SkScaledCodec should implement onRewind()

tests/CodexTest.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "Resources.h"
 #include "SkBitmap.h"
 #include "SkCodec.h"
@@ skipping 202 matching lines @@
         if (supportsSubsetDecoding) {
             REPORTER_ASSERT(r, result == SkCodec::kSuccess);
             // Webp is the only codec that supports subsets, and it will have modified the subset
             // to have even left/top.
             REPORTER_ASSERT(r, SkIsAlign2(subset.fLeft) && SkIsAlign2(subset.fTop));
         } else {
             // No subsets will work.
             REPORTER_ASSERT(r, result == SkCodec::kUnimplemented);
         }
     }
+
+    // SkScaledCodec tests
+    {
+        SkAutoTDelete<SkStream> stream(resource(path));
+        if (!stream) {
+            SkDebugf("Missing resource '%s'\n", path);
+            return;
+        }
+        SkAutoTDelete<SkCodec> codec(SkScaledCodec::NewFromStream(stream.detach()));
+        if (!codec) {
+            ERRORF(r, "Unable to decode '%s'", path);
+            return;
+        }
+
+        SkImageInfo info = codec->getInfo().makeColorType(kN32_SkColorType);
+        REPORTER_ASSERT(r, info.dimensions() == size);
+
+        // FIXME: We will be able to run this test on ICOs as well, after we have implemented
+        //        scanline decoding for ICO.
+        if (SkEncodedFormat::kICO_SkEncodedFormat != codec->getEncodedFormat()) {

[scroggo, 2015/10/02 20:56:06]

Another way you could do this - not sure if it's better:

You could run this whole block only if (supportsScanlineDecoding), which would
eliminate ICO (until we update ICO)... The awkward part is that you need to also
consider webp, so it becomes

if (supportsScanlineDecoding || supportsSubsetDecoding)

[msarett, 2015/10/05 14:26:51]

Done.

+            SkBitmap bm;
+            bm.allocPixels(info);
+            SkAutoLockPixels autoLockPixels(bm);
+            SkCodec::Result result =
+                codec->getPixels(info, bm.getPixels(), bm.rowBytes(), nullptr, nullptr, nullptr);

[scroggo, 2015/10/02 20:56:06]

nit: This is copied and pasted, so I know it's the same as the other code, but
this could all fit on one line if you call the other version of getPixels and
leave out the three nullptrs.

On that note, maybe this should be factored out into another method? (I
considered it to share with test_info, but wasn't sure it would be better.

Actually, wait, shouldn't this look identical to the non SkScaledCodec version?
This whole block can just be:

(Note: "digest" here means the digest you shadowed, which you do not need to
shadow - just use the same one since it should match the original.)

test_info(r, codec, info, SkCodec::kSuccess, &digest);

// Verify that re-decoding (and thus rewinding) gives the same result
test_info(r, codec, info, SkCodec::kSuccess, &digest);

[msarett, 2015/10/05 14:26:51]

I will refactor into a different method and check that SkScaledCodec digests
match SkCodec digests.

+            REPORTER_ASSERT(r, result == SkCodec::kSuccess);
+
+            SkMD5::Digest digest;
+            md5(bm, &digest);
+
+            // Verify that re-decoding gives the same result.
+            test_info(r, codec, info, SkCodec::kSuccess, &digest);
+        }
+    }
 }
 
 DEF_TEST(Codec, r) {
     // WBMP
     check(r, "mandrill.wbmp", SkISize::Make(512, 512), true, false);
 
     // WEBP
     check(r, "baby_tux.webp", SkISize::Make(386, 395), false, true);
     check(r, "color_wheel.webp", SkISize::Make(128, 128), false, true);
     check(r, "yellow_rose.webp", SkISize::Make(400, 301), false, true);
@@ skipping 266 matching lines @@
     REPORTER_ASSERT(r, SkCodec::kInvalidParameters == result);
     result = decoder->startScanlineDecode(
         decoder->getInfo().makeColorType(kIndex_8_SkColorType));
     REPORTER_ASSERT(r, SkCodec::kInvalidParameters == result);
 }
 
 DEF_TEST(Codec_Params, r) {
     test_invalid_parameters(r, "index8.png");
     test_invalid_parameters(r, "mandrill.wbmp");
 }