Add a SkPixelSerializer SkImage encode variant

R=reed@google.com
BUG=skia:4285

Review URL: https://codereview.chromium.org/1310633006

include/core/SkImage.h

@@ -21,6 +21,7 @@ class SkColorTable;
 class SkImageGenerator;
 class SkPaint;
 class SkPicture;
+class SkPixelSerializer;
 class SkString;
 class SkSurface;
 class SkSurfaceProps;
@@ -234,12 +235,27 @@ public:
      *
      *  If the image type cannot be encoded, or the requested encoder type is
      *  not supported, this will return NULL.
+     *
+     *  Note: this will attempt to encode the image's pixels in the specified format,
+     *  even if the image returns a data from refEncoded(). That data will be ignored.
      */
     SkData* encode(SkImageEncoder::Type, int quality) const;
 
-    SkData* encode() const {
+    /**
-        return this->encode(SkImageEncoder::kPNG_Type, 100);
+     *  Encode the image and return the result as a caller-managed SkData.  This will
-    }
+     *  attempt to reuse existing encoded data (as returned by refEncoded).
+     *
+     *  We defer to the SkPixelSerializer both for vetting existing encoded data
+     *  (useEncodedData) and for encoding the image (encodePixels) when no such data is
+     *  present or is rejected by the serializer.
+     *
+     *  If not specified, we use a default serializer which 1) always accepts existing data
+     *  (in any format) and 2) encodes to PNG.
+     *
+     *  If no compatible encoded data exists and encoding fails, this method will also
+     *  fail (return NULL).
+     */
+    SkData* encode(SkPixelSerializer* = nullptr) const;
 
     /**
      *  If the image already has its contents in encoded form (e.g. PNG or JPEG), return a ref

src/core/SkWriteBuffer.cpp

@@ -218,31 +218,16 @@ void SkWriteBuffer::writeBitmap(const SkBitmap& bitmap) {
     SkBitmap::WriteRawPixels(this, bitmap);
 }
 
-static bool try_write_encoded(SkWriteBuffer* buffer, SkData* encoded) {
-    SkPixelSerializer* ps = buffer->getPixelSerializer();
-    // Assumes that if the client did not set a serializer, they are
-    // happy to get the encoded data.
-    if (!ps || ps->useEncodedData(encoded->data(), encoded->size())) {
-        write_encoded_bitmap(buffer, encoded, SkIPoint::Make(0, 0));
-        return true;
-    }
-    return false;
-}
-
 void SkWriteBuffer::writeImage(const SkImage* image) {
     this->writeInt(image->width());
     this->writeInt(image->height());
 
-    SkAutoTUnref<SkData> encoded(image->refEncoded());
+    SkAutoTUnref<SkData> encoded(image->encode(this->getPixelSerializer()));
-    if (encoded && try_write_encoded(this, encoded)) {
+    if (encoded) {
+        write_encoded_bitmap(this, encoded, SkIPoint::Make(0, 0));
         return;
     }
 
-    encoded.reset(image->encode(SkImageEncoder::kPNG_Type, 100));
-    if (encoded && try_write_encoded(this, encoded)) {
-        return;
-    }
-    
     this->writeUInt(0); // signal no pixels (in place of the size of the encoded data)
 }
 

src/image/SkImage.cpp

@@ -13,6 +13,7 @@
 #include "SkImage_Base.h"
 #include "SkNextID.h"
 #include "SkPixelRef.h"
+#include "SkPixelSerializer.h"
 #include "SkReadPixelsRec.h"
 #include "SkString.h"
 #include "SkSurface.h"
@@ -71,6 +72,40 @@ SkData* SkImage::encode(SkImageEncoder::Type type, int quality) const {
     return nullptr;
 }
 
+namespace {
+
+class DefaultSerializer :  public SkPixelSerializer {
+protected:
+    bool onUseEncodedData(const void *data, size_t len) override {
+        return true;
+    }
+
+    SkData* onEncodePixels(const SkImageInfo& info, const void* pixels, size_t rowBytes) override {
+        return SkImageEncoder::EncodeData(info, pixels, rowBytes, SkImageEncoder::kPNG_Type, 100);
+    }
+};
+
+} // anonymous namespace
+
+SkData* SkImage::encode(SkPixelSerializer* serializer) const {
+    DefaultSerializer defaultSerializer;
+    SkPixelSerializer* effectiveSerializer = serializer ? serializer : &defaultSerializer;
+
+    SkAutoTUnref<SkData> encoded(this->refEncoded());
+    if (encoded && effectiveSerializer->useEncodedData(encoded->data(), encoded->size())) {
+        return encoded.detach();
+    }
+
+    SkBitmap bm;
+    SkAutoPixmapUnlock apu;
+    if (as_IB(this)->getROPixels(&bm) && bm.requestLock(&apu)) {
+        const SkPixmap& pmap = apu.pixmap();
+        return effectiveSerializer->encodePixels(pmap.info(), pmap.addr(), pmap.rowBytes());
+    }
+
+    return nullptr;
+}
+
 SkData* SkImage::refEncoded() const {
     return as_IB(this)->onRefEncoded();
 }

tests/ImageTest.cpp

@@ -10,6 +10,7 @@
 #include "SkDevice.h"
 #include "SkImageEncoder.h"
 #include "SkImage_Base.h"
+#include "SkPixelSerializer.h"
 #include "SkRRect.h"
 #include "SkSurface.h"
 #include "SkUtils.h"
@@ -104,6 +105,36 @@ DEF_GPUTEST(Image_Encode_Gpu, reporter, factory) {
 }
 #endif
 
+namespace {
+
+const char* kSerializedData = "serialized";
+
+class MockSerializer : public SkPixelSerializer {
+protected:
+    bool onUseEncodedData(const void*, size_t) override {
+        return false;
+    }
+
+    SkData* onEncodePixels(const SkImageInfo&, const void*, size_t) override {
+        return SkData::NewWithCString(kSerializedData);
+    }
+};
+
+} // anonymous namespace
+
+// Test that SkImage encoding observes custom pixel serializers.
+DEF_TEST(Image_Encode_Serializer, reporter) {
+    MockSerializer serializer;
+    const SkIRect ir = SkIRect::MakeXYWH(5, 5, 10, 10);
+    SkAutoTUnref<SkImage> image(make_image(nullptr, 20, 20, ir));
+    SkAutoTUnref<SkData> encoded(image->encode(&serializer));
+    SkAutoTUnref<SkData> reference(SkData::NewWithCString(kSerializedData));
+
+    REPORTER_ASSERT(reporter, encoded);
+    REPORTER_ASSERT(reporter, encoded->size() > 0);
+    REPORTER_ASSERT(reporter, encoded->equals(reference));
+}
+
 DEF_TEST(Image_NewRasterCopy, reporter) {
     const SkPMColor red =   SkPackARGB32(0xFF, 0xFF, 0, 0);
     const SkPMColor green = SkPackARGB32(0xFF, 0, 0xFF, 0);