render_pictures: add --mismatchPath flag

tools/image_expectations.cpp

Index: tools/image_expectations.cpp
diff --git a/tools/image_expectations.cpp b/tools/image_expectations.cpp
index 9b180da5feded20795c7e900a8cd2ff7cf9159c5..24c91755415d62e4e292cbd72d0af0b76f4045cc 100644
--- a/tools/image_expectations.cpp
+++ b/tools/image_expectations.cpp
@@ -104,7 +104,7 @@ namespace sk_tools {
     }
 
     void ImageResultsAndExpectations::add(const char *sourceName, const char *fileName,
-                                  const ImageDigest &digest, const int *tileNumber) {
+                                          const ImageDigest &digest, const int *tileNumber) {
         // Get expectation, if any.
         Json::Value expectedImage;
         if (!fExpectedResults.isNull()) {
@@ -146,6 +146,29 @@ namespace sk_tools {
         }
     }
 
+    bool ImageResultsAndExpectations::matchesExpectation(const char *sourceName,
+                                                         const ImageDigest &digest,
+                                                         const int *tileNumber) {
+        if (fExpectedResults.isNull()) {
+            return false;
+        }
+
+        Json::Value expectedImage;
+        if (NULL == tileNumber) {
+            expectedImage = fExpectedResults[sourceName][kJsonKey_Source_WholeImage];
+        } else {
+            expectedImage = fExpectedResults[sourceName][kJsonKey_Source_TiledImages][*tileNumber];
+        }
+        if (expectedImage.isNull()) {
+            return false;
+        }
+
+        Json::Value actualChecksumAlgorithm = digest.getHashType().c_str();
+        Json::Value actualChecksumValue = Json::UInt64(digest.getHashValue());
+        return ((actualChecksumAlgorithm == expectedImage[kJsonKey_Image_ChecksumAlgorithm]) &&
+                (actualChecksumValue == expectedImage[kJsonKey_Image_ChecksumValue]));
+    }
+
     void ImageResultsAndExpectations::writeToFile(const char *filename) const {
         Json::Value header;
         header[kJsonKey_Header_Type] = kJsonValue_Header_Type;