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qpdf/libqpdf/QPDFPageLabelDocumentHelper.cc

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#include <qpdf/QPDFPageLabelDocumentHelper.hh>
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#include <qpdf/QTC.hh>
QPDFPageLabelDocumentHelper::QPDFPageLabelDocumentHelper(QPDF& qpdf) :
QPDFDocumentHelper(qpdf),
m(new Members())
{
QPDFObjectHandle root = qpdf.getRoot();
if (root.hasKey("/PageLabels")) {
this->m->labels = std::make_shared<QPDFNumberTreeObjectHelper>(
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root.getKey("/PageLabels"), this->qpdf);
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}
}
bool
QPDFPageLabelDocumentHelper::hasPageLabels()
{
return nullptr != this->m->labels.get();
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}
QPDFObjectHandle
QPDFPageLabelDocumentHelper::getLabelForPage(long long page_idx)
{
QPDFObjectHandle result(QPDFObjectHandle::newNull());
if (!hasPageLabels()) {
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return result;
}
QPDFNumberTreeObjectHelper::numtree_number offset = 0;
QPDFObjectHandle label;
if (!this->m->labels->findObjectAtOrBelow(page_idx, label, offset)) {
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return result;
}
if (!label.isDictionary()) {
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return result;
}
QPDFObjectHandle S = label.getKey("/S"); // type (D, R, r, A, a)
QPDFObjectHandle P = label.getKey("/P"); // prefix
QPDFObjectHandle St = label.getKey("/St"); // starting number
long long start = 1;
if (St.isInteger()) {
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start = St.getIntValue();
}
QIntC::range_check(start, offset);
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start += offset;
result = QPDFObjectHandle::newDictionary();
result.replaceKey("/S", S);
result.replaceKey("/P", P);
result.replaceKey("/St", QPDFObjectHandle::newInteger(start));
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return result;
}
void
QPDFPageLabelDocumentHelper::getLabelsForPageRange(
long long start_idx,
long long end_idx,
long long new_start_idx,
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std::vector<QPDFObjectHandle>& new_labels)
{
// Start off with a suitable label for the first page. For every
// remaining page, if that page has an explicit entry, copy it.
// Otherwise, let the subsequent page just sequence from the prior
// entry. If there is no entry for the first page, fabricate one
// that would match how the page would look in a new file in which
// it also didn't have an explicit label.
QPDFObjectHandle label = getLabelForPage(start_idx);
if (label.isNull()) {
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label = QPDFObjectHandle::newDictionary();
label.replaceKey(
"/St", QPDFObjectHandle::newInteger(1 + new_start_idx));
}
// See if the new label is redundant based on the previous entry
// in the vector. If so, don't add it.
size_t size = new_labels.size();
bool skip_first = false;
if (size >= 2) {
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QPDFObjectHandle last = new_labels.at(size - 1);
QPDFObjectHandle last_idx = new_labels.at(size - 2);
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if (last_idx.isInteger() && last.isDictionary() &&
(label.getKey("/S").unparse() == last.getKey("/S").unparse()) &&
(label.getKey("/P").unparse() == last.getKey("/P").unparse()) &&
label.getKey("/St").isInteger() && last.getKey("/St").isInteger()) {
long long int st_delta = label.getKey("/St").getIntValue() -
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last.getKey("/St").getIntValue();
long long int idx_delta = new_start_idx - last_idx.getIntValue();
if (st_delta == idx_delta) {
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QTC::TC("qpdf", "QPDFPageLabelDocumentHelper skip first");
skip_first = true;
}
}
}
if (!skip_first) {
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new_labels.push_back(QPDFObjectHandle::newInteger(new_start_idx));
new_labels.push_back(label);
}
long long int idx_offset = new_start_idx - start_idx;
for (long long i = start_idx + 1; i <= end_idx; ++i) {
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if (this->m->labels->hasIndex(i) &&
(label = getLabelForPage(i)).isDictionary()) {
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new_labels.push_back(QPDFObjectHandle::newInteger(i + idx_offset));
new_labels.push_back(label);
}
}
}