Added first version of pages API.

Tobias Hoffmann · Jay Berkenbilt
1 parent 405a549f
Showing 2 changed files with 170 additions and 0 deletions
include/qpdf/QPDF.hh
libqpdf/QPDF.cc
@@ -344,9 +344,24 @@ class QPDF
     QPDF_DLL
     std::vector<QPDFObjectHandle> const& getAllPages();
  
+    // QPDF internally caches the /Pages tree.  This method will clear
+    // the cache when e.g. direct modifications have been made.
     QPDF_DLL
     void clearPagesCache();
  
+    // Add new page at the beginning or the end of the current pdf
+    QPDF_DLL
+    void addPage(QPDFObjectHandle newpage, bool first);
+
+    // Add new page before or after refpage
+    QPDF_DLL
+    void addPageAt(QPDFObjectHandle newpage, bool before,
+                   QPDFObjectHandle const& refpage);
+
+    // Remove pageoh from the pdf.
+    QPDF_DLL
+    void removePage(QPDFObjectHandle const& pageoh);
+
     // Resolver class is restricted to QPDFObjectHandle so that only
     // it can resolve indirect references.
     class Resolver
@@ -521,8 +536,17 @@ class QPDF
 			off_t offset, size_t length,
 			QPDFObjectHandle dict,
 			Pipeline* pipeline);
+
+    // methods to support page handling
+
     void getAllPagesInternal(QPDFObjectHandle cur_pages,
 			     std::vector<QPDFObjectHandle>& result);
+    // creates pageobj_to_pages_pos if necessary
+    // returns position, or -1 if not found
+    int findPage(int objid, int generation);
+    int findPage(QPDFObjectHandle const& pageoh); // convenience
+
+    void flattenPagesTree();
  
     // methods to support encryption -- implemented in QPDF_encryption.cc
     encryption_method_e interpretCF(QPDFObjectHandle);
@@ -887,6 +911,7 @@ class QPDF
     std::map<ObjGen, ObjCache> obj_cache;
     QPDFObjectHandle trailer;
     std::vector<QPDFObjectHandle> all_pages;
+    std::map<ObjGen, int> pageobj_to_pages_pos;
     std::vector<QPDFExc> warnings;
  
     // Linearization data
@@ -4,6 +4,7 @@
 #include <map>
 #include <string.h>
 #include <memory.h>
+#include <assert.h>
  
 #include <qpdf/QTC.hh>
 #include <qpdf/QUtil.hh>
@@ -2203,8 +2204,152 @@ QPDF::getAllPagesInternal(QPDFObjectHandle cur_pages,
     }
 }
  
+// FIXXX here down
+
 void
 QPDF::clearPagesCache()
 {
     this->all_pages.clear();
+    this->pageobj_to_pages_pos.clear();
+}
+
+void
+QPDF::flattenPagesTree()
+{
+    clearPagesCache();
+
+    // FIXME: more specific method, we don't want to generate the extra stuff.
+    // We also need cheap fixup after addPage/removePage.
+
+    // no compressed objects to be produced here...
+    std::map<int, int> object_stream_data;
+    optimize(object_stream_data); // push down inheritance
+
+    std::vector<QPDFObjectHandle> kids = this->getAllPages();
+    QPDFObjectHandle pages = this->trailer.getKey("/Root").getKey("/Pages");
+
+    const int len = kids.size();
+    for (int pos = 0; pos < len; ++pos)
+    {
+        // populate pageobj_to_pages_pos
+        ObjGen og(kids[pos].getObjectID(), kids[pos].getGeneration());
+        if (! this->pageobj_to_pages_pos.insert(std::make_pair(og, pos)).second)
+        {
+            // insert failed: duplicate entry found
+            *out_stream << "WARNING: duplicate page reference found, "
+                        << "but currently not fully supported." << std::endl;
+        }
+
+        // fix parent links
+        kids[pos].replaceKey("/Parent", pages);
+    }
+
+    pages.replaceKey("/Kids", QPDFObjectHandle::newArray(kids));
+    // /Count has not changed
+    assert(pages.getKey("/Count").getIntValue() == len);
+}
+
+int
+QPDF::findPage(int objid, int generation)
+{
+    if (this->pageobj_to_pages_pos.empty())
+    {
+        flattenPagesTree();
+    }
+    std::map<ObjGen, int>::iterator it =
+        this->pageobj_to_pages_pos.find(ObjGen(objid, generation));
+    if (it != this->pageobj_to_pages_pos.end())
+    {
+        return (*it).second;
+    }
+    return -1; // throw?
+}
+
+int
+QPDF::findPage(QPDFObjectHandle const& pageoh)
+{
+    if (!pageoh.isInitialized())
+    {
+        return -1;
+        // TODO? throw
+    }
+    return findPage(pageoh.getObjectID(), pageoh.getGeneration());
+}
+
+void
+QPDF::addPage(QPDFObjectHandle newpage, bool first)
+{
+    if (this->pageobj_to_pages_pos.empty())
+    {
+        flattenPagesTree();
+    }
+
+    newpage.assertPageObject(); // FIXME: currently private
+
+    QPDFObjectHandle pages = this->trailer.getKey("/Root").getKey("/Pages");
+    QPDFObjectHandle kids = pages.getKey("/Kids");
+
+    newpage.replaceKey("/Parent", pages);
+    if (first)
+    {
+        kids.insertItem(0, newpage);
+    }
+    else
+    {
+        kids.appendItem(newpage);
+    }
+    pages.replaceKey("/Count",
+                     QPDFObjectHandle::newInteger(kids.getArrayNItems()));
+
+    // FIXME: this is overkill, but cache is now stale
+    clearPagesCache();
+}
+
+void
+QPDF::addPageAt(QPDFObjectHandle newpage, bool before,
+                QPDFObjectHandle const &refpage)
+{
+    int refpos = findPage(refpage); // also ensures flat /Pages
+    if (refpos == -1)
+    {
+        throw "Could not find refpage";
+    }
+
+    newpage.assertPageObject();
+
+    QPDFObjectHandle pages = this->trailer.getKey("/Root").getKey("/Pages");
+    QPDFObjectHandle kids = pages.getKey("/Kids");
+
+    if (! before)
+    {
+        ++refpos;
+    }
+
+    newpage.replaceKey("/Parent", pages);
+    kids.insertItem(refpos, newpage);
+    pages.replaceKey("/Count",
+                     QPDFObjectHandle::newInteger(kids.getArrayNItems()));
+
+    // FIXME: this is overkill, but cache is now stale
+    clearPagesCache();
+}
+
+void
+QPDF::removePage(QPDFObjectHandle const& pageoh)
+{
+    int pos = findPage(pageoh); // also ensures flat /Pages
+    if (pos == -1)
+    {
+        throw "Can't remove non-existing page";
+    }
+
+    QPDFObjectHandle pages = this->trailer.getKey("/Root").getKey("/Pages");
+    QPDFObjectHandle kids = pages.getKey("/Kids");
+
+    kids.eraseItem(pos);
+    pages.replaceKey("/Count",
+                     QPDFObjectHandle::newInteger(kids.getArrayNItems()));
+
+    // FIXME: this is overkill, but cache is now stale
+    clearPagesCache();
 }