Deserialize pictures with custom image-deserializer

src/core/SkReadBuffer.cpp

Index: src/core/SkReadBuffer.cpp
diff --git a/src/core/SkReadBuffer.cpp b/src/core/SkReadBuffer.cpp
index 54f684acaa7379633f7cefb9193c1d3f010f2e38..2f6b513c16ebded97347979f4e2a2fddded5fdb0 100644
--- a/src/core/SkReadBuffer.cpp
+++ b/src/core/SkReadBuffer.cpp
@@ -13,6 +13,26 @@
 #include "SkStream.h"
 #include "SkTypeface.h"
 
+namespace {
+
+    // This generator intentionally should always fail on all attempts to get its pixels,
+    // simulating a bad or empty codec stream.
+    class EmptyImageGenerator final : public SkImageGenerator {
+    public:
+        EmptyImageGenerator(const SkImageInfo& info) : INHERITED(info) { }
+
+    private:
+        typedef SkImageGenerator INHERITED;
+    };
+
+    static sk_sp<SkImage> MakeEmptyImage(int width, int height) {
+        return SkImage::MakeFromGenerator(
+            new EmptyImageGenerator(SkImageInfo::MakeN32Premul(width, height)));
+    }
+    
+} // anonymous namespace
+
+
 static uint32_t default_flags() {
     uint32_t flags = 0;
     flags |= SkReadBuffer::kScalarIsFloat_Flag;
@@ -32,7 +52,8 @@ SkReadBuffer::SkReadBuffer() {
 
     fFactoryArray = nullptr;
     fFactoryCount = 0;
-    fBitmapDecoder = nullptr;
+//    fBitmapDecoder = nullptr;
+    fImageDeserializer = nullptr;
 #ifdef DEBUG_NON_DETERMINISTIC_ASSERT
     fDecodedBitmapIndex = -1;
 #endif // DEBUG_NON_DETERMINISTIC_ASSERT
@@ -49,7 +70,8 @@ SkReadBuffer::SkReadBuffer(const void* data, size_t size) {
 
     fFactoryArray = nullptr;
     fFactoryCount = 0;
-    fBitmapDecoder = nullptr;
+//    fBitmapDecoder = nullptr;
+    fImageDeserializer = nullptr;
 #ifdef DEBUG_NON_DETERMINISTIC_ASSERT
     fDecodedBitmapIndex = -1;
 #endif // DEBUG_NON_DETERMINISTIC_ASSERT
@@ -68,7 +90,8 @@ SkReadBuffer::SkReadBuffer(SkStream* stream) {
 
     fFactoryArray = nullptr;
     fFactoryCount = 0;
-    fBitmapDecoder = nullptr;
+//    fBitmapDecoder = nullptr;
+    fImageDeserializer = nullptr;
 #ifdef DEBUG_NON_DETERMINISTIC_ASSERT
     fDecodedBitmapIndex = -1;
 #endif // DEBUG_NON_DETERMINISTIC_ASSERT
@@ -179,7 +202,7 @@ uint32_t SkReadBuffer::getArrayCount() {
     return *(uint32_t*)fReader.peek();
 }
 
-bool SkReadBuffer::readBitmap(SkBitmap* bitmap) {
+sk_sp<SkImage> SkReadBuffer::readBitmapAsImage() {
     const int width = this->readInt();
     const int height = this->readInt();
 
@@ -203,6 +226,8 @@ bool SkReadBuffer::readBitmap(SkBitmap* bitmap) {
             const void* data = this->skip(length);
             const int32_t xOffset = this->readInt();
             const int32_t yOffset = this->readInt();
+            SkIRect subset = SkIRect::MakeXYWH(xOffset, yOffset, width, height);
+#if 0
             if (fBitmapDecoder != nullptr && fBitmapDecoder(data, length, bitmap)) {
                 if (bitmap->width() == width && bitmap->height() == height) {
 #ifdef DEBUG_NON_DETERMINISTIC_ASSERT
@@ -230,12 +255,20 @@ bool SkReadBuffer::readBitmap(SkBitmap* bitmap) {
                 //SkASSERT(width <= bitmap->width() && height <= bitmap->height());
 
                 SkBitmap subsetBm;
-                SkIRect subset = SkIRect::MakeXYWH(xOffset, yOffset, width, height);
                 if (bitmap->extractSubset(&subsetBm, subset)) {
                     bitmap->swap(subsetBm);
                     return true;
                 }
             }
+#else
+            if (fImageDeserializer) {
+                sk_sp<SkImage> image =
+                    fImageDeserializer->deserialize(SkData::MakeWithCopy(data, length), &subset);
+                if (image) {
+                    return image;
+                }
+            }
+#endif
             // This bitmap was encoded when written, but we are unable to decode, possibly due to
             // not having a decoder.
             SkErrorInternals::SetError(kParseError_SkError,
@@ -243,32 +276,20 @@ bool SkReadBuffer::readBitmap(SkBitmap* bitmap) {
             // Even though we weren't able to decode the pixels, the readbuffer should still be
             // intact, so we return true with an empty bitmap, so we don't force an abort of the
             // larger deserialize.
-            bitmap->setInfo(SkImageInfo::MakeUnknown(width, height));
-            return true;
-        } else if (SkBitmap::ReadRawPixels(this, bitmap)) {
-            return true;
+            return MakeEmptyImage(width, height);
+        } else {
+            SkBitmap bitmap;
+            if (SkBitmap::ReadRawPixels(this, &bitmap)) {
+                bitmap.setImmutable();
+                return SkImage::MakeFromBitmap(bitmap);
+            }
         }
     }
     // Could not read the SkBitmap. Use a placeholder bitmap.
-    bitmap->setInfo(SkImageInfo::MakeUnknown(width, height));
-    return false;
+    return nullptr;
 }
 
-namespace {
-
-// This generator intentionally should always fail on all attempts to get its pixels,
-// simulating a bad or empty codec stream.
-class EmptyImageGenerator final : public SkImageGenerator {
-public:
-    EmptyImageGenerator(const SkImageInfo& info) : INHERITED(info) { }
-
-private:
-    typedef SkImageGenerator INHERITED;
-};
-
-} // anonymous namespace
-
-SkImage* SkReadBuffer::readImage() {
+sk_sp<SkImage> SkReadBuffer::readImage() {
     int width = this->read32();
     int height = this->read32();
     if (width <= 0 || height <= 0) {    // SkImage never has a zero dimension
@@ -276,25 +297,20 @@ SkImage* SkReadBuffer::readImage() {
         return nullptr;
     }
 
-    auto placeholder = [=] {
-        return SkImage::MakeFromGenerator(
-            new EmptyImageGenerator(SkImageInfo::MakeN32Premul(width, height))).release();
-    };
-
     uint32_t encoded_size = this->getArrayCount();
     if (encoded_size == 0) {
         // The image could not be encoded at serialization time - return an empty placeholder.
         (void)this->readUInt();  // Swallow that encoded_size == 0 sentinel.
-        return placeholder();
+        return MakeEmptyImage(width, height);
     }
     if (encoded_size == 1) {
         // We had to encode the image as raw pixels via SkBitmap.
         (void)this->readUInt();  // Swallow that encoded_size == 1 sentinel.
         SkBitmap bm;
         if (SkBitmap::ReadRawPixels(this, &bm)) {
-            return SkImage::MakeFromBitmap(bm).release();
+            return SkImage::MakeFromBitmap(bm);
         }
-        return placeholder();
+        return MakeEmptyImage(width, height);
     }
 
     // The SkImage encoded itself.
@@ -308,13 +324,14 @@ SkImage* SkReadBuffer::readImage() {
     }
 
     const SkIRect subset = SkIRect::MakeXYWH(originX, originY, width, height);
-    SkImage* image = SkImage::MakeFromEncoded(std::move(encoded), &subset).release();
-    if (image) {
-        return image;
-    }
 
-    return SkImage::MakeFromGenerator(
-            new EmptyImageGenerator(SkImageInfo::MakeN32Premul(width, height))).release();
+    sk_sp<SkImage> image;
+    if (fImageDeserializer) {
+        image = fImageDeserializer->deserialize(std::move(encoded), &subset);
+    } else {
+        image = SkImage::MakeFromEncoded(std::move(encoded), &subset);
+    }
+    return image ? image : MakeEmptyImage(width, height);
 }
 
 SkTypeface* SkReadBuffer::readTypeface() {