Expand pixelref to return SkImageInfo and rowbytes

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
 
@@ skipping 45 matching lines @@
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 /**
  *  Describes how to interpret the components of a pixel.
  */
 enum SkColorType {
     kAlpha_8_SkColorType,
     kRGB_565_SkColorType,
+    kARGB_4444_SkColorType,
     kRGBA_8888_SkColorType,
     kBGRA_8888_SkColorType,
     kIndex8_SkColorType,
 
     kLastEnum_SkColorType = kIndex8_SkColorType,
 
 #if SK_PMCOLOR_BYTE_ORDER(B,G,R,A)
     kPMColor_SkColorType = kBGRA_8888_SkColorType
 #elif SK_PMCOLOR_BYTE_ORDER(R,G,B,A)
     kPMColor_SkColorType = kRGBA_8888_SkColorType
 #else
 #error "SK_*32_SHFIT values must correspond to BGRA or RGBA byte order"
 #endif
 };
 
 static int SkColorTypeBytesPerPixel(SkColorType ct) {
     static const uint8_t gSize[] = {
         1,  // Alpha_8
         2,  // RGB_565
+        2,  // ARGB_4444
         4,  // RGBA_8888
         4,  // BGRA_8888
         1,  // kIndex_8
     };
     SK_COMPILE_ASSERT(SK_ARRAY_COUNT(gSize) == (size_t)(kLastEnum_SkColorType + 1),
                       size_mismatch_with_SkColorType_enum);
 
     SkASSERT((size_t)ct < SK_ARRAY_COUNT(gSize));
     return gSize[ct];
 }
@@ skipping 10 matching lines @@
     SkAlphaType fAlphaType;
 
     bool isOpaque() const {
         return SkAlphaTypeIsOpaque(fAlphaType);
     }
 
     int bytesPerPixel() const {
         return SkColorTypeBytesPerPixel(fColorType);
     }
 
+    size_t minRowBytes() const {
+        return fWidth * this->bytesPerPixel();
+    }
+
     bool operator==(const SkImageInfo& other) const {
         return 0 == memcmp(this, &other, sizeof(other));
     }
     bool operator!=(const SkImageInfo& other) const {
         return 0 != memcmp(this, &other, sizeof(other));
     }
+
+    bool isValid() const {
+        return  fWidth >= 0 &&
+                fHeight >= 0 &&
+                fColorType <= kLastEnum_SkColorType &&
+                fAlphaType <= kLastEnum_SkAlphaType;
+    }
+
+    void validate() const {
+        SkASSERT(this->isValid());
+    }
 };
 
 #endif