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 561 matching lines @@
 
     /**
      * Calculates the maximum scale factor of the matrix. 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 -1 will be returned and scaleFactors will

[reed1, 2014/05/20 15:17:55]

-1 --> false

[bsalomon, 2014/05/20 15:32:42]

Done.

+     * be unchanged.
+     */
+    bool getScaleFactors(SkScalar scaleFactors[2]) const;

[reed1, 2014/05/20 15:17:55]

1. do we need this entrypoint and the other two?
2. getMinMaxScaleFactors() ?

[bsalomon, 2014/05/20 15:32:42]

Most call sites only require 1 of the 2 and computing both can add an extra
branch and sqrt.
changed to getMinMaxScales() (to be consistent with getMinScale(),
getMaxScale())

+        
+    /**
      *  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