Qt实现svg图片在label上显示（图片可放大缩小）

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These rights are described in The Qt Company LGPL Exception ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. ** ** $QT_END_LICENSE$ ** ****************************************************************************/ #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); connect(m_quitButton, SIGNAL(pressed()), QApplication::instance(), SLOT(quit())); if (m_renderer->animated()) connect(m_renderer, SIGNAL(repaintNeeded()), this, SLOT(update())); 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(); }