15.1.114. tablet_qt/diagnosis/flatproxymodel.h

/*
    Copyright (C) 2012, University of Cambridge, Department of Psychiatry.
    Created by Rudolf Cardinal (rnc1001@cam.ac.uk).

    This file is part of CamCOPS.

    CamCOPS is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    CamCOPS is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with CamCOPS. If not, see <https://www.gnu.org/licenses/>.
*/

#pragma once
#include <QAbstractProxyModel>
#include <QMap>

/*

This proxy model makes a flat model out of a tree, so we can use a QListView
for searching.

It also ensures we can't see/pick something marked as unselectable.

This is pretty basic; see

    http://stackoverflow.com/questions/21564976/how-to-create-a-proxy-model-that-would-flatten-nodes-of-a-qabstractitemmodel-int

but for more extensive things, Google also "FlatProxyModel"; there are others,
e.g.
    https://api.kde.org/bundled-apps-api/calligra-apidocs/plan/html/kptflatproxymodel_8h_source.html
    https://api.kde.org/bundled-apps-api/calligra-apidocs/plan/html/kptflatproxymodel_8cpp_source.html

However, also:

    http://www.qtcentre.org/threads/25884-Proxy-model-index-mapping

... you can't reimplement mapFromSource() and mapToSource() for
    QSortFilterProxyModel because it needs its own implementation; instead
    subclass QAbstractProxyModel to do the flattening, and either flatten
    something filtered or (in our case) filter something flattened.
*/

class FlatProxyModel : public QAbstractProxyModel
{
    Q_OBJECT

public:
    using QAbstractProxyModel::QAbstractProxyModel;

    virtual void setSourceModel(QAbstractItemModel* src_model) override;
    virtual QModelIndex mapFromSource(const QModelIndex& src_index
    ) const override;
    virtual QModelIndex mapToSource(const QModelIndex& proxy_index
    ) const override;
    virtual int columnCount(const QModelIndex& proxy_parent) const override;
    virtual int rowCount(const QModelIndex& proxy_parent) const override;
    virtual QModelIndex index(
        int proxy_row, int proxy_column, const QModelIndex& proxy_parent
    ) const override;
    virtual QModelIndex parent(const QModelIndex& proxy_child) const override;
    virtual bool hasChildren(const QModelIndex& proxy_parent) const override;

protected:
    int buildMap(
        QAbstractItemModel* src_model,
        const QModelIndex& src_parent = QModelIndex(),
        int proxy_row = 0
    );
protected slots:
    void sourceDataChanged(
        const QModelIndex& src_top_left,
        const QModelIndex& src_bottom_right,
        const QVector<int>& roles = QVector<int>()
    );

protected:
    QMap<QModelIndex, int> m_row_from_src_index;
    QMap<int, QModelIndex> m_src_index_from_row;
};