allow output to stdout -- Timo Stripf

git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk/program@1114 a5681a0c-68f1-0310-ab6d-d61299d08faa

diff --git a/src/rrd_graph.c b/src/rrd_graph.c
index e838121..f71f6dc 100644 (file)
--- a/src/rrd_graph.c
+++ b/src/rrd_graph.c
@@ -1971,6 +1971,10 @@ double frexp10(
     return mnt;
 }
 
+/* from http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm */
+/* yes we are loosing precision by doing tos with floats instead of doubles
+   but it seems more stable this way. */
+
 static int AlmostEqual2sComplement(
     float A,
     float B,
@@ -2844,9 +2848,17 @@ int graph_size_location(
     return 0;
 }
 
-/* from http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm */
-/* yes we are loosing precision by doing tos with floats instead of doubles
-   but it seems more stable this way. */
+
+
+static cairo_status_t cairo_write_func_file(
+       void *closure,
+       const unsigned char *data,
+       unsigned int length)
+{
+       if (fwrite(data, length, 1, closure) != 1)
+               return CAIRO_STATUS_WRITE_ERROR;
+       return CAIRO_STATUS_SUCCESS;
+}
 
 
 /* draw that picture thing ... */
@@ -3276,11 +3288,20 @@ int graph_paint(
 
     switch (im->imgformat) {
     case IF_PNG:
-        if (cairo_surface_write_to_png(im->surface, im->graphfile) !=
-            CAIRO_STATUS_SUCCESS) {
-            rrd_set_error("Could not save png to '%s'", im->graphfile);
-            return 1;
-        }
+               {
+                       cairo_status_t status;
+               
+                       if (strcmp(im->graphfile, "-") == 0) {
+               status = cairo_surface_write_to_png_stream(im->surface, &cairo_write_func_file, (void*)stdout);
+                       } else {
+               status = cairo_surface_write_to_png(im->surface, im->graphfile);
+                       }
+               
+               if (status != CAIRO_STATUS_SUCCESS) {
+               rrd_set_error("Could not save png to '%s'", im->graphfile);
+                   return 1;
+               }
+               }
         break;
     default:
         cairo_show_page(im->cr);