[gegl] tools: Allow passing the max permitted difference to gegl-imgcmp

[Mukund Sivaraman <muks src gnome org>]

commit de8d1a187980a1100ff73d5665bae47d00a97428
Author: Mukund Sivaraman <muks banu com>
Date:   Sat Dec 20 17:12:30 2014 +0530

    tools: Allow passing the max permitted difference to gegl-imgcmp

 tools/gegl-imgcmp.c |   26 ++++++++++++++++++++++----
 1 files changed, 22 insertions(+), 4 deletions(-)
---
diff --git a/tools/gegl-imgcmp.c b/tools/gegl-imgcmp.c
index daf872a..c312815 100644
--- a/tools/gegl-imgcmp.c
+++ b/tools/gegl-imgcmp.c
@@ -1,7 +1,11 @@
 #include <gegl.h>
+#include <stdlib.h>
+#include <errno.h>
 #include <math.h>
 #include <string.h>
 
+#define DEFAULT_ERROR_DIFFERENCE 1.5
+
 #define SQR(x) ((x) * (x))
 
 typedef enum {
@@ -18,19 +22,33 @@ main (gint    argc,
   GeglNode      *gegl, *imgA, *imgB, *comparison;
   GeglRectangle  boundsA, boundsB;
   gdouble        max_diff, avg_diff_wrong, avg_diff_total;
+  gdouble        error_diff;
   gint           wrong_pixels, total_pixels;
 
   gegl_init (&argc, &argv);
 
-  if (argc != 3)
+  if ((argc != 3) && (argc != 4))
     {
       g_print ("This is simple image difference detection tool for use in regression testing.\n"
                "Exit code is non zero if images are different, if they are equal"
                "the output will contain the string identical.\n");
-      g_print ("Usage: %s <imageA> <imageB>\n", argv[0]);
+      g_print ("Usage: %s <imageA> <imageB> [<error-difference>]\n", argv[0]);
       return ERROR_WRONG_ARGUMENTS;
     }
 
+  error_diff = DEFAULT_ERROR_DIFFERENCE;
+  if (argc == 4)
+    {
+      gdouble t;
+      char *end;
+
+      end = NULL;
+      errno = 0;
+      t = strtod(argv[3], &end);
+      if ((errno != ERANGE) && (end != argv[3]) && (end != NULL) && (*end == 0))
+        error_diff = t;
+    }
+
   gegl = gegl_node_new ();
   imgA = gegl_node_new_child (gegl,
                               "operation", "gegl:load",
@@ -94,13 +112,13 @@ main (gint    argc,
           /*gegl_graph (sink=gegl_node ("gegl:png-save",
                                       "path", debug_path, NULL,
                                       gegl_node ("gegl:buffer-source", "buffer", debug_buf, NULL)));*/
-          if (max_diff > 1.5)
+          if (max_diff > error_diff)
             return ERROR_PIXELS_DIFFERENT;
         }
       if (strstr (argv[2], "broken"))
         g_print ("because the test is expected to fail ");
       else
-        g_print ("because the error is small ");
+        g_print ("because the error is smaller than %0.2f ", error_diff);
       g_print ("we'll say ");
     }