MultiMC5/launcher/ui/widgets/VersionListView.cpp

/* Copyright 2013-2021 MultiMC Contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <QHeaderView>
#include <QApplication>
#include <QMouseEvent>
#include <QDrag>
#include <QPainter>
#include "VersionListView.h"

VersionListView::VersionListView(QWidget *parent)
    :QTreeView ( parent )
{
    m_emptyString = tr("No versions are currently available.");
}

void VersionListView::rowsInserted(const QModelIndex &parent, int start, int end)
{
    m_itemCount += end-start+1;
    updateEmptyViewPort();
    QTreeView::rowsInserted(parent, start, end);
}


void VersionListView::rowsAboutToBeRemoved(const QModelIndex &parent, int start, int end)
{
    m_itemCount -= end-start+1;
    updateEmptyViewPort();
    QTreeView::rowsInserted(parent, start, end);
}

void VersionListView::setModel(QAbstractItemModel *model)
{
    m_itemCount = model->rowCount();
    updateEmptyViewPort();
    QTreeView::setModel(model);
}

void VersionListView::reset()
{
    if(model())
    {
        m_itemCount = model()->rowCount();
    }
    else {
        m_itemCount = 0;
    }
    updateEmptyViewPort();
    QTreeView::reset();
}

void VersionListView::setEmptyString(QString emptyString)
{
    m_emptyString = emptyString;
    updateEmptyViewPort();
}

void VersionListView::setEmptyErrorString(QString emptyErrorString)
{
    m_emptyErrorString = emptyErrorString;
    updateEmptyViewPort();
}

void VersionListView::setEmptyMode(VersionListView::EmptyMode mode)
{
    m_emptyMode = mode;
    updateEmptyViewPort();
}

void VersionListView::updateEmptyViewPort()
{
#ifndef QT_NO_ACCESSIBILITY
    setAccessibleDescription(currentEmptyString());
#endif /* !QT_NO_ACCESSIBILITY */

    if(!m_itemCount)
    {
        viewport()->update();
    }
}

void VersionListView::paintEvent(QPaintEvent *event)
{
    if(m_itemCount)
    {
        QTreeView::paintEvent(event);
    }
    else
    {
        paintInfoLabel(event);
    }
}

QString VersionListView::currentEmptyString() const
{
    if(m_itemCount) {
        return QString();
    }
    switch(m_emptyMode)
    {
        default:
        case VersionListView::Empty:
            return QString();
        case VersionListView::String:
            return m_emptyString;
        case VersionListView::ErrorString:
            return m_emptyErrorString;
    }
}


void VersionListView::paintInfoLabel(QPaintEvent *event) const
{
    QString emptyString = currentEmptyString();

    //calculate the rect for the overlay
    QPainter painter(viewport());
    painter.setRenderHint(QPainter::Antialiasing, true);
    QFont font("sans", 20);
    font.setBold(true);

    QRect bounds = viewport()->geometry();
    bounds.moveTop(0);
    auto innerBounds = bounds;
    innerBounds.adjust(10, 10, -10, -10);

    QColor background = QApplication::palette().color(QPalette::Foreground);
    QColor foreground = QApplication::palette().color(QPalette::Base);
    foreground.setAlpha(190);
    painter.setFont(font);
    auto fontMetrics = painter.fontMetrics();
    auto textRect = fontMetrics.boundingRect(innerBounds, Qt::AlignHCenter | Qt::TextWordWrap, emptyString);
    textRect.moveCenter(bounds.center());

    auto wrapRect = textRect;
    wrapRect.adjust(-10, -10, 10, 10);

    //check if we are allowed to draw in our area
    if (!event->rect().intersects(wrapRect)) {
        return;
    }

    painter.setBrush(QBrush(background));
    painter.setPen(foreground);
    painter.drawRoundedRect(wrapRect, 5.0, 5.0);

    painter.setPen(foreground);
    painter.setFont(font);
    painter.drawText(textRect, Qt::AlignHCenter | Qt::TextWordWrap, emptyString);
}