Adding premul and 565 swizzles for bmp:

src/codec/SkCodec_libpng.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCodec_libpng.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 329 matching lines @@
     , fInfo_ptr(info_ptr) {}
 
 SkPngCodec::~SkPngCodec() {
     png_destroy_read_struct(&fPng_ptr, &fInfo_ptr, png_infopp_NULL);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // Getting the pixels
 ///////////////////////////////////////////////////////////////////////////////
 
-static bool conversion_possible(const SkImageInfo& A, const SkImageInfo& B) {
+static bool conversion_possible(const SkImageInfo& dst, const SkImageInfo& src) {
     // TODO: Support other conversions
-    if (A.colorType() != B.colorType()) {
+    if (dst.colorType() != src.colorType()) {
         return false;
     }
-    if (A.profileType() != B.profileType()) {
+    if (dst.profileType() != src.profileType()) {

[scroggo, 2015/03/18 13:33:20]

BMP doesn't make this check, but it should. (I'm guessing all of BMP will be
linear?)

[msarett, 2015/03/18 14:09:12]

Done.

         return false;
     }
-    if (A.alphaType() == B.alphaType()) {
+    if (dst.alphaType() == src.alphaType()) {
         return true;
     }
-    return premul_and_unpremul(A.alphaType(), B.alphaType())
-            || premul_and_unpremul(B.alphaType(), A.alphaType());
+    return kPremul_SkAlphaType == dst.alphaType() &&
+            kUnpremul_SkAlphaType == src.alphaType();
 }
 
 SkCodec::Result SkPngCodec::onGetPixels(const SkImageInfo& requestedInfo, void* dst,
                                         size_t rowBytes, const Options& options,
                                         SkPMColor ctable[], int* ctableCount) {
     if (!this->rewindIfNeeded()) {
         return kCouldNotRewind;
     }
     if (requestedInfo.dimensions() != this->getOriginalInfo().dimensions()) {
         return kInvalidScale;
@@ skipping 107 matching lines @@
 
     // FIXME: do we need substituteTranspColor?
 
     if (reallyHasAlpha && requestedInfo.alphaType() != kOpaque_SkAlphaType) {
         // FIXME: We want to alert the caller. Is this the right way?
         SkImageInfo* modInfo = const_cast<SkImageInfo*>(&requestedInfo);
         *modInfo = requestedInfo.makeAlphaType(kOpaque_SkAlphaType);
     }
     return kSuccess;
 }