multicombobox.cpp

//------------------------------------------------------------------------------
// multicombobox.cpp
//------------------------------------------------------------------------------
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
// 02110-1301  USA
//
//------------------------------------------------------------------------------
// Copyright (C) 2013 "Zalewa" <zalewapl@gmail.com>
//------------------------------------------------------------------------------
#include "multicombobox.h"
#include <QAbstractItemView>
#include <QApplication>
#include <QCheckBox>
#include <QItemDelegate>
#include <QStylePainter>

// internal private editor
class MultiComboBoxEditor : public QCheckBox
{
public:
        MultiComboBoxEditor(QWidget *parent)
                : QCheckBox(parent) {}

protected:
        bool hitButton(const QPoint &pos) const override
        {
                // Omit QCheckBox::hitButton() check as it returns true only if
                // user actually clicked on the checkbox or on its title. In this
                // case, we want to detect hits on entire widget, which spans
                // as a whitespace area covering entire row in combobox' list.
                return QAbstractButton::hitButton(pos);
        }
};


// internal private delegate
class MultiComboBoxDelegate : public QItemDelegate
{
public:

        MultiComboBoxDelegate(QObject *parent)
                : QItemDelegate(parent) {}

        void paint(QPainter *painter, const QStyleOptionViewItem &option,
                const QModelIndex &index) const override
        {
                //Get item data
                bool value = index.data(Qt::UserRole).toBool();
                QString text = index.data(Qt::DisplayRole).toString();

                // fill style options with item data
                const QStyle *style = QApplication::style();
                QStyleOptionButton opt;
                opt.state |= value ? QStyle::State_On : QStyle::State_Off;
                opt.state |= QStyle::State_Enabled;
                opt.text = text;
                opt.rect = option.rect;

                // draw item data as CheckBox
                style->drawControl(QStyle::CE_CheckBox, &opt, painter);
        }

        QWidget *createEditor(QWidget *parent,
                const QStyleOptionViewItem &option,
                const QModelIndex &index ) const override
        {
                Q_UNUSED(option)
                Q_UNUSED(index)
                return new MultiComboBoxEditor(parent);
        }

        void setEditorData(QWidget *editor, const QModelIndex &index) const override
        {
                auto myEditor = static_cast<QCheckBox *>(editor);
                myEditor->setText(index.data(Qt::DisplayRole).toString());
                myEditor->setChecked(index.data(Qt::UserRole).toBool());
        }

        void setModelData(QWidget *editor, QAbstractItemModel *model,
                const QModelIndex &index) const override
        {
                //get the value from the editor (CheckBox)
                auto myEditor = static_cast<QCheckBox *>(editor);
                bool value = myEditor->isChecked();


                //set model data
                QMap<int, QVariant> data;
                data.insert(Qt::DisplayRole, myEditor->text());
                data.insert(Qt::UserRole, value);
                model->setItemData(index, data);
        }

        void updateEditorGeometry(QWidget *editor,
                const QStyleOptionViewItem &option, const QModelIndex &index ) const override
        {
                Q_UNUSED(index);
                editor->setGeometry(option.rect);
        }
};


//min-width:10em;
MultiComboBox::MultiComboBox(QWidget *widget )
        : QComboBox(widget)
{
        view()->setItemDelegate(new MultiComboBoxDelegate(this));
        // Enable editing on items view
        view()->setEditTriggers(QAbstractItemView::CurrentChanged);
        view()->viewport()->installEventFilter(this);
        view()->setAlternatingRowColors(true);
}


MultiComboBox::~MultiComboBox()
{
}

QString MultiComboBox::displayText() const
{
        return selectedItemTexts().join(", ");
}

bool MultiComboBox::eventFilter(QObject *object, QEvent *event)
{
        if (object == view()->viewport())
        {
                if (handleViewViewportEvent(event))
                        return true;
        }
        return QComboBox::eventFilter(object, event);
}

bool MultiComboBox::handleViewViewportEvent(QEvent *event)
{
        switch (event->type())
        {
        default:
                break;

        case QEvent::Hide:
                // TODO: Have this react only if value actually changed.
                emit valueChanged();
                break;

        case QEvent::Show:
                if (count() >= 1)
                {
                        // Without this, the first object on the list will be
                        // impossible to edit unless other object is hovered
                        // over first, or in case if there's only one object
                        // on the list, the list won't be editable at all.
                        view()->edit(model()->index(0, 0));
                }
                break;

        case QEvent::MouseButtonRelease:
                // Don't close items view after we release the mouse button
                // by simple eating MouseButtonRelease in viewport of items
                // view.
                return true;
        }
        return false;
}

void MultiComboBox::paintEvent(QPaintEvent *)
{
        QStylePainter painter(this);
        painter.setPen(palette().color(QPalette::Text));

        // draw the combobox frame, focusrect and selected etc.
        QStyleOptionComboBox opt;
        initStyleOption(&opt);

        // draw the icon and text
        opt.currentText = displayText();
        painter.drawComplexControl(QStyle::CC_ComboBox, opt);
        painter.drawControl(QStyle::CE_ComboBoxLabel, opt);
}

QStringList MultiComboBox::selectedItemTexts() const
{
        QStringList result;
        for (int i = 0; i < count(); ++i)
        {
                bool checked = itemData(i).toBool();
                if (checked)
                        result << itemText(i);
        }
        return result;
}

void MultiComboBox::setSelectedTexts(const QStringList &texts)
{
        for (int i = 0; i < count(); ++i)
                setItemData(i, static_cast<bool>(texts.contains(itemText(i))));
        // Prompt widget repaint or the display text may not change.
        update();
}