Add progress reporting for QPDFWriter (fixes #200)

ChangeLog

@@ -1,5 +1,11 @@
 2018-06-22  Jay Berkenbilt  <ejb@ql.org>
 
+	* Add progress reporting to QPDFWriter. Programmatically, you can
+	register a progress reporter with registerProgressReporter(). From
+	the command line, passing --progress will give progress indicators
+	in increments of no less than 1% as output files are written.
+	Fixes #200.
+
 	* Add new method QPDF::getObjectCount(). This gives an approximate
 	(upper bound) account of objects in the QPDF object.
 

include/qpdf/QPDFWriter.hh

@@ -76,6 +76,19 @@ class QPDFWriter
     QPDF_DLL
     ~QPDFWriter();
 
+    class ProgressReporter
+    {
+      public:
+        virtual ~ProgressReporter()
+        {
+        }
+
+        // This method is called with a value from 0 to 100 to
+        // indicate approximate progress through the write process.
+        // See registerProgressReporter.
+        virtual void reportProgress(int) = 0;
+    };
+
     // 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.
@@ -386,6 +399,11 @@ class QPDFWriter
     QPDF_DLL
     void setPCLm(bool);
 
+    // If you want to be notified of progress, derive a class from
+    // ProgressReporter and override the reportProgress method.
+    QPDF_DLL
+    void registerProgressReporter(PointerHolder<ProgressReporter>);
+
     QPDF_DLL
     void write();
 
@@ -450,6 +468,7 @@ class QPDFWriter
     void prepareFileForWrite();
     void enqueueObjectsStandard();
     void enqueueObjectsPCLm();
+    void indicateProgress(bool decrement, bool finished);
     void writeStandard();
     void writeLinearized();
     void enqueuePart(std::vector<QPDFObjectHandle>& part);
@@ -583,6 +602,12 @@ class QPDFWriter
         std::string lin_pass1_filename;
         std::map<int, int> obj_renumber_no_gen;
         std::map<int, int> object_to_object_stream_no_gen;
+
+        // For progress reporting
+        PointerHolder<ProgressReporter> progress_reporter;
+        int events_expected;
+        int events_seen;
+        int next_progress_report;
     };
 
     // Keep all member variables inside the Members object, which we

libqpdf/QPDFWriter.cc

@@ -62,7 +62,10 @@ QPDFWriter::Members::Members(QPDF& pdf) :
     added_newline(false),
     max_ostream_index(0),
     deterministic_id(false),
-    md5_pipeline(0)
+    md5_pipeline(0),
+    events_expected(0),
+    events_seen(0),
+    next_progress_report(0)
 {
 }
 
@@ -1856,6 +1859,10 @@ QPDFWriter::writeObjectStream(QPDFObjectHandle object)
 	    if (pass == 1)
 	    {
 		offsets.push_back(this->m->pipeline->getCount());
+                // To avoid double-counting objects being written in
+                // object streams for progress reporting, decrement in
+                // pass 1.
+                indicateProgress(true, false);
 	    }
 	    writeObject(this->m->pdf.getObjectByObjGen(obj), count);
 
@@ -1929,6 +1936,7 @@ QPDFWriter::writeObject(QPDFObjectHandle object, int object_stream_index)
 	return;
     }
 
+    indicateProgress(false, false);
     int new_id = this->m->obj_renumber[old_og];
     if (this->m->qdf_mode)
     {
@@ -2253,6 +2261,7 @@ QPDFWriter::prepareFileForWrite()
 	    {
 		continue;
 	    }
+            indicateProgress(false, false);
 	    visited.insert(node.getObjectID());
 	}
 
@@ -2500,6 +2509,15 @@ QPDFWriter::write()
 	setMinimumPDFVersion("1.5");
     }
 
+    // Set up progress reporting. We spent about equal amounts of time
+    // preparing and writing one pass. To get a rough estimate of
+    // progress, we track handling of indirect objects. For linearized
+    // files, we write two passes. events_expected is an
+    // approximation, but it's good enough for progress reporting,
+    // which is mostly a guess anyway.
+    this->m->events_expected = (
+        this->m->pdf.getObjectCount() * (this->m->linearized ? 3 : 2));
+
     prepareFileForWrite();
 
     if (this->m->linearized)
@@ -2522,6 +2540,7 @@ QPDFWriter::write()
 	this->m->output_buffer = this->m->buffer_pipeline->getBuffer();
 	this->m->buffer_pipeline = 0;
     }
+    indicateProgress(false, true);
 }
 
 void
@@ -3311,6 +3330,45 @@ QPDFWriter::enqueueObjectsPCLm()
     enqueueObject(trailer.getKey("/Root"));
 }
 
+void
+QPDFWriter::indicateProgress(bool decrement, bool finished)
+{
+    if (decrement)
+    {
+        --this->m->events_seen;
+        return;
+    }
+
+    ++this->m->events_seen;
+
+    if (! this->m->progress_reporter.getPointer())
+    {
+        return;
+    }
+
+    if (finished || (this->m->events_seen >= this->m->next_progress_report))
+    {
+        int percentage = (
+            finished
+            ? 100
+            : this->m->next_progress_report == 0
+            ? 0
+            : std::min(99, 1 + ((100 * this->m->events_seen) /
+                                this->m->events_expected)));
+        this->m->progress_reporter->reportProgress(percentage);
+    }
+    while (this->m->events_seen >= this->m->next_progress_report)
+    {
+        this->m->next_progress_report += (this->m->events_expected / 100);
+    }
+}
+
+void
+QPDFWriter::registerProgressReporter(PointerHolder<ProgressReporter> pr)
+{
+    this->m->progress_reporter = pr;
+}
+
 void
 QPDFWriter::writeStandard()
 {

qpdf/qpdf.cc

@@ -60,6 +60,7 @@ struct Options
         decrypt(false),
         split_pages(0),
         verbose(false),
+        progress(false),
         copy_encryption(false),
         encryption_file(0),
         encryption_file_password(0),
@@ -123,6 +124,7 @@ struct Options
     bool decrypt;
     int split_pages;
     bool verbose;
+    bool progress;
     bool copy_encryption;
     char const* encryption_file;
     char const* encryption_file_password;
@@ -204,6 +206,29 @@ class DiscardContents: public QPDFObjectHandle::ParserCallbacks
     virtual void handleEOF() {}
 };
 
+class ProgressReporter: public QPDFWriter::ProgressReporter
+{
+  public:
+    ProgressReporter(char const* filename) :
+        filename(filename)
+    {
+    }
+    virtual ~ProgressReporter()
+    {
+    }
+
+    virtual void reportProgress(int);
+  private:
+    std::string filename;
+};
+
+void
+ProgressReporter::reportProgress(int percentage)
+{
+    std::cout << whoami << ": " << filename << ": write progress: "
+              << percentage << "%" << std::endl;
+}
+
 // Note: let's not be too noisy about documenting the fact that this
 // software purposely fails to enforce the distinction between user
 // and owner passwords.  A user password is sufficient to gain full
@@ -235,6 +260,7 @@ Basic Options\n\
 --help                  show command-line argument help\n\
 --password=password     specify a password for accessing encrypted files\n\
 --verbose               provide additional informational output\n\
+--progress              give progress indicators while writing output\n\
 --linearize             generated a linearized (web optimized) file\n\
 --copy-encryption=file  copy encryption parameters from specified file\n\
 --encryption-file-password=password\n\
@@ -1642,6 +1668,10 @@ static void parse_options(int argc, char* argv[], Options& o)
             {
                 o.verbose = true;
             }
+            else if (strcmp(arg, "progress") == 0)
+            {
+                o.progress = true;
+            }
             else if (strcmp(arg, "deterministic-id") == 0)
             {
                 o.deterministic_id = true;
@@ -2350,6 +2380,10 @@ static void set_writer_options(QPDF& pdf, Options& o, QPDFWriter& w)
         parse_version(o.force_version, version, extension_level);
         w.forcePDFVersion(version, extension_level);
     }
+    if (o.progress && o.outfilename)
+    {
+        w.registerProgressReporter(new ProgressReporter(o.outfilename));
+    }
 }
 
 static void write_outfile(QPDF& pdf, Options& o)