Add QPDFPageLabelDocumentHelper

1 files changed, 100 insertions, 0 deletions

diff --git a/include/qpdf/QPDFPageLabelDocumentHelper.hh b/include/qpdf/QPDFPageLabelDocumentHelper.hh
new file mode 100644
index 00000000..a5a13ff2
--- /dev/null
+++ b/include/qpdf/QPDFPageLabelDocumentHelper.hh
@@ -0,0 +1,100 @@
+// Copyright (c) 2005-2018 Jay Berkenbilt
+//
+// This file is part of qpdf.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Versions of qpdf prior to version 7 were released under the terms
+// of version 2.0 of the Artistic License. At your option, you may
+// continue to consider qpdf to be licensed under those terms. Please
+// see the manual for additional information.
+
+#ifndef QPDFPAGELABELDOCUMENTHELPER_HH
+#define QPDFPAGELABELDOCUMENTHELPER_HH
+
+#include <qpdf/QPDFDocumentHelper.hh>
+
+#include <qpdf/QPDF.hh>
+#include <qpdf/QPDFNumberTreeObjectHelper.hh>
+#include <vector>
+
+#include <qpdf/DLL.h>
+
+// Page labels are discussed in the PDF spec (ISO-32000) in section
+// 12.4.2.
+//
+// Page labels are implemented as a number tree. Each key is a page
+// index, numbered from 0. The values are dictionaries with the
+// following keys, all optional:
+//
+// * /Type: if present, must be /PageLabel
+// * /S: one of /D, /R, /r, /A, or /a for decimal, upper-case and
+//   lower-case Roman numeral, or upper-case and lower-case alphabetic
+// * /P: if present, a fixed prefix string that is prepended to each
+//   page number
+// * /St: the starting number, or 1 if not specified
+
+class QPDFPageLabelDocumentHelper: public QPDFDocumentHelper
+{
+  public:
+    QPDF_DLL
+    QPDFPageLabelDocumentHelper(QPDF&);
+
+    QPDF_DLL
+    bool hasPageLabels();
+
+    // Return a page label dictionary representing the page label for
+    // the given page. The page does not need to appear explicitly in
+    // the page label dictionary. This method will adjust /St as
+    // needed to produce a label that is suitable for the page.
+    QPDF_DLL
+    QPDFObjectHandle getLabelForPage(long long page_idx);
+
+    // Append to the incoming vector a list of objects suitable for
+    // inclusion in a /PageLabels dictionary's /Nums field. start_idx
+    // and end_idx are the indexes to the starting and ending pages
+    // (inclusive) in the original file, and new_start_idx is the
+    // index to the first page in the new file. For example, if pages
+    // 10 through 12 of one file are being copied to a new file as
+    // pages 6 through 8, you would call getLabelsForPageRange(10, 12,
+    // 6), which would return as many entries as are required to add
+    // to the new file's PageLabels. This method fabricates a suitable
+    // entry even if the original document has no page labels. This
+    // behavior facilitates using this function to incrementally build
+    // up a page labels tree when merging files.
+    QPDF_DLL
+    void
+    getLabelsForPageRange(long long start_idx, long long end_idx,
+                          long long new_start_idx,
+                          std::vector<QPDFObjectHandle>& new_labels);
+
+  private:
+    class Members
+    {
+        friend class QPDFPageLabelDocumentHelper;
+
+      public:
+        QPDF_DLL
+        ~Members();
+
+      private:
+        Members();
+        Members(Members const&);
+
+        PointerHolder<QPDFNumberTreeObjectHelper> labels;
+    };
+
+    PointerHolder<Members> m;
+};
+
+#endif // QPDFPAGELABELDOCUMENTHELPER_HH