1 /* 2 * Copyright 2013 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef SkMatrixUtils_DEFINED 9 #define SkMatrixUtils_DEFINED 10 11 #include "SkMatrix.h" 12 13 /** 14 * Number of subpixel bits used in skia's bilerp. 15 * See SkBitmapProcState_procs.h and SkBitmapProcState_filter.h 16 */ 17 #define kSkSubPixelBitsForBilerp 4 18 19 /** 20 * Given a matrix and width/height, return true if the computed dst-rect would 21 * align such that there is a 1-to-1 coorspondence between src and dst pixels. 22 * This can be called by drawing code to see if drawBitmap can be turned into 23 * drawSprite (which is faster). 24 * 25 * The src-rect is defined to be { 0, 0, width, height } 26 * 27 * The "closeness" test is based on the subpixelBits parameter. Pass 0 for 28 * round-to-nearest behavior (e.g. nearest neighbor sampling). Pass the number 29 * of subpixel-bits to simulate filtering. 30 */ 31 bool SkTreatAsSprite(const SkMatrix&, int width, int height, 32 unsigned subpixelBits); 33 34 /** 35 * Calls SkTreatAsSprite() with default subpixelBits value to match Skia's 36 * filter-bitmap implementation (i.e. kSkSubPixelBitsForBilerp). 37 */ 38 static inline bool SkTreatAsSpriteFilter(const SkMatrix& matrix, 39 int width, int height) { 40 return SkTreatAsSprite(matrix, width, height, kSkSubPixelBitsForBilerp); 41 } 42 43 /** Decomposes the upper-left 2x2 of the matrix into a rotation (represented by 44 the cosine and sine of the rotation angle), followed by a non-uniform scale, 45 followed by another rotation. If there is a reflection, one of the scale 46 factors will be negative. 47 Returns true if successful. Returns false if the matrix is degenerate. 48 */ 49 bool SkDecomposeUpper2x2(const SkMatrix& matrix, 50 SkPoint* rotation1, 51 SkPoint* scale, 52 SkPoint* rotation2); 53 54 #endif 55
