make info real in SkPixelRef, and add bitmap::asImageInfo

src/image/SkImagePriv.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImagePriv_DEFINED
 #define SkImagePriv_DEFINED
 
 #include "SkBitmap.h"
 #include "SkImage.h"
 
 class SkPicture;
 
 extern SkBitmap::Config SkImageInfoToBitmapConfig(const SkImageInfo&);
 
-extern int SkImageBytesPerPixel(SkColorType);
-
-extern bool SkBitmapToImageInfo(const SkBitmap&, SkImageInfo*);
-
 // Call this if you explicitly want to use/share this pixelRef in the image
 extern SkImage* SkNewImageFromPixelRef(const SkImageInfo&, SkPixelRef*,
                                        size_t rowBytes);
 
 /**
  *  Examines the bitmap to decide if it can share the existing pixelRef, or
  *  if it needs to make a deep-copy of the pixels. The bitmap's pixelref will
  *  be shared if either the bitmap is marked as immutable, or canSharePixelRef
  *  is true.
  *
  *  If the bitmap's config cannot be converted into a corresponding
  *  SkImageInfo, or the bitmap's pixels cannot be accessed, this will return
  *  NULL.
  */
 extern SkImage* SkNewImageFromBitmap(const SkBitmap&, bool canSharePixelRef);
 
 extern void SkImagePrivDrawPicture(SkCanvas*, SkPicture*,
                                    SkScalar x, SkScalar y, const SkPaint*);
 
 extern void SkImagePrivDrawPicture(SkCanvas*, SkPicture*,
                                    const SkRect*, const SkRect&, const SkPaint*);
 
 /**
  *  Return an SkImage whose contents are those of the specified picture. Note:
  *  The picture itself is unmodified, and may continue to be used for recording
  */
 extern SkImage* SkNewImageFromPicture(const SkPicture*);
 
 static inline size_t SkImageMinRowBytes(const SkImageInfo& info) {
-    size_t rb = info.fWidth * SkImageBytesPerPixel(info.fColorType);
-    return SkAlign4(rb);
+    return SkAlign4(info.minRowBytes());

[scroggo, 2013/12/09 21:33:41]

Why is this function different (from minRowBytes()) that it needs to be 4 byte
aligned? Can you document that difference?

[reed1, 2013/12/09 21:46:14]

Don't know. I was just keeping the old behavior.

 }
 
 // Given an image created from SkNewImageFromBitmap, return its pixelref. This
 // may be called to see if the surface and the image share the same pixelref,
 // in which case the surface may need to perform a copy-on-write.
 extern SkPixelRef* SkBitmapImageGetPixelRef(SkImage* rasterImage);
 
 // Given an image created with NewPicture, return its SkPicture.
 extern SkPicture* SkPictureImageGetPicture(SkImage* pictureImage);
 
 // Given an image created with NewTexture, return its GrTexture. This
 // may be called to see if the surface and the image share the same GrTexture,
 // in which case the surface may need to perform a copy-on-write.
 extern GrTexture* SkTextureImageGetTexture(SkImage* textureImage);
 
 // Update the texture wrapped by an image created with NewTexture. This
 // is called when a surface and image share the same GrTexture and the
 // surface needs to perform a copy-on-write
 extern void SkTextureImageSetTexture(SkImage* image, GrTexture* texture);
 
 #endif