SkPixelSerializer: support indexed pixels

By taking a SkPixmap, SkPixelSerializer::encode() can now handle colortables.

Review URL: https://codereview.chromium.org/1501303002

include/core/SkImage.h

@@ -267,7 +267,7 @@ public:
      *  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
+     *  (useEncodedData) and for encoding the image (encode) 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

include/core/SkPixelSerializer.h

@@ -9,9 +9,9 @@
 #define SkPixelSerializer_DEFINED
 
 #include "SkRefCnt.h"
+#include "SkPixmap.h"
 
 class SkData;
-struct SkImageInfo;
 
 /**
  *  Interface for serializing pixels, e.g. SkBitmaps in an SkPicture.
@@ -32,8 +32,10 @@ public:
      *  Call to get the client's version of encoding these pixels. If it
      *  returns NULL, serialize the raw pixels.
      */
-    SkData* encodePixels(const SkImageInfo& info, const void* pixels, size_t rowBytes) {
-        return this->onEncodePixels(info, pixels, rowBytes);
+    SkData* encode(const SkPixmap& pixmap) {
+        SkData* data = this->onEncode(pixmap);
+        return data ? data : this->onEncodePixels(
+                pixmap.info(), pixmap.addr(), pixmap.rowBytes());
     }
 
 protected:
@@ -47,6 +49,15 @@ protected:
      *  If you want to encode these pixels, return the encoded data as an SkData
      *  Return null if you want to serialize the raw pixels.
      */
-    virtual SkData* onEncodePixels(const SkImageInfo&, const void* pixels, size_t rowBytes) = 0;
+    // NOTE: onEncodePixels() is deprecated and removed in a later CL.
+    // Subclasses should implement onEncode() instead.  Subclasses
+    // should implement at least one of onEncodePixels() or
+    // onUseEncodedData().
+    virtual SkData* onEncodePixels(const SkImageInfo&,
+                                   const void* /*pixels*/,
+                                   size_t /*rowBytes*/) {
+        return nullptr;
+    }
+    virtual SkData* onEncode(const SkPixmap&) { return nullptr; }
 };
 #endif // SkPixelSerializer_DEFINED

src/core/SkWriteBuffer.cpp

@@ -200,11 +200,8 @@ void SkWriteBuffer::writeBitmap(const SkBitmap& bitmap) {
         // see if the caller wants to manually encode
         SkAutoPixmapUnlock result;
         if (fPixelSerializer && bitmap.requestLock(&result)) {
-            const SkPixmap& pmap = result.pixmap();
             SkASSERT(nullptr == fBitmapHeap);
-            SkAutoDataUnref data(fPixelSerializer->encodePixels(pmap.info(),
-                                                                pmap.addr(),
-                                                                pmap.rowBytes()));
+            SkAutoDataUnref data(fPixelSerializer->encode(result.pixmap()));
             if (data.get() != nullptr) {
                 // if we have to "encode" the bitmap, then we assume there is no
                 // offset to share, since we are effectively creating a new pixelref

src/image/SkImage.cpp

@@ -185,9 +185,16 @@ 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);
+    SkData* onEncode(const SkPixmap& pixmap) override {
+        SkBitmap bm;
+        if (!bm.installPixels(pixmap.info(),
+                              const_cast<void*>(pixmap.addr()),
+                              pixmap.rowBytes(),
+                              pixmap.ctable(),
+                              nullptr, nullptr)) {
+            return nullptr;
+        }
+        return SkImageEncoder::EncodeData(bm, SkImageEncoder::kPNG_Type, 100);
     }
 };
 
@@ -205,8 +212,7 @@ SkData* SkImage::encode(SkPixelSerializer* serializer) const {
     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 effectiveSerializer->encode(apu.pixmap());
     }
 
     return nullptr;