Implement user-provided stream filters

Refactor QPDF_Stream to use stream filter classes to handle supported
stream filters as well.

1 files changed, 153 insertions, 0 deletions

diff --git a/libqpdf/SF_FlateLzwDecode.cc b/libqpdf/SF_FlateLzwDecode.cc
new file mode 100644
index 00000000..29064cc0
--- /dev/null
+++ b/libqpdf/SF_FlateLzwDecode.cc
@@ -0,0 +1,153 @@
+#include <qpdf/SF_FlateLzwDecode.hh>
+#include <qpdf/Pl_PNGFilter.hh>
+#include <qpdf/Pl_TIFFPredictor.hh>
+#include <qpdf/Pl_Flate.hh>
+#include <qpdf/Pl_LZWDecoder.hh>
+#include <qpdf/QTC.hh>
+#include <qpdf/QIntC.hh>
+
+SF_FlateLzwDecode::SF_FlateLzwDecode(bool lzw) :
+    lzw(lzw),
+    // Initialize values to their defaults as per the PDF spec
+    predictor(1),
+    columns(0),
+    colors(1),
+    bits_per_component(8),
+    early_code_change(true)
+{
+}
+
+bool
+SF_FlateLzwDecode::setDecodeParms(QPDFObjectHandle decode_parms)
+{
+    if (decode_parms.isNull())
+    {
+        return true;
+    }
+
+    bool filterable = true;
+    std::set<std::string> keys = decode_parms.getKeys();
+    for (auto const& key: keys)
+    {
+        QPDFObjectHandle value = decode_parms.getKey(key);
+        if (key == "/Predictor")
+        {
+            if (value.isInteger())
+            {
+                this->predictor = value.getIntValueAsInt();
+                if (! ((this->predictor == 1) || (this->predictor == 2) ||
+                       ((this->predictor >= 10) && (this->predictor <= 15))))
+                {
+                    filterable = false;
+                }
+            }
+            else
+            {
+                filterable = false;
+            }
+        }
+        else if ((key == "/Columns") ||
+                 (key == "/Colors") ||
+                 (key == "/BitsPerComponent"))
+        {
+            if (value.isInteger())
+            {
+                int val = value.getIntValueAsInt();
+                if (key == "/Columns")
+                {
+                    this->columns = val;
+                }
+                else if (key == "/Colors")
+                {
+                    this->colors = val;
+                }
+                else if (key == "/BitsPerComponent")
+                {
+                    this->bits_per_component = val;
+                }
+            }
+            else
+            {
+                filterable = false;
+            }
+        }
+        else if (lzw && (key == "/EarlyChange"))
+        {
+            if (value.isInteger())
+            {
+                int earlychange = value.getIntValueAsInt();
+                this->early_code_change = (earlychange == 1);
+                if (! ((earlychange == 0) || (earlychange == 1)))
+                {
+                    filterable = false;
+                }
+            }
+            else
+            {
+                filterable = false;
+            }
+        }
+    }
+
+    if ((this->predictor > 1) && (this->columns == 0))
+    {
+	filterable = false;
+    }
+
+    return filterable;
+}
+
+
+
+Pipeline*
+SF_FlateLzwDecode::getDecodePipeline(Pipeline* next)
+{
+    std::shared_ptr<Pipeline> pipeline;
+    if ((this->predictor >= 10) && (this->predictor <= 15))
+    {
+        QTC::TC("qpdf", "SF_FlateLzwDecode PNG filter");
+        pipeline = std::make_shared<Pl_PNGFilter>(
+            "png decode", next, Pl_PNGFilter::a_decode,
+            QIntC::to_uint(this->columns),
+            QIntC::to_uint(this->colors),
+            QIntC::to_uint(this->bits_per_component));
+        this->pipelines.push_back(pipeline);
+        next = pipeline.get();
+    }
+    else if (this->predictor == 2)
+    {
+        QTC::TC("qpdf", "SF_FlateLzwDecode TIFF predictor");
+        pipeline = std::make_shared<Pl_TIFFPredictor>(
+            "tiff decode", next, Pl_TIFFPredictor::a_decode,
+            QIntC::to_uint(this->columns),
+            QIntC::to_uint(this->colors),
+            QIntC::to_uint(this->bits_per_component));
+        this->pipelines.push_back(pipeline);
+        next = pipeline.get();
+    }
+
+    if (lzw)
+    {
+        pipeline = std::make_shared<Pl_LZWDecoder>(
+            "lzw decode", next, early_code_change);
+    }
+    else
+    {
+        pipeline = std::make_shared<Pl_Flate>(
+            "stream inflate", next, Pl_Flate::a_inflate);
+    }
+    this->pipelines.push_back(pipeline);
+    return pipeline.get();
+}
+
+std::shared_ptr<QPDFStreamFilter>
+SF_FlateLzwDecode::flate_factory()
+{
+    return std::make_shared<SF_FlateLzwDecode>(false);
+}
+
+std::shared_ptr<QPDFStreamFilter>
+SF_FlateLzwDecode::lzw_factory()
+{
+    return std::make_shared<SF_FlateLzwDecode>(true);
+}