Revert of replace kIgnore_SkAlphaType with kUnknown_SkAlphaType

include/core/SkImageInfo.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImageInfo_DEFINED
 #define SkImageInfo_DEFINED
 
 #include "SkMath.h"
 #include "SkRect.h"
 #include "SkSize.h"
 
 class SkReadBuffer;
 class SkWriteBuffer;
 
 /**
  *  Describes how to interpret the alpha compoent of a pixel.
  */
 enum SkAlphaType {
-    kUnknown_SkAlphaType,
+    /**
+     *  All pixels should be treated as opaque, regardless of the value stored
+     *  in their alpha field. Used for legacy images that wrote 0 or garbarge
+     *  in their alpha field, but intended the RGB to be treated as opaque.
+     */
+    kIgnore_SkAlphaType,
 
     /**
      *  All pixels are stored as opaque. This differs slightly from kIgnore in
      *  that kOpaque has correct "opaque" values stored in the pixels, while
      *  kIgnore may not, but in both cases the caller should treat the pixels
      *  as opaque.
      */
     kOpaque_SkAlphaType,
 
     /**
      *  All pixels have their alpha premultiplied in their color components.
      *  This is the natural format for the rendering target pixels.
      */
     kPremul_SkAlphaType,
 
     /**
      *  All pixels have their color components stored without any regard to the
      *  alpha. e.g. this is the default configuration for PNG images.
      *
      *  This alpha-type is ONLY supported for input images. Rendering cannot
      *  generate this on output.
      */
     kUnpremul_SkAlphaType,
 
     kLastEnum_SkAlphaType = kUnpremul_SkAlphaType
 };
 
 static inline bool SkAlphaTypeIsOpaque(SkAlphaType at) {
-    return kOpaque_SkAlphaType == at;
+    SK_COMPILE_ASSERT(kIgnore_SkAlphaType < kOpaque_SkAlphaType, bad_alphatype_order);
+    SK_COMPILE_ASSERT(kPremul_SkAlphaType > kOpaque_SkAlphaType, bad_alphatype_order);
+    SK_COMPILE_ASSERT(kUnpremul_SkAlphaType > kOpaque_SkAlphaType, bad_alphatype_order);
+
+    return (unsigned)at <= kOpaque_SkAlphaType;
 }
 
 static inline bool SkAlphaTypeIsValid(unsigned value) {
     return value <= kLastEnum_SkAlphaType;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 /**
  *  Describes how to interpret the components of a pixel.
@@ skipping 83 matching lines @@
 /**
  *  Describe an image's dimensions and pixel type.
  *  Used for both src images and render-targets (surfaces).
  */
 struct SK_API SkImageInfo {
 public:
     SkImageInfo()
         : fWidth(0)
         , fHeight(0)
         , fColorType(kUnknown_SkColorType)
-        , fAlphaType(kUnknown_SkAlphaType)
+        , fAlphaType(kIgnore_SkAlphaType)
         , fProfileType(kLinear_SkColorProfileType)
     {}
 
     static SkImageInfo Make(int width, int height, SkColorType ct, SkAlphaType at,
                             SkColorProfileType pt = kLinear_SkColorProfileType) {
         return SkImageInfo(width, height, ct, at, pt);
     }
 
     /**
      *  Sets colortype to the native ARGB32 type.
@@ skipping 18 matching lines @@
                                      SkColorProfileType pt = kLinear_SkColorProfileType) {
         return MakeN32Premul(size.width(), size.height(), pt);
     }
 
     static SkImageInfo MakeA8(int width, int height) {
         return SkImageInfo(width, height, kAlpha_8_SkColorType, kPremul_SkAlphaType,
                            kLinear_SkColorProfileType);
     }
 
     static SkImageInfo MakeUnknown(int width, int height) {
-        return SkImageInfo(width, height, kUnknown_SkColorType, kUnknown_SkAlphaType,
+        return SkImageInfo(width, height, kUnknown_SkColorType, kIgnore_SkAlphaType,
                            kLinear_SkColorProfileType);
     }
 
     static SkImageInfo MakeUnknown() {
         return SkImageInfo();
     }
 
     int width() const { return fWidth; }
     int height() const { return fHeight; }
     SkColorType colorType() const { return fColorType; }
@@ skipping 84 matching lines @@
         , fHeight(height)
         , fColorType(ct)
         , fAlphaType(at)
         , fProfileType(pt)
     {}
 
     SkColorProfileType  fProfileType;
 };
 
 #endif