Restructure optimize to allow skipping parameters of filtered streams

1 files changed, 26 insertions, 10 deletions

diff --git a/include/qpdf/QPDF.hh b/include/qpdf/QPDF.hh
index b0e9b717..a6f49b4b 100644
--- a/include/qpdf/QPDF.hh
+++ b/include/qpdf/QPDF.hh
@@ -564,16 +564,28 @@ class QPDF
     // QPDF_optimization.cc
 
     // The object_stream_data map maps from a "compressed" object to
-    // the object stream that contains it.  This enables optimize to
+    // the object stream that contains it. This enables optimize to
     // populate the object <-> user maps with only uncompressed
-    // objects.  If allow_changes is false, an exception will be
-    // thrown if any changes are made during the optimization process.
-    // This is available so that the test suite can make sure that a
-    // linearized file is already optimized.  When called in this way,
-    // optimize() still populates the object <-> user maps
+    // objects. If allow_changes is false, an exception will be thrown
+    // if any changes are made during the optimization process. This
+    // is available so that the test suite can make sure that a
+    // linearized file is already optimized. When called in this way,
+    // optimize() still populates the object <-> user maps. The
+    // optional skip_stream_parameters parameter, if present, is
+    // called for each stream object. The function should return 2 if
+    // optimization should discard /Length, /Filter, and /DecodeParms;
+    // 1 if it should discard /Length, and 0 if it should preserve all
+    // keys. This is used by QPDFWriter to avoid creation of dangling
+    // objects for stream dictionary keys it will be regenerating.
     QPDF_DLL
     void optimize(std::map<int, int> const& object_stream_data,
 		  bool allow_changes = true);
+    // ABI: make function optional and merge overloaded versions
+    QPDF_DLL
+    void optimize(
+        std::map<int, int> const& object_stream_data,
+        bool allow_changes,
+        std::function<int(QPDFObjectHandle&)> skip_stream_parameters);
 
     // Traverse page tree return all /Page objects. It also detects
     // and resolves cases in which the same /Page object is
@@ -1356,10 +1368,14 @@ class QPDF
 	std::vector<QPDFObjectHandle>& all_pages,
 	bool allow_changes, bool warn_skipped_keys,
         std::set<QPDFObjGen>& visited);
-    void updateObjectMaps(ObjUser const& ou, QPDFObjectHandle oh);
-    void updateObjectMapsInternal(ObjUser const& ou, QPDFObjectHandle oh,
-				  std::set<QPDFObjGen>& visited, bool top,
-                                  int depth);
+    void updateObjectMaps(
+        ObjUser const& ou, QPDFObjectHandle oh,
+        std::function<int(QPDFObjectHandle&)> skip_stream_parameters);
+    void updateObjectMapsInternal(
+        ObjUser const& ou, QPDFObjectHandle oh,
+        std::function<int(QPDFObjectHandle&)> skip_stream_parameters,
+        std::set<QPDFObjGen>& visited, bool top,
+        int depth);
     void filterCompressedObjects(std::map<int, int> const& object_stream_data);
 
     // Type conversion helper methods