DM: lazy decoding on SKP playback

dm/DMSrcSink.cpp

Index: dm/DMSrcSink.cpp
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 6f6664f27ce2266bd12156f1ae973cada399ec25..f678f41b61a0c10b17d666915edec61184073d17 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -2,8 +2,10 @@
 #include "SamplePipeControllers.h"
 #include "SkCommonFlags.h"
 #include "SkCodec.h"
+#include "SkData.h"
 #include "SkDocument.h"
 #include "SkError.h"
+#include "SkImageGenerator.h"
 #include "SkMultiPictureDraw.h"
 #include "SkNullCanvas.h"
 #include "SkOSFile.h"
@@ -15,6 +17,17 @@
 #include "SkXMLWriter.h"
 
 DEFINE_bool(codec, false, "Use SkCodec instead of SkImageDecoder");
+DEFINE_bool(deferDecode, false, "if true, defer decoding of bitmaps until they are locked.");
+
+static bool lazy_decode_bitmap(const void* src, size_t size, SkBitmap* dst) {
+    SkAutoTUnref<SkData> encoded(SkData::NewWithCopy(src, size));
+    return encoded && SkInstallDiscardablePixelRef(encoded, dst);
+}
+
+static SkPicture* create_picture_from_stream(SkStream* stream) {
+    return FLAGS_deferDecode ? SkPicture::CreateFromStream(stream, &lazy_decode_bitmap)
+                             : SkPicture::CreateFromStream(stream);
+}
 
 namespace DM {
 
@@ -83,6 +96,11 @@ Error ImageSrc::draw(SkCanvas* canvas) const {
                     // Everything else is considered a failure.
                     return SkStringPrintf("Couldn't getPixels %s.", fPath.c_str());
             }
+        } else if (FLAGS_deferDecode) {
+            if (!SkInstallDiscardablePixelRef(encoded, &bitmap)) {
+                return SkStringPrintf("SkInstallDiscardablePixelRef failed for %s.",
+                                      fPath.c_str());
+            }
         } else {
             if (!SkImageDecoder::DecodeMemory(encoded->data(), encoded->size(), &bitmap,
                                               dstColorType, SkImageDecoder::kDecodePixels_Mode)) {
@@ -151,6 +169,10 @@ SkISize ImageSrc::size() const {
             return SkISize::Make(0,0);
         }
         return info.dimensions();
+    } else if (FLAGS_deferDecode) {
+        SkAutoTDelete<SkImageGenerator> gen(SkImageGenerator::NewFromData(encoded));
+        SkImageInfo info;
+        return gen && gen->getInfo(&info) ? info.dimensions() : SkISize::Make(0,0);
     } else {
         SkBitmap bitmap;
         if (!encoded || !SkImageDecoder::DecodeMemory(encoded->data(),
@@ -179,7 +201,7 @@ Error SKPSrc::draw(SkCanvas* canvas) const {
     if (!stream) {
         return SkStringPrintf("Couldn't read %s.", fPath.c_str());
     }
-    SkAutoTUnref<SkPicture> pic(SkPicture::CreateFromStream(stream));
+    SkAutoTUnref<SkPicture> pic(create_picture_from_stream(stream));
     if (!pic) {
         return SkStringPrintf("Couldn't decode %s as a picture.", fPath.c_str());
     }
@@ -479,7 +501,7 @@ Error ViaSerialization::draw(const Src& src, SkBitmap* bitmap, SkWStream* stream
     SkDynamicMemoryWStream wStream;
     pic->serialize(&wStream);
     SkAutoTDelete<SkStream> rStream(wStream.detachAsStream());
-    SkAutoTUnref<SkPicture> deserialized(SkPicture::CreateFromStream(rStream));
+    SkAutoTUnref<SkPicture> deserialized(create_picture_from_stream(rStream));
 
     // Turn that deserialized picture into a Src, draw it into our Sink to fill bitmap or stream.
     struct ProxySrc : public Src {