skpdiff: add ability to write the diff scores in a csv file (one line per pair of diff images, with…

experimental/skpdiff/main.cpp

Index: experimental/skpdiff/main.cpp
===================================================================
--- experimental/skpdiff/main.cpp	(revision 10191)
+++ experimental/skpdiff/main.cpp	(working copy)
@@ -32,6 +32,7 @@
 DEFINE_string2(patterns, p, "", "Use two patterns to compare images: <baseline> <test>");
 DEFINE_string2(output, o, "skpdiff_output.json", "Writes the output of these diffs to output: <output>");
 DEFINE_bool(jsonp, true, "Output JSON with padding");
+DEFINE_string(csv, "", "Writes the output of these diffs to a csv file");
 
 #if SK_SUPPORT_OPENCL
 /// A callback for any OpenCL errors
@@ -169,6 +170,13 @@
         }
     }
 
+    if (!FLAGS_csv.isEmpty()) {
+        if (1 != FLAGS_csv.count()) {
+            SkDebugf("csv flag expects one argument: <csv file>\n");
+            return 1;
+        }
+    }
+
     SkDiffContext ctx;
     ctx.setDiffers(chosenDiffers);