text: /*
   * Copyright 2013 Google Inc.
   *
   * Use of this source code is governed by a BSD-style license that can be
   * found in the LICENSE file.
   */
  
  #ifndef SkMatrixUtils_DEFINED
  #define SkMatrixUtils_DEFINED
  
  #include "SkMatrix.h"
  
  /**
   *  Number of subpixel bits used in skia's bilerp.
   *  See SkBitmapProcState_procs.h and SkBitmapProcState_filter.h
   */
  #define kSkSubPixelBitsForBilerp   4
  
  /**
   *  Given a matrix and width/height, return true if the computed dst-rect would
   *  align such that there is a 1-to-1 coorspondence between src and dst pixels.
   *  This can be called by drawing code to see if drawBitmap can be turned into
   *  drawSprite (which is faster).
   *
   *  The src-rect is defined to be { 0, 0, width, height }
   *
   *  The "closeness" test is based on the subpixelBits parameter. Pass 0 for
   *  round-to-nearest behavior (e.g. nearest neighbor sampling). Pass the number
   *  of subpixel-bits to simulate filtering.
   */
  bool SkTreatAsSprite(const SkMatrix&, int width, int height,
                       unsigned subpixelBits);
  
  /**
   *  Calls SkTreatAsSprite() with default subpixelBits value to match Skia's
   *  filter-bitmap implementation (i.e. kSkSubPixelBitsForBilerp).
   */
  static inline bool SkTreatAsSpriteFilter(const SkMatrix& matrix,
                                           int width, int height) {
      return SkTreatAsSprite(matrix, width, height, kSkSubPixelBitsForBilerp);
  }
  
  /** Decomposes the upper-left 2x2 of the matrix into a rotation (represented by
      the cosine and sine of the rotation angle), followed by a non-uniform scale,
      followed by another rotation. If there is a reflection, one of the scale
      factors will be negative.
      Returns true if successful. Returns false if the matrix is degenerate.
      */
  bool SkDecomposeUpper2x2(const SkMatrix& matrix,
                           SkPoint* rotation1,
                           SkPoint* scale,
                           SkPoint* rotation2);
  
  #endif
  