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/*
* 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
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