Simplify flattening to just write enough to call the factory

src/effects/SkDropShadowImageFilter.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkDropShadowImageFilter.h"
 
 #include "SkBitmap.h"
 #include "SkBlurImageFilter.h"
 #include "SkCanvas.h"
 #include "SkColorMatrixFilter.h"
 #include "SkDevice.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 
 SkDropShadowImageFilter::SkDropShadowImageFilter(SkScalar dx, SkScalar dy,
                                                  SkScalar sigmaX, SkScalar sigmaY, SkColor color,
                                                  SkImageFilter* input, const CropRect* cropRect)
     : INHERITED(1, &input, cropRect)
     , fDx(dx)
     , fDy(dy)
     , fSigmaX(sigmaX)
     , fSigmaY(sigmaY)
     , fColor(color)
 {
 }
 
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
 SkDropShadowImageFilter::SkDropShadowImageFilter(SkReadBuffer& buffer)
  : INHERITED(1, buffer) {
     fDx = buffer.readScalar();
     fDy = buffer.readScalar();
     fSigmaX = buffer.readScalar();
     fSigmaY = buffer.readScalar();
     fColor = buffer.readColor();
     buffer.validate(SkScalarIsFinite(fDx) &&
                     SkScalarIsFinite(fDy) &&
                     SkScalarIsFinite(fSigmaX) &&
                     SkScalarIsFinite(fSigmaY));
 }
+#endif
 
-void SkDropShadowImageFilter::flatten(SkWriteBuffer& buffer) const
-{
+SkFlattenable* SkDropShadowImageFilter::CreateProc(SkReadBuffer& buffer) {
+    SK_IMAGEFILTER_UNFLATTEN_COMMON(1);
+    SkScalar dx = buffer.readScalar();
+    SkScalar dy = buffer.readScalar();
+    SkScalar sigmaX = buffer.readScalar();
+    SkScalar sigmaY = buffer.readScalar();
+    SkColor color = buffer.readColor();
+    return Create(dx, dy, sigmaX, sigmaY, color);
+}
+
+void SkDropShadowImageFilter::flatten(SkWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
     buffer.writeScalar(fDx);
     buffer.writeScalar(fDy);
     buffer.writeScalar(fSigmaX);
     buffer.writeScalar(fSigmaY);
     buffer.writeColor(fColor);
 }
 
 bool SkDropShadowImageFilter::onFilterImage(Proxy* proxy, const SkBitmap& source,
                                             const Context& ctx,
@@ skipping 63 matching lines @@
     bounds.offset(-SkScalarCeilToInt(offsetVec.x()),
                   -SkScalarCeilToInt(offsetVec.y()));
     SkVector sigma = SkVector::Make(fSigmaX, fSigmaY);
     ctm.mapVectors(&sigma, 1);
     bounds.outset(SkScalarCeilToInt(SkScalarMul(sigma.x(), SkIntToScalar(3))),
                   SkScalarCeilToInt(SkScalarMul(sigma.y(), SkIntToScalar(3))));
     bounds.join(src);
     *dst = bounds;
     return true;
 }