Make SkSHA1 and SkM5 use common SkDigestHash result type

gm/gmmain.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /*
  * Code for the "gm" (Golden Master) rendering comparison tool.
  *
@@ skipping 696 matching lines @@
      *        results to the JSON summary.  (This is so that we will always
      *        report errors across rendering modes, such as pipe vs tiled.
      *        See https://codereview.chromium.org/13650002/ )
      */
     ErrorCombination compare_to_expectations(Expectations expectations,
                                              const SkBitmap& actualBitmap,
                                              const SkString& baseNameString,
                                              const char renderModeDescriptor[],
                                              bool addToJsonSummary) {
         ErrorCombination errors;
-        SkHashDigest actualBitmapHash;
-        // TODO(epoger): Better handling for error returned by ComputeDigest()?
-        // For now, we just report a digest of 0 in error cases, like before.
+        BITMAP_HASH_TYPE actualBitmapHash;
         if (!SkBitmapHasher::ComputeDigest(actualBitmap, &actualBitmapHash)) {

[epoger, 2013/04/18 18:07:13]

Unlike SkData objects, SkHashDigest objects are mutable.  That allows
ComputeDigest() to "fill in" the result in the &actualBitmapHash parameter, and
return the "success" boolean separately.

If ComputeDigest() returned its results as an SkData object, I guess it would
return that SkData object instead of a bool... but then, how would it signal
errors?  Maybe by returning an empty SkData object?  Or returning SkData *
instead of SkData, and NULL in case of an error?

I guess those approaches would work... any thoughts on what might be preferable?

-            actualBitmapHash = 0;
+            // TODO(epoger): Better handling for error returned by ComputeDigest()?
+            // For now, we just leave actualBitmapHash empty.
         }
         SkString completeNameString = baseNameString;
         completeNameString.append(renderModeDescriptor);
         const char* completeName = completeNameString.c_str();
 
         if (expectations.empty()) {
             errors.add(kMissingExpectations_ErrorType);
         } else if (!expectations.match(actualBitmapHash)) {
             addToJsonSummary = true;
             // The error mode we record depends on whether this was running
@@ skipping 29 matching lines @@
         }
 
         return errors;
     }
 
     /**
      * Add this result to the appropriate JSON collection of actual results,
      * depending on status.
      */
     void add_actual_results_to_json_summary(const char testName[],
-                                            const SkHashDigest& actualBitmapHash,
+                                            const BITMAP_HASH_TYPE& actualBitmapHash,
                                             ErrorCombination result,
                                             bool ignoreFailure) {
         Json::Value actualResults;
         actualResults[kJsonKey_ActualResults_AnyStatus_Checksum] =
             asJsonValue(actualBitmapHash);
         if (result.isEmpty()) {
             this->fJsonActualResults_Succeeded[testName] = actualResults;
         } else {
             if (ignoreFailure) {
                 // TODO: Once we have added the ability to compare
@@ skipping 75 matching lines @@
              * hash digest of actualBitmap, which *has* been run through
              * force_all_opaque().
              * See comments above complete_bitmap() for more detail.
              */
             Expectations expectations = expectationsSource->get(name.c_str());
             errors.add(compare_to_expectations(expectations, actualBitmap,
                                                name, "", true));
         } else {
             // If we are running without expectations, we still want to
             // record the actual results.
-            SkHashDigest actualBitmapHash;
-            // TODO(epoger): Better handling for error returned by ComputeDigest()?
-            // For now, we just report a digest of 0 in error cases, like before.
+            BITMAP_HASH_TYPE actualBitmapHash;
             if (!SkBitmapHasher::ComputeDigest(actualBitmap, &actualBitmapHash)) {
-                actualBitmapHash = 0;
+                // TODO(epoger): Better handling for error returned by ComputeDigest()?
+                // For now, we just leave actualBitmapHash empty.
             }
             add_actual_results_to_json_summary(name.c_str(), actualBitmapHash,
                                                ErrorCombination(kMissingExpectations_ErrorType),
                                                false);
             RecordTestResults(ErrorCombination(kMissingExpectations_ErrorType), name, "");
         }
 
         // TODO: Consider moving this into compare_to_expectations(),
         // similar to fMismatchPath... for now, we don't do that, because
         // we don't want to write out the actual bitmaps for all
@@ skipping 1032 matching lines @@
     if (FLAGS_forceBWtext) {
         canvas->setDrawFilter(SkNEW(BWTextDrawFilter))->unref();
     }
 }
 
 #if !defined(SK_BUILD_FOR_IOS) && !defined(SK_BUILD_FOR_NACL)
 int main(int argc, char * const argv[]) {
     return tool_main(argc, (char**) argv);
 }
 #endif