More work to integrate skimage with rebaseline tools.

tools/skimage_main.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.
  */
 
 #include "gm_expectations.h"
 #include "SkBitmap.h"
 #include "SkColorPriv.h"
@@ skipping 13 matching lines @@
 
 DEFINE_string(config, "None", "Preferred config to decode into. [None|8888|565|A8]");
 DEFINE_string(createExpectationsPath, "", "Path to write JSON expectations.");
 DEFINE_string(mismatchPath, "", "Folder to write mismatched images to.");
 DEFINE_string2(readPath, r, "", "Folder(s) and files to decode images. Required.");
 DEFINE_string(readExpectationsPath, "", "Path to read JSON expectations from.");
 DEFINE_bool(reencode, true, "Reencode the images to test encoding.");
 DEFINE_int32(sampleSize, 1, "Set the sampleSize for decoding.");
 DEFINE_bool(skip, false, "Skip writing zeroes.");
 DEFINE_bool(testSubsetDecoding, true, "Test decoding subsets of images.");
+DEFINE_bool(writeChecksumBasedFilenames, false,  "When writing out actual images, use checksum-"
+            "based filenames, as rebaseline.py will use when downloading them from Google Storage");
 DEFINE_string2(writePath, w, "",  "Write rendered images into this directory.");
 
 struct Format {
     SkImageEncoder::Type    fType;
     SkImageDecoder::Format  fFormat;
     const char*             fSuffix;
 };
 
 static const Format gFormats[] = {
     { SkImageEncoder::kBMP_Type, SkImageDecoder::kBMP_Format, ".bmp" },
@@ skipping 34 matching lines @@
 
 static void make_outname(SkString* dst, const char outDir[], const char src[],
                          const char suffix[]) {
     SkString basename = SkOSPath::SkBasename(src);
     dst->set(SkOSPath::SkPathJoin(outDir, basename.c_str()));
     if (!dst->endsWith(suffix)) {
         const char* cstyleDst = dst->c_str();
         const char* dot = strrchr(cstyleDst, '.');
         if (dot != NULL) {
             int32_t index = SkToS32(dot - cstyleDst);
-            dst->remove(index, dst->size() - index);
+            const size_t amountToRemove = dst->size() - index;
+            // Only remove if this is a 4-5 character suffix (including '.').
+            if (amountToRemove == 4 || amountToRemove == 5) {
+                dst->remove(index, amountToRemove);
+            }
         }
         dst->append(suffix);
     }
 }
 
 // Store the names of the filenames to report later which ones failed, succeeded, and were
 // invalid.
 // FIXME: Add more arrays, for more specific types of errors, and make the output simpler.
 // If each array holds one type of error, the output can change from:
 //
@@ skipping 23 matching lines @@
 // For files that are expected to fail.
 static SkTArray<SkString, false> gKnownFailures;
 static SkTArray<SkString, false> gKnownSubsetFailures;
 
 static SkBitmap::Config gPrefConfig(SkBitmap::kNo_Config);
 
 // Expections read from a file specified by readExpectationsPath. The expectations must have been
 // previously written using createExpectationsPath.
 SkAutoTUnref<skiagm::JsonExpectationsSource> gJsonExpectations;
 
-static bool write_bitmap(const char outName[], const SkBitmap& bm) {
-    if (SkImageEncoder::EncodeFile(outName, bm, SkImageEncoder::kPNG_Type, 100)) {
+/**
+ *  Encode the bitmap to a file, written one of two ways, depending on
+ *  FLAGS_writeChecksumBasedFilenames. If true, the final image will be
+ *  written to:
+ *      outDir/hashType/src/digestValue.png
+ *  If false, the final image will be written out to:
+ *      outDir/src.png
+ *  The function returns whether the file was successfully written.
+ */
+static bool write_bitmap(const char outDir[], const char src[],
+                         const skiagm::BitmapAndDigest& bitmapAndDigest) {
+    SkString filename;
+    if (FLAGS_writeChecksumBasedFilenames) {
+        // First create the directory for the hashtype.
+        const SkString hashType = bitmapAndDigest.fDigest.getHashType();
+        const SkString hashDir = SkOSPath::SkPathJoin(outDir, hashType.c_str());
+        if (!sk_mkdir(hashDir.c_str())) {
+            return false;
+        }
+
+        // Now create the name of the folder specific to this image.
+        SkString basename = SkOSPath::SkBasename(src);
+        const SkString imageDir = SkOSPath::SkPathJoin(hashDir.c_str(), basename.c_str());
+        if (!sk_mkdir(imageDir.c_str())) {
+            return false;
+        }
+
+        // Name the file <digest>.png
+        SkString checksumBasedName = bitmapAndDigest.fDigest.getDigestValue();
+        checksumBasedName.append(".png");
+
+        filename = SkOSPath::SkPathJoin(imageDir.c_str(), checksumBasedName.c_str());
+    } else {
+        make_outname(&filename, outDir, src, ".png");
+    }
+
+    const SkBitmap& bm = bitmapAndDigest.fBitmap;
+    if (SkImageEncoder::EncodeFile(filename.c_str(), bm, SkImageEncoder::kPNG_Type, 100)) {
         return true;
     }
 
     if (bm.config() == SkBitmap::kARGB_8888_Config) {
         // First attempt at encoding failed, and the bitmap was already 8888. Making
         // a copy is not going to help.
         return false;
     }
 
     // Encoding failed. Copy to 8888 and try again.
     SkBitmap bm8888;
     if (!bm.copyTo(&bm8888, SkBitmap::kARGB_8888_Config)) {
         return false;
     }
-    return SkImageEncoder::EncodeFile(outName, bm8888, SkImageEncoder::kPNG_Type, 100);
+    return SkImageEncoder::EncodeFile(filename.c_str(), bm8888, SkImageEncoder::kPNG_Type, 100);
 }
 
 /**
  *  Return a random SkIRect inside the range specified.
  *  @param rand Random number generator.
  *  @param maxX Exclusive maximum x-coordinate. SkIRect's fLeft and fRight will be
  *      in the range [0, maxX)
  *  @param maxY Exclusive maximum y-coordinate. SkIRect's fTop and fBottom will be
  *      in the range [0, maxY)
  *  @return SkIRect Non-empty, non-degenerate rectangle.
@@ skipping 23 matching lines @@
             rect.fTop--;
         } else {
             rect.fBottom++;
             // Again, this must be in range.
             SkASSERT(rect.fBottom < maxY);
         }
     }
     return rect;
 }
 
+/**
+ *  Return a string which includes the name of the file and the pref config,
+ *  matching the pattern of gm_json.py's IMAGE_FILENAME_PATTERN: "name_config.png"
+ */
+static SkString create_json_key(const char* filename) {
+    SkASSERT(FLAGS_config.count() == 1);
+    return SkStringPrintf("%s_%s.png", filename, FLAGS_config[0]);
+}
+
 // Stored expectations to be written to a file if createExpectationsPath is specified.
 static Json::Value gExpectationsToWrite;
 
 /**
- *  If expectations are to be recorded, record the bitmap expectations into global
- *  expectations array.
- */
-static void write_expectations(const SkBitmap& bitmap, const char* filename) {
-    if (!FLAGS_createExpectationsPath.isEmpty()) {
-        // Creates an Expectations object, and add it to the list to write.
-        skiagm::Expectations expectation(bitmap);
-        Json::Value value = expectation.asJsonValue();
-        gExpectationsToWrite[filename] = value;
-    }
-}
-
-/**
- *  Compare against an expectation for this filename, if there is one.
- *  @param digest GmResultDigest, computed from the decoded bitmap, to compare to the
- *          expectation.
- *  @param filename String used to find the expected value.
+ *  This function performs two purposes:
+ *      1) If --createExpectationsPath is set, record the expectations to the global
+ *         expectations object, for future writing to a file, which will later be
+ *         used for comparisons.
+ *      2) If --readExpectationsPath is set, compare this bitmap to the json expectations
+ *         provided. Whether this bitmap matches determines the return value.
+ *  The two purposes share a function so they can share filenames and expectations.
+ *  @param bitmapAndDigest BitmapAndDigest, computed from the decoded bitmap, to both
+ *         write and compare to the existing expectation.
+ *  @param filename String used to record the new expectation and to find the existing
+ *         expectation.
  *  @param failureArray Array to add a failure message to on failure.
  *  @param missingArray Array to add failure message to when missing image
  *          expectation.
  *  @param ignoreArray Array to add failure message to when the image does not match
  *          the expectation, but this is a failure we can ignore.
  *  @return bool True in any of these cases:
  *                  - the bitmap matches the expectation.
  *               False in any of these cases:
  *                  - there is no expectations file.
  *                  - there is an expectations file, but no expectation for this bitmap.
  *                  - there is an expectation for this bitmap, but it did not match.
  *                  - expectation could not be computed from the bitmap.
  */
-static bool compare_to_expectations_if_necessary(const skiagm::GmResultDigest& digest,
-                                                 const char* filename,
-                                                 SkTArray<SkString, false>* failureArray,
-                                                 SkTArray<SkString, false>* missingArray,
-                                                 SkTArray<SkString, false>* ignoreArray) {
+static bool write_and_compare_expectations(const skiagm::BitmapAndDigest& bitmapAndDigest,
+                                           const char* filename,
+                                           SkTArray<SkString, false>* failureArray,
+                                           SkTArray<SkString, false>* missingArray,
+                                           SkTArray<SkString, false>* ignoreArray) {
+    // For both writing and reading, the key for this entry will include the name
+    // of the file and the pref config, matching the pattern of gm_json.py's
+    // IMAGE_FILENAME_PATTERN: "name_config.png"
+    const SkString name_config = create_json_key(filename);
+
+    // Record the new expectation.
+    if (!FLAGS_createExpectationsPath.isEmpty()) {
+        // Creates an Expectations object, and add it to the list to write.
+        skiagm::Expectations expectation(bitmapAndDigest);
+        Json::Value value = expectation.asJsonValue();
+        gExpectationsToWrite[name_config.c_str()] = value;
+    }
+
+    // Compare to the existing expectation.
+    const skiagm::GmResultDigest& digest = bitmapAndDigest.fDigest;
     if (!digest.isValid()) {
         if (failureArray != NULL) {
             failureArray->push_back().printf("decoded %s, but could not create a GmResultDigest.",
                                              filename);
         }
         return false;
     }
 
     if (NULL == gJsonExpectations.get()) {
         return false;
     }
 
-    skiagm::Expectations jsExpectation = gJsonExpectations->get(filename);
+    skiagm::Expectations jsExpectation = gJsonExpectations->get(name_config.c_str());
     if (jsExpectation.empty()) {
         if (missingArray != NULL) {
             missingArray->push_back().printf("decoded %s, but could not find expectation.",
                                              filename);
         }
         return false;
     }
 
     if (jsExpectation.match(digest)) {
         return true;
     }
 
     if (jsExpectation.ignoreFailure()) {
         ignoreArray->push_back().printf("%s does not match expectation, but this is known.",
                                         filename);
     } else if (failureArray != NULL) {
         failureArray->push_back().printf("decoded %s, but the result does not match "
                                          "expectations.",
                                          filename);
     }
     return false;
 }
 
 /**
  *  Helper function to write a bitmap subset to a file. Only called if subsets were created
- *  and a writePath was provided. Creates a subdirectory called 'subsets' and writes a PNG to
- *  that directory. Also creates a subdirectory called 'extracted' and writes a bitmap created
- *  using extractSubset to a PNG in that directory. Both files will represent the same
- *  subrectangle and have the same name for comparison.
+ *  and a writePath was provided. Behaves differently depending on
+ *  FLAGS_writeChecksumBasedFilenames. If true:
+ *      Writes the image to a PNG file named according to the digest hash, as described in
+ *      write_bitmap.
+ *  If false:
+ *      Creates a subdirectory called 'subsets' and writes a PNG to that directory. Also
+ *      creates a subdirectory called 'extracted' and writes a bitmap created using
+ *      extractSubset to a PNG in that directory. Both files will represent the same
+ *      subrectangle and have the same name for convenient comparison. In this case, the
+ *      digest is ignored.
  *  @param writePath Parent directory to hold the folders for the PNG files to write. Must
  *      not be NULL.
- *  @param filename Basename of the original file. Used to name the new files. Must not be
- *      NULL.
- *  @param subsetDim String representing the dimensions of the subset. Used to name the new
- *      files. Must not be NULL.
- *  @param bitmapFromDecodeSubset Pointer to SkBitmap created by SkImageDecoder::DecodeSubset,
- *      using rect as the area to decode.
+ *  @param subsetName Basename of the original file, with the dimensions of the subset tacked
+ *      on. Used to name the new file/folder.
+ *  @param bitmapAndDigestFromDecodeSubset SkBitmap (with digest) created by
+ *      SkImageDecoder::DecodeSubset, using rect as the area to decode.
  *  @param rect Rectangle of the area decoded into bitmapFromDecodeSubset. Used to call
  *      extractSubset on originalBitmap to create a bitmap with the same dimensions/pixels as
  *      bitmapFromDecodeSubset (assuming decodeSubset worked properly).
  *  @param originalBitmap SkBitmap decoded from the same stream as bitmapFromDecodeSubset,
  *      using SkImageDecoder::decode to get the entire image. Used to create a PNG file for
- *      comparison to the PNG created by bitmapFromDecodeSubset.
+ *      comparison to the PNG created by bitmapAndDigestFromDecodeSubset's bitmap.
  *  @return bool Whether the function succeeded at drawing the decoded subset and the extracted
  *      subset to files.
  */
-static bool write_subset(const char* writePath, const char* filename, const char* subsetDim,
-                          SkBitmap* bitmapFromDecodeSubset, SkIRect rect,
-                          const SkBitmap& originalBitmap) {
+static bool write_subset(const char* writePath, const SkString& subsetName,
+                          const skiagm::BitmapAndDigest bitmapAndDigestFromDecodeSubset,
+                          SkIRect rect, const SkBitmap& originalBitmap) {
     // All parameters must be valid.
     SkASSERT(writePath != NULL);
-    SkASSERT(filename != NULL);
-    SkASSERT(subsetDim != NULL);
-    SkASSERT(bitmapFromDecodeSubset != NULL);
 
-    // Create a subdirectory to hold the results of decodeSubset.
-    SkString dir = SkOSPath::SkPathJoin(writePath, "subsets");
-    if (!sk_mkdir(dir.c_str())) {
-        gFailedSubsetDecodes.push_back().printf("Successfully decoded %s from %s, but failed to "
-                                                "create a directory to write to.", subsetDim,
-                                                 filename);
-        return false;
+    SkString subsetPath;
+    if (FLAGS_writeChecksumBasedFilenames) {
+        subsetPath.set(writePath);
+    } else {
+        // Create a subdirectory to hold the results of decodeSubset.
+        subsetPath = SkOSPath::SkPathJoin(writePath, "subsets");
+        if (!sk_mkdir(subsetPath.c_str())) {
+            gFailedSubsetDecodes.push_back().printf("Successfully decoded subset %s, but "
+                                                    "failed to create a directory to write to.",
+                                                     subsetName.c_str());
+            return false;
+        }
     }
+    SkAssertResult(write_bitmap(subsetPath.c_str(), subsetName.c_str(),
+                                bitmapAndDigestFromDecodeSubset));
+    gSuccessfulSubsetDecodes.push_back().printf("\twrote %s", subsetName.c_str());
 
-    // Write the subset to a file whose name includes the dimensions.
-    SkString suffix = SkStringPrintf("_%s.png", subsetDim);
-    SkString outPath;
-    make_outname(&outPath, dir.c_str(), filename, suffix.c_str());
-    SkAssertResult(write_bitmap(outPath.c_str(), *bitmapFromDecodeSubset));
-    gSuccessfulSubsetDecodes.push_back().printf("\twrote %s", outPath.c_str());
+    if (!FLAGS_writeChecksumBasedFilenames) {
+        // FIXME: The goal of extracting the subset is for visual comparison/using skdiff/skpdiff.
+        // Currently disabling for writeChecksumBasedFilenames since it will be trickier to
+        // determine which files to compare.
 
-    // Also use extractSubset from the original for visual comparison.
-    // Write the result to a file in a separate subdirectory.
-    SkBitmap extractedSubset;
-    if (!originalBitmap.extractSubset(&extractedSubset, rect)) {
-        gFailedSubsetDecodes.push_back().printf("Successfully decoded %s from %s, but failed to "
-                                                "extract a similar subset for comparison.",
-                                                subsetDim, filename);
-        return false;
+        // Also use extractSubset from the original for visual comparison.
+        // Write the result to a file in a separate subdirectory.
+        SkBitmap extractedSubset;
+        if (!originalBitmap.extractSubset(&extractedSubset, rect)) {
+            gFailedSubsetDecodes.push_back().printf("Successfully decoded subset %s, but failed "
+                                                    "to extract a similar subset for comparison.",
+                                                    subsetName.c_str());
+            return false;
+        }
+
+        SkString dirExtracted = SkOSPath::SkPathJoin(writePath, "extracted");
+        if (!sk_mkdir(dirExtracted.c_str())) {
+            gFailedSubsetDecodes.push_back().printf("Successfully decoded subset%s, but failed "
+                                                    "to create a directory for extractSubset "
+                                                    "comparison.",
+                                                    subsetName.c_str());
+            return false;
+        }
+
+        skiagm::BitmapAndDigest bitmapAndDigestFromExtractSubset(extractedSubset);
+        SkAssertResult(write_bitmap(dirExtracted.c_str(), subsetName.c_str(),
+                                    bitmapAndDigestFromExtractSubset));
     }
-
-    SkString dirExtracted = SkOSPath::SkPathJoin(writePath, "extracted");
-    if (!sk_mkdir(dirExtracted.c_str())) {
-        gFailedSubsetDecodes.push_back().printf("Successfully decoded %s from %s, but failed to "
-                                                "create a directory for extractSubset comparison.",
-                                                subsetDim, filename);
-        return false;
-    }
-
-    make_outname(&outPath, dirExtracted.c_str(), filename, suffix.c_str());
-    SkAssertResult(write_bitmap(outPath.c_str(), extractedSubset));
     return true;
 }
 
 // FIXME: This test could be run on windows/mac once we remove their dependence on
 // getLength. See https://code.google.com/p/skia/issues/detail?id=1570
 #if defined(SK_BUILD_FOR_ANDROID) || defined(SK_BUILD_FOR_UNIX)
 
 /**
  *  Dummy class for testing to ensure that a stream without a length decodes the same
  *  as a stream with a length.
@@ skipping 45 matching lines @@
                                             "a digest\n", srcPath);
         return;
     }
     if (!lengthLessDigest.equals(digest)) {
         gDecodeFailures.push_back().appendf("Without using getLength, %s did not match digest "
                                             "that uses getLength\n", srcPath);
     }
 }
 #endif // defined(SK_BUILD_FOR_ANDROID) || defined(SK_BUILD_FOR_UNIX)
 
+/**
+ *  Replace all instances of oldChar with newChar in str.
+ */
+static void replace_char(SkString* str, const char oldChar, const char newChar) {
+    if (NULL == str) {
+        return;
+    }
+    for (size_t i = 0; i < str->size(); ++i) {
+        if (oldChar == str->operator[](i)) {
+            str->operator[](i) = newChar;
+        }
+    }
+}
+
 static void decodeFileAndWrite(const char srcPath[], const SkString* writePath) {
     SkBitmap bitmap;
     SkFILEStream stream(srcPath);
     if (!stream.isValid()) {
         gInvalidStreams.push_back().set(srcPath);
         return;
     }
 
     SkImageDecoder* codec = SkImageDecoder::Factory(&stream);
     if (NULL == codec) {
         gMissingCodecs.push_back().set(srcPath);
         return;
     }
 
     SkAutoTDelete<SkImageDecoder> ad(codec);
 
     codec->setSkipWritingZeroes(FLAGS_skip);
     codec->setSampleSize(FLAGS_sampleSize);
     stream.rewind();
 
     // Create a string representing just the filename itself, for use in json expectations.
     SkString basename = SkOSPath::SkBasename(srcPath);
+    // Replace '_' with '-', so that the names can fit gm_json.py's IMAGE_FILENAME_PATTERN
+    replace_char(&basename, '_', '-');
     const char* filename = basename.c_str();
 
     if (!codec->decode(&stream, &bitmap, gPrefConfig,
                        SkImageDecoder::kDecodePixels_Mode)) {
         if (NULL != gJsonExpectations.get()) {
-            skiagm::Expectations jsExpectations = gJsonExpectations->get(filename);
+            const SkString name_config = create_json_key(filename);
+            skiagm::Expectations jsExpectations = gJsonExpectations->get(name_config.c_str());
             if (jsExpectations.ignoreFailure()) {
                 // This is a known failure.
                 gKnownFailures.push_back().appendf(
                     "failed to decode %s, which is a known failure.", srcPath);
                 return;
             }
             if (jsExpectations.empty()) {
                 // This is a failure, but it is a new file. Mark it as missing, with
                 // a note that it should be marked failing.
                 gMissingExpectations.push_back().appendf(
@@ skipping 17 matching lines @@
             gDecodeFailures.push_back() = failure;
         } else {
             // Now check that the bounds match:
             if (dim.width() != bitmap.width() || dim.height() != bitmap.height()) {
                 SkString failure = SkStringPrintf("bounds do not match for %s", srcPath);
                 gDecodeFailures.push_back() = failure;
             }
         }
     }
 
-    skiagm::GmResultDigest digest(bitmap);
-    if (compare_to_expectations_if_necessary(digest, filename,
-                                             &gDecodeFailures,
-                                             &gMissingExpectations,
-                                             &gKnownFailures)) {
+    skiagm::BitmapAndDigest bitmapAndDigest(bitmap);
+    if (write_and_compare_expectations(bitmapAndDigest, filename, &gDecodeFailures,
+                                       &gMissingExpectations, &gKnownFailures)) {
         gSuccessfulDecodes.push_back().printf("%s [%d %d]", srcPath, bitmap.width(),
                                               bitmap.height());
     } else if (!FLAGS_mismatchPath.isEmpty()) {
-        SkString outPath;
-        make_outname(&outPath, FLAGS_mismatchPath[0], srcPath, ".png");
-        if (write_bitmap(outPath.c_str(), bitmap)) {
-            gSuccessfulDecodes.push_back().appendf("\twrote %s", outPath.c_str());
+        if (write_bitmap(FLAGS_mismatchPath[0], filename, bitmapAndDigest)) {
+            gSuccessfulDecodes.push_back().appendf("\twrote %s", filename);
         } else {
-            gEncodeFailures.push_back().set(outPath);
+            gEncodeFailures.push_back().set(filename);
         }
     }
 
 // FIXME: This test could be run on windows/mac once we remove their dependence on
 // getLength. See https://code.google.com/p/skia/issues/detail?id=1570
 #if defined(SK_BUILD_FOR_ANDROID) || defined(SK_BUILD_FOR_UNIX)
-    test_stream_without_length(srcPath, codec, digest);
+    test_stream_without_length(srcPath, codec, bitmapAndDigest.fDigest);
 #endif
 
     if (writePath != NULL) {
-        SkString outPath;
-        make_outname(&outPath, writePath->c_str(), srcPath, ".png");
-        if (write_bitmap(outPath.c_str(), bitmap)) {
-            gSuccessfulDecodes.push_back().appendf("\twrote %s", outPath.c_str());
+        if (write_bitmap(writePath->c_str(), filename, bitmapAndDigest)) {
+            gSuccessfulDecodes.push_back().appendf("\twrote %s", filename);
         } else {
-            gEncodeFailures.push_back().set(outPath);
+            gEncodeFailures.push_back().set(filename);
         }
     }
 
-    write_expectations(bitmap, filename);
-
     if (FLAGS_testSubsetDecoding) {
         SkDEBUGCODE(bool couldRewind =) stream.rewind();
         SkASSERT(couldRewind);
         int width, height;
         // Build the tile index for decoding subsets. If the image is 1x1, skip subset
         // decoding since there are no smaller subsets.
         if (codec->buildTileIndex(&stream, &width, &height) && width > 1 && height > 1) {
             SkASSERT(bitmap.width() == width && bitmap.height() == height);
             // Call decodeSubset multiple times:
             SkRandom rand(0);
             for (int i = 0; i < 5; i++) {
                 SkBitmap bitmapFromDecodeSubset;
                 // FIXME: Come up with a more representative set of rectangles.
                 SkIRect rect = generate_random_rect(&rand, width, height);
                 SkString subsetDim = SkStringPrintf("[%d,%d,%d,%d]", rect.fLeft, rect.fTop,
                                                     rect.fRight, rect.fBottom);
                 if (codec->decodeSubset(&bitmapFromDecodeSubset, rect, gPrefConfig)) {
-                    SkString subsetName = SkStringPrintf("%s_%s", filename, subsetDim.c_str());
-                    skiagm::GmResultDigest subsetDigest(bitmapFromDecodeSubset);
-                    if (compare_to_expectations_if_necessary(subsetDigest,
-                                                             subsetName.c_str(),
-                                                             &gFailedSubsetDecodes,
-                                                             &gMissingSubsetExpectations,
-                                                             &gKnownSubsetFailures)) {
+                    SkString subsetName = SkStringPrintf("%s-%s", filename, subsetDim.c_str());
+                    skiagm::BitmapAndDigest subsetBitmapAndDigest(bitmapFromDecodeSubset);
+                    if (write_and_compare_expectations(subsetBitmapAndDigest,
+                                                       subsetName.c_str(),
+                                                       &gFailedSubsetDecodes,
+                                                       &gMissingSubsetExpectations,
+                                                       &gKnownSubsetFailures)) {
                         gSuccessfulSubsetDecodes.push_back().printf("Decoded subset %s from %s",
                                                               subsetDim.c_str(), srcPath);
                     } else if (!FLAGS_mismatchPath.isEmpty()) {
-                        write_subset(FLAGS_mismatchPath[0], filename, subsetDim.c_str(),
-                                     &bitmapFromDecodeSubset, rect, bitmap);
+                        write_subset(FLAGS_mismatchPath[0], subsetName,
+                                     subsetBitmapAndDigest, rect, bitmap);
                     }
 
-                    write_expectations(bitmapFromDecodeSubset, subsetName.c_str());
                     if (writePath != NULL) {
-                        write_subset(writePath->c_str(), filename, subsetDim.c_str(),
-                                     &bitmapFromDecodeSubset, rect, bitmap);
+                        write_subset(writePath->c_str(), subsetName,
+                                     subsetBitmapAndDigest, rect, bitmap);
                     }
                 } else {
                     gFailedSubsetDecodes.push_back().printf("Failed to decode region %s from %s",
                                                             subsetDim.c_str(), srcPath);
                 }
             }
         }
     }
 
     // Do not attempt to re-encode A8, since our image encoders do not support encoding to A8.
@@ skipping 204 matching lines @@
     print_strings("Known failures", gKnownFailures);
 
     return failed ? -1 : 0;
 }
 
 #if !defined SK_BUILD_FOR_IOS
 int main(int argc, char * const argv[]) {
     return tool_main(argc, (char**) argv);
 }
 #endif