qt-creator/src/plugins/imageviewer/imageview.cpp

/****************************************************************************
**
** Copyright (C) 2016 Denis Mingulov.
** Copyright (C) 2016 The Qt Company Ltd.
** Copyright (C) 2016 Denis Mingulov.
** Copyright (C) 2016 The Qt Company Ltd.
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#include "imageview.h"

#include "imageviewerfile.h"

#include <QWheelEvent>
#include <QMouseEvent>
#include <QGraphicsRectItem>
#include <QPixmap>
#include <qmath.h>

namespace ImageViewer {
namespace Constants {
    const qreal DEFAULT_SCALE_FACTOR = 1.2;
}

namespace Internal {

ImageView::ImageView(ImageViewerFile *file)
    : m_file(file)
{
    setScene(new QGraphicsScene(this));
    setTransformationAnchor(AnchorUnderMouse);
    setDragMode(ScrollHandDrag);
    setViewportUpdateMode(FullViewportUpdate);
    setFrameShape(QFrame::NoFrame);
    setRenderHint(QPainter::SmoothPixmapTransform);

    // Prepare background check-board pattern
    QPixmap tilePixmap(64, 64);
    tilePixmap.fill(Qt::white);
    QPainter tilePainter(&tilePixmap);
    QColor color(220, 220, 220);
    tilePainter.fillRect(0, 0, 0x20, 0x20, color);
    tilePainter.fillRect(0x20, 0x20, 0x20, 0x20, color);
    tilePainter.end();

    setBackgroundBrush(tilePixmap);
}

ImageView::~ImageView()
{
}

void ImageView::reset()
{
    scene()->clear();
    resetTransform();
}

void ImageView::createScene()
{
    m_imageItem = m_file->createGraphicsItem();
    if (!m_imageItem) // failed to load
        return;
    m_imageItem->setCacheMode(QGraphicsItem::NoCache);
    m_imageItem->setZValue(0);

    // background item
    m_backgroundItem = new QGraphicsRectItem(m_imageItem->boundingRect());
    m_backgroundItem->setBrush(Qt::white);
    m_backgroundItem->setPen(Qt::NoPen);
    m_backgroundItem->setVisible(m_showBackground);
    m_backgroundItem->setZValue(-1);

    // outline
    m_outlineItem = new QGraphicsRectItem(m_imageItem->boundingRect());
    QPen outline(Qt::black, 1, Qt::DashLine);
    outline.setCosmetic(true);
    m_outlineItem->setPen(outline);
    m_outlineItem->setBrush(Qt::NoBrush);
    m_outlineItem->setVisible(m_showOutline);
    m_outlineItem->setZValue(1);

    QGraphicsScene *s = scene();
    s->addItem(m_backgroundItem);
    s->addItem(m_imageItem);
    s->addItem(m_outlineItem);

    emitScaleFactor();
}

void ImageView::drawBackground(QPainter *p, const QRectF &)
{
    p->save();
    p->resetTransform();
    p->drawTiledPixmap(viewport()->rect(), backgroundBrush().texture());
    p->restore();
}

void ImageView::setViewBackground(bool enable)
{
    m_showBackground = enable;
    if (m_backgroundItem)
        m_backgroundItem->setVisible(enable);
}

void ImageView::setViewOutline(bool enable)
{
    m_showOutline = enable;
    if (m_outlineItem)
        m_outlineItem->setVisible(enable);
}

void ImageView::doScale(qreal factor)
{
    qreal currentScale = transform().m11();
    qreal newScale = currentScale * factor;
    qreal actualFactor = factor;
    // cap to 0.001 - 1000
    if (newScale > 1000)
        actualFactor = 1000./currentScale;
    else if (newScale < 0.001)
        actualFactor = 0.001/currentScale;

    scale(actualFactor, actualFactor);
    emitScaleFactor();
    if (QGraphicsPixmapItem *pixmapItem = dynamic_cast<QGraphicsPixmapItem *>(m_imageItem))
        pixmapItem->setTransformationMode(
                    transform().m11() < 1 ? Qt::SmoothTransformation : Qt::FastTransformation);
}

void ImageView::wheelEvent(QWheelEvent *event)
{
    qreal factor = qPow(Constants::DEFAULT_SCALE_FACTOR, event->delta() / 240.0);
    doScale(factor);
    event->accept();
}

void ImageView::zoomIn()
{
    doScale(Constants::DEFAULT_SCALE_FACTOR);
}

void ImageView::zoomOut()
{
    doScale(1. / Constants::DEFAULT_SCALE_FACTOR);
}

void ImageView::resetToOriginalSize()
{
    resetTransform();
    emitScaleFactor();
}

void ImageView::fitToScreen()
{
    fitInView(m_imageItem, Qt::KeepAspectRatio);
    emitScaleFactor();
}

void ImageView::emitScaleFactor()
{
    // get scale factor directly from the transform matrix
    qreal factor = transform().m11();
    emit scaleFactorChanged(factor);
}

void ImageView::showEvent(QShowEvent *)
{
    m_file->updateVisibility();
}

void ImageView::hideEvent(QHideEvent *)
{
    m_file->updateVisibility();
}

} // namespace Internal
} // namespace ImageView