From 31966e6ef45bc52d64abf361c61d51b745c9b193 Mon Sep 17 00:00:00 2001
From: "Emden R. Gansner" <erg@alum.mit.edu>
Date: Sun, 26 Jan 2014 19:38:09 -0500
Subject: [PATCH] Reset gvc->write_fn in gv.renderchannel and gv.renderresult
 so that later calls to gv.render, which requires the default I/O, work.

---
 tclpkg/gv/gv.cpp          | 3 +++
 tclpkg/gv/gv_dummy_init.c | 1 +
 tclpkg/gv/gv_php_init.c   | 1 +
 tclpkg/gv/gv_tcl_init.c   | 2 ++
 4 files changed, 7 insertions(+)

diff --git a/tclpkg/gv/gv.cpp b/tclpkg/gv/gv.cpp
index a8459f843..cf98d4326 100644
--- a/tclpkg/gv/gv.cpp
+++ b/tclpkg/gv/gv.cpp
@@ -18,6 +18,7 @@
 extern "C" {
 extern void gv_string_writer_init(GVC_t *gvc);
 extern void gv_channel_writer_init(GVC_t *gvc);
+extern void gv_writer_reset(GVC_t *gvc);
 }
 
 #define agfindattr(x,s) agattrsym(x,s)
@@ -850,6 +851,7 @@ bool renderchannel(Agraph_t *g, const char *format, const char *channelname)
         return false;
     gv_channel_writer_init(gvc);
     err = gvRender(gvc, g, format, (FILE*)channelname);
+    gv_writer_reset (gvc);   /* Reset to default */
     return (! err);
 }
 
@@ -873,6 +875,7 @@ void renderresult(Agraph_t *g, const char *format, char *outdata)
         return;
     gv_string_writer_init(gvc);
     err = gvRender(gvc, g, format, (FILE*)outdata);
+    gv_writer_reset (gvc);   /* Reset to default */
 }
 
 // render to a malloc'ed data string, to be free'd by caller.
diff --git a/tclpkg/gv/gv_dummy_init.c b/tclpkg/gv/gv_dummy_init.c
index 096f2a970..dfdf2b986 100644
--- a/tclpkg/gv/gv_dummy_init.c
+++ b/tclpkg/gv/gv_dummy_init.c
@@ -2,3 +2,4 @@
 
 void gv_string_writer_init (GVC_t *gvc) {}
 void gv_channel_writer_init (GVC_t *gvc) {}
+void gv_writer_reset (GVC_t *gvc) {}
diff --git a/tclpkg/gv/gv_php_init.c b/tclpkg/gv/gv_php_init.c
index a56b273b6..57503cfc7 100644
--- a/tclpkg/gv/gv_php_init.c
+++ b/tclpkg/gv/gv_php_init.c
@@ -43,3 +43,4 @@ void gv_channel_writer_init(GVC_t *gvc)
     gvc->write_fn = gv_channel_writer;
 }
 
+void gv_writer_reset (GVC_t *gvc) {gvc->write_fn = NULL;}
diff --git a/tclpkg/gv/gv_tcl_init.c b/tclpkg/gv/gv_tcl_init.c
index dca5fa746..9940540a5 100644
--- a/tclpkg/gv/gv_tcl_init.c
+++ b/tclpkg/gv/gv_tcl_init.c
@@ -37,3 +37,5 @@ void gv_channel_writer_init(GVC_t *gvc)
 {
     gvc->write_fn = gv_channel_writer;
 }
+
+void gv_writer_reset (GVC_t *gvc) {gvc->write_fn = NULL;}
-- 
2.40.0