qt-everywhere-src-5.15.1/qtsvg/examples/svg/embeddedsvgviewer/embeddedsvgviewer.cpp

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#include <QPainter>
#include <QApplication>

#include "embeddedsvgviewer.h"



EmbeddedSvgViewer::EmbeddedSvgViewer(const QString &filePath)
{
    qApp->setStyleSheet(" QSlider:vertical { width: 50px; } \
                          QSlider::groove:vertical { border: 1px solid black; border-radius: 3px; width: 6px; } \
                          QSlider::handle:vertical { height: 25px; margin: 0 -22px; image: url(':/files/v-slider-handle.svg'); } \
                       ");

    m_renderer = new QSvgRenderer(filePath);
    m_imageSize = m_renderer->viewBox().size();

    m_viewBoxCenter = (QPointF(m_imageSize.width() / qreal(2.0), m_imageSize.height() / qreal(2.0)));

    m_zoomSlider = new QSlider(Qt::Vertical, this);
    m_zoomSlider->setMaximum(150);
    m_zoomSlider->setMinimum(1);

    connect(m_zoomSlider, SIGNAL(valueChanged(int)), this, SLOT(setZoom(int)));
    m_zoomSlider->setValue(100);

    m_quitButton = new QPushButton("Quit", this);

    connect(m_quitButton, SIGNAL(pressed()), QApplication::instance(), SLOT(quit()));

    if (m_renderer->animated())
        connect(m_renderer, SIGNAL(repaintNeeded()), this, SLOT(update()));

}

void EmbeddedSvgViewer::paintEvent(QPaintEvent *event)
{
    Q_UNUSED(event)
    QPainter painter(this);
    m_renderer->setViewBox(m_viewBox);
    m_renderer->render(&painter);
}


void EmbeddedSvgViewer::mouseMoveEvent ( QMouseEvent * event )
{
    int incX = int((event->globalX() - m_mousePress.x()) * m_imageScale);
    int incY = int((event->globalY() - m_mousePress.y()) * m_imageScale);

    QPointF newCenter;
    newCenter.setX(m_viewBoxCenterOnMousePress.x() - incX);
    newCenter.setY(m_viewBoxCenterOnMousePress.y() - incY);
  
    QRectF newViewBox = getViewBox(newCenter);


    // Do a bounded move on the horizontal:
    if ( (newViewBox.left() >= m_viewBoxBounds.left()) &&
         (newViewBox.right() <= m_viewBoxBounds.right()) ) 
    {
        m_viewBoxCenter.setX(newCenter.x());
        m_viewBox.setLeft(newViewBox.left());
        m_viewBox.setRight(newViewBox.right());
    }

    // do a bounded move on the vertical:
    if (  (newViewBox.top() >= m_viewBoxBounds.top()) &&
          (newViewBox.bottom() <= m_viewBoxBounds.bottom()) )
    {
        m_viewBoxCenter.setY(newCenter.y());
        m_viewBox.setTop(newViewBox.top());
        m_viewBox.setBottom(newViewBox.bottom());
    }

    update();
}

void EmbeddedSvgViewer::mousePressEvent ( QMouseEvent * event )
{
    m_viewBoxCenterOnMousePress = m_viewBoxCenter;
    m_mousePress = event->globalPos();
}


QRectF EmbeddedSvgViewer::getViewBox(QPointF viewBoxCenter)
{
    QRectF result;
    result.setLeft(viewBoxCenter.x() - (m_viewBoxSize.width() / 2));
    result.setTop(viewBoxCenter.y() - (m_viewBoxSize.height() / 2));
    result.setRight(viewBoxCenter.x() + (m_viewBoxSize.width() / 2));
    result.setBottom(viewBoxCenter.y() + (m_viewBoxSize.height() / 2));
    return result;
}

void EmbeddedSvgViewer::updateImageScale()
{
    m_imageScale = qMax( (qreal)m_imageSize.width() / (qreal)width(), 
                               (qreal)m_imageSize.height() / (qreal)height())*m_zoomLevel;

    m_viewBoxSize.setWidth((qreal)width() * m_imageScale);
    m_viewBoxSize.setHeight((qreal)height() * m_imageScale);
}


void EmbeddedSvgViewer::resizeEvent ( QResizeEvent * /* event */ )
{
    qreal origZoom = m_zoomLevel;

    // Get the new bounds:
    m_zoomLevel = 1.0;
    updateImageScale();
    m_viewBoxBounds = getViewBox(QPointF(m_imageSize.width() / 2.0, m_imageSize.height() / 2.0));

    m_zoomLevel = origZoom;
    updateImageScale();
    m_viewBox = getViewBox(m_viewBoxCenter);

    QRect sliderRect;
    sliderRect.setLeft(width() - m_zoomSlider->sizeHint().width());
    sliderRect.setRight(width());
    sliderRect.setTop(height()/4);
    sliderRect.setBottom(height() - (height()/4));
    m_zoomSlider->setGeometry(sliderRect);
}


void EmbeddedSvgViewer::setZoom(int newZoom)
{
    m_zoomLevel = qreal(newZoom) / qreal(100);
    
    updateImageScale();
    m_viewBox = getViewBox(m_viewBoxCenter);

    update();
}