Disable png encodes from Alpha8, Float16

src/images/SkPNGImageEncoder.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkImageEncoder.h"
 #include "SkColor.h"
 #include "SkColorPriv.h"
@@ skipping 166 matching lines @@
                   SkAlphaType alphaType, int colorType,
                   int bitDepth, SkColorType ct,
                   png_color_8& sig_bit);
 
     typedef SkImageEncoder INHERITED;
 };
 
 bool SkPNGImageEncoder::onEncode(SkWStream* stream,
                                  const SkBitmap& originalBitmap,
                                  int /*quality*/) {
     SkBitmap copy;

[scroggo, 2016/09/12 17:23:29]

It looks like "copy" is no longer used.

[msarett, 2016/09/12 18:03:44]

Removed.

     const SkBitmap* bitmap = &originalBitmap;
     switch (originalBitmap.colorType()) {
         case kIndex_8_SkColorType:
         case kGray_8_SkColorType:
         case kRGBA_8888_SkColorType:
         case kBGRA_8888_SkColorType:
         case kARGB_4444_SkColorType:
         case kRGB_565_SkColorType:
             break;
         default:
-            // TODO(scroggo): support Alpha_8 as Grayscale(black)+Alpha
-            if (originalBitmap.copyTo(&copy, kN32_SkColorType)) {
-                bitmap = ©
-            }
+            return false;
     }
     SkColorType ct = bitmap->colorType();
 
     SkAlphaType alphaType = bitmap->alphaType();
     switch (alphaType) {
         case kUnpremul_SkAlphaType:
             if (kARGB_4444_SkColorType == ct) {
                 return false;
             }
 
@@ skipping 149 matching lines @@
 
 ///////////////////////////////////////////////////////////////////////////////
 DEFINE_ENCODER_CREATOR(PNGImageEncoder);
 ///////////////////////////////////////////////////////////////////////////////
 
 SkImageEncoder* sk_libpng_efactory(SkImageEncoder::Type t) {
     return (SkImageEncoder::kPNG_Type == t) ? new SkPNGImageEncoder : nullptr;
 }
 
 static SkImageEncoder_EncodeReg gEReg(sk_libpng_efactory);