qpdfview.cpp

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// Copyright (C) 2017 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Tobias König <tobias.koenig@kdab.com>
// Copyright (C) 2022 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qpdfview.h"
#include "qpdfview_p.h"
 
#include "qpdfpagerenderer.h"
 
#include <QGuiApplication>
#include <QLoggingCategory>
#include <QPainter>
#include <QPaintEvent>
#include <QPdfDocument>
#include <QPdfPageNavigator>
#include <QPdfSearchModel>
#include <QScreen>
#include <QScrollBar>
 
QT_BEGIN_NAMESPACE
 
Q_LOGGING_CATEGORY(qLcWLink, "qt.pdf.widgets.links")
//#define DEBUG_LINKS
 
static const QColor SearchResultHighlight("#80B0C4DE");
static const QColor CurrentSearchResultHighlight(Qt::cyan);
static const int CurrentSearchResultWidth(2);
 
QPdfViewPrivate::QPdfViewPrivate(QPdfView *q)
    : q_ptr(q)
    , m_document(nullptr)
    , m_pageNavigator(nullptr)
    , m_pageRenderer(nullptr)
    , m_pageMode(QPdfView::PageMode::SinglePage)
    , m_zoomMode(QPdfView::ZoomMode::Custom)
    , m_zoomFactor(1.0)
    , m_pageSpacing(3)
    , m_documentMargins(6, 6, 6, 6)
    , m_blockPageScrolling(false)
    , m_pageCacheLimit(20)
    , m_screenResolution(QGuiApplication::primaryScreen()->logicalDotsPerInch() / 72.0)
{
}
 
void QPdfViewPrivate::init()
{
    Q_Q(QPdfView);
 
    m_pageNavigator = new QPdfPageNavigator(q);
    m_pageRenderer = new QPdfPageRenderer(q);
    m_pageRenderer->setRenderMode(QPdfPageRenderer::RenderMode::MultiThreaded);
}
 
void QPdfViewPrivate::documentStatusChanged()
{
    updateDocumentLayout();
    invalidatePageCache();
}
 
void QPdfViewPrivate::currentPageChanged(int currentPage)
{
    Q_Q(QPdfView);
 
    if (m_blockPageScrolling)
        return;
 
    q->verticalScrollBar()->setValue(yPositionForPage(currentPage));
 
    if (m_pageMode == QPdfView::PageMode::SinglePage)
        invalidateDocumentLayout();
}
 
void QPdfViewPrivate::calculateViewport()
{
    Q_Q(QPdfView);
 
    const int x = q->horizontalScrollBar()->value();
    const int y = q->verticalScrollBar()->value();
    const int width = q->viewport()->width();
    const int height = q->viewport()->height();
 
    setViewport(QRect(x, y, width, height));
}
 
void QPdfViewPrivate::setViewport(QRect viewport)
{
    if (m_viewport == viewport)
        return;
 
    const QSize oldSize = m_viewport.size();
 
    m_viewport = viewport;
 
    if (oldSize != m_viewport.size()) {
        updateDocumentLayout();
 
        if (m_zoomMode != QPdfView::ZoomMode::Custom) {
            invalidatePageCache();
        }
    }
 
    if (m_pageMode == QPdfView::PageMode::MultiPage) {
        // An imaginary, 2px height line at the upper half of the viewport, which is used to
        // determine which page is currently located there -> we propagate that as 'current' page
        // to the QPdfPageNavigator object
        const QRect currentPageLine(m_viewport.x(), m_viewport.y() + m_viewport.height() * 0.4, m_viewport.width(), 2);
 
        int currentPage = 0;
        for (auto it = m_documentLayout.pageGeometryAndScale.cbegin();
             it != m_documentLayout.pageGeometryAndScale.cend(); ++it) {
            const QRect pageGeometry = it.value().first;
            if (pageGeometry.intersects(currentPageLine)) {
                currentPage = it.key();
                break;
            }
        }
 
        if (currentPage != m_pageNavigator->currentPage()) {
            m_blockPageScrolling = true;
            // ΤODO give location on the page
            m_pageNavigator->jump(currentPage, {}, m_zoomFactor);
            m_blockPageScrolling = false;
        }
    }
}
 
void QPdfViewPrivate::updateScrollBars()
{
    Q_Q(QPdfView);
 
    const QSize p = q->viewport()->size();
    const QSize v = m_documentLayout.documentSize;
 
    q->horizontalScrollBar()->setRange(0, v.width() - p.width());
    q->horizontalScrollBar()->setPageStep(p.width());
    q->verticalScrollBar()->setRange(0, v.height() - p.height());
    q->verticalScrollBar()->setPageStep(p.height());
}
 
void QPdfViewPrivate::pageRendered(int pageNumber, QSize imageSize, const QImage &image, quint64 requestId)
{
    Q_Q(QPdfView);
 
    Q_UNUSED(imageSize);
    Q_UNUSED(requestId);
 
    if (!m_cachedPagesLRU.contains(pageNumber)) {
        if (m_cachedPagesLRU.size() > m_pageCacheLimit)
            m_pageCache.remove(m_cachedPagesLRU.takeFirst());
 
        m_cachedPagesLRU.append(pageNumber);
    }
 
    m_pageCache.insert(pageNumber, image);
 
    q->viewport()->update();
}
 
void QPdfViewPrivate::invalidateDocumentLayout()
{
    updateDocumentLayout();
    invalidatePageCache();
}
 
void QPdfViewPrivate::invalidatePageCache()
{
    Q_Q(QPdfView);
 
    m_pageCache.clear();
    q->viewport()->update();
}
 
QPdfViewPrivate::DocumentLayout QPdfViewPrivate::calculateDocumentLayout() const
{
    // The DocumentLayout describes a virtual layout where all pages are positioned inside
    //    - For SinglePage mode, this is just an area as large as the current page surrounded
    //      by the m_documentMargins.
    //    - For MultiPage mode, this is the area that is covered by all pages which are placed
    //      below each other, with m_pageSpacing inbetween and surrounded by m_documentMargins
 
    DocumentLayout documentLayout;
 
    if (!m_document || m_document->status() != QPdfDocument::Status::Ready)
        return documentLayout;
 
    QHash<int, QPair<QRect, qreal>> pageGeometryAndScale;
 
    const int pageCount = m_document->pageCount();
 
    int totalWidth = 0;
 
    const int startPage = (m_pageMode == QPdfView::PageMode::SinglePage ? m_pageNavigator->currentPage() : 0);
    const int endPage = (m_pageMode == QPdfView::PageMode::SinglePage ? m_pageNavigator->currentPage() + 1 : pageCount);
 
    // calculate page sizes
    for (int page = startPage; page < endPage; ++page) {
        QSize pageSize;
        qreal pageScale = m_zoomFactor;
        if (m_zoomMode == QPdfView::ZoomMode::Custom) {
            pageSize = QSizeF(m_document->pagePointSize(page) * m_screenResolution * m_zoomFactor).toSize();
        } else if (m_zoomMode == QPdfView::ZoomMode::FitToWidth) {
            pageSize = QSizeF(m_document->pagePointSize(page) * m_screenResolution).toSize();
            pageScale = (qreal(m_viewport.width() - m_documentMargins.left() - m_documentMargins.right()) /
                         qreal(pageSize.width()));
            pageSize *= pageScale;
        } else if (m_zoomMode == QPdfView::ZoomMode::FitInView) {
            const QSize viewportSize(m_viewport.size() +
                                     QSize(-m_documentMargins.left() - m_documentMargins.right(), -m_pageSpacing));
 
            pageSize = QSizeF(m_document->pagePointSize(page) * m_screenResolution).toSize();
            QSize scaledSize = pageSize.scaled(viewportSize, Qt::KeepAspectRatio);
            // because of KeepAspectRatio, the ratio of widths should be the same as the ratio of heights
            pageScale = qreal(scaledSize.width()) / qreal(pageSize.width());
            pageSize = scaledSize;
        }
 
        totalWidth = qMax(totalWidth, pageSize.width());
 
        pageGeometryAndScale[page] = {QRect(QPoint(0, 0), pageSize), pageScale};
    }
 
    totalWidth += m_documentMargins.left() + m_documentMargins.right();
 
    int pageY = m_documentMargins.top();
 
    // calculate page positions
    for (int page = startPage; page < endPage; ++page) {
        const QSize pageSize = pageGeometryAndScale[page].first.size();
 
        // center horizontal inside the viewport
        const int pageX = (qMax(totalWidth, m_viewport.width()) - pageSize.width()) / 2;
 
        pageGeometryAndScale[page].first.moveTopLeft(QPoint(pageX, pageY));
 
        pageY += pageSize.height() + m_pageSpacing;
    }
 
    pageY += m_documentMargins.bottom();
 
    documentLayout.pageGeometryAndScale = pageGeometryAndScale;
 
    // calculate overall document size
    documentLayout.documentSize = QSize(totalWidth, pageY);
 
    return documentLayout;
}
 
qreal QPdfViewPrivate::yPositionForPage(int pageNumber) const
{
    const auto it = m_documentLayout.pageGeometryAndScale.constFind(pageNumber);
    if (it == m_documentLayout.pageGeometryAndScale.cend())
        return 0.0;
 
    return (*it).first.y();
}
 
QTransform QPdfViewPrivate::screenScaleTransform(int page) const
{
    qreal scale = m_screenResolution * m_zoomFactor;
    switch (m_zoomMode) {
    case QPdfView::ZoomMode::FitToWidth:
    case QPdfView::ZoomMode::FitInView:
        scale = m_screenResolution * m_documentLayout.pageGeometryAndScale[page].second;
        break;
    default:
        break;
    }
 
    return QTransform::fromScale(scale, scale);
}
 
void QPdfViewPrivate::updateDocumentLayout()
{
    m_documentLayout = calculateDocumentLayout();
 
    updateScrollBars();
}
 
QPdfView::QPdfView(QWidget *parent)
    : QAbstractScrollArea(parent)
    , d_ptr(new QPdfViewPrivate(this))
{
    Q_D(QPdfView);
 
    d->init();
 
    connect(d->m_pageNavigator, &QPdfPageNavigator::currentPageChanged, this,
            [d](int page){ d->currentPageChanged(page); });
 
    connect(d->m_pageRenderer, &QPdfPageRenderer::pageRendered, this,
            [d](int pageNumber, QSize imageSize, const QImage &image, QPdfDocumentRenderOptions, quint64 requestId) {
                d->pageRendered(pageNumber, imageSize, image, requestId); });
 
    verticalScrollBar()->setSingleStep(20);
    horizontalScrollBar()->setSingleStep(20);
 
    setMouseTracking(true);
    d->calculateViewport();
}
 
QPdfView::~QPdfView()
{
}
 
void QPdfView::setDocument(QPdfDocument *document)
{
    Q_D(QPdfView);
 
    if (d->m_document == document)
        return;
 
    if (d->m_document)
        disconnect(d->m_documentStatusChangedConnection);
 
    d->m_document = document;
    emit documentChanged(d->m_document);
 
    if (d->m_document)
        d->m_documentStatusChangedConnection =
                connect(d->m_document.data(), &QPdfDocument::statusChanged, this,
                        [d](){ d->documentStatusChanged(); });
 
    d->m_pageRenderer->setDocument(d->m_document);
    d->m_linkModel.setDocument(d->m_document);
 
    d->documentStatusChanged();
}
 
QPdfDocument *QPdfView::document() const
{
    Q_D(const QPdfView);
 
    return d->m_document;
}
 
void QPdfView::setSearchModel(QPdfSearchModel *searchModel)
{
    Q_D(QPdfView);
    if (d->m_searchModel == searchModel)
        return;
 
    if (d->m_searchModel)
        d->m_searchModel->disconnect(this);
 
    d->m_searchModel = searchModel;
    emit searchModelChanged(searchModel);
 
    if (searchModel) {
        connect(searchModel, &QPdfSearchModel::dataChanged, this,
                [this](const QModelIndex &, const QModelIndex &, const QList<int> &) { update(); });
    }
    setCurrentSearchResultIndex(-1);
}
 
QPdfSearchModel *QPdfView::searchModel() const
{
    Q_D(const QPdfView);
    return d->m_searchModel;
}
 
void QPdfView::setCurrentSearchResultIndex(int currentResult)
{
    Q_D(QPdfView);
    if (d->m_currentSearchResultIndex == currentResult)
        return;
 
    d->m_currentSearchResultIndex = currentResult;
    emit currentSearchResultIndexChanged(currentResult);
    viewport()->update(); //update();
}
 
int QPdfView::currentSearchResultIndex() const
{
    Q_D(const QPdfView);
    return d->m_currentSearchResultIndex;
}
 
QPdfPageNavigator *QPdfView::pageNavigator() const
{
    Q_D(const QPdfView);
 
    return d->m_pageNavigator;
}
 
QPdfView::PageMode QPdfView::pageMode() const
{
    Q_D(const QPdfView);
 
    return d->m_pageMode;
}
 
void QPdfView::setPageMode(PageMode mode)
{
    Q_D(QPdfView);
 
    if (d->m_pageMode == mode)
        return;
 
    d->m_pageMode = mode;
    d->invalidateDocumentLayout();
 
    emit pageModeChanged(d->m_pageMode);
}
 
QPdfView::ZoomMode QPdfView::zoomMode() const
{
    Q_D(const QPdfView);
 
    return d->m_zoomMode;
}
 
void QPdfView::setZoomMode(ZoomMode mode)
{
    Q_D(QPdfView);
 
    if (d->m_zoomMode == mode)
        return;
 
    d->m_zoomMode = mode;
    d->invalidateDocumentLayout();
 
    emit zoomModeChanged(d->m_zoomMode);
}
 
qreal QPdfView::zoomFactor() const
{
    Q_D(const QPdfView);
 
    return d->m_zoomFactor;
}
 
void QPdfView::setZoomFactor(qreal factor)
{
    Q_D(QPdfView);
 
    if (d->m_zoomFactor == factor)
        return;
 
    d->m_zoomFactor = factor;
    d->invalidateDocumentLayout();
 
    emit zoomFactorChanged(d->m_zoomFactor);
}
 
int QPdfView::pageSpacing() const
{
    Q_D(const QPdfView);
 
    return d->m_pageSpacing;
}
 
void QPdfView::setPageSpacing(int spacing)
{
    Q_D(QPdfView);
 
    if (d->m_pageSpacing == spacing)
        return;
 
    d->m_pageSpacing = spacing;
    d->invalidateDocumentLayout();
 
    emit pageSpacingChanged(d->m_pageSpacing);
}
 
QMargins QPdfView::documentMargins() const
{
    Q_D(const QPdfView);
 
    return d->m_documentMargins;
}
 
void QPdfView::setDocumentMargins(QMargins margins)
{
    Q_D(QPdfView);
 
    if (d->m_documentMargins == margins)
        return;
 
    d->m_documentMargins = margins;
    d->invalidateDocumentLayout();
 
    emit documentMarginsChanged(d->m_documentMargins);
}
 
void QPdfView::paintEvent(QPaintEvent *event)
{
    Q_D(QPdfView);
 
    QPainter painter(viewport());
    painter.fillRect(event->rect(), palette().brush(QPalette::Dark));
    painter.translate(-d->m_viewport.x(), -d->m_viewport.y());
 
    for (auto it = d->m_documentLayout.pageGeometryAndScale.cbegin();
         it != d->m_documentLayout.pageGeometryAndScale.cend(); ++it) {
        const QRect pageGeometry = it.value().first;
        if (pageGeometry.intersects(d->m_viewport)) { // page needs to be painted
            painter.fillRect(pageGeometry, Qt::white);
 
            const int page = it.key();
            const auto pageIt = d->m_pageCache.constFind(page);
            if (pageIt != d->m_pageCache.cend()) {
                const QImage &img = pageIt.value();
                painter.drawImage(pageGeometry, img);
            } else {
                d->m_pageRenderer->requestPage(page, pageGeometry.size() * devicePixelRatioF());
            }
 
            const QTransform scaleTransform = d->screenScaleTransform(page);
#ifdef DEBUG_LINKS
            const QString fmt = u"page %1 @ %2, %3"_s;
            d->m_linkModel.setPage(page);
            const int linkCount = d->m_linkModel.rowCount({});
            for (int i = 0; i < linkCount; ++i) {
                const QRectF linkBounds = scaleTransform.mapRect(
                            d->m_linkModel.data(d->m_linkModel.index(i),
                                                int(QPdfLinkModel::Role::Rect)).toRectF())
                        .translated(pageGeometry.topLeft());
                painter.setPen(Qt::blue);
                painter.drawRect(linkBounds);
                painter.setPen(Qt::red);
                const QPoint loc = d->m_linkModel.data(d->m_linkModel.index(i),
                                                       int(QPdfLinkModel::Role::Location)).toPoint();
                // TODO maybe draw destination URL if that's what it is
                painter.drawText(linkBounds.bottomLeft() + QPoint(2, -2),
                                 fmt.arg(d->m_linkModel.data(d->m_linkModel.index(i),
                                                             int(QPdfLinkModel::Role::Page)).toInt())
                                 .arg(loc.x()).arg(loc.y()));
            }
#endif
            if (d->m_searchModel) {
                for (const QPdfLink &result : d->m_searchModel->resultsOnPage(page)) {
                    for (const QRectF &rect : result.rectangles())
                        painter.fillRect(scaleTransform.mapRect(rect).translated(pageGeometry.topLeft()), SearchResultHighlight);
                }
 
                if (d->m_currentSearchResultIndex >= 0 && d->m_currentSearchResultIndex < d->m_searchModel->rowCount({})) {
                    const QPdfLink &cur = d->m_searchModel->resultAtIndex(d->m_currentSearchResultIndex);
                    if (cur.page() == page) {
                        painter.setPen({CurrentSearchResultHighlight, CurrentSearchResultWidth});
                        for (const auto &rect : cur.rectangles())
                            painter.drawRect(scaleTransform.mapRect(rect).translated(pageGeometry.topLeft()));
                    }
                }
            }
        }
    }
}
 
void QPdfView::resizeEvent(QResizeEvent *event)
{
    Q_D(QPdfView);
 
    QAbstractScrollArea::resizeEvent(event);
 
    d->updateScrollBars();
    d->calculateViewport();
}
 
void QPdfView::scrollContentsBy(int dx, int dy)
{
    Q_D(QPdfView);
 
    QAbstractScrollArea::scrollContentsBy(dx, dy);
 
    d->calculateViewport();
}
 
void QPdfView::mousePressEvent(QMouseEvent *event)
{
    Q_ASSERT(event->isAccepted());
}
 
void QPdfView::mouseMoveEvent(QMouseEvent *event)
{
    Q_D(QPdfView);
    for (auto it = d->m_documentLayout.pageGeometryAndScale.cbegin();
         it != d->m_documentLayout.pageGeometryAndScale.cend(); ++it) {
        const int page = it.key();
        const QTransform screenInvTransform = d->screenScaleTransform(page).inverted();
        const QRect pageGeometry = it.value().first;
        if (pageGeometry.contains(event->position().toPoint())) {
            const QPointF posInPoints = screenInvTransform.map(event->position() - pageGeometry.topLeft());
            d->m_linkModel.setPage(page);
            auto dest = d->m_linkModel.linkAt(posInPoints);
            setCursor(dest.isValid() ? Qt::PointingHandCursor : Qt::ArrowCursor);
            if (dest.isValid())
                qCDebug(qLcWLink) << event->position() << ":" << posInPoints << "pt ->" << dest;
        }
    }
}
 
void QPdfView::mouseReleaseEvent(QMouseEvent *event)
{
    Q_D(QPdfView);
    for (auto it = d->m_documentLayout.pageGeometryAndScale.cbegin();
         it != d->m_documentLayout.pageGeometryAndScale.cend(); ++it) {
        const int page = it.key();
        const QTransform screenInvTransform = d->screenScaleTransform(page).inverted();
        const QRect pageGeometry = it.value().first;
        if (pageGeometry.contains(event->position().toPoint())) {
            const QPointF posInPoints = screenInvTransform.map(event->position() - pageGeometry.topLeft());
            d->m_linkModel.setPage(page);
            auto dest = d->m_linkModel.linkAt(posInPoints);
            if (dest.isValid()) {
                qCDebug(qLcWLink) << event << ": jumping to" << dest;
                d->m_pageNavigator->jump(dest.page(), dest.location(), dest.zoom());
                // TODO scroll and zoom to where the link tells us to
            }
            return;
        }
    }
}
 
QT_END_NAMESPACE
 
#include "moc_qpdfview.cpp"