Add rowBytesAsPixels and shiftPerPixel to SkPixmap

include/core/SkPixmap.h

Index: include/core/SkPixmap.h
diff --git a/include/core/SkPixmap.h b/include/core/SkPixmap.h
index 3a7abdf13451f712f4e47f10a81d44c713d4f8ce..5f90273a97dacfba6217e820217546c78d8b73a8 100644
--- a/include/core/SkPixmap.h
+++ b/include/core/SkPixmap.h
@@ -71,6 +71,17 @@ public:
 
     SkIRect bounds() const { return SkIRect::MakeWH(this->width(), this->height()); }
 
+    /**
+     *  Return the rowbytes expressed as a number of pixels (like width and height).
+     */
+    int rowBytesAsPixels() const { return int(fRowBytes >> this->shiftPerPixel()); }
+
+    /**
+     *  Return the shift amount per pixel (i.e. 0 for 1-byte per pixel, 1 for 2-bytes per pixel
+     *  colortypes, 2 for 4-bytes per pixel colortypes). Return 0 for kUnknown_SkColorType.
+     */
+    int shiftPerPixel() const { return fInfo.bytesPerPixel() >> 1; }
+
     uint64_t getSize64() const { return sk_64_mul(fInfo.height(), fRowBytes); }
     uint64_t getSafeSize64() const { return fInfo.getSafeSize64(fRowBytes); }
     size_t getSafeSize() const { return fInfo.getSafeSize(fRowBytes); }