Add getYUV8Planes() API to SkCodec

src/codec/SkCodecImageGenerator.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 "SkCodecImageGenerator.h"
 
 SkImageGenerator* SkCodecImageGenerator::NewFromEncodedCodec(SkData* data) {
     SkCodec* codec = SkCodec::NewFromData(data);
     if (nullptr == codec) {
         return nullptr;
     }
 
     return new SkCodecImageGenerator(codec, data);
 }
 
+static SkImageInfo make_premul(const SkImageInfo& info) {
+    if (kUnpremul_SkAlphaType == info.alphaType()) {
+        return info.makeAlphaType(kPremul_SkAlphaType);
+    }
+
+    return info;
+}
+
 SkCodecImageGenerator::SkCodecImageGenerator(SkCodec* codec, SkData* data)
-    : INHERITED(codec->getInfo())
+    : INHERITED(make_premul(codec->getInfo()))
     , fCodec(codec)
     , fData(SkRef(data))
 {}
 
 SkData* SkCodecImageGenerator::onRefEncodedData(SK_REFENCODEDDATA_CTXPARAM) {
     return SkRef(fData.get());
 }
 
 bool SkCodecImageGenerator::onGetPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
         SkPMColor ctable[], int* ctableCount) {
 
     SkCodec::Result result = fCodec->getPixels(info, pixels, rowBytes, nullptr, ctable,
             ctableCount);
     switch (result) {
         case SkCodec::kSuccess:
         case SkCodec::kIncompleteInput:
             return true;
         default:
             return false;
     }
 }
 
 bool SkCodecImageGenerator::onGetYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3],
         SkYUVColorSpace* colorSpace) {
-    return false;
+    // TODO (msarett): Change the YUV API in ImageGenerator to match SkCodec.
+    //                 This function is currently a hack to match the implementation

[msarett, 2016/01/15 19:22:03]

This hack is unbelievably ugly.

Maybe this CL should become a mega-change that changes the YUV API everywhere?

Or maybe I should just follow-up quickly?

[scroggo, 2016/01/19 18:37:48]

I would leave changing the YUV API to its own CL, just because it's going to
have its own complications - you'll need to change the Chromium code that
depends on it.

+    //                 in SkCodec with the old API.
+
+    // If planes is NULL, we just need to return the size.
+    if (nullptr == planes) {
+        SkCodec::YUVPlanesWidthBytes widthBytes;
+        bool result = fCodec->queryYUV8((SkCodec::YUVPlanesSizes*) sizes, &widthBytes, colorSpace);
+        if (result) {
+            // Save the true widths
+            fYWidth = sizes[0].fWidth;
+            fUWidth = sizes[1].fWidth;
+            fVWidth = sizes[2].fWidth;
+
+            // Adjust the widths so the client allocates enough memory
+            sizes[0].fWidth = widthBytes.YWidthBytes;
+            sizes[1].fWidth = widthBytes.UWidthBytes;
+            sizes[2].fWidth = widthBytes.VWidthBytes;
+        }
+        return result;
+    }
+
+    // Restore the true widths

[scroggo, 2016/01/19 18:37:48]

Just to make sure I follow - the old API *requires* getYUV8Planes to be called
first with nullptr == planes, so these values will be set already?

[msarett, 2016/01/19 22:35:27]

I can't say that it's *required*.

That is how it's used though.  I'm not sure how a client could know the correct
size without asking for it first.

This would fail (when it should succeed) if the client somehow knew the correct
size without querying for it first.  Or it could even think it succeeds (when it
should fail) and write to memory that is the wrong size.

I think it's tricky to fix, but it could be done by adding a ton of checks. 
Given that CodecImageGenerator is only used in test code right now, I would
prefer to leave as is until the API can be changed.

+    sizes[0].fWidth = fYWidth;
+    sizes[1].fWidth = fUWidth;
+    sizes[2].fWidth = fVWidth;
+    bool result = fCodec->getYUV8Planes((const SkCodec::YUVPlanesSizes*)sizes, planes,
+            (const SkCodec::YUVPlanesWidthBytes*) rowBytes);
+    if (result && colorSpace) {
+        *colorSpace = kJPEG_SkYUVColorSpace;
+    }
+
+    return result;
 }