PDF4QT/Pdf4QtLib/sources/pdfpagenavigation.cpp

175 lines
5.5 KiB
C++

// Copyright (C) 2020-2021 Jakub Melka
//
// This file is part of Pdf4Qt.
//
// Pdf4Qt is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// with the written consent of the copyright owner, any later version.
//
// Pdf4Qt is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with Pdf4Qt. If not, see <https://www.gnu.org/licenses/>.
#include "pdfpagenavigation.h"
namespace pdf
{
PDFPageNavigation::PDFPageNavigation(const PDFDocument* document, QObject* parent) :
QObject(parent),
m_currentPageIndex(0),
m_document(document)
{
if (m_document && m_document->getCatalog()->getPageCount() > 0)
{
navigateToPage(0);
}
}
void PDFPageNavigation::navigateToPage(size_t pageIndex)
{
if (m_currentPageIndex == pageIndex)
{
// Jakub Melka: We are at the same page! Do nothing.
return;
}
const bool isForward = pageIndex > m_currentPageIndex;
const PDFObjectStorage* const storage = &m_document->getStorage();
const PDFPage* page = m_document->getCatalog()->getPage(pageIndex);
// We will perform steps as in PDF 2.0 specification, chapter 12.4.4.2
// Step a) navigate to page and set current navigation node
m_currentPageIndex = pageIndex;
m_transition = PDFPageTransition::parse(storage, page->getTransition(storage));
m_currentNavigationNode = PDFNavigationNode::parse(storage, page->getFirstSubpageNavigationNode(storage));
// Step b) Execute initially page navigation node. If we are navigating forward,
// then "next" action should be executed and current node should be changed to next.
// If we are navigating backward, then "previous" action should be executed
// and current node should be changed to previous.
executeNavigationNode(isForward ? Direction::Forward : Direction::Backward);
// Step c) Navigate to new page - send navigation request.
emit pageChangeRequest(m_currentPageIndex, &m_transition);
}
void PDFPageNavigation::navigateForward()
{
if (m_currentNavigationNode)
{
executeNavigationNode(Direction::Forward);
}
else if (m_currentPageIndex + 1 < m_document->getCatalog()->getPageCount())
{
navigateToPage(m_currentPageIndex + 1);
}
}
void PDFPageNavigation::navigateBackward()
{
if (m_currentNavigationNode)
{
executeNavigationNode(Direction::Backward);
}
else if (m_currentPageIndex > 0)
{
navigateToPage(m_currentPageIndex - 1);
}
}
void PDFPageNavigation::executeNavigationNode(Direction direction)
{
if (!m_currentNavigationNode)
{
return;
}
// We will make a copy of object, because this object can change,
// when actions are executed.
PDFNavigationNode copy = *m_currentNavigationNode;
m_currentNavigationNode = PDFNavigationNode::parse(&m_document->getStorage(), m_document->getObjectByReference((direction == Direction::Forward) ? copy.getNextNode() : copy.getPreviousNode()));
switch (direction)
{
case Direction::Forward:
{
if (const PDFAction* action = copy.getNextAction().get())
{
for (const PDFAction* currentAction : action->getActionList())
{
emit actionTriggered(currentAction);
}
}
break;
}
case Direction::Backward:
{
if (const PDFAction* action = copy.getPreviousAction().get())
{
for (const PDFAction* currentAction : action->getActionList())
{
emit actionTriggered(currentAction);
}
}
break;
}
default:
Q_ASSERT(false);
break;
}
}
PDFActionPtr PDFNavigationNode::getPreviousAction() const
{
return m_previousAction;
}
PDFActionPtr PDFNavigationNode::getNextAction() const
{
return m_nextAction;
}
PDFObjectReference PDFNavigationNode::getPreviousNode() const
{
return m_previousNode;
}
PDFObjectReference PDFNavigationNode::getNextNode() const
{
return m_nextNode;
}
PDFReal PDFNavigationNode::getDuration() const
{
return m_duration;
}
std::optional<PDFNavigationNode> PDFNavigationNode::parse(const PDFObjectStorage* storage, PDFObject object)
{
std::optional<PDFNavigationNode> result;
if (const PDFDictionary* dictionary = storage->getDictionaryFromObject(object))
{
PDFDocumentDataLoaderDecorator loader(storage);
result = PDFNavigationNode();
result->m_nextAction = PDFAction::parse(storage, dictionary->get("NA"));
result->m_previousAction = PDFAction::parse(storage, dictionary->get("PA"));
result->m_previousNode = loader.readReferenceFromDictionary(dictionary, "Prev");
result->m_nextNode = loader.readReferenceFromDictionary(dictionary, "Next");
result->m_duration = loader.readNumberFromDictionary(dictionary, "Dur", 0.0);
}
return result;
}
} // namespace pdf