>
#include <QMap>

class CurrencyModel : public QAbstractTableModel
{
public:
    CurrencyModel(QObject *parent = 0);

    void setCurrencyMap(const QMap<QString, double> &map);
    int rowCount(const QModelIndex &parent) const;
    int columnCount(const QModelIndex &parent) const;
    QVariant data(const QModelIndex &index, int role) const;
    QVariant headerData(int section, Qt::Orientation orientation,
                        int role) const;

private:
    QString currencyAt(int offset) const;

    QMap<QString, double> currencyMap;
};

#endif
           

currencymodel.cpp

#include <QtCore>

#include "currencymodel.h"

CurrencyModel::CurrencyModel(QObject *parent)
    : QAbstractTableModel(parent)
{
}

void CurrencyModel::setCurrencyMap(const QMap<QString, double> &map)
{
    currencyMap = map;
    //重置模型至原始狀态，告訴所有視圖，他們資料都無效，強制重新整理資料
    reset();
}

//傳回行數
int CurrencyModel::rowCount(const QModelIndex & /* parent */) const
{
    return currencyMap.count();
}
//傳回列數
int CurrencyModel::columnCount(const QModelIndex & /* parent */) const
{
    return currencyMap.count();
}

//傳回一個項的任意角色的值，這個項被指定為QModelIndex
QVariant CurrencyModel::data(const QModelIndex &index, int role) const
{
    if (!index.isValid())
        return QVariant();

    if (role == Qt::TextAlignmentRole) {
        return int(Qt::AlignRight | Qt::AlignVCenter);
    } else if (role == Qt::DisplayRole) {
        QString rowCurrency = currencyAt(index.row());
        QString columnCurrency = currencyAt(index.column());

        if (currencyMap.value(rowCurrency) == 0.0)
            return "####";

        double amount = currencyMap.value(columnCurrency)
                        / currencyMap.value(rowCurrency);

        return QString("%1").arg(amount, 0, 'f', 4);
    }
    return QVariant();
}
//傳回表頭名稱,(行号或列号，水準或垂直，角色)
QVariant CurrencyModel::headerData(int section,
                                   Qt::Orientation /* orientation */,
                                   int role) const
{
    if (role != Qt::DisplayRole)
        return QVariant();
    return currencyAt(section);
}
//擷取目前關鍵字
QString CurrencyModel::currencyAt(int offset) const
{
    return (currencyMap.begin() + offset).key();
}
           

例子2代碼

Main.cpp

#include <QApplication>
#include <QHeaderView>
#include <QTableView>

#include "citymodel.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    //儲存城市名
    QStringList cities;
    cities << "Arvika" << "Boden" << "Eskilstuna" << "Falun"
           << "Filipstad" << "Halmstad" << "Helsingborg" << "Karlstad"
           << "Kiruna" << "Kramfors" << "Motala" << "Sandviken"
           << "Skara" << "Stockholm" << "Sundsvall" << "Trelleborg";
    //模型
    CityModel cityModel;
    //
    cityModel.setCities(cities);

    QTableView tableView;
    tableView.setModel(&cityModel);
    tableView.setAlternatingRowColors(true);
    tableView.setWindowTitle(QObject::tr("Cities"));
    tableView.show();

    return app.exec();
}
           

citymodel.h

#ifndef CITYMODEL_H
#define CITYMODEL_H

#include <QAbstractTableModel>
#include <QStringList>
#include <QVector>

class CityModel : public QAbstractTableModel
{
    Q_OBJECT

public:
    CityModel(QObject *parent = 0);

    void setCities(const QStringList &cityNames);
    int rowCount(const QModelIndex &parent) const;
    int columnCount(const QModelIndex &parent) const;
    QVariant data(const QModelIndex &index, int role) const;
    bool setData(const QModelIndex &index, const QVariant &value,
                 int role);
    QVariant headerData(int section, Qt::Orientation orientation,
                        int role) const;
    Qt::ItemFlags flags(const QModelIndex &index) const;

private:
    int offsetOf(int row, int column) const;

    QStringList cities;
    QVector<int> distances;
};

#endif
           

citymodel.cpp

#include <QtCore>

#include "citymodel.h"

CityModel::CityModel(QObject *parent)
    : QAbstractTableModel(parent)
{
}
//設定一下資料源
void CityModel::setCities(const QStringList &cityNames)
{
    cities = cityNames;
    //重新設定一下QVector distances的矩陣大小的，中間對角線為0不用存
    distances.resize(cities.count() * (cities.count() - 1) / 2);
    //填充所有距離值為0
    distances.fill(0);
    //重新整理所有視圖資料
    reset();
}
//模型行數
int CityModel::rowCount(const QModelIndex & /* parent */) const
{
    return cities.count();
}
//模型列數
int CityModel::columnCount(const QModelIndex & /* parent */) const
{
    return cities.count();
}
//指派模型每個項的資料
QVariant CityModel::data(const QModelIndex &index, int role) const
{
    if (!index.isValid())
        return QVariant();

    if (role == Qt::TextAlignmentRole) {
        return int(Qt::AlignRight | Qt::AlignVCenter);
    } else if (role == Qt::DisplayRole) {
        if (index.row() == index.column())
            return 0;
        int offset = offsetOf(index.row(), index.column());
        return distances[offset];
    }
    return QVariant();
}
//編輯一個項
bool CityModel::setData(const QModelIndex &index,
                        const QVariant &value, int role)
{
    if (index.isValid() && index.row() != index.column()
            && role == Qt::EditRole) {
        int offset = offsetOf(index.row(), index.column());
        distances[offset] = value.toInt();
        //交換對應項的模型索引
        QModelIndex transposedIndex = createIndex(index.column(),
                                                  index.row());
        //某項發生改變，發射信号( between topLeft and bottomRight inclusive)
        emit dataChanged(index, index);
        emit dataChanged(transposedIndex, transposedIndex);
        return true;
    }
    return false;
}

//傳回清單頭
QVariant CityModel::headerData(int section,
                               Qt::Orientation /* orientation */,
                               int role) const
{
    //傳回在Cities字元串清單中給定偏移量的城市名稱
    if (role == Qt::DisplayRole)
        return cities[section];
    return QVariant();
}
//傳回對一個項相關的操作的辨別符（例如，是否可以編輯或者是否已選中等）
Qt::ItemFlags CityModel::flags(const QModelIndex &index) const
{
    Qt::ItemFlags flags = QAbstractItemModel::flags(index);
    if (index.row() != index.column())
        flags |= Qt::ItemIsEditable;
    return flags;
}
//計算偏移量
int CityModel::offsetOf(int row, int column) const
{
    if (row < column)
        qSwap(row, column);
    return (row * (row - 1) / 2) + column;
}