Add SkCodec, including PNG implementation.

dm/DMSrcSink.cpp

Index: dm/DMSrcSink.cpp
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index b44f1d78180e94e9d9f5505789024e5db42c4007..a615b78e7aa34b5296e8332f5ea4036531800a39 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -1,6 +1,7 @@
 #include "DMSrcSink.h"
 #include "SamplePipeControllers.h"
 #include "SkCommonFlags.h"
+#include "SkCodec.h"
 #include "SkDocument.h"
 #include "SkMultiPictureDraw.h"
 #include "SkNullCanvas.h"
@@ -11,6 +12,8 @@
 #include "SkStream.h"
 #include "SkXMLWriter.h"
 
+DEFINE_bool(codec, false, "Use SkCodec instead of SkImageDecoder");
+
 namespace DM {
 
 GMSrc::GMSrc(skiagm::GMRegistry::Factory factory) : fFactory(factory) {}
@@ -45,9 +48,32 @@ Error ImageSrc::draw(SkCanvas* canvas) const {
     if (fDivisor == 0) {
         // Decode the full image.
         SkBitmap bitmap;
-        if (!SkImageDecoder::DecodeMemory(encoded->data(), encoded->size(), &bitmap,
-                                          dstColorType, SkImageDecoder::kDecodePixels_Mode)) {
-            return SkStringPrintf("Couldn't decode %s.", fPath.c_str());
+        if (FLAGS_codec) {
+            SkAutoTDelete<SkCodec> codec(SkCodec::NewFromData(encoded));
+            if (!codec) {
+                return SkStringPrintf("Couldn't decode %s.", fPath.c_str());
+            }
+            SkImageInfo info;
+            if (!codec->getInfo(&info)) {
+                return SkStringPrintf("Couldn't getInfo %s.", fPath.c_str());
+            }
+            info = info.makeColorType(dstColorType);
+            if (info.alphaType() == kUnpremul_SkAlphaType) {
+                // FIXME: Currently we cannot draw unpremultiplied sources.
+                info = info.makeAlphaType(kPremul_SkAlphaType);
+            }
+            bitmap.allocPixels(info);
+            SkAutoLockPixels alp(bitmap);

[djsollen, 2015/02/25 16:02:19]

aren't the pixels locked during allocPixels if you use the default (heap)
allocator?  Also what about calling tryAllocPixels and throw an error in case
the image was so large we couldn't hold it?  I think it is better to not crash
in that event and let the other tests continue to run.  

[scroggo, 2015/02/25 18:00:54]

Yes. In fact I initially left this line out, if you look at my earlier
patchsets. That said, the fact that they are locked appears to be an
implementation detail. The fact that they are locked is not guaranteed by the
comments.
Done.

+            const SkImageGenerator::Result result = codec->getPixels(info, bitmap.getPixels(),
+                                                                     bitmap.rowBytes());
+            if (result != SkImageGenerator::kSuccess) {
+                return SkStringPrintf("Couldn't getPixels %s.", fPath.c_str());
+            }
+        } else {

[djsollen, 2015/02/25 16:02:19]

else if

[scroggo, 2015/02/25 18:00:54]

In this case, I actually like the current code better, since it more clearly (at
least to me) delineates between FLAGS_codec and !FLAGS_codec.

+            if (!SkImageDecoder::DecodeMemory(encoded->data(), encoded->size(), &bitmap,
+                                              dstColorType, SkImageDecoder::kDecodePixels_Mode)) {
+                return SkStringPrintf("Couldn't decode %s.", fPath.c_str());
+            }
         }
         encoded.reset((SkData*)NULL);  // Might as well drop this when we're done with it.
         canvas->drawBitmap(bitmap, 0,0);