store SkAlphaType inside SkBitmap, on road to support unpremul

src/images/SkImageDecoder.cpp

Index: src/images/SkImageDecoder.cpp
diff --git a/src/images/SkImageDecoder.cpp b/src/images/SkImageDecoder.cpp
index 15cd1a60c0dd6dc27bf517f0a85d9453e5301e70..6787a5f80aad402f8a1c332bdb2f94b636323605 100644
--- a/src/images/SkImageDecoder.cpp
+++ b/src/images/SkImageDecoder.cpp
@@ -245,8 +245,8 @@ bool SkImageDecoder::cropBitmap(SkBitmap *dst, SkBitmap *src, int sampleSize,
     }
     // if the destination has no pixels then we must allocate them.
     if (dst->isNull()) {
-        dst->setConfig(src->getConfig(), w, h);
-        dst->setIsOpaque(src->isOpaque());
+        dst->setConfig(src->getConfig(), w, h, 0, src->isOpaque() ?

[scroggo, 2013/10/18 19:32:40]

src->alphaType()

+                       kOpaque_SkAlphaType : kPremul_SkAlphaType);
 
         if (!this->allocPixelRef(dst, NULL)) {
             SkDEBUGF(("failed to allocate pixels needed to crop the bitmap"));