Expand pixelref to return SkImageInfo and rowbytes

include/core/SkMallocPixelRef.h

Index: include/core/SkMallocPixelRef.h
diff --git a/include/core/SkMallocPixelRef.h b/include/core/SkMallocPixelRef.h
index 100a15d90abb4ca55b30aa9af47e5ce17f18fa67..90be8c2e183c4ae75a19ea3207bcf45985c17e0b 100644
--- a/include/core/SkMallocPixelRef.h
+++ b/include/core/SkMallocPixelRef.h
@@ -17,33 +17,60 @@
 */
 class SkMallocPixelRef : public SkPixelRef {
 public:
-    /** Allocate the specified buffer for pixels. The memory is freed when the
-        last owner of this pixelref is gone. If addr is NULL, sk_malloc_throw()
-        is called to allocate it.
+    /**
+     *  Return a new SkMallocPixelRef with the provided pixel storage, rowBytes,
+     *  and optional colortable. The caller is responsible for managing the
+     *  lifetime of the pixel storage buffer, as the pixelref will not try
+     *  to delete the storage.
+     *
+     *  This pixelref will ref() the specified colortable (if not NULL).
+     *
+     *  Returns NULL on failure.
      */
-    SkMallocPixelRef(void* addr, size_t size, SkColorTable* ctable, bool ownPixels = true);
-    virtual ~SkMallocPixelRef();
+    static SkMallocPixelRef* NewDirect(const SkImageInfo&, void* addr,
+                                       size_t rowBytes, SkColorTable*);
+
+    /**
+     *  Return a new SkMallocPixelRef, automatically allocating storage for the
+     *  pixels. If rowBytes are 0, an optimal value will be chosen automatically.
+     *  If rowBytes is > 0, then it will be respected, or NULL will be returned
+     *  if rowBytes is invalid for the specified info.
+     *
+     *  This pixelref will ref() the specified colortable (if not NULL).
+     *
+     *  Returns NULL on failure.
+     */
+    static SkMallocPixelRef* NewAllocate(const SkImageInfo& info,
+                                         size_t rowBytes, SkColorTable*);
 
     void* getAddr() const { return fStorage; }
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkMallocPixelRef)
 
 protected:
-    // overrides from SkPixelRef
-    virtual void* onLockPixels(SkColorTable**);
-    virtual void onUnlockPixels();
-
-    SkMallocPixelRef(SkFlattenableReadBuffer& buffer);
+    virtual bool onNewLockPixels(LockRec*) SK_OVERRIDE;
+    virtual void onUnlockPixels() SK_OVERRIDE;
     virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE;
+    virtual size_t getAllocatedSizeInBytes() const SK_OVERRIDE;

[scroggo, 2013/12/06 14:50:33]

I don't like that this returns something that may or may not be the same as what
was actually allocated. For NewDirect, we don't actually know what the allocated
size is (or maybe it's zero, since we allocated nothing?) but for NewAllocate
this returns a totally different number.

[reed1, 2013/12/06 15:48:46]

I agree. This virtual was not added as part of this CL. I think it should be
renamed to something about safeSize. Something to do outside of this CL I think.

[scroggo, 2013/12/06 15:55:20]

Haha - the danger of looking at the changes since the last patch is that I think
you added it.

 
-    // Returns the allocation size for the pixels
-    virtual size_t getAllocatedSizeInBytes() const SK_OVERRIDE { return fSize; }
+    SkMallocPixelRef(SkFlattenableReadBuffer& buffer);
+    SkMallocPixelRef(const SkImageInfo&, void* addr, size_t rb, SkColorTable*,
+                     bool ownsPixels);
+    virtual ~SkMallocPixelRef();
 
 private:
-    void*           fStorage;
-    size_t          fSize;
-    SkColorTable*   fCTable;
-    bool            fOwnPixels;
+    void*               fStorage;
+    SkColorTable*       fCTable;
+    size_t              fRB;
+    const bool          fOwnPixels;
+
+    size_t computeMinSize() const {

[scroggo, 2013/12/06 14:50:33]

Is this function needed?

[reed1, 2013/12/06 15:48:46]

It is called twice, but I may be able to call the new method on SkImageInfo
instead.

+        const SkImageInfo& info = this->info();
+        if (info.fHeight == 0) {
+            return 0;
+        }
+        return (info.fHeight - 1) * fRB + info.minRowBytes();
+    }
 
     typedef SkPixelRef INHERITED;
 };