Make SkMatrix::get*Scale[s]() fail on NaN

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 617 matching lines @@
      * @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);
 
     void dump() const;
     void toString(SkString*) const;
 
     /**
      * 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.
+     * left 2x2. If the max scale factor cannot be computed (for example overflow or perspective)
+     * -1 is returned.
      *
-     * @return minumum scale factor
+     * @return minimum scale factor
      */
     SkScalar getMinScale() const;
 
     /**
      * 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.
+     * left 2x2. If the max scale factor cannot be computed (for example overflow or 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.
+     * is scaleFactors[1]. If the min/max scale factors cannot be computed false is returned and the
+     * values of scaleFactors[] are undefined.
      */
-    bool getMinMaxScales(SkScalar scaleFactors[2]) const;
+    bool SK_WARN_UNUSED_RESULT getMinMaxScales(SkScalar scaleFactors[2]) const;
 
     /**
      *  Attempt to decompose this matrix into a scale-only component and whatever remains, where
      *  the scale component is to be applied first.
      *
      *  M -> Remaining * Scale
      *
      *  On success, return true and assign the scale and remaining components (assuming their
      *  respective parameters are not null). On failure return false and ignore the parameters.
      *
@@ skipping 155 matching lines @@
 
     static void Affine_vpts(const SkMatrix&, SkPoint dst[], const SkPoint[], int);
 
     static const MapPtsProc gMapPtsProcs[];
 
     friend class SkPerspIter;
 };
 SK_END_REQUIRE_DENSE
 
 #endif