rebaseline_server: use just skpdiff, not Python Image Library

tools/skpdiff/skpdiff_main.cpp

Index: tools/skpdiff/skpdiff_main.cpp
diff --git a/tools/skpdiff/skpdiff_main.cpp b/tools/skpdiff/skpdiff_main.cpp
index b1bf9173c7c5fad03e6d30aa23f12f17d3a34afe..178ceea4593adbf11c0a816cce5eab5c04a55bf2 100644
--- a/tools/skpdiff/skpdiff_main.cpp
+++ b/tools/skpdiff/skpdiff_main.cpp
@@ -37,10 +37,12 @@ DEFINE_bool2(list, l, false, "List out available differs");
 DEFINE_string2(differs, d, "", "The names of the differs to use or all of them by default");
 DEFINE_string2(folders, f, "", "Compare two folders with identical subfile names: <baseline folder> <test folder>");
 DEFINE_string2(patterns, p, "", "Use two patterns to compare images: <baseline> <test>");
-DEFINE_string2(output, o, "", "Writes the output of these diffs to output: <output>");
-DEFINE_string(alphaDir, "", "Writes the alpha mask of these diffs to output: <output>");
+DEFINE_string2(output, o, "", "Writes a JSON summary of these diffs to file: <filepath>");
+DEFINE_string(alphaDir, "", "If the differ can generate an alpha mask, write it into directory: <dirpath>");
+DEFINE_string(rgbDiffDir, "", "If the differ can generate an image showing the RGB diff at each pixel, write it into directory: <dirpath>");
+DEFINE_string(whiteDiffDir, "", "If the differ can generate an image showing every changed pixel in white, write it into directory: <dirpath>");
 DEFINE_bool(jsonp, true, "Output JSON with padding");
-DEFINE_string(csv, "", "Writes the output of these diffs to a csv file");
+DEFINE_string(csv, "", "Writes the output of these diffs to a csv file: <filepath>");
 DEFINE_int32(threads, -1, "run N threads in parallel [default is derived from CPUs available]");
 
 #if SK_SUPPORT_OPENCL
@@ -193,12 +195,30 @@ int tool_main(int argc, char * argv[]) {
             return 1;
         }
     }
+    if (!FLAGS_rgbDiffDir.isEmpty()) {
+        if (1 != FLAGS_rgbDiffDir.count()) {
+            SkDebugf("rgbDiffDir flag expects one argument: <directory>\n");
+            return 1;
+        }
+    }
+    if (!FLAGS_whiteDiffDir.isEmpty()) {
+        if (1 != FLAGS_whiteDiffDir.count()) {
+            SkDebugf("whiteDiffDir flag expects one argument: <directory>\n");
+            return 1;
+        }
+    }
 
     SkDiffContext ctx;
     ctx.setDiffers(chosenDiffers);
 
     if (!FLAGS_alphaDir.isEmpty()) {
-        ctx.setDifferenceDir(SkString(FLAGS_alphaDir[0]));
+        ctx.setAlphaMaskDir(SkString(FLAGS_alphaDir[0]));
+    }
+    if (!FLAGS_rgbDiffDir.isEmpty()) {
+        ctx.setRgbDiffDir(SkString(FLAGS_rgbDiffDir[0]));
+    }
+    if (!FLAGS_whiteDiffDir.isEmpty()) {
+        ctx.setWhiteDiffDir(SkString(FLAGS_whiteDiffDir[0]));
     }
 
     if (FLAGS_threads >= 0) {