qpdfpagenavigator.cpp

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// 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 "qpdfpagenavigator.h"
#include "qpdfdocument.h"
#include "qpdflink_p.h"
 
#include <QtCore/qloggingcategory.h>
#include <QtCore/qpointer.h>
 
QT_BEGIN_NAMESPACE
 
Q_LOGGING_CATEGORY(qLcNav, "qt.pdf.pagenavigator")
 
struct QPdfPageNavigatorPrivate
{
    QPdfPageNavigator *q = nullptr;
 
    QList<QExplicitlySharedDataPointer<QPdfLinkPrivate>> pageHistory;
    int currentHistoryIndex = 0;
    bool changing = false;
};
 
QPdfPageNavigator::QPdfPageNavigator(QObject *parent)
    : QObject(parent), d(new QPdfPageNavigatorPrivate)
{
    d->q = this;
    clear();
}
 
QPdfPageNavigator::~QPdfPageNavigator()
{
}
 
void QPdfPageNavigator::forward()
{
    if (d->currentHistoryIndex >= d->pageHistory.size() - 1)
        return;
    const bool backAvailableWas = backAvailable();
    const bool forwardAvailableWas = forwardAvailable();
    QPointF currentLocationWas = currentLocation();
    qreal currentZoomWas = currentZoom();
    ++d->currentHistoryIndex;
    d->changing = true;
    emit jumped(currentLink());
    if (currentZoomWas != currentZoom())
        emit currentZoomChanged(currentZoom());
    emit currentPageChanged(currentPage());
    if (currentLocationWas != currentLocation())
        emit currentLocationChanged(currentLocation());
    if (!backAvailableWas)
        emit backAvailableChanged(backAvailable());
    if (forwardAvailableWas != forwardAvailable())
        emit forwardAvailableChanged(forwardAvailable());
    d->changing = false;
    qCDebug(qLcNav) << "forward: index" << d->currentHistoryIndex << "page" << currentPage()
                    << "@" << currentLocation() << "zoom" << currentZoom();
}
 
void QPdfPageNavigator::back()
{
    if (d->currentHistoryIndex <= 0)
        return;
    const bool backAvailableWas = backAvailable();
    const bool forwardAvailableWas = forwardAvailable();
    QPointF currentLocationWas = currentLocation();
    qreal currentZoomWas = currentZoom();
    --d->currentHistoryIndex;
    d->changing = true;
    emit jumped(currentLink());
    if (currentZoomWas != currentZoom())
        emit currentZoomChanged(currentZoom());
    emit currentPageChanged(currentPage());
    if (currentLocationWas != currentLocation())
        emit currentLocationChanged(currentLocation());
    if (backAvailableWas != backAvailable())
        emit backAvailableChanged(backAvailable());
    if (!forwardAvailableWas)
        emit forwardAvailableChanged(forwardAvailable());
    d->changing = false;
    qCDebug(qLcNav) << "back: index" << d->currentHistoryIndex << "page" << currentPage()
                    << "@" << currentLocation() << "zoom" << currentZoom();
}
int QPdfPageNavigator::currentPage() const
{
    if (d->currentHistoryIndex < 0 || d->currentHistoryIndex >= d->pageHistory.size())
        return -1; // only until ctor or clear() runs
    return d->pageHistory.at(d->currentHistoryIndex)->page;
}
 
QPointF QPdfPageNavigator::currentLocation() const
{
    if (d->currentHistoryIndex < 0 || d->currentHistoryIndex >= d->pageHistory.size())
        return QPointF();
    return d->pageHistory.at(d->currentHistoryIndex)->location;
}
 
qreal QPdfPageNavigator::currentZoom() const
{
    if (d->currentHistoryIndex < 0 || d->currentHistoryIndex >= d->pageHistory.size())
        return 1;
    return d->pageHistory.at(d->currentHistoryIndex)->zoom;
}
 
QPdfLink QPdfPageNavigator::currentLink() const
{
    if (d->currentHistoryIndex < 0 || d->currentHistoryIndex >= d->pageHistory.size())
        return QPdfLink();
    return QPdfLink(d->pageHistory.at(d->currentHistoryIndex).data());
}
 
void QPdfPageNavigator::clear()
{
    d->pageHistory.clear();
    d->currentHistoryIndex = 0;
    // Begin with an implicit jump to page 0, so that
    // backAvailable() will become true after jump() is called one more time.
    d->pageHistory.append(QExplicitlySharedDataPointer<QPdfLinkPrivate>(new QPdfLinkPrivate(0, {}, 1)));
}
 
void QPdfPageNavigator::jump(QPdfLink destination)
{
    const bool zoomChange = !qFuzzyCompare(destination.zoom(), currentZoom());
    const bool pageChange = (destination.page() != currentPage());
    const bool locationChange = (destination.location() != currentLocation());
    const bool backAvailableWas = backAvailable();
    const bool forwardAvailableWas = forwardAvailable();
    if (!d->changing) {
        if (d->currentHistoryIndex >= 0 && forwardAvailableWas)
            d->pageHistory.remove(d->currentHistoryIndex + 1, d->pageHistory.size() - d->currentHistoryIndex - 1);
        d->pageHistory.append(destination.d);
        d->currentHistoryIndex = d->pageHistory.size() - 1;
    }
    if (zoomChange)
        emit currentZoomChanged(currentZoom());
    if (pageChange)
        emit currentPageChanged(currentPage());
    if (locationChange)
        emit currentLocationChanged(currentLocation());
    if (d->changing)
        return;
    if (backAvailableWas != backAvailable())
        emit backAvailableChanged(backAvailable());
    if (forwardAvailableWas != forwardAvailable())
        emit forwardAvailableChanged(forwardAvailable());
    emit jumped(currentLink());
    qCDebug(qLcNav) << "push: index" << d->currentHistoryIndex << destination << "-> history" <<
        [this]() {
            QStringList ret;
            for (auto d : d->pageHistory)
                ret << QString::number(d->page);
            return ret.join(QLatin1Char(','));
        }();
}
 
void QPdfPageNavigator::jump(int page, const QPointF &location, qreal zoom)
{
    if (page == currentPage() && location == currentLocation() && zoom == currentZoom())
        return;
    if (qFuzzyIsNull(zoom))
        zoom = currentZoom();
    const bool zoomChange = !qFuzzyCompare(zoom, currentZoom());
    const bool pageChange = (page != currentPage());
    const bool locationChange = (location != currentLocation());
    const bool backAvailableWas = backAvailable();
    const bool forwardAvailableWas = forwardAvailable();
    if (!d->changing) {
        if (d->currentHistoryIndex >= 0 && forwardAvailableWas)
            d->pageHistory.remove(d->currentHistoryIndex + 1, d->pageHistory.size() - d->currentHistoryIndex - 1);
        d->pageHistory.append(QExplicitlySharedDataPointer<QPdfLinkPrivate>(new QPdfLinkPrivate(page, location, zoom)));
        d->currentHistoryIndex = d->pageHistory.size() - 1;
    }
    if (zoomChange)
        emit currentZoomChanged(currentZoom());
    if (pageChange)
        emit currentPageChanged(currentPage());
    if (locationChange)
        emit currentLocationChanged(currentLocation());
    if (d->changing)
        return;
    if (backAvailableWas != backAvailable())
        emit backAvailableChanged(backAvailable());
    if (forwardAvailableWas != forwardAvailable())
        emit forwardAvailableChanged(forwardAvailable());
    emit jumped(currentLink());
    qCDebug(qLcNav) << "push: index" << d->currentHistoryIndex << "page" << page
                    << "@" << location << "zoom" << zoom << "-> history" <<
        [this]() {
            QStringList ret;
            for (auto d : d->pageHistory)
                ret << QString::number(d->page);
            return ret.join(QLatin1Char(','));
        }();
}
 
void QPdfPageNavigator::update(int page, const QPointF &location, qreal zoom)
{
    if (d->currentHistoryIndex < 0 || d->currentHistoryIndex >= d->pageHistory.size())
        return;
    int currentPageWas = currentPage();
    QPointF currentLocationWas = currentLocation();
    qreal currentZoomWas = currentZoom();
    if (page == currentPageWas && location == currentLocationWas && zoom == currentZoomWas)
        return;
    d->pageHistory[d->currentHistoryIndex]->page = page;
    d->pageHistory[d->currentHistoryIndex]->location = location;
    d->pageHistory[d->currentHistoryIndex]->zoom = zoom;
    if (currentZoomWas != zoom)
        emit currentZoomChanged(currentZoom());
    if (currentPageWas != page)
        emit currentPageChanged(currentPage());
    if (currentLocationWas != location)
        emit currentLocationChanged(currentLocation());
    qCDebug(qLcNav) << "update: index" << d->currentHistoryIndex << "page" << page
                    << "@" << location << "zoom" << zoom << "-> history" <<
        [this]() {
            QStringList ret;
            for (auto d : d->pageHistory)
                ret << QString::number(d->page);
            return ret.join(QLatin1Char(','));
        }();
}
 
bool QPdfPageNavigator::backAvailable() const
{
    return d->currentHistoryIndex > 0;
}
 
bool QPdfPageNavigator::forwardAvailable() const
{
    return d->currentHistoryIndex < d->pageHistory.size() - 1;
}
 
QT_END_NAMESPACE
 
#include "moc_qpdfpagenavigator.cpp"