implement ability to save PDF to memory, also update ChangeLog

ChangeLog

@@ -1,3 +1,20 @@
+2011-08-10  Jay Berkenbilt  <ejb@ql.org>
+
+	* include/qpdf/QPDFWriter.hh: add a new constructor that takes
+	only a QPDF reference and leaves specification of output for
+	later.  Add methods setOutputFilename() to set the output to a
+	filename or stdout, and setOutputMemory() to indicate that output
+	should go to a memory buffer.  Add method getBuffer() to retrieve
+	the buffer used if output was saved to a memory buffer.
+
+	* include/qpdf/QPDF.hh: add methods replaceObject() and
+	swapObjects() to allow replacement of an object and swapping of
+	two objects by object ID.
+
+	* include/qpdf/QPDFObjectHandle.hh: add new methods getDictAsMap()
+	and getArrayAsVector() for returning the elements of a dictionary
+	or an array as a map or vector.
+
 2011-06-25  Jay Berkenbilt  <ejb@ql.org>
 
 	* 2.2.4: release

include/qpdf/QPDFWriter.hh

@@ -24,6 +24,7 @@
 
 #include <qpdf/QPDFXRefEntry.hh>
 
+#include <qpdf/Pl_Buffer.hh>
 #include <qpdf/PointerHolder.hh>
 #include <qpdf/Pipeline.hh>
 #include <qpdf/Buffer.hh>
@@ -35,6 +36,24 @@ class Pl_Count;
 class QPDFWriter
 {
   public:
+    // Construct a QPDFWriter object without specifying output.  You
+    // must call one of the output setting routines defined below.
+    QPDF_DLL
+    QPDFWriter(QPDF& pdf);
+
+    // Create a QPDFWriter object that writes its output to a file or
+    // to stdout.  This is equivalent to using the previous
+    // constructor and then calling setOutputFilename().  See
+    // setOutputFilename() for details.
+    QPDF_DLL
+    QPDFWriter(QPDF& pdf, char const* filename);
+    QPDF_DLL
+    ~QPDFWriter();
+
+    // Setting Output.  Output may be set only one time.  If you don't
+    // use the filename version of the QPDFWriter constructor, you
+    // must call exactly one of these methods.
+
     // Passing null as filename means write to stdout.  QPDFWriter
     // will create a zero-length output file upon construction.  If
     // write fails, the empty or partially written file will not be
@@ -42,10 +61,20 @@ class QPDFWriter
     // useful for tracking down problems.  If your application doesn't
     // want the partially written file to be left behind, you should
     // delete it the eventual call to write fails.
-    QPDF_DLL
-    QPDFWriter(QPDF& pdf, char const* filename);
-    QPDF_DLL
-    ~QPDFWriter();
+    void setOutputFilename(char const* filename);
+
+    // Indicate that QPDFWriter should create a memory buffer to
+    // contain the final PDF file.  Obtain the memory by calling
+    // getBuffer().
+    void setOutputMemory();
+
+    // Return the buffer object containing the PDF file.  If
+    // setOutputMemory() has been called, this method may be called
+    // exactly one time after write() has returned.  The caller is
+    // responsible for deleting the buffer when done.
+    Buffer* getBuffer();
+
+    // Setting Parameters
 
     // Set the value of object stream mode.  In disable mode, we never
     // generate any object streams.  In preserve mode, we preserve
@@ -177,6 +206,7 @@ class QPDFWriter
 
     enum trailer_e { t_normal, t_lin_first, t_lin_second };
 
+    void init();
     int bytesNeeded(unsigned long n);
     void writeBinary(unsigned long val, unsigned int bytes);
     void writeString(std::string const& str);
@@ -253,6 +283,7 @@ class QPDFWriter
     // clearPipelineStack is called.
     Pipeline* pushPipeline(Pipeline*);
     void activatePipelineStack();
+    void initializePipelineStack(Pipeline *);
 
     // Calls finish on the current pipeline and pops the pipeline
     // stack until the top of stack is a previous active top of stack,
@@ -269,6 +300,8 @@ class QPDFWriter
     char const* filename;
     FILE* file;
     bool close_file;
+    Pl_Buffer* buffer_pipeline;
+    Buffer* output_buffer;
     bool normalize_content_set;
     bool normalize_content;
     bool stream_data_mode_set;

libqpdf/QPDFWriter.cc

@@ -4,7 +4,6 @@
 #include <qpdf/Pl_StdioFile.hh>
 #include <qpdf/Pl_Count.hh>
 #include <qpdf/Pl_Discard.hh>
-#include <qpdf/Pl_Buffer.hh>
 #include <qpdf/Pl_RC4.hh>
 #include <qpdf/Pl_AES_PDF.hh>
 #include <qpdf/Pl_Flate.hh>
@@ -21,32 +20,65 @@
 
 #include <stdlib.h>
 
-QPDFWriter::QPDFWriter(QPDF& pdf, char const* filename) :
-    pdf(pdf),
-    filename(filename),
-    file(0),
-    close_file(false),
-    normalize_content_set(false),
-    normalize_content(false),
-    stream_data_mode_set(false),
-    stream_data_mode(qpdf_s_compress),
-    qdf_mode(false),
-    static_id(false),
-    suppress_original_object_ids(false),
-    direct_stream_lengths(true),
-    encrypted(false),
-    preserve_encryption(true),
-    linearized(false),
-    object_stream_mode(qpdf_o_preserve),
-    encrypt_metadata(true),
-    encrypt_use_aes(false),
-    encryption_dict_objid(0),
-    next_objid(1),
-    cur_stream_length_id(0),
-    cur_stream_length(0),
-    added_newline(false),
-    max_ostream_index(0)
+QPDFWriter::QPDFWriter(QPDF& pdf) :
+    pdf(pdf)
 {
+    init();
+}
+
+QPDFWriter::QPDFWriter(QPDF& pdf, char const* filename) :
+    pdf(pdf)
+{
+    init();
+    setOutputFilename(filename);
+}
+
+void
+QPDFWriter::init()
+{
+    filename = 0;
+    file = 0;
+    close_file = false;
+    buffer_pipeline = 0;
+    output_buffer = 0;
+    normalize_content_set = false;
+    normalize_content = false;
+    stream_data_mode_set = false;
+    stream_data_mode = qpdf_s_compress;
+    qdf_mode = false;
+    static_id = false;
+    suppress_original_object_ids = false;
+    direct_stream_lengths = true;
+    encrypted = false;
+    preserve_encryption = true;
+    linearized = false;
+    object_stream_mode = qpdf_o_preserve;
+    encrypt_metadata = true;
+    encrypt_use_aes = false;
+    encryption_dict_objid = 0;
+    next_objid = 1;
+    cur_stream_length_id = 0;
+    cur_stream_length = 0;
+    added_newline = false;
+    max_ostream_index = 0;
+}
+
+QPDFWriter::~QPDFWriter()
+{
+    if (file && close_file)
+    {
+	fclose(file);
+    }
+    if (output_buffer)
+    {
+	delete output_buffer;
+    }
+}
+
+void
+QPDFWriter::setOutputFilename(char const* filename)
+{
+    this->filename = filename;
     if (filename == 0)
     {
 	this->filename = "standard output";
@@ -61,19 +93,25 @@ QPDFWriter::QPDFWriter(QPDF& pdf, char const* filename) :
 				    fopen(filename, "wb+"));
 	close_file = true;
     }
-    Pipeline* p = new Pl_StdioFile("qdf output", file);
+    Pipeline* p = new Pl_StdioFile("qpdf output", file);
     to_delete.push_back(p);
-    pipeline = new Pl_Count("qdf count", p);
-    to_delete.push_back(pipeline);
-    pipeline_stack.push_back(pipeline);
+    initializePipelineStack(p);
 }
 
-QPDFWriter::~QPDFWriter()
+void
+QPDFWriter::setOutputMemory()
 {
-    if (file && close_file)
-    {
-	fclose(file);
-    }
+    this->buffer_pipeline = new Pl_Buffer("qpdf output");
+    to_delete.push_back(this->buffer_pipeline);
+    initializePipelineStack(this->buffer_pipeline);
+}
+
+Buffer*
+QPDFWriter::getBuffer()
+{
+    Buffer* result = this->output_buffer;
+    this->output_buffer = 0;
+    return result;
 }
 
 void
@@ -565,6 +603,14 @@ QPDFWriter::pushPipeline(Pipeline* p)
     return p;
 }
 
+void
+QPDFWriter::initializePipelineStack(Pipeline *p)
+{
+    this->pipeline = new Pl_Count("qpdf count", p);
+    to_delete.push_back(this->pipeline);
+    this->pipeline_stack.push_back(this->pipeline);
+}
+
 void
 QPDFWriter::activatePipelineStack()
 {
@@ -1503,6 +1549,8 @@ QPDFWriter::generateObjectStreams()
 void
 QPDFWriter::write()
 {
+    // XXX Check output
+
     // Do preliminary setup
 
     if (this->linearized)
@@ -1656,6 +1704,11 @@ QPDFWriter::write()
 	fclose(this->file);
     }
     this->file = 0;
+    if (this->buffer_pipeline)
+    {
+	this->output_buffer = this->buffer_pipeline->getBuffer();
+	this->buffer_pipeline = 0;
+    }
 }
 
 void

qpdf/test_driver.cc

@@ -584,10 +584,18 @@ void runtest(int n, char const* filename)
 		      << std::endl;
 	}
 
-	QPDFWriter w(pdf, "a.pdf");
+	// Exercise writing to memory buffer
+	QPDFWriter w(pdf);
+	w.setOutputMemory();
 	w.setStaticID(true);
 	w.setStreamDataMode(qpdf_s_preserve);
 	w.write();
+	Buffer* b = w.getBuffer();
+	FILE* f = QUtil::fopen_wrapper(std::string("open a.pdf"),
+				       fopen("a.pdf", "wb"));
+	fwrite(b->getBuffer(), b->getSize(), 1, f);
+	fclose(f);
+	delete b;
     }
     else
     {