Modify skpdiff to write diffs directly to provided directories

tools/skpdiff/SkDiffContext.cpp

Index: tools/skpdiff/SkDiffContext.cpp
diff --git a/tools/skpdiff/SkDiffContext.cpp b/tools/skpdiff/SkDiffContext.cpp
index ea44c90da1e2efe22077bbc42c6b1d73a1353d34..8e193419a05c1c614bfab24c5d69db5bd46cf5f2 100644
--- a/tools/skpdiff/SkDiffContext.cpp
+++ b/tools/skpdiff/SkDiffContext.cpp
@@ -18,6 +18,9 @@
 #include "SkImageDiffer.h"
 #include "skpdiff_util.h"
 
+#include <string>
+#include <algorithm>
+
 SkDiffContext::SkDiffContext() {
     fDiffers = NULL;
     fDifferCount = 0;
@@ -48,6 +51,10 @@ void SkDiffContext::setWhiteDiffDir(const SkString& path) {
     }
 }
 
+void SkDiffContext::setLongNames(const bool useLongNames) {
+    longNames = useLongNames;
+}
+
 void SkDiffContext::setDiffers(const SkTDArray<SkImageDiffer*>& differs) {
     // Delete whatever the last array of differs was
     if (NULL != fDiffers) {
@@ -79,6 +86,20 @@ static SkString get_common_prefix(const SkString& a, const SkString& b) {
     }
 }
 
+static SkString sanitize_name(const SkString& str) {
+    std::string result = std::string(str.c_str());
+    std::replace(result.begin(), result.end(), '.', '_');
+
+    return SkString(result.c_str());
+}
+
+static SkString get_combined_name(const SkString& a, const SkString& b) {
+    SkString result = a;
+    result.append("-vs-");
+    result.append(b);
+    return sanitize_name(result);
+}
+
 void SkDiffContext::addDiff(const char* baselinePath, const char* testPath) {
     // Load the images at the paths
     SkBitmap baselineBitmap;
@@ -100,7 +121,13 @@ void SkDiffContext::addDiff(const char* baselinePath, const char* testPath) {
     // compute the common name
     SkString baseName = SkOSPath::Basename(baselinePath);
     SkString testName = SkOSPath::Basename(testPath);
-    newRecord->fCommonName = get_common_prefix(baseName, testName);
+
+    if (longNames) {
+        newRecord->fCommonName = get_combined_name(baseName, testName);
+    } else {
+        newRecord->fCommonName = get_common_prefix(baseName, testName);
+    }
+    newRecord->fCommonName.append(".png");
 
     newRecord->fBaselinePath = baselinePath;
     newRecord->fTestPath = testPath;