From 6ee49770e066ed045984e31c527c0e8f615f802e Mon Sep 17 00:00:00 2001
From: =?utf8?q?Jos=C3=A9=20Fonseca?= <jose.r.fonseca@gmail.com>
Date: Mon, 5 Sep 2011 23:18:41 +0100
Subject: [PATCH] Embedded the call no in PNM images as a comment.

---
 glretrace_main.cpp | 4 +++-
 image.hpp          | 6 +++---
 image_pnm.cpp      | 6 +++++-
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/glretrace_main.cpp b/glretrace_main.cpp
index 56ee763..3a90092 100644
--- a/glretrace_main.cpp
+++ b/glretrace_main.cpp
@@ -131,7 +131,9 @@ void snapshot(unsigned call_no) {
 
     if (snapshot_prefix) {
         if (snapshot_prefix[0] == '-' && snapshot_prefix[1] == 0) {
-            src->writePNM(std::cout);
+            char comment[21];
+            snprintf(comment, sizeof comment, "%u", call_no);
+            src->writePNM(std::cout, comment);
         } else {
             char filename[PATH_MAX];
             snprintf(filename, sizeof filename, "%s%010u.png", snapshot_prefix, call_no);
diff --git a/image.hpp b/image.hpp
index 44fc4f4..dc53ec9 100644
--- a/image.hpp
+++ b/image.hpp
@@ -83,14 +83,14 @@ public:
 
     bool writeBMP(const char *filename) const;
 
-    void writePNM(std::ostream &os) const;
+    void writePNM(std::ostream &os, const char *comment = NULL) const;
 
-    inline bool writePNM(const char *filename) const {
+    inline bool writePNM(const char *filename, const char *comment = NULL) const {
         std::ofstream os(filename, std::ofstream::binary);
         if (!os) {
             return false;
         }
-        writePNM(os);
+        writePNM(os, comment);
         return true;
     }
 
diff --git a/image_pnm.cpp b/image_pnm.cpp
index 6625f3d..44ae624 100644
--- a/image_pnm.cpp
+++ b/image_pnm.cpp
@@ -35,12 +35,16 @@ namespace Image {
 
 /**
  * http://en.wikipedia.org/wiki/Netpbm_format
+ * http://netpbm.sourceforge.net/doc/ppm.html
  */
 void
-Image::writePNM(std::ostream &os) const {
+Image::writePNM(std::ostream &os, const char *comment) const {
     assert(channels == 1 || channels >= 3);
 
     os << (channels == 1 ? "P5" : "P6") << "\n";
+    if (comment) {
+        os << "#" << comment << "\n";
+    }
     os << width << " " << height << "\n";
     os << "255" << "\n";
 
-- 
2.43.0