SkEncodedOrigin.h

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/*
 * Copyright 2017 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
#ifndef SkEncodedOrigin_DEFINED
#define SkEncodedOrigin_DEFINED
 
#include "include/core/SkMatrix.h"
 
// These values match the orientation www.exif.org/Exif2-2.PDF.
enum SkEncodedOrigin {
    kTopLeft_SkEncodedOrigin     = 1, // Default
    kTopRight_SkEncodedOrigin    = 2, // Reflected across y-axis
    kBottomRight_SkEncodedOrigin = 3, // Rotated 180
    kBottomLeft_SkEncodedOrigin  = 4, // Reflected across x-axis
    kLeftTop_SkEncodedOrigin     = 5, // Reflected across x-axis, Rotated 90 CCW
    kRightTop_SkEncodedOrigin    = 6, // Rotated 90 CW
    kRightBottom_SkEncodedOrigin = 7, // Reflected across x-axis, Rotated 90 CW
    kLeftBottom_SkEncodedOrigin  = 8, // Rotated 90 CCW
    kDefault_SkEncodedOrigin     = kTopLeft_SkEncodedOrigin,
    kLast_SkEncodedOrigin        = kLeftBottom_SkEncodedOrigin,
};
 
/**
 * Given an encoded origin and the width and height of the source data, returns a matrix
 * that transforms the source rectangle with upper left corner at [0, 0] and origin to a correctly
 * oriented destination rectangle of [0, 0, w, h].
 */
static inline SkMatrix SkEncodedOriginToMatrix(SkEncodedOrigin origin, int w, int h) {
    switch (origin) {
        case     kTopLeft_SkEncodedOrigin: return SkMatrix::I();
        case    kTopRight_SkEncodedOrigin: return SkMatrix::MakeAll(-1,  0, w,  0,  1, 0, 0, 0, 1);
        case kBottomRight_SkEncodedOrigin: return SkMatrix::MakeAll(-1,  0, w,  0, -1, h, 0, 0, 1);
        case  kBottomLeft_SkEncodedOrigin: return SkMatrix::MakeAll( 1,  0, 0,  0, -1, h, 0, 0, 1);
        case     kLeftTop_SkEncodedOrigin: return SkMatrix::MakeAll( 0,  1, 0,  1,  0, 0, 0, 0, 1);
        case    kRightTop_SkEncodedOrigin: return SkMatrix::MakeAll( 0, -1, w,  1,  0, 0, 0, 0, 1);
        case kRightBottom_SkEncodedOrigin: return SkMatrix::MakeAll( 0, -1, w, -1,  0, h, 0, 0, 1);
        case  kLeftBottom_SkEncodedOrigin: return SkMatrix::MakeAll( 0,  1, 0, -1,  0, h, 0, 0, 1);
    }
    SK_ABORT("Unexpected origin");
}
 
/**
 * Return true if the encoded origin includes a 90 degree rotation, in which case the width
 * and height of the source data are swapped relative to a correctly oriented destination.
 */
static inline bool SkEncodedOriginSwapsWidthHeight(SkEncodedOrigin origin) {
    return origin >= kLeftTop_SkEncodedOrigin;
}
 
#endif // SkEncodedOrigin_DEFINED