Add Pl_DCT::make_compress_config

Jay Berkenbilt
1 parent 0f85e452
Showing 5 changed files with 43 additions and 3 deletions
include/qpdf/Pl_DCT.hh
libqpdf/Pl_DCT.cc
libqpdf/QPDFJob.cc
libtests/dct_compress.cc
manual/release-notes.rst
@@ -24,6 +24,7 @@
 #include <qpdf/Pl_Buffer.hh>
 #include <cstddef>
+#include <functional>
 // jpeglib.h must be included after cstddef or else it messes up the definition of size_t.
 #include <jpeglib.h>
@@ -62,6 +63,10 @@ class QPDF_DLL_CLASS Pl_DCT: public Pipeline
         virtual void apply(jpeg_compress_struct*) = 0;
     };
+    QPDF_DLL
+    static std::shared_ptr<CompressConfig>
+        make_compress_config(std::function<void(jpeg_compress_struct*)>);
+
     // Constructor for compressing image data
     QPDF_DLL
     Pl_DCT(
 #include <qpdf/Pl_DCT.hh>
-#include "qpdf/QPDFLogger.hh"
 #include <qpdf/QIntC.hh>
 #include <qpdf/QTC.hh>
@@ -14,6 +13,23 @@
 namespace
 {
+    class FunctionCallbackConfig: public Pl_DCT::CompressConfig
+    {
+      public:
+        explicit FunctionCallbackConfig(std::function<void(jpeg_compress_struct*)> f) :
+            f(std::move(f))
+        {
+        }
+        ~FunctionCallbackConfig() override = default;
+        void
+        apply(jpeg_compress_struct* config) override
+        {
+            f(config);
+        };
+
+        std::function<void(jpeg_compress_struct*)> f;
+    };
+
     struct qpdf_jpeg_error_mgr
     {
         struct jpeg_error_mgr pub;
@@ -407,3 +423,9 @@ Pl_DCT::decompress(void* cinfo_p, Buffer* b)
     (void)jpeg_finish_decompress(cinfo);
     next()->finish();
 }
+
+std::shared_ptr<Pl_DCT::CompressConfig>
+Pl_DCT::make_compress_config(std::function<void(jpeg_compress_struct*)> f)
+{
+    return std::make_shared<FunctionCallbackConfig>(f);
+}
@@ -57,6 +57,7 @@ namespace
         size_t oi_min_height;
         size_t oi_min_area;
         QPDFObjectHandle image;
+        std::shared_ptr<Pl_DCT::CompressConfig> config;
     };
     class DiscardContents: public QPDFObjectHandle::ParserCallbacks
@@ -115,6 +116,7 @@ ImageOptimizer::ImageOptimizer(
     oi_min_area(oi_min_area),
     image(image)
 {
+    config = Pl_DCT::make_compress_config([](jpeg_compress_struct* config) {});
 }
 std::shared_ptr<Pipeline>
@@ -195,7 +197,7 @@ ImageOptimizer::makePipeline(std::string const&amp; description, Pipeline* next)
         return result;
     }
-    result = std::make_shared<Pl_DCT>("jpg", next, w, h, components, cs);
+    result = std::make_shared<Pl_DCT>("jpg", next, w, h, components, cs, config.get());
     return result;
 }
 #include <qpdf/Pl_DCT.hh>
 #include <qpdf/Pl_StdioFile.hh>
 #include <qpdf/QUtil.hh>
+#include <qpdf/assert_test.h>
 #include <cstdio>
 #include <cstdlib>
@@ -50,12 +51,16 @@ main(int argc, char* argv[])
     FILE* infile = QUtil::safe_fopen(infilename, "rb");
     FILE* outfile = QUtil::safe_fopen(outfilename, "wb");
     Pl_StdioFile out("stdout", outfile);
+    bool called = false;
+    auto callback = [&called](jpeg_compress_struct*) { called = true; };
+    auto config = Pl_DCT::make_compress_config(callback);
     unsigned char buf[100];
-    Pl_DCT dct("dct", &out, width, height, components, cs);
+    Pl_DCT dct("dct", &out, width, height, components, cs, config.get());
     while (size_t len = fread(buf, 1, sizeof(buf), infile)) {
         dct.write(buf, len);
     }
     dct.finish();
+    assert(called);
     fclose(infile);
     fclose(outfile);
@@ -38,6 +38,12 @@ more detail.
       unencrypted. qpdf has always incorrectly handled all
       ``/Metadata`` streams as special with cleartext metadata.
+  - Library Enhancements
+
+    - Add function ``Pl_DCT::make_compress_config`` to return a
+      ``Pl_DCT::CompressConfig`` shared pointer from a
+      ``std::function`` for a more modern configuration option.
+
   - CLI Enhancements
     - New :qpdf:ref:`--remove-structure` option to exclude the document