From b1e0dcff16740d5a99e58c298284c5d589b3034f Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Sun, 5 Sep 2010 15:00:44 +0000
Subject: handle stream filter abbreviations from table H.1

git-svn-id: svn+q:///qpdf/trunk@1025 71b93d88-0707-0410-a8cf-f5a4172ac649
---
 libqpdf/QPDFWriter.cc       |  4 +++-
 libqpdf/QPDF_Stream.cc      | 26 +++++++++++++++++++++++++-
 libqpdf/qpdf/QPDF_Stream.hh |  2 ++
 3 files changed, 30 insertions(+), 2 deletions(-)

(limited to 'libqpdf')

diff --git a/libqpdf/QPDFWriter.cc b/libqpdf/QPDFWriter.cc
index 2985118a..68fd62f5 100644
--- a/libqpdf/QPDFWriter.cc
+++ b/libqpdf/QPDFWriter.cc
@@ -993,7 +993,9 @@ QPDFWriter::unparseObject(QPDFObjectHandle object, int level,
 	    // compressed with a lossy compression scheme, but we
 	    // don't support any of those right now.
 	    QPDFObjectHandle filter_obj = stream_dict.getKey("/Filter");
-	    if (filter_obj.isName() && (filter_obj.getName() == "/FlateDecode"))
+	    if (filter_obj.isName() &&
+		((filter_obj.getName() == "/FlateDecode") ||
+		 (filter_obj.getName() == "/Fl")))
 	    {
 		QTC::TC("qpdf", "QPDFWriter not recompressing /FlateDecode");
 		filter = false;
diff --git a/libqpdf/QPDF_Stream.cc b/libqpdf/QPDF_Stream.cc
index 72be2e32..db6cfb58 100644
--- a/libqpdf/QPDF_Stream.cc
+++ b/libqpdf/QPDF_Stream.cc
@@ -18,6 +18,8 @@
 
 #include <stdexcept>
 
+std::map<std::string, std::string> QPDF_Stream::filter_abbreviations;
+
 QPDF_Stream::QPDF_Stream(QPDF* qpdf, int objid, int generation,
 			 QPDFObjectHandle stream_dict,
 			 off_t offset, int length) :
@@ -93,6 +95,21 @@ QPDF_Stream::filterable(std::vector<std::string>& filters,
 			int& predictor, int& columns,
 			bool& early_code_change)
 {
+    if (filter_abbreviations.empty())
+    {
+	// The PDF specification provides these filter abbreviations
+	// for use in inline images, but according to table H.1 in the
+	// pre-ISO versions of the PDF specification, Adobe Reader
+	// also accepts them for stream filters.
+	filter_abbreviations["/AHx"] = "/ASCIIHexDecode";
+	filter_abbreviations["/A85"] = "/ASCII85Decode";
+	filter_abbreviations["/LZW"] = "/LZWDecode";
+	filter_abbreviations["/Fl"] = "/FlateDecode";
+	filter_abbreviations["/RL"] = "/RunLengthDecode";
+	filter_abbreviations["/CCF"] = "/CCITTFaxDecode";
+	filter_abbreviations["/DCT"] = "/DCTDecode";
+    }
+
     // Initialize values to their defaults as per the PDF spec
     predictor = 1;
     columns = 0;
@@ -243,7 +260,14 @@ QPDF_Stream::filterable(std::vector<std::string>& filters,
     for (std::vector<std::string>::iterator iter = filters.begin();
 	 iter != filters.end(); ++iter)
     {
-	std::string const& filter = *iter;
+	std::string& filter = *iter;
+
+	if (filter_abbreviations.count(filter))
+	{
+	    QTC::TC("qpdf", "QPDF_Stream expand filter abbreviation");
+	    filter = filter_abbreviations[filter];
+	}
+
 	if (! ((filter == "/Crypt") ||
 	       (filter == "/FlateDecode") ||
 	       (filter == "/LZWDecode") ||
diff --git a/libqpdf/qpdf/QPDF_Stream.hh b/libqpdf/qpdf/QPDF_Stream.hh
index ed70ae8f..144a9274 100644
--- a/libqpdf/qpdf/QPDF_Stream.hh
+++ b/libqpdf/qpdf/QPDF_Stream.hh
@@ -38,6 +38,8 @@ class QPDF_Stream: public QPDFObject
     void setObjGen(int objid, int generation);
 
   private:
+    static std::map<std::string, std::string> filter_abbreviations;
+
     void replaceFilterData(QPDFObjectHandle const& filter,
 			   QPDFObjectHandle const& decode_parms,
 			   size_t length);
-- 
cgit v1.2.3-54-g00ecf