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