ImageWidget.cpp

/*
 *  Copyright (C) 2018 Shawn Rutledge <s@ecloud.org>
 *  This file is part of Phototonic Image Viewer.
 *
 *  Phototonic 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.
 *
 *  Phototonic 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 Phototonic.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "ImageWidget.h"
#include <QDebug>
#include <QPainter>
#include <QPaintEvent>

ImageWidget::ImageWidget(QWidget *parent) : QWidget(parent)
{
}

bool ImageWidget::empty()
{
    return m_image.isNull();
}

QImage ImageWidget::image()
{
    return m_image;
}

void ImageWidget::setImage(const QImage &i)
{
    m_image = i;
    m_rotation = 0;
    update();
}

void ImageWidget::setRotation(qreal r)
{
    m_rotation = r;
    update();
}

QPoint ImageWidget::mapToImage(QPoint p)
{
    QPoint upperLeft;
    QPoint center(width() / 2, height() / 2);
    if (width() > m_image.width())
        upperLeft.setX(center.x() - m_image.width() / 2);
    if (height() > m_image.height())
        upperLeft.setY(center.y() - m_image.height() / 2);
    return QPoint(p.x() - upperLeft.x(), p.y() - upperLeft.y());
}

QSize ImageWidget::imageSize() const
{
    return m_image.size();
}

QSize ImageWidget::sizeHint() const
{
    return m_image.size();
}

void ImageWidget::paintEvent(QPaintEvent *ev)
{
    float scale = qMax(float(width()) / m_image.width(), float(height()) / m_image.height());

    QPainter painter(this);

    if (qFuzzyIsNull(m_rotation)) {
        const float sx = qMax(-x() / scale, 0.f);
        const float sy = qMax(-y() / scale, 0.f);
        const float sw = qMin<float>(width() / scale, m_image.width());
        const float sh = qMin<float>(height() / scale, m_image.height());

        QRectF sourceRect(sx, sy, sw, sh);
        QRectF targetRect = rect();
        targetRect &= ev->rect();
        sourceRect &= QRectF(ev->rect().x() / scale, ev->rect().y() / scale, ev->rect().width() / scale, ev->rect().height() / scale);

        if (sourceRect.width() * sourceRect.height() < 500 * 500) {
            painter.drawImage(targetRect.topLeft(), m_image.copy(sourceRect.toRect()).scaled(targetRect.toRect().size(), Qt::KeepAspectRatioByExpanding, Qt::SmoothTransformation));

        } else {
            painter.drawImage(targetRect, m_image, sourceRect);
        }

        return;
    }
    painter.scale(scale, scale);
    QPoint center(width() / 2, height() / 2);
    painter.translate(center);
    painter.rotate(m_rotation);
    painter.translate(center * -1);
    QPoint upperLeft;
    if (width() > m_image.width() * scale)
        upperLeft.setX(center.x() - scale*m_image.width() / 2);
    if (height() > m_image.height() * scale)
        upperLeft.setY(center.y() - scale*m_image.height() / 2);
    painter.drawImage(upperLeft, m_image);
}