Add function to get both min and max scale factors from matrix

include/core/SkMatrix.h

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkMatrix_DEFINED
@@ skipping 545 matching lines @@
      * @param length Amount of memory available in the buffer
      * @return number of bytes read (must be a multiple of 4) or
      *         0 if there was not enough memory available
      */
     size_t readFromMemory(const void* buffer, size_t length);
 
     SkDEVCODE(void dump() const;)
     SK_TO_STRING_NONVIRT()
 
     /**
-     * Calculates the minimum scaling factor of the matrix. If the matrix has
-     * perspective -1 is returned.
+     * Calculates the minimum scaling factor of the matrix as computed from the SVD of the upper
+     * left 2x2. If the matrix has perspective -1 is returned.
      *
      * @return minumum scale factor
      */
     SkScalar getMinScale() const;
 
     /**
-     * Calculates the maximum scale factor of the matrix. If the matrix has
-     * perspective -1 is returned.
+     * Calculates the maximum scaling factor of the matrix as computed from the SVD of the upper
+     * left 2x2. If the matrix has perspective -1 is returned.
      *
      * @return maximum scale factor
      */
     SkScalar getMaxScale() const;
 
     /**
+     * Gets both the min and max scale factors. The min scale factor is scaleFactors[0] and the max
+     * is scaleFactors[1]. If the matrix has perspective false will be returned and scaleFactors
+     * will be unchanged.
+     */
+    bool getMinMaxScales(SkScalar scaleFactors[2]) const;
+        
+    /**
      *  Return a reference to a const identity matrix
      */
     static const SkMatrix& I();
 
     /**
      *  Return a reference to a const matrix that is "invalid", one that could
      *  never be used.
      */
     static const SkMatrix& InvalidMatrix();
 
@@ skipping 111 matching lines @@
     static void RotTrans_pts(const SkMatrix&, SkPoint dst[], const SkPoint[],
                              int count);
     static void Persp_pts(const SkMatrix&, SkPoint dst[], const SkPoint[], int);
 
     static const MapPtsProc gMapPtsProcs[];
 
     friend class SkPerspIter;
 };
 
 #endif